Speedy Mlss Development From Cow Dung, Wastewater Treatment and Sludge Recovery From the Activated Sludge Process (a-b Process) of a Paper Mill That Use Waste Paper as Raw Material - A Case Study

Speedy Mlss Development From Cow Dung, Wastewater Treatment and Sludge Recovery From the Activated Sludge Process (a-b Process) of a Paper Mill That Use Waste Paper as Raw Material - A Case Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Speedy Mlss Development From Cow Dung, Wastewater Treatment and Sludge Recovery From the Activated Sludge Process (a-b Process) of a Paper Mill That Use Waste Paper as Raw Material - A Case Study Kochu Thresya Sojan, Grasius Mattamana Geevarghese This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3006713/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract In this case study, process startup and operation of the Effluent Treatment plant of a paper mill that converts waste paper to paper and paper boards were investigated for 120 days. To meet water requirements for a revised production target of 100 t/d, apart from recycling 1000 m 3 /d of wastewater after DAF process, required additional facilities to provide secondary treatment for another 1000 m 3 /d of wastewater in ASP (A-B process) were provided. A new ASP (A) with an AT of 900 m 3 was arranged to work in line with the existing ASP (B) of 1200 m 3 capacity. Initiating culture development, 19.6 tons of fresh cow dung (seed) was added to AT of unit B containing 600 m 3 of fresh ground water and the tank content was aerated. N, P, micronutrients and protein were added to AT every day. Good flocs were observed on 9th day of operation. MLSS of 1500 mg/l and a sludge volume 50 ml/l was observed on 27th day of aeration. Addition of appropriate nutrients and protein are believed to have aided sludge development and floc formation. During secondary startup, wastewater addition started (108 m 3 /d) on a regular basis on 27th day and was increased stepwise to 388 m 3 /d in 7 days and was continued till the end of this phase of the study. During 33 days of secondary startup influent BOD was in the range of 1170–1500 mg/l, organic loading ranged from 0.13 to 0.46 kg BOD/m 3 .d and F/M ratio ranged between 0.07 to 0.17 kg BOD/kg MLSS/d. BOD/N/P ratio of 200/5/1.5 was maintained along with addition of micronutrients and protein. On 60th day, MLSS was 6050 mg/l indicating that culture developed from cow dung got acclimatized easily to paper mill waste mostly containing cellulose. Initiating the next phase, required quantity of sludge was transferred from B to A to get an MLSS of 2800 mg/l in A and of 4200 mg/l in B. The wastewater flow of 388 m 3 /d, then flowing to B, was made to flow in the A-B process by providing stepwise increase to A, correspondingly reducing direct flow to B in 43 days. On 104th day, the MLSS rose to 11400 mg/l in A. During these 43 days of operation, unit A stabilized a total BOD of 6870 kg, and the volatile content of the sludge yielded was 4644 kg resulting in a yield coefficient, Y of 0.68. Organic loading ranged from 0.35 to 1.09 kgCOD/m 3 .d and F/M ranged between 0.04 to 0.12 kg COD/kg MLSS.d. Effluent COD ranged from 500 − 63 mg/l for an average inlet COD of 1940 mg/l. There after MLSS in A was reduced to 3600 mg/l in 4 days by harvesting sludge and the same was recycled to the pulping section of the mill. Flow was increased to 488 m 3 /d stepwise and the MLSS increased to 7800 mg/l in next 12 days in A. Effluent COD of A ranged from 550 − 258 mg/l and COD of the final effluent, that is, of unit B ranged from 98–105 mg/l. The production seized in the paper mill due to Covid 19 and hence this study was terminated at this stage. DAF ASP AT A-B Process MLSS SV SVI F/M Figures Figure 1 Figure 2 Figure 3 Figure 4 1. INTRODUCTION Paper Industry, one of the important industrial sector of any developing country, mainly relies on forest based raw material like bamboo, wood, etc. Thanks to the present-day environmental consciousness, large scale use of non-wood pulp based raw material came into existence, since the availability of raw material from forest has dwindled. In this case study, the paper mill uses recycled cellulose fibre as their raw material for the manufacturing of Kraft paper. Kraft paper is the leading paper type used for wrapping heavy bundles after corrugation. It is used in many types of packaging and is an important packaging material. Kraft papers or brown papers are strong and flexible (entrepreneurindia.co). The manufacturing of kraft paper consumes large amount of fresh water and hence is a major source of wastewater. The wastewater from the Kraft paper mill contains variety of organic and inorganic contaminants. The wastewater has high COD, TSS and TDS. The treated wastewater can be recycled for reuse in the pulp and paper industry, if the required quality could be achieved, or it can be released to the environment if its quality meets the environmental standards (Omid Ashraf, Laleh Yerushalami & Fariborz Haghighat 2015). The treatment of wastewater can either be done using physico-chemical process which produces large quantity of sludge thereby causing, disposal a further issue, or be done using biological process which results in the ultimate treatment by converting organic matter to CO 2 (Rao & Dhatta 1979). The wastewater is considered to be amenable for biological treatment without acclimatization, if the COD/BOD ratio is 0.6 or above. Many paper industries go for Activated Sludge Process (ASP) after possible cellulose recovery (DAF) and physico-chemical process (Metcalf and Eddy 2004). If the COD/BOD ratio is between 0.3 and 0.6, the wastewater needs acclimatization for biological treatment. If the COD/BOD ratio is less than 0.3, other methods are suggested for treatment (Rao & Dhatta 1979). In the case studied, the Kraft paper mill was using biological process for the wastewater treatment but the COD/BOD ratio was found to be mostly below 0.3 in analysis done many times previously in this paper mill. Moreover, the wastewater from the Kraft paper mill is known to be deficient in nutrients and micronutrients as raw material (waste paper) mainly contain only cellulose. The main challenge in employing ASP in this case study was the development of active biological sludge acclimatized to the cellulose waste. Secondly, the fluctuations in characteristics of wastewater affects the biological sludge microstructure caused by the development of filamentous organisms and non-flocculating organisms leading to poor settleability of sludge, thereby resulting in poor quality effluent. These issues are believed to be solved to a greater extent by employing A-B Process (Gray 1990 ) for such types of wastewaters. 2. A-B PROCESS Figure 1 shows the A-B Process. The process comprises two ASP units in series. A-Stage can receive high BOD loading (3–6 kg BOD/kg MLSS/d) and B-Stage receives normal BOD loading (0.15–0.3 kg BOD/kg MLSS/d). Effluent after preliminary treatment is first treated in A-stage. A-stage effluent is further treated in B-stage. A-stage effectively buffers the B-stage from variations in flow rate and influent quality parameters. This makes B-stage very stable, resulting in excellent quality effluent (Gray, 1990 ). This A-B process is employed in the present study. 3. OBJECTIVE In order to provide biological treatment for 1000 m 3 /d of the kraft paper mill effluent, the paper mill had provided an additional ASP unit (Unit A) consisting of an AT of volume 900 m 3 and an SST of required size. This unit, A, was desired to operate in series with then existing unit (Unit B), thus implementing a two stage Activated Sludge System (A-B Process). The main objectives of this case study were to: Develop active biological aerobic sludge using cow dung as seed. Develop sufficient quantity of biological sludge acclimatized to specific wastewater emanating from the paper mill to be used in both aeration tanks of the A-B Process. Operate the A-B Process using the sludge developed. Evaluate Sludge production (MLSS), reduction in COD and BOD, sludge yield. 4. METHODOLOGY CSON PAPER MILLS PVT. LTD is a craft paper mill with an earlier production capacity of 50 tons/d. They use wastepaper, ie., recycled cellulose fiber (RCF) as raw material. The paper mill had an efficiently working ASP provided after Dissolved Air Flotation (DAF) process. They desired to increase the production capacity from 50 tons/d to 100 tons/d, in which case, additional wastewater generation had to be expected. In order to take care of this wastewater, an additional ASP, with an AT volume of 900 m 3 was provided and was desired to be operated as Unit A, while the existing ASP having AT volume of 1200 m 3 was desired to be operated as Unit B. The above two units were designed to be operated in A-B mode where the wastewater shall be first treated in Unit A, and its effluent shall be further treated in Unit B. This case study reports some operational details of the process for a period of 120 days and the details of performance evaluated during these days of operation. 5. MATERIALS AND METHODS 5.1 MATERIALS 5.1.1 Additional ASP, Unit A, with an aeration tank of size 25 m x 8 m x 4.5 m (volume, 900 m 3 ) and a clarifier of 8 m diameter with 3.5 m depth was constructed. (Designed as per Arceivala 2003 and Metcalf and Eddy 2004). 5.1.2 Aerobic culture development was done in the AT of Unit B. The seed used for sludge development in the aeration tank was fresh cow dung with dry content varying from 18 to 20%. A total of 19.6 tons of cow dung was added. 5.1.3 Nutrients supplied during the primary startup process (culture development) were urea, factom phos, a baby food, groundnut cake. Urea contained 46% of Nitrogen (as per manufactures) and factom phos contained 20% of nitrogen and 20% of phosphorus (as per manufactures). Baby Food, given to supply other nutrients contained 15.5 g protein, 9 g fat, 68.9 g carbohydrates, 3.8 g sugar, 0.06 g sodium, 1.4 g total nitrogen, 1.5 g linoleate, 0.54 g total phosphrous (Adapted from manufacturs and Grasius 1996 ) per 100 g. Groundnut cake contained 45–60% protein, 22–30% carbohydrate, 3.8–7.5% crude fibre, 4–6% minerals. 