Assessing the purity and fertilizing potential of struvite derived from domestic wastewater using dolomite rock as a magnesium source

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The objective of this study was to ascertain the ideal dosage and a sustainable fertilizer efficacy of the recovered struvite. The resulting product was brownish in color and chemically different from pure struvite; it had 1.01% nitrogen, 2.66% phosphorus, 0.06% potassium, 2.58% magnesium, and a high 11.77% calcium content, indicating considerable calcium co-precipitation that impacted the purity of the product. To measure the growth response based on stem height, stem circumference, leaf number, leaf width, and dry biomass, maize plants were fed with different doses of struvite (8, 12, 16, and 20 g). According to the findings, an 8 g dose considerably increased plant growth, surpassing larger doses and exhibiting a plateau effect. The recovered struvite, in spite of its impure state, turned out to be a viable and efficient substitute for traditional fertilizers. This study emphasizes how nutrient recovery from wastewater can help promote environmentally friendly agricultural practices. Biological sciences/Ecology Earth and environmental sciences/Ecology Earth and environmental sciences/Environmental sciences Biological sciences/Plant sciences pure Struvite dolomite rock domestic wastewater fertilizing efficiency optimal dose nutrient recovery sustainable fertilizer 1 Introduction Agricultural productivity in Africa is strongly dependent on the availability and efficient use of fertilizers, especially phosphorus-based fertilizers. As the continent’s population grows and the demand for food rises, the need to restore and maintain soil fertility has become increasingly urgent (Ludemann et al., 2022 ). However, access to conventional fertilizers in many African countries remains limited due to high costs, inadequate infrastructure, and reliance on imports(Vanlauwe et al., 2014 ). These challenges contribute to declining soil fertility and stagnant crop yields across large areas of Sub-Saharan Africa. To address this, there is a pressing need for sustainable and locally available alternatives to conventional fertilizers. Phosphorus (P) is an essential macronutrient for plant development, playing a central role in photosynthesis, energy transfer, and root formation(Cordell et al., 2009 ). The primary source of phosphorus used in fertilizer production is phosphate rock, a finite and non-renewable resource(Cordell et al., 2009 ). Globally, phosphate rock reserves are highly concentrated, with more than 70% located in Morocco and Western Sahara alone(Jasinski, 2023 ). The uneven geographical distribution and diminishing quality of phosphate rock pose serious threats to long-term global food security and make phosphorus a potentially critical resource in the coming decades (Cordell & White, 2013 ). Recovering phosphorus from wastewater presents a sustainable alternative that can help close the nutrient loop, reduce environmental pollution, and preserve natural phosphate rock reserves(Petzet & Cornel, 2011 ). Domestic wastewater, in particular, contains considerable quantities of phosphorus and nitrogen, which if not properly managed, can lead to eutrophication of water bodies(Liu et al., 2013 ; Rahman et al., 2014 ; Smith et al., 1999 ). One of the most promising technologies for nutrient recovery is the precipitation of struvite (magnesium ammonium phosphate hexahydrate – MgNH₄PO₄·6H₂O), which can be harvested from wastewater under controlled condition(Le Corre et al., 2009 ; Martí et al., 2010 ). Struvite is recognized for its slow-release properties, making it an efficient and environmentally friendly fertilizer that minimizes nutrient losses and enhances nutrient uptake by crops(Johnston A.E.