5.1.4 Wheat flour was used to supplement organic matter (COD) during the culture development. In 1g/l solution of wheat flour was found to have a COD of 1180 mg/l. 5.1.5 Buffering was done by addition of soda ash (Na2CO3) and the culture pH was maintained in the range of 7.6–7.8 in the AT. 5.2 METHODS 5.2.1 Different phases of reactor operation Figure 2 shows the different phases of reactor operations during 120 days of study. The study was conducted in 4 phases of different durations conducted with specific objectives. These phases are briefly presented in Fig. 2 . 5.2.1.1 Phase 1, from 0 to 27th day of operation (primary startup) : The aim of this phase was to develop active aerobic sludge from a culture seed material rich in cellulose. Here, cow dung was used for the purpose. On the starting day, AT of B with 1200 m 3 liquid volume was filled with 600 m 3 of fresh water and cow dung was added in slurry form after filtering out long pieces of straw or grass. By the 3rd day of operation, cow dung added was 7 tons. Addition of baby food and groundnut cake at the rate 300 g and 1 kg respectively per 12-hour shift was started on the same day. By 4th day, the total cow dung added was 14.76 tons, addition of baby food and groundnut cake was increased to 450 g and 2 kg respectively on the day and the same was continued till the end. Addition of urea and factom phos was started on 7th day and continued till the end of the study. Wheat flour also was started from 7th day onwards as an organic source rich in fibre. Cow dung addition was resumed on 14th day and by 16th day, the total cow dung added was 19.61 tons. Hereafter no cow dung was added. Addition of groundnut cake and wheat flour was increased from 20th day to 3 kg and 4 kg respectively. Wastewater addition was done on 23rd, 25th, 26th and 27th and the total quantities applied on each day are shown in Table. 1. During these days of Primary startup, the sludge volume (SV) of AT and Mixed Liquor Suspended Solids (MLSS) of AT were determined from 7th day and 10th day onwards respectively. 5.2.1.2 Phase 2, from 27th to 60th day of operation (secondary startup) : With the intention of developing sufficient quantity of acclimatized aerobic sludge that can be used in the aeration tanks of unit A and B, the wastewater flow rate was increased from 108 m 3 /d stepwise. A regular pattern in flow increase could not be maintained because of the non-availability of wastewater from the production side as and when desired. But it was increased stepwise depending on its availability. A flow rate of 108 m 3 /d was to be continued up to 32nd day, up on which it was increased to 222 m 3 /d and was continued up to 34th day. The increase to 388 m 3 /d was given on 34th day and any further increase could not be given due to shortage of wastewater. In this phase of study, urea and factom phos were added to maintain a BOD/N/P ratio of 200/5/1.5. Baby food and Groundnut cake were added as given in Table. 2 to ensure micronutrients required for the bacterial growth. No wheat flour was added during this phase. During these 33 days, SV, MLSS of the AT and COD of AT inlet were done every day. The BOD of inlet was done once in six days. The floc was measured using rectangular V-notch. 5.2.1.3 Phase 3, from 60th to 104th day of operation (putting A-B process into operation) : On 60th day of operation, the MLSS of the AT was found to be 6050 mg/l. Initiating this phase of operation, required quantity of sludge from the recirculation line of B was transferred to AT of A on 60th and 61st day to result in an MLSS of 2800 mg/l in AT of A and 4200 mg/l in AT of B. On 61st day, 132 m 3 /d raw wastewater, that is, about 1/3rd of the total flow of 388 m 3 /d was given to A and the remaining 256 m 3 /d of wastewater to B. Additionally, B was fed with the effluent of A, thus A receiving a total flow of 388 m 3 /d. Feed to A was increased by 50 m 3 /d at 7 days interval and balance of 388 m 3 /d being fed to B. On 96th day the entire flow of 388 m 3 /d was received by unit A and its outlet to B, thus achieving the flow pattern of A-B process. This flow pattern was continued for the next 8 days, that is till 104th day. All through this phase, a BOD/N/P ratio of 200/5/1.5 was maintained by addition of urea and factom phos. Baby food was added at the rate of 2 g/kg BODin and groundnut cake at the rate of 150 g per 100 kg BODin also was added. 5.2.1.4 Phase 4, from 104th to 120th day of operation (sludge harvesting and flow increment) : From 104th to 108th day, sludge was harvested from unit A by diverting the sludge recirculation line to the pulping section of the mill. During the subsequent 12 days of operation, flow was increased from 388 m 3 /d to 488 m 3 /d. Maintenance of BOD/N/P ratio, feeding of Baby food and Groundnut cake were done as in case of Phase 3. During the last 60 days of reactor operation, the flow to section A and B were measured using rectangular V-notch. MLSS of both aeration tanks, influent COD and effluent COD of both clarifier of A and of B were measured every day. 5.2.2 Analytical Techniques The suspended solids of the AT content, named as, Mixed Liquor Suspended Solids (MLSS), the settleable solids in AT content, named as, Sludge Volume (SV), Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD), pH of samples were determined as per the methods outlined in Standard Methods (2005) 6. RESULTS AND DISCUSSION 6.1 Operations for 27 days Startup schedule, nutrient addition and some salient observations are outlined in Table. 1. As the wastewater of the Paper mill mostly contains cellulose and as cow dung is known to provide good cellulose rich environment, cow dung was used as a seed material. Cow dung addition started on the 1st day and by 4th day of operation 14.76 tons of cow dung was added. Addition of baby food and groundnut cake were started on the 3rd day. Nutrients such as urea and factom phos were started on 7th day and continued till the end of the study. Wheat flour was added to supply organic matter (COD) from 7th day onwards. On 9th day, good flocs were observed. MLSS of 800 mg/l and 40 ml sludge volume were observed on 10th day. Addition of nutrients like Nitrogen (N), Phosphorus (P) along with micronutrients through baby food seems to have accelerated microbial growth and floc formation. Cow dung addition resumed on 14th day as no appreciable increase in MLSS was observed from 10th to 13th day and by 16th day, 19.61 tons of cow dung was added. Gradual increase in MLSS was observed from 15th day and on 21st day, MLSS was found to be 1350 mg/l. This increase in MLSS observed could be due to the presence of undigested cow dung solids. On 27th day, MLSS was 1500 mg/l and sludge observed to be of good settleability (sludge volume- 50 ml and sludge volume index (SVI) – 33.3 ml/g). From records of the company, it was found that this level of MLSS was obtained only after 45 days of operation earlier. An early sludge development, as seen in this study, may be mainly due to the supplementation of micronutrients and protein through baby food and groundnut cake. As good flocs were observed on 9th day, and with an MLSS of 800 mg/l on 10th day, wastewater feeding could have been started at this stage. This might have resulted in an MLSS of 1500 mg/l, still at an early stage. However, as the production has not started on a regular basis in the company, wastewater was not available. It is also felt that a second phase addition of 4.85 tons of cow dung done from 14th to 16th day could have been avoided. During 13 days of operation from 10th day, the MLSS increased from 800 mg/l to 1100 mg/l. During 3 days of further operation from 23rd, 125.5 m 3 wastewater was added and by the end, that is on 27th day, the MLSS was found to be 1500 mg/l. From this study it may be concluded that on addition of 25 kg (dry weight) of fresh cow dung per m 3 of fresh ground water as seed and on aeration of the medium with addition of N, P and other micronutrients, aerobic microbial flocs of good settleability shall be developed within 10 days of operation. Also, that once an MLSS of 1000 mg/l is observed in AT, wastewater loading can be started slowly. Table 1 Startup schedule and salient observations DAYS OF OPERATION SEED/NUTRIENT MLSS/SV/OBSERVATION WASTEWATER FLOW 0 Cow dung addition started 600 m 3 fresh water in AT, B 0 4 Cow dung added – 14.76 tons (cumulative) BF/GC 450g/2kg per 12 hr shift No flocs observed in the liquid zone. Sludge zone was mostly cow dung debris 0 7 U/FP/BF/GC/WF– 250/250/450/2kg/1kg SV-50 ml – no flocs found; sludge contained mostly cow dung debris 0 9 U/FP/BF/GC/WF– 250/250/450/2kg/1kg Good flocs observed in the liquid zone 0 10 U/FP/BF/GC/WF– 250/250/450/2kg/1kg MLSS-800 mg/l SV-40 ml Good flocs observed 0 13 U/FP/BF/GC/WF– 250/250/450/2kg/1kg MLSS-900 mg/l SV-40 ml Good flocs 0 15 Cow dung added-17.18 tons (Cumulative) MLSS-1000 mg/l SV-50 ml 0 16 Cow dung added-19.61 tons (Cumulative) MLSS-1200 mg/l SV-50 ml 0 21 U/FP/BF/GC/WF– 250/250/450/3kg/4kg MLSS-1350 mg/l SV-50 ml 0 23 U/FP/BF/GC/WF– 250/250/450/3kg/4kg MLSS-1100 mg/l SV-40 ml A total of 20.5 m 3 in the day 25 U/FP/BF/GC/WF– 250/250/450/3kg/4kg MLSS-1300 mg/l SV-50 ml A total of 40 m 3 in the day 26 U/FP/BF/GC/WF– 250/250/450/3kg/4kg MLSS-1400 mg/l SV-50 ml A total of 65 m 3 in the day 27 U/FP/BF/GC/WF– 250/250/450/3kg/4kg MLSS-1500 mg/l SV-50 ml A total of 108 m 3 in the day U – urea; FP – Factom phos; BF – Baby food; GC – Groundnut cake; WF – Wheat flour; SV – Sludge volume; MLSS – Mixed Liquor Suspended Solids 6.2 Reactor operations from 27th – 60th day (secondary startup) and reactor performances Table. 2 gives the details of stepwise changes made on specific days on parameter like wastewater flow rate to the AT, its organic strength in terms of BOD, the resulting MLSS concentration in AT, the applied organic loading based on reactor volume and organic loading based on MLSS concentration (F/M ratio). The wastewater flow rate was increased stepwise on specific days. This increase was not on a regular basis but was depending on the wastewater availability. The wastewater BOD on these days ranged from 1170 mg/l 1500 mg/l. The resulting volumetric organic loading corresponding to the provided flow rate ranged from 0.13 kg BOD/m 3 /d to 0.46 kg BOD/m 3 /d. The MLSS increased from 1500 mg/l to 6050 mg/l. It shall be noted that in 21 days of operation in this phase from 27th to 48th day, the increase in sludge concentration was 2200 mg/l whereas during the subsequent 12 days of operation, from 48th to 60th day, the sludge concentration increase was 2350 mg/l. During the later 14 days of this 21 days and till the end of this phase of study, the volumetric loading was in the range of 0.38 to 0.46 kg BOD/m 3 /d. This shows a slower bacterial growth at the initial stage in spite of a relatively high organic loading and a higher rate at the second stage. This is indicative of the usually observed ‘lag phase’ in bacterial growth (Monod 1949 ) explained to be due to the delay in adaptation to the new substrate, here the cellulose, and maximum rate of metabolic activity such a lag in growth can be seen in Fig. 3 . The increased sludge production during the last 12 days in this phase and a final MLSS value of 6050 mg/l after 33 days of operation of secondary startup initially starting from 1500 mg/l indicated that the culture developed from cow dung got easily acclimatized to paper mill wastewater mostly containing cellulose. The acclimatization time required may be concluded to be around 20 days in the field condition of this study. An F/M ratio of 0.1 kg BOD/kg MLSS/d or less, from 48th day were due to higher MLSS concentration. Lower F/M ratio results in production of exocellular enzymes by bacterial cells resulting in better floc formation (Gray 1990 ). Table 2 Hydraulic and organic loading with MLSS development in ASP during secondary startup operation DAY FLOW IN m 3 /d INFLUENT BOD mg/l MLSS mg/l APPLIED VOL.ORG.LOAD kgBOD/m 3 /d F/M RATIO kgBOD/kg/MLSS/d NUTRIENTS ADDITION 27 108 1430 1500 0.13 0.09 -BOD/N/P of 200/5/1.5 was maintained -Baby food added was 1–3 g/kg BOD in -Groundnut cake; Starting – 2 kg/100 kg BOD and was gradually decreased to 150g/100 kg BOD at the end 32 222 1500 2200 0.28 0.13 34 388 1430 2800 0.46 0.17 36 388 1340 2800 0.43 0.15 42 388 1240 2800 0.4 0.14 48 388 1170 3700 0.38 0.10 54 388 1200 4900 0.39 0.08 60 388 1310 6050 0.42 0.07 6 . 3 Putting A-B process into operation and performance evaluation Figure 4 shows the A-B process operation. In addition, Table. 3 shows the data related to the shift inflow from B to A, MLSS development in A and B, influent and effluent COD of both A and B along with the organic loading and F/M ratio from day 61 to 120. On 61st day, 132 m 3 /d raw wastewater was given to A and 256 m 3 /d to B with an MLSS concentration 2800 mg/l and 4200 mg/l respectively. Additionally, B received effluent of A, thus receiving a total flow of 388 m 3 /d. During the subsequent 35 days of operation feed to A was increased by 50 m 3 /d at 7 days interval and balance of 388 m 3 /d being fed to B. On 96th day the entire flow of 388 m 3 /d was received by unit A and its outlet to B, thus achieving flow pattern of A-B process (Fig. 4 ). On 104th day (43 days of operation) the MLSS was found to be 11400 mg/l in the aeration tank of A that has a volume 900 m 3 . Average BOD/COD ratio of ten samples (random) collected and analyzed during 77 days was 0.35. BOD/COD ratio of effluent of A was 0.25 and that of B was 0.15. The total BOD stabilized in unit A in 43 days (day 61–104) was 6870 kg (considering average of COD these days and average of BOD/COD ratio of 0.35). Volatile fraction of sludge yielded in A was determined to be 0.6 and thus volatile content of the total sludge was calculated to be 4644 kg. Yield coefficient, Y was found to be 0.68. During 43 days of operation, the influent COD ranged from 1120 to 2530 mg/l; the average being 1940 mg/l. On 104th day the effluent COD of unit A was 90 mg/l and that of B was 80 mg/l. From 104th to 108th day, sludge was harvested from unit A reducing the MLSS from 11400 mg/l to 3600 mg/l. The harvested sludge, 7020 kg was used in the pulping section of the papermill effecting resource recovery. During the subsequent 12 days of operation, flow was increased from 388 m 3 /d to 488 m 3 /d. MLSS increased from 3600 mg/l to 7800 mg/l. For an influent COD ranging from 1703 to 1986 mg/l, the effluent COD of A ranged from 550 mg/l to 258 mg/l and that of B ranged from 105mg/l to 78 mg/l. During the 60 days of operation (61–120 days), the volumetric COD loading ranged from 0.35 kg COD/m 3 /d to 1.09 kg COD/m 3 /d and F/M ratio ranged from 0.04 to 0.24 kg COD/m 3 d. Figure 4 shows the variation in influent and effluent COD along with the variation in MLSS. Table 3 Putting A-B process into operation and performance evaluation (61 to 120 days) Day Direct Wastewater Flow in m 3 /d to Total Wastewater Flow to B in m 3 /d MLSS mg/l of AT of Influent COD mg/l Vol.COD.Loading kgCOD/ m 3 .d (A) F/M Ratio kgCOD/ kgMLSS.d (A) Effluent COD mg/l Clarifier of A B Direct + Effluent of A A B A B 61 132 256 388 2800 4200 1558 - - 68 182 206 388 3750 3800 2358 0.35 0.09 510 885 75 233 155 388 3800 4700 1958 0.40 0.11 188 418 82 285 103 388 4400 4100 1974 0.51 0.12 160 680 89 338 50 388 8300 3000 1120 0.35 0.04 95 130 96 388 0 388 9100 5600 2083 0.78 0.08 63 (96%) 151 104 388 0 388 11400 7200 2530 1.09 0.09 90 (96%) 80 108 388 0 388 3600 4700 1986 0.85 0.24 550 (72%) 98 115 438 0 438 5400 4000 1703 0.73 0.13 258 (84%) 78 120 488 0 488 7800 4200 1850 0.9 0.11 275 (85%) 105 7. CONCLUSION The study includes 120 days of reactor operation and performance evaluation. The operations were carried out in three phases. The following conclusions can be drawn from the study. In the first phase of this study, cow dung rich in microbial consortium were successfully used as a seed material for developing aerobic culture and flocs of good settleability. On addition 25 kg (dry weight) of fresh cow dung per m 3 of fresh ground water as seed and on aeration of the medium with supply of N, P and other micronutrients by addition of baby food and groundnut cake, good flocs were observed on 9th day of operation. On 10th day the MLSS in the AT was 800 mg/l and the sludge volume was 40 ml/litre with a sludge volume index (SVI) of 50 ml/g. This indicates that the sludge developed was of good settleability. Addition of nutrients like N, P along with micronutrients through the addition of baby food and groundnut cake from 7th day and 3rd day seem to have accelerated microbial growth and floc formation. In spite of the second phase cow dung addition of 8 kg (dry weight) per m 3 of the medium, the MLSS increase from 10th day to 23rd day was only 300 mg/l whereas addition of a total of 125.5 m 3 of wastewater from 23rd day of operation resulted in an increase in MLSS of 400 mg/l by 27th day. It shall be concluded that up on addition of cow dung at the rate of 25 kg (dry weight) per m 3 of medium, as seed, and on addition of N, P and other micronutrients, microbial flocs with good settleability can be obtained within 9 to 10 days of aeration. Once an MLSS of 1000 mg/l in the AT is obtained, organic loading by the addition of wastewater can be started subsequently. During the second startup operation for 33 days the aerobic bacterial flocs developed from cow dung, known to be rich in cellulose, was successfully fed with wastewater from a paper mill that use waste paper as raw material. During 33 days of operation, the applied organic loading was increased by increasing the wastewater flow to the AT and as a result the MLSS increased from 1500 mg/l to 6050 mg/l. During the last 26 days of operation the organic loading was in the range of 0.38 to 0.46 kg BOD/m 3 /d. In the initial 21 days of operation the MLSS increase was 2200 mg/l whereas during the remaining 12 days, the increase was 2350 mg/l. This initial delay in sludge development shall be attributed to the time required for the acclimatization to the new substrate, here cellulose, which is usually referred to as lag phase of growth. However, a more specific information on the extend of lag phase could be obtained if the higher organic loading rate was maintained from the initial days itself. During the 3rd phase of this study, the entire flow of 388 m 3 /d was made to flow in the A-B process by providing stepwise increase to A, correspondingly reducing direct flow to B in 43 days. During these 43 days, MLSS in A increased from 2800 to 11400 mg/l. The total BOD stabilized was 6870 kg and sludge yielded in A (volatile fraction) was 4644 kg, resulting in a yield coefficient, Y of 0.68. In 4 days since 104th day, 7020 kg (dry weight) was harvested and utilized in the pulping section. During 12 days of operation from 108th day, effluent COD of A ranged from 550 mg/l to 258 mg/l, effluent COD of B ranged from 105 mg/l to 78 mg/l where the influent COD ranged from 1986 mg/l to 1703 mg/l and flow increased from 388 m 3 /d to 488 m 3 /d. The volumetric loading was in the range of 0.73 to 0.9 kg COD/m 3 .d and F/M ratio was in the range of 0.11 to 0.24 kg COD/kg MLSS in A. Declarations Ethical approval Not applicable Consent to participate Not applicable Consent to publish Not applicable Authors contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Kochu Thresya Sojan and Dr. Grasius Mattamana Geevarghese. Kochu Thresya Sojan and Dr. Grasius Mattamana Geevarghese together wrote the manuscript. All Authors read and approved the final manuscript. Funding No funding was received Competing interests Financial interests: Kochu Thresya Sojan declare she has no financial interests. Dr Grasius Mattamana Geevarghese is consultant to CSons Paper Mills Pvt. Ltd.; Puthupady PO, Ernakulam district, India. Non-financial interests: none. Availability of data and materials All data generated or analysed during the present study are not included in this published article. Only the data pertaining to the manuscript is included. References Arceivala SJ, Shyam R Asolekar (2003) Wastewater Treatment for Pollution Control and Reuse. Tata McGraw-Hill Publishing Company Ltd, New Delhi Gray NF (1990) Activated Sludge Theory and Practice. Oxford University press, New York Grasius MG (1996) Design, Development and Performance Evaluation of a modified UASB Reactor for Treatment of Low-Strength Wastewaters. Ph.D. thesis submitted to Dept. of Civil Engineering, IIT Kanpur, India Kraft Paper Industry - Investment Project Opportunity for Startups and Entrepreneurs : Poised for Continuous and Rapid Growth in the Coming Years. https://www.entrepreneurindia.co/Document/Download/pdfanddoc-912958-.pdf Metcalf & Eddy (2004) Wastewater Engineering, Treatment and Reuse. Tata McGraw-Hill Publishing Company Ltd, New Delhi Rao MN, Datta AK (1979) Waste Water Treatment Rational Methods of Design and Industrial Practises. Oxford & IBH Publishing Co., New Delhi Monod J (1949) “The Growth of Bacterial Cultures,” Annual Review of Microbiology, 3,371 (1949) Omid Ashraf L, Fariborz Haghighat (2015) Yerushalmi & Wastewater treatment in the pulp and paper industry: A review of treatment process and the associated greenhouse gas emission Standard Methods for the Examination of Water and Wastewater (2005) (21st Ed.) Jointly published by American Public Health Association, American Water Works Association, and Water Environment Federation, Washington, D.C. 20001 – 3710 Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 10 Sep, 2023 Reviewers invited by journal 10 Sep, 2023 Editor invited by journal 21 Jun, 2023 Editor assigned by journal 14 Jun, 2023 First submitted to journal 08 Jun, 2023 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3006713","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":232033292,"identity":"546b6077-5d46-402a-a534-14282e485707","order_by":0,"name":"Kochu Thresya Sojan","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxUlEQVRIiWNgGAWjYBACCQiVIAciDzwgSgsbRIsxWEsCKVoSG8AUMVok57c/YPjxJy19ftjhh0Bb7OR0GwhokWbjMWDsbcvJ3Xg7zQCoJdnY7AABLXJsPAwMvA0VuRtnJ4C0HEjcRlgL+wPGP38q0g1np38gTos0G4MBMw9bToK8dA6Rtki25Rgclm1LM9wgnVNwIMGACL9IHD7+8OGbP8ny8rPTN3/4UGEnR1ALCIDVGEBIIpTDgXwDKapHwSgYBaNgRAEAuehCuPevVOMAAAAASUVORK5CYII=","orcid":"https://orcid.org/0009-0007-5285-463X","institution":"Viswajyothi College of Engineering and Technology","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Kochu","middleName":"Thresya","lastName":"Sojan","suffix":""},{"id":232033293,"identity":"ca30830d-dd57-4606-9c07-5f365689c428","order_by":1,"name":"Grasius Mattamana Geevarghese","email":"","orcid":"","institution":"Viswajyothi College of Engineering and Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Grasius","middleName":"Mattamana","lastName":"Geevarghese","suffix":""}],"badges":[],"createdAt":"2023-05-31 19:19:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3006713/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3006713/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":43157193,"identity":"415264bb-5e08-4569-bddd-6125041d00ea","added_by":"auto","created_at":"2023-09-14 20:44:25","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":65933,"visible":true,"origin":"","legend":"\u003cp\u003eA-B Process\u003c/p\u003e","description":"","filename":"F1.png","url":"https://assets-eu.researchsquare.com/files/rs-3006713/v1/778a1a8afdd232a9b7c0917e.png"},{"id":43157196,"identity":"e505536b-f45a-4001-b68b-7e165a695407","added_by":"auto","created_at":"2023-09-14 20:44:25","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":56795,"visible":true,"origin":"","legend":"\u003cp\u003eDifferent phase of operations during 120 days of reactor running\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-3006713/v1/3ab2d668fcc8294a959d594b.png"},{"id":43157195,"identity":"235d5638-b980-48f3-b844-04f3ebba53d1","added_by":"auto","created_at":"2023-09-14 20:44:25","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":37767,"visible":true,"origin":"","legend":"\u003cp\u003eOrganic loading by wastewater addition and MLSS development\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-3006713/v1/4d955de3cf54f9207c42f306.png"},{"id":43157194,"identity":"90eade03-b1e1-44a0-8db2-71959afd002f","added_by":"auto","created_at":"2023-09-14 20:44:25","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":121839,"visible":true,"origin":"","legend":"\u003cp\u003eA-B Process operation and performance evaluation\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-3006713/v1/ce2c4c5ebf72022bd02bbe4d.jpeg"},{"id":43157214,"identity":"32bd1403-e998-430e-a4e5-cf95b214f57c","added_by":"auto","created_at":"2023-09-14 20:44:35","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":641842,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3006713/v1/86422c68-5a9d-4f82-ad53-757f6acaab45.pdf"},{"id":43157212,"identity":"44b35e58-516e-4009-b8a3-502652e35632","added_by":"auto","created_at":"2023-09-14 20:44:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":435432,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3006713/v1/6ddde620-eb5d-4774-9052-c602f2d68e7e.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eSpeedy Mlss Development From Cow Dung, Wastewater Treatment and Sludge Recovery From the Activated Sludge Process (a-b Process) of a Paper Mill That Use Waste Paper as Raw Material - A Case Study\u003c/p\u003e","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003ePaper Industry, one of the important industrial sector of any developing country, mainly relies on forest based raw material like bamboo, wood, etc. Thanks to the present-day environmental consciousness, large scale use of non-wood pulp based raw material came into existence, since the availability of raw material from forest has dwindled. In this case study, the paper mill uses recycled cellulose fibre as their raw material for the manufacturing of Kraft paper. Kraft paper is the leading paper type used for wrapping heavy bundles after corrugation. It is used in many types of packaging and is an important packaging material. Kraft papers or brown papers are strong and flexible (entrepreneurindia.co). The manufacturing of kraft paper consumes large amount of fresh water and hence is a major source of wastewater. The wastewater from the Kraft paper mill contains variety of organic and inorganic contaminants. The wastewater has high COD, TSS and TDS. The treated wastewater can be recycled for reuse in the pulp and paper industry, if the required quality could be achieved, or it can be released to the environment if its quality meets the environmental standards (Omid Ashraf, Laleh Yerushalami \u0026amp; Fariborz Haghighat 2015). The treatment of wastewater can either be done using physico-chemical process which produces large quantity of sludge thereby causing, disposal a further issue, or be done using biological process which results in the ultimate treatment by converting organic matter to CO\u003csub\u003e2\u003c/sub\u003e (Rao \u0026amp; Dhatta 1979). The wastewater is considered to be amenable for biological treatment without acclimatization, if the COD/BOD ratio is 0.6 or above. Many paper industries go for Activated Sludge Process (ASP) after possible cellulose recovery (DAF) and physico-chemical process (Metcalf and Eddy 2004). If the COD/BOD ratio is between 0.3 and 0.6, the wastewater needs acclimatization for biological treatment. If the COD/BOD ratio is less than 0.3, other methods are suggested for treatment (Rao \u0026amp; Dhatta 1979). In the case studied, the Kraft paper mill was using biological process for the wastewater treatment but the COD/BOD ratio was found to be mostly below 0.3 in analysis done many times previously in this paper mill. Moreover, the wastewater from the Kraft paper mill is known to be deficient in nutrients and micronutrients as raw material (waste paper) mainly contain only cellulose. The main challenge in employing ASP in this case study was the development of active biological sludge acclimatized to the cellulose waste. Secondly, the fluctuations in characteristics of wastewater affects the biological sludge microstructure caused by the development of filamentous organisms and non-flocculating organisms leading to poor settleability of sludge, thereby resulting in poor quality effluent. These issues are believed to be solved to a greater extent by employing A-B Process (Gray \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1990\u003c/span\u003e) for such types of wastewaters.\u003c/p\u003e"},{"header":"2. A-B PROCESS","content":"\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the A-B Process. The process comprises two ASP units in series. A-Stage can receive high BOD loading (3\u0026ndash;6 kg BOD/kg MLSS/d) and B-Stage receives normal BOD loading (0.15\u0026ndash;0.3 kg BOD/kg MLSS/d). Effluent after preliminary treatment is first treated in A-stage. A-stage effluent is further treated in B-stage. A-stage effectively buffers the B-stage from variations in flow rate and influent quality parameters. This makes B-stage very stable, resulting in excellent quality effluent (Gray, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1990\u003c/span\u003e). This A-B process is employed in the present study.\u003c/p\u003e "},{"header":"3. OBJECTIVE","content":"\u003cp\u003eIn order to provide biological treatment for 1000 m\u003csup\u003e3\u003c/sup\u003e/d of the kraft paper mill effluent, the paper mill had provided an additional ASP unit (Unit A) consisting of an AT of volume 900 m\u003csup\u003e3\u003c/sup\u003e and an SST of required size. This unit, A, was desired to operate in series with then existing unit (Unit B), thus implementing a two stage Activated Sludge System (A-B Process). The main objectives of this case study were to:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eDevelop active biological aerobic sludge using cow dung as seed.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eDevelop sufficient quantity of biological sludge acclimatized to specific wastewater emanating from the paper mill to be used in both aeration tanks of the A-B Process.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eOperate the A-B Process using the sludge developed.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eEvaluate Sludge production (MLSS), reduction in COD and BOD, sludge yield.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e"},{"header":"4. METHODOLOGY","content":"\u003cp\u003eCSON PAPER MILLS PVT. LTD is a craft paper mill with an earlier production capacity of 50 tons/d. They use wastepaper, ie., recycled cellulose fiber (RCF) as raw material. The paper mill had an efficiently working ASP provided after Dissolved Air Flotation (DAF) process. They desired to increase the production capacity from 50 tons/d to 100 tons/d, in which case, additional wastewater generation had to be expected. In order to take care of this wastewater, an additional ASP, with an AT volume of 900 m\u003csup\u003e3\u003c/sup\u003e was provided and was desired to be operated as Unit A, while the existing ASP having AT volume of 1200 m\u003csup\u003e3\u003c/sup\u003e was desired to be operated as Unit B. The above two units were designed to be operated in A-B mode where the wastewater shall be first treated in Unit A, and its effluent shall be further treated in Unit B. This case study reports some operational details of the process for a period of 120 days and the details of performance evaluated during these days of operation.\u003c/p\u003e"},{"header":"5. MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n \u003ch2\u003e5.1 MATERIALS\u003c/h2\u003e\u003cspan\u003e\n \u003cp\u003e5.1.1 Additional ASP, Unit A, with an aeration tank of size 25 m x 8 m x 4.5 m (volume, 900 m\u003csup\u003e3\u003c/sup\u003e) and a clarifier of 8 m diameter with 3.5 m depth was constructed. (Designed as per Arceivala \u003cspan class=\"CitationRef\"\u003e2003\u003c/span\u003e and Metcalf and Eddy 2004).\u003c/p\u003e\n \u003c/span\u003e \u003cspan\u003e\n \u003cp\u003e5.1.2 Aerobic culture development was done in the AT of Unit B. The seed used for sludge development in the aeration tank was fresh cow dung with dry content varying from 18 to 20%. A total of 19.6 tons of cow dung was added.\u003c/p\u003e\n \u003c/span\u003e \u003cspan\u003e\n \u003cp\u003e5.1.3 Nutrients supplied during the primary startup process (culture development) were urea, factom phos, a baby food, groundnut cake. Urea contained 46% of Nitrogen (as per manufactures) and factom phos contained 20% of nitrogen and 20% of phosphorus (as per manufactures). Baby Food, given to supply other nutrients contained 15.5 g protein, 9 g fat, 68.9 g carbohydrates, 3.8 g sugar, 0.06 g sodium, 1.4 g total nitrogen, 1.5 g linoleate, 0.54 g total phosphrous (Adapted from manufacturs and Grasius \u003cspan class=\"CitationRef\"\u003e1996\u003c/span\u003e) per 100 g. Groundnut cake contained 45\u0026ndash;60% protein, 22\u0026ndash;30% carbohydrate, 3.8\u0026ndash;7.5% crude fibre, 4\u0026ndash;6% minerals.\u003c/p\u003e\n \u003c/span\u003e \u003cspan\u003e\n \u003cp\u003e5.1.4 Wheat flour was used to supplement organic matter (COD) during the culture development. In 1g/l solution of wheat flour was found to have a COD of 1180 mg/l.\u003c/p\u003e\n \u003c/span\u003e \u003cspan\u003e\n \u003cp\u003e5.1.5 Buffering was done by addition of soda ash (Na2CO3) and the culture pH was maintained in the range of 7.6\u0026ndash;7.8 in the AT.\u003c/p\u003e\n \u003c/span\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003e5.2 METHODS\u003c/h2\u003e\n \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\n \u003ch2\u003e5.2.1 Different phases of reactor operation\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e shows the different phases of reactor operations during 120 days of study. The study was conducted in 4 phases of different durations conducted with specific objectives. These phases are briefly presented in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n \u003c/div\u003e\u003cspan\u003e\n \u003cp\u003e\u003cstrong\u003e5.2.1.1 Phase 1, from 0 to 27th day of operation (primary startup)\u003c/strong\u003e: The aim of this phase was to develop active aerobic sludge from a culture seed material rich in cellulose. Here, cow dung was used for the purpose. On the starting day, AT of B with 1200 m\u003csup\u003e3\u003c/sup\u003e liquid volume was filled with 600 m\u003csup\u003e3\u003c/sup\u003e of fresh water and cow dung was added in slurry form after filtering out long pieces of straw or grass. By the 3rd day of operation, cow dung added was 7 tons. Addition of baby food and groundnut cake at the rate 300 g and 1 kg respectively per 12-hour shift was started on the same day. By 4th day, the total cow dung added was 14.76 tons, addition of baby food and groundnut cake was increased to 450 g and 2 kg respectively on the day and the same was continued till the end. Addition of urea and factom phos was started on 7th day and continued till the end of the study. Wheat flour also was started from 7th day onwards as an organic source rich in fibre. Cow dung addition was resumed on 14th day and by 16th day, the total cow dung added was 19.61 tons. Hereafter no cow dung was added. Addition of groundnut cake and wheat flour was increased from 20th day to 3 kg and 4 kg respectively. Wastewater addition was done on 23rd, 25th, 26th and 27th and the total quantities applied on each day are shown in Table. 1. During these days of Primary startup, the sludge volume (SV) of AT and Mixed Liquor Suspended Solids (MLSS) of AT were determined from 7th day and 10th day onwards respectively.\u003c/p\u003e\n \u003c/span\u003e \u003cspan\u003e\n \u003cp\u003e\u003cstrong\u003e5.2.1.2 Phase 2, from 27th to 60th day of operation (secondary startup)\u003c/strong\u003e: With the intention of developing sufficient quantity of acclimatized aerobic sludge that can be used in the aeration tanks of unit A and B, the wastewater flow rate was increased from 108 m\u003csup\u003e3\u003c/sup\u003e/d stepwise. A regular pattern in flow increase could not be maintained because of the non-availability of wastewater from the production side as and when desired. But it was increased stepwise depending on its availability. A flow rate of 108 m\u003csup\u003e3\u003c/sup\u003e/d was to be continued up to 32nd day, up on which it was increased to 222 m\u003csup\u003e3\u003c/sup\u003e/d and was continued up to 34th day. The increase to 388 m\u003csup\u003e3\u003c/sup\u003e/d was given on 34th day and any further increase could not be given due to shortage of wastewater. In this phase of study, urea and factom phos were added to maintain a BOD/N/P ratio of 200/5/1.5. Baby food and Groundnut cake were added as given in Table. 2 to ensure micronutrients required for the bacterial growth. No wheat flour was added during this phase. During these 33 days, SV, MLSS of the AT and COD of AT inlet were done every day. The BOD of inlet was done once in six days. The floc was measured using rectangular V-notch.\u003c/p\u003e\n \u003c/span\u003e \u003cspan\u003e\n \u003cp\u003e\u003cstrong\u003e5.2.1.3 Phase 3, from 60th to 104th day of operation (putting A-B process into operation)\u003c/strong\u003e: On 60th day of operation, the MLSS of the AT was found to be 6050 mg/l. Initiating this phase of operation, required quantity of sludge from the recirculation line of B was transferred to AT of A on 60th and 61st day to result in an MLSS of 2800 mg/l in AT of A and 4200 mg/l in AT of B. On 61st day, 132 m\u003csup\u003e3\u003c/sup\u003e/d raw wastewater, that is, about 1/3rd of the total flow of 388 m\u003csup\u003e3\u003c/sup\u003e/d was given to A and the remaining 256 m\u003csup\u003e3\u003c/sup\u003e/d of wastewater to B. Additionally, B was fed with the effluent of A, thus A receiving a total flow of 388 m\u003csup\u003e3\u003c/sup\u003e/d. Feed to A was increased by 50 m\u003csup\u003e3\u003c/sup\u003e/d at 7 days interval and balance of 388 m\u003csup\u003e3\u003c/sup\u003e/d being fed to B. On 96th day the entire flow of 388 m\u003csup\u003e3\u003c/sup\u003e/d was received by unit A and its outlet to B, thus achieving the flow pattern of A-B process. This flow pattern was continued for the next 8 days, that is till 104th day. All through this phase, a BOD/N/P ratio of 200/5/1.5 was maintained by addition of urea and factom phos. Baby food was added at the rate of 2 g/kg BODin and groundnut cake at the rate of 150 g per 100 kg BODin also was added.\u003c/p\u003e\n \u003c/span\u003e \u003cspan\u003e\n \u003cp\u003e\u003cstrong\u003e5.2.1.4 Phase 4, from 104th to 120th day of operation (sludge harvesting and flow increment)\u003c/strong\u003e: From 104th to 108th day, sludge was harvested from unit A by diverting the sludge recirculation line to the pulping section of the mill. During the subsequent 12 days of operation, flow was increased from 388 m\u003csup\u003e3\u003c/sup\u003e/d to 488 m\u003csup\u003e3\u003c/sup\u003e/d. Maintenance of BOD/N/P ratio, feeding of Baby food and Groundnut cake were done as in case of Phase 3. During the last 60 days of reactor operation, the flow to section A and B were measured using rectangular V-notch. MLSS of both aeration tanks, influent COD and effluent COD of both clarifier of A and of B were measured every day.\u003c/p\u003e\n \u003c/span\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\n \u003ch2\u003e5.2.2 Analytical Techniques\u003c/h2\u003e\n \u003cp\u003eThe suspended solids of the AT content, named as, Mixed Liquor Suspended Solids (MLSS), the settleable solids in AT content, named as, Sludge Volume (SV), Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD), pH of samples were determined as per the methods outlined in Standard Methods (2005)\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"6. RESULTS AND DISCUSSION","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e6.1 Operations for 27 days\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eStartup schedule, nutrient addition and some salient observations are outlined in Table. 1. As the wastewater of the Paper mill mostly contains cellulose and as cow dung is known to provide good cellulose rich environment, cow dung was used as a seed material. Cow dung addition started on the 1st day and by 4th day of operation 14.76 tons of cow dung was added. Addition of baby food and groundnut cake were started on the 3rd day. Nutrients such as urea and factom phos were started on 7th day and continued till the end of the study. Wheat flour was added to supply organic matter (COD) from 7th day onwards. On 9th day, good flocs were observed. MLSS of 800 mg/l and 40 ml sludge volume were observed on 10th day. Addition of nutrients like Nitrogen (N), Phosphorus (P) along with micronutrients through baby food seems to have accelerated microbial growth and floc formation. Cow dung addition resumed on 14th day as no appreciable increase in MLSS was observed from 10th to 13th day and by 16th day, 19.61 tons of cow dung was added. Gradual increase in MLSS was observed from 15th day and on 21st day, MLSS was found to be 1350 mg/l. This increase in MLSS observed could be due to the presence of undigested cow dung solids. On 27th day, MLSS was 1500 mg/l and sludge observed to be of good settleability (sludge volume- 50 ml and sludge volume index (SVI) \u0026ndash; 33.3 ml/g). From records of the company, it was found that this level of MLSS was obtained only after 45 days of operation earlier. An early sludge development, as seen in this study, may be mainly due to the supplementation of micronutrients and protein through baby food and groundnut cake. As good flocs were observed on 9th day, and with an MLSS of 800 mg/l on 10th day, wastewater feeding could have been started at this stage. This might have resulted in an MLSS of 1500 mg/l, still at an early stage. However, as the production has not started on a regular basis in the company, wastewater was not available. It is also felt that a second phase addition of 4.85 tons of cow dung done from 14th to 16th day could have been avoided. During 13 days of operation from 10th day, the MLSS increased from 800 mg/l to 1100 mg/l. During 3 days of further operation from 23rd, 125.5 m\u003csup\u003e3\u003c/sup\u003e wastewater was added and by the end, that is on 27th day, the MLSS was found to be 1500 mg/l. From this study it may be concluded that on addition of 25 kg (dry weight) of fresh cow dung per m\u003csup\u003e3\u003c/sup\u003e of fresh ground water as seed and on aeration of the medium with addition of N, P and other micronutrients, aerobic microbial flocs of good settleability shall be developed within 10 days of operation. Also, that once an MLSS of 1000 mg/l is observed in AT, wastewater loading can be started slowly.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eStartup schedule and salient observations\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDAYS OF OPERATION\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSEED/NUTRIENT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS/SV/OBSERVATION\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWASTEWATER FLOW\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCow dung addition started\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e600 m\u003csup\u003e3\u003c/sup\u003e fresh water in AT, B\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCow dung added \u0026ndash; 14.76 tons (cumulative)\u003c/p\u003e \u003cp\u003eBF/GC\u003c/p\u003e \u003cp\u003e450g/2kg per 12 hr shift\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo flocs observed in the liquid zone. Sludge zone was mostly cow dung debris\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eU/FP/BF/GC/WF\u0026ndash; 250/250/450/2kg/1kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSV-50 ml \u0026ndash; no flocs found; sludge contained mostly cow dung debris\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eU/FP/BF/GC/WF\u0026ndash; 250/250/450/2kg/1kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eGood flocs observed\u003c/em\u003e in the liquid zone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eU/FP/BF/GC/WF\u0026ndash; 250/250/450/2kg/1kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS-800 mg/l\u003c/p\u003e \u003cp\u003eSV-40 ml\u003c/p\u003e \u003cp\u003e\u003cem\u003eGood flocs observed\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eU/FP/BF/GC/WF\u0026ndash; 250/250/450/2kg/1kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS-900 mg/l\u003c/p\u003e \u003cp\u003eSV-40 ml Good flocs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCow dung added-17.18 tons (Cumulative)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS-1000 mg/l\u003c/p\u003e \u003cp\u003eSV-50 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCow dung added-19.61 tons (Cumulative)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS-1200 mg/l\u003c/p\u003e \u003cp\u003eSV-50 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eU/FP/BF/GC/WF\u0026ndash; 250/250/450/3kg/4kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS-1350 mg/l\u003c/p\u003e \u003cp\u003eSV-50 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eU/FP/BF/GC/WF\u0026ndash; 250/250/450/3kg/4kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS-1100 mg/l\u003c/p\u003e \u003cp\u003eSV-40 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA total of 20.5 m\u003csup\u003e3\u003c/sup\u003e in the day\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eU/FP/BF/GC/WF\u0026ndash; 250/250/450/3kg/4kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS-1300 mg/l\u003c/p\u003e \u003cp\u003eSV-50 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA total of 40 m\u003csup\u003e3\u003c/sup\u003e in the day\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eU/FP/BF/GC/WF\u0026ndash; 250/250/450/3kg/4kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS-1400 mg/l\u003c/p\u003e \u003cp\u003eSV-50 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA total of 65 m\u003csup\u003e3\u003c/sup\u003e in the day\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eU/FP/BF/GC/WF\u0026ndash; 250/250/450/3kg/4kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMLSS-1500 mg/l\u003c/p\u003e \u003cp\u003eSV-50 ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA total of 108 m\u003csup\u003e3\u003c/sup\u003e in the day\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eU \u0026ndash; urea; FP \u0026ndash; Factom phos; BF \u0026ndash; Baby food; GC \u0026ndash; Groundnut cake; WF \u0026ndash; Wheat flour; SV \u0026ndash; Sludge volume; MLSS \u0026ndash; Mixed Liquor Suspended Solids\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003e6.2 Reactor operations from 27th \u0026ndash; 60th day (secondary startup) and reactor performances\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eTable. 2 gives the details of stepwise changes made on specific days on parameter like wastewater flow rate to the AT, its organic strength in terms of BOD, the resulting MLSS concentration in AT, the applied organic loading based on reactor volume and organic loading based on MLSS concentration (F/M ratio). The wastewater flow rate was increased stepwise on specific days. This increase was not on a regular basis but was depending on the wastewater availability. The wastewater BOD on these days ranged from 1170 mg/l 1500 mg/l. The resulting volumetric organic loading corresponding to the provided flow rate ranged from 0.13 kg BOD/m\u003csup\u003e3\u003c/sup\u003e/d to 0.46 kg BOD/m\u003csup\u003e3\u003c/sup\u003e/d. The MLSS increased from 1500 mg/l to 6050 mg/l. It shall be noted that in 21 days of operation in this phase from 27th to 48th day, the increase in sludge concentration was 2200 mg/l whereas during the subsequent 12 days of operation, from 48th to 60th day, the sludge concentration increase was 2350 mg/l. During the later 14 days of this 21 days and till the end of this phase of study, the volumetric loading was in the range of 0.38 to 0.46 kg BOD/m\u003csup\u003e3\u003c/sup\u003e/d. This shows a slower bacterial growth at the initial stage in spite of a relatively high organic loading and a higher rate at the second stage. This is indicative of the usually observed \u0026lsquo;lag phase\u0026rsquo; in bacterial growth (Monod \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e1949\u003c/span\u003e) explained to be due to the delay in adaptation to the new substrate, here the cellulose, and maximum rate of metabolic activity such a lag in growth can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The increased sludge production during the last 12 days in this phase and a final MLSS value of 6050 mg/l after 33 days of operation of secondary startup initially starting from 1500 mg/l indicated that the culture developed from cow dung got easily acclimatized to paper mill wastewater mostly containing cellulose. The acclimatization time required may be concluded to be around 20 days in the field condition of this study.\u003c/p\u003e \u003cp\u003eAn F/M ratio of 0.1 kg BOD/kg MLSS/d or less, from 48th day were due to higher MLSS concentration. Lower F/M ratio results in production of exocellular enzymes by bacterial cells resulting in better floc formation (Gray \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1990\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eHydraulic and organic loading with MLSS development in ASP during secondary startup operation\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDAY\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFLOW IN\u003c/p\u003e \u003cp\u003em\u003csup\u003e3\u003c/sup\u003e/d\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eINFLUENT BOD\u003c/p\u003e \u003cp\u003emg/l\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMLSS\u003c/p\u003e \u003cp\u003emg/l\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAPPLIED VOL.ORG.LOAD\u003c/p\u003e \u003cp\u003ekgBOD/m\u003csup\u003e3\u003c/sup\u003e/d\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eF/M RATIO\u003c/p\u003e \u003cp\u003ekgBOD/kg/MLSS/d\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNUTRIENTS ADDITION\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e108\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1430\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"7\" rowspan=\"8\"\u003e \u003cp\u003e-BOD/N/P of 200/5/1.5 was maintained\u003c/p\u003e \u003cp\u003e-Baby food added was 1\u0026ndash;3 g/kg BOD in\u003c/p\u003e \u003cp\u003e-Groundnut cake;\u003c/p\u003e \u003cp\u003eStarting \u0026ndash; 2 kg/100 kg BOD and was gradually decreased to 150g/100 kg BOD at the end\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e222\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1430\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.17\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1340\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1170\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4900\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1310\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6050\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003e6\u003c/b\u003e.\u003cb\u003e3 Putting A-B process into operation and performance evaluation\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the A-B process operation. In addition, Table. 3 shows the data related to the shift inflow from B to A, MLSS development in A and B, influent and effluent COD of both A and B along with the organic loading and F/M ratio from day 61 to 120. On 61st day, 132 m\u003csup\u003e3\u003c/sup\u003e/d raw wastewater was given to A and 256 m\u003csup\u003e3\u003c/sup\u003e/d to B with an MLSS concentration 2800 mg/l and 4200 mg/l respectively. Additionally, B received effluent of A, thus receiving a total flow of 388 m\u003csup\u003e3\u003c/sup\u003e/d. During the subsequent 35 days of operation feed to A was increased by 50 m\u003csup\u003e3\u003c/sup\u003e/d at 7 days interval and balance of 388 m\u003csup\u003e3\u003c/sup\u003e/d being fed to B. On 96th day the entire flow of 388 m\u003csup\u003e3\u003c/sup\u003e/d was received by unit A and its outlet to B, thus achieving flow pattern of A-B process (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). On 104th day (43 days of operation) the MLSS was found to be 11400 mg/l in the aeration tank of A that has a volume 900 m\u003csup\u003e3\u003c/sup\u003e. Average BOD/COD ratio of ten samples (random) collected and analyzed during 77 days was 0.35. BOD/COD ratio of effluent of A was 0.25 and that of B was 0.15. The total BOD stabilized in unit A in 43 days (day 61\u0026ndash;104) was 6870 kg (considering average of COD these days and average of BOD/COD ratio of 0.35). Volatile fraction of sludge yielded in A was determined to be 0.6 and thus volatile content of the total sludge was calculated to be 4644 kg. Yield coefficient, Y was found to be 0.68. During 43 days of operation, the influent COD ranged from 1120 to 2530 mg/l; the average being 1940 mg/l. On 104th day the effluent COD of unit A was 90 mg/l and that of B was 80 mg/l. From 104th to 108th day, sludge was harvested from unit A reducing the MLSS from 11400 mg/l to 3600 mg/l. The harvested sludge, 7020 kg was used in the pulping section of the papermill effecting resource recovery. During the subsequent 12 days of operation, flow was increased from 388 m\u003csup\u003e3\u003c/sup\u003e/d to 488 m\u003csup\u003e3\u003c/sup\u003e/d. MLSS increased from 3600 mg/l to 7800 mg/l. For an influent COD ranging from 1703 to 1986 mg/l, the effluent COD of A ranged from 550 mg/l to 258 mg/l and that of B ranged from 105mg/l to 78 mg/l. During the 60 days of operation (61\u0026ndash;120 days), the volumetric COD loading ranged from 0.35 kg COD/m\u003csup\u003e3\u003c/sup\u003e/d to 1.09 kg COD/m\u003csup\u003e3\u003c/sup\u003e/d and F/M ratio ranged from 0.04 to 0.24 kg COD/m\u003csup\u003e3\u003c/sup\u003ed. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the variation in influent and effluent COD along with the variation in MLSS.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePutting A-B process into operation and performance evaluation (61 to 120 days)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eDay\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eDirect Wastewater Flow in m\u003csup\u003e3\u003c/sup\u003e/d to\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTotal Wastewater Flow to B in m\u003csup\u003e3\u003c/sup\u003e/d\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eMLSS\u003c/p\u003e \u003cp\u003emg/l\u003c/p\u003e \u003cp\u003eof AT of\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eInfluent COD\u003c/p\u003e \u003cp\u003emg/l\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eVol.COD.Loading\u003c/p\u003e \u003cp\u003ekgCOD/ m\u003csup\u003e3\u003c/sup\u003e.d\u003c/p\u003e \u003cp\u003e(A)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eF/M Ratio\u003c/p\u003e \u003cp\u003ekgCOD/ kgMLSS.d\u003c/p\u003e \u003cp\u003e(A)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003eEffluent COD\u003c/p\u003e \u003cp\u003emg/l\u003c/p\u003e \u003cp\u003eClarifier of\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDirect\u0026thinsp;+\u0026thinsp;Effluent of\u003c/p\u003e \u003cp\u003eA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e132\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e256\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1558\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e182\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e206\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3750\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e2358\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e510\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e885\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e233\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e155\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1958\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e188\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e418\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e285\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e103\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1974\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e160\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e680\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e338\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e130\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e2083\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e63\u003c/p\u003e \u003cp\u003e(96%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e151\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e7200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e2530\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e90\u003c/p\u003e \u003cp\u003e(96%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e108\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1986\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e550\u003c/p\u003e \u003cp\u003e(72%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e98\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e115\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e438\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e438\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1703\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e258\u003c/p\u003e \u003cp\u003e(84%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e78\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e488\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e488\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1850\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e275\u003c/p\u003e \u003cp\u003e(85%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e105\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"7. CONCLUSION","content":"\u003cp\u003eThe study includes 120 days of reactor operation and performance evaluation. The operations were carried out in three phases. The following conclusions can be drawn from the study.\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eIn the first phase of this study, cow dung rich in microbial consortium were successfully used as a seed material for developing aerobic culture and flocs of good settleability.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eOn addition 25 kg (dry weight) of fresh cow dung per m\u003csup\u003e3\u003c/sup\u003e of fresh ground water as seed and on aeration of the medium with supply of N, P and other micronutrients by addition of baby food and groundnut cake, good flocs were observed on 9th day of operation.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eOn 10th day the MLSS in the AT was 800 mg/l and the sludge volume was 40 ml/litre with a sludge volume index (SVI) of 50 ml/g. This indicates that the sludge developed was of good settleability.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eAddition of nutrients like N, P along with micronutrients through the addition of baby food and groundnut cake from 7th day and 3rd day seem to have accelerated microbial growth and floc formation.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eIn spite of the second phase cow dung addition of 8 kg (dry weight) per m\u003csup\u003e3\u003c/sup\u003e of the medium, the MLSS increase from 10th day to 23rd day was only 300 mg/l whereas addition of a total of 125.5 m\u003csup\u003e3\u003c/sup\u003e of wastewater from 23rd day of operation resulted in an increase in MLSS of 400 mg/l by 27th day.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eIt shall be concluded that up on addition of cow dung at the rate of 25 kg (dry weight) per m\u003csup\u003e3\u003c/sup\u003e of medium, as seed, and on addition of N, P and other micronutrients, microbial flocs with good settleability can be obtained within 9 to 10 days of aeration. Once an MLSS of 1000 mg/l in the AT is obtained, organic loading by the addition of wastewater can be started subsequently.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eDuring the second startup operation for 33 days the aerobic bacterial flocs developed from cow dung, known to be rich in cellulose, was successfully fed with wastewater from a paper mill that use waste paper as raw material.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eDuring 33 days of operation, the applied organic loading was increased by increasing the wastewater flow to the AT and as a result the MLSS increased from 1500 mg/l to 6050 mg/l.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eDuring the last 26 days of operation the organic loading was in the range of 0.38 to 0.46 kg BOD/m\u003csup\u003e3\u003c/sup\u003e/d. In the initial 21 days of operation the MLSS increase was 2200 mg/l whereas during the remaining 12 days, the increase was 2350 mg/l. This initial delay in sludge development shall be attributed to the time required for the acclimatization to the new substrate, here cellulose, which is usually referred to as lag phase of growth.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eHowever, a more specific information on the extend of lag phase could be obtained if the higher organic loading rate was maintained from the initial days itself.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eDuring the 3rd phase of this study, the entire flow of 388 m\u003csup\u003e3\u003c/sup\u003e/d was made to flow in the A-B process by providing stepwise increase to A, correspondingly reducing direct flow to B in 43 days.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eDuring these 43 days, MLSS in A increased from 2800 to 11400 mg/l. The total BOD stabilized was 6870 kg and sludge yielded in A (volatile fraction) was 4644 kg, resulting in a yield coefficient, Y of 0.68.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eIn 4 days since 104th day, 7020 kg (dry weight) was harvested and utilized in the pulping section.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eDuring 12 days of operation from 108th day, effluent COD of A ranged from 550 mg/l to 258 mg/l, effluent COD of B ranged from 105 mg/l to 78 mg/l where the influent COD ranged from 1986 mg/l to 1703 mg/l and flow increased from 388 m\u003csup\u003e3\u003c/sup\u003e/d to 488 m\u003csup\u003e3\u003c/sup\u003e/d.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe volumetric loading was in the range of 0.73 to 0.9 kg COD/m\u003csup\u003e3\u003c/sup\u003e.d and F/M ratio was in the range of 0.11 to 0.24 kg COD/kg MLSS in A.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to publish\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Kochu Thresya Sojan and Dr. Grasius Mattamana Geevarghese. Kochu Thresya Sojan and Dr. Grasius Mattamana Geevarghese together wrote the manuscript. All Authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was received\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFinancial interests: Kochu Thresya Sojan declare she has no financial interests. Dr Grasius Mattamana Geevarghese is consultant to CSons Paper Mills Pvt. Ltd.; Puthupady PO, Ernakulam district, India.\u003c/p\u003e\n\u003cp\u003eNon-financial interests: none.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analysed during the present study are not included in this published article. Only the data pertaining to the manuscript is included.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eArceivala SJ, Shyam R Asolekar (2003) Wastewater Treatment for Pollution Control and Reuse. Tata McGraw-Hill Publishing Company Ltd, New Delhi\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGray NF (1990) Activated Sludge Theory and Practice. Oxford University press, New York\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGrasius MG (1996) Design, Development and Performance Evaluation of a modified UASB Reactor for Treatment of Low-Strength Wastewaters. Ph.D. thesis submitted to Dept. of Civil Engineering, IIT Kanpur, India\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKraft Paper Industry - Investment Project Opportunity for Startups and Entrepreneurs : Poised for Continuous and Rapid Growth in the Coming Years. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.entrepreneurindia.co/Document/Download/pdfanddoc-912958-.pdf\u003c/span\u003e\u003cspan address=\"https://www.entrepreneurindia.co/Document/Download/pdfanddoc-912958-.pdf\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMetcalf \u0026amp; Eddy (2004) Wastewater Engineering, Treatment and Reuse. Tata McGraw-Hill Publishing Company Ltd, New Delhi\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRao MN, Datta AK (1979) Waste Water Treatment Rational Methods of Design and Industrial Practises. Oxford \u0026amp; IBH Publishing Co., New Delhi\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMonod J (1949) \u0026ldquo;The Growth of Bacterial Cultures,\u0026rdquo; Annual Review of Microbiology, 3,371 (1949)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOmid Ashraf L, Fariborz Haghighat (2015) Yerushalmi \u0026amp; Wastewater treatment in the pulp and paper industry: A review of treatment process and the associated greenhouse gas emission\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStandard Methods for the Examination of Water and Wastewater (2005) (21st Ed.) Jointly published by American Public Health Association, American Water Works Association, and Water Environment Federation, Washington, D.C. 20001 \u0026ndash; 3710\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"environmental-science-and-pollution-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"espr","sideBox":"Learn more about [Environmental Science and Pollution Research](https://www.springer.com/journal/11356)","snPcode":"11356","submissionUrl":"https://submission.nature.com/new-submission/11356/3","title":"Environmental Science and Pollution Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"DAF, ASP, AT, A-B Process, MLSS, SV, SVI, F/M","lastPublishedDoi":"10.21203/rs.3.rs-3006713/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3006713/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this case study, process startup and operation of the Effluent Treatment plant of a paper mill that converts waste paper to paper and paper boards were investigated for 120 days. To meet water requirements for a revised production target of 100 t/d, apart from recycling 1000 m\u003csup\u003e3\u003c/sup\u003e/d of wastewater after DAF process, required additional facilities to provide secondary treatment for another 1000 m\u003csup\u003e3\u003c/sup\u003e/d of wastewater in ASP (A-B process) were provided. A new ASP (A) with an AT of 900 m\u003csup\u003e3\u003c/sup\u003e was arranged to work in line with the existing ASP (B) of 1200 m\u003csup\u003e3\u003c/sup\u003e capacity. Initiating culture development, 19.6 tons of fresh cow dung (seed) was added to AT of unit B containing 600 m\u003csup\u003e3\u003c/sup\u003e of fresh ground water and the tank content was aerated. N, P, micronutrients and protein were added to AT every day. Good flocs were observed on 9th day of operation. MLSS of 1500 mg/l and a sludge volume 50 ml/l was observed on 27th day of aeration. Addition of appropriate nutrients and protein are believed to have aided sludge development and floc formation. During secondary startup, wastewater addition started (108 m\u003csup\u003e3\u003c/sup\u003e/d) on a regular basis on 27th day and was increased stepwise to 388 m\u003csup\u003e3\u003c/sup\u003e/d in 7 days and was continued till the end of this phase of the study. During 33 days of secondary startup influent BOD was in the range of 1170\u0026ndash;1500 mg/l, organic loading ranged from 0.13 to 0.46 kg BOD/m\u003csup\u003e3\u003c/sup\u003e.d and F/M ratio ranged between 0.07 to 0.17 kg BOD/kg MLSS/d. BOD/N/P ratio of 200/5/1.5 was maintained along with addition of micronutrients and protein. On 60th day, MLSS was 6050 mg/l indicating that culture developed from cow dung got acclimatized easily to paper mill waste mostly containing cellulose. Initiating the next phase, required quantity of sludge was transferred from B to A to get an MLSS of 2800 mg/l in A and of 4200 mg/l in B. The wastewater flow of 388 m\u003csup\u003e3\u003c/sup\u003e/d, then flowing to B, was made to flow in the A-B process by providing stepwise increase to A, correspondingly reducing direct flow to B in 43 days. On 104th day, the MLSS rose to 11400 mg/l in A. During these 43 days of operation, unit A stabilized a total BOD of 6870 kg, and the volatile content of the sludge yielded was 4644 kg resulting in a yield coefficient, Y of 0.68. Organic loading ranged from 0.35 to 1.09 kgCOD/m\u003csup\u003e3\u003c/sup\u003e.d and F/M ranged between 0.04 to 0.12 kg COD/kg MLSS.d. Effluent COD ranged from 500\u0026thinsp;\u0026minus;\u0026thinsp;63 mg/l for an average inlet COD of 1940 mg/l. There after MLSS in A was reduced to 3600 mg/l in 4 days by harvesting sludge and the same was recycled to the pulping section of the mill. Flow was increased to 488 m\u003csup\u003e3\u003c/sup\u003e/d stepwise and the MLSS increased to 7800 mg/l in next 12 days in A. Effluent COD of A ranged from 550\u0026thinsp;\u0026minus;\u0026thinsp;258 mg/l and COD of the final effluent, that is, of unit B ranged from 98\u0026ndash;105 mg/l. The production seized in the paper mill due to Covid 19 and hence this study was terminated at this stage.\u003c/p\u003e","manuscriptTitle":"Speedy Mlss Development From Cow Dung, Wastewater Treatment and Sludge Recovery From the Activated Sludge Process (a-b Process) of a Paper Mill That Use Waste Paper as Raw Material - A Case Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-09-14 20:44:20","doi":"10.21203/rs.3.rs-3006713/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2023-09-10T10:04:29+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2023-09-10T10:03:45+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Environmental Science and Pollution Research","date":"2023-06-21T18:31:28+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2023-06-14T05:38:28+00:00","index":"","fulltext":""},{"type":"submitted","content":"Environmental Science and Pollution Research","date":"2023-06-08T07:41:57+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"environmental-science-and-pollution-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"espr","sideBox":"Learn more about [Environmental Science and Pollution Research](https://www.springer.com/journal/11356)","snPcode":"11356","submissionUrl":"https://submission.nature.com/new-submission/11356/3","title":"Environmental Science and Pollution Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"1e13cd64-b156-4b70-b22d-2b1c0a8d45c4","owner":[],"postedDate":"September 14th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2023-09-14T20:44:20+00:00","versionOfRecord":[],"versionCreatedAt":"2023-09-14 20:44:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3006713","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3006713","identity":"rs-3006713","version":["v1"]},"buildId":"ehx78VzkSd0WSzXnipQa-","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}