* & Richards, 2003). Conventional struvite production typically requires the addition of commercial magnesium salts such as MgCl₂ or MgSO₄, which can be cost-prohibitive for widespread use in low-income regions(Yetilmezsoy et al., 2017 ). In contrast, dolomite rock (CaMg(CO₃)₂), a naturally occurring and widely available mineral, presents a cost-effective alternative magnesium source for struvite precipitation(Rahman et al., 2014 ). Utilizing dolomite aligns with resource-efficient strategies suited for decentralized wastewater treatment systems, particularly in developing regions. However, to ensure the agricultural suitability and environmental safety of struvite produced from dolomite, it is essential to assess its chemical purity and fertilizing sufficiency. This study aims to evaluate the quality and nutrient release potential of struvite precipitated from domestic wastewater using dolomite rock as a magnesium source. The findings will contribute to the development of low-cost, sustainable fertilizer alternatives while promoting integrated waste management and resource recovery in the African context. 2 Materials and Methodology 2.1 Description of the study area The research was carried out at Arba Minch, the city of South Ethiopia Regional state. With its network of springs and close vicinity to Lake Abaya and Lake Chamo, Arba Minch, which translates to "Forty Springs," is well-known for its plentiful natural water resources. According to National Meteorology Agency of Ethiopia the area is situated geographically at 6° 2˝ N 37° 33˝ E, and its elevation is 1,390 meters above sea level. Approximately 17.37°C is the mean minimum temperature and 30.30°C is the mean maximum temperature. December saw the lowest recorded mean minimum temperature of 15.13°C and the highest recorded at 32°C. 2.2 Dolomite dissolution For struvite precipitation, dolomite rock served as a supply of magnesium(Rahman et al., 2014 ). 2M hydrochloric acid (HCl) was used to dissolve the crushed and dried dolomite in a 25% solid-to-liquid ratio after it had been sieved through a 425µm sieve. For ten minutes, the dissolution process was conducted with continuous stirring at a speed of 200 rpm to guarantee that the dolomite was completely dissolved(Yildirim, 2008 ). The solution was then placed in a thermostatically controlled water bath (KOTTER MANN) for 30 minutes at 80 degrees Celsius to release the calcium and magnesium ions(Yildirim & Akarsu, 2010 ). After cooling, any remaining particles were filtered out of the resultant solution using a 0.45µm pore size WHAT-MAN filter paper, and stored for subsequent experiments According to (Saldi et al., 2021 ),the following reaction may happen when dolomite is dissolved in 2M hydrochloric acid: CA Mg (CO 3 ) 2 + 4H + = Ca 2+ + Mg 2+ + 2H 2 CO 3 . An atomic absorption spectrophotometer was used to analyze the concentrations of Ca 2+ , Mg 2+ , Na + , and K + ions (Yildirim & Akarsu, 2010 ). 2.3 Struvite precipitation process The dolomite solution prepared earlier was mixed with the wastewater in varying ratios to investigate its efficiency in nutrient recovery through struvite precipitation. The pH of the mixtures was adjusted to 8.0 (Darwish et al., 2016 ; Le Corre et al., 2009 ; Zhou et al., 2023 ) using 1M sodium hydroxide (NaOH) to create optimal conditions for struvite formation. The mixture was stirred continuously by using orbital shaker at a stirring speed of 76rpm (Darwish et al., 2016 ; Ohlinger, 2018 ) for 25 minutes (Darwish et al., 2016 ) to allow for sufficient interaction between the dolomite solution and the wastewater. In order to separate the solid precipitates, the mixtures were filtered through a 0.45µm pore size WHAT-MAN filter paper after the reaction had been allowed to settle for six hours(Etter et al., 2011 ). Nutrient recovery percentages were computed by analyzing the filtrate for residual amounts of (NH 4 -N) and (PO 4 3− -p). The production of the solid precipitate (struvite) was measured by weighing it after it had been dried in the sunlight(Etter et al., 2011 ). 2.4 Characterization of the struvite 2M hydrochloric acid (HCl) was used to dissolve the crushed and dried struvite in a 25% solid-to-liquid ratio after it had been sieved through a 425µm sieve. For ten minutes, the dissolution process was conducted with continuous stirring at a speed of 200 rpm to guarantee that the dolomite was completely dissolved(Yildirim, 2008 ). The solution was then placed in a thermostatically controlled water bath (KOTTER MANN) for 30 minutes at 80 degrees Celsius to release the calcium and magnesium ions(Yildirim & Akarsu, 2010 ). After cooling, any remaining particles were filtered out of the resultant solution using a 0.45µm pore size WHAT-MAN filter paper, and stored for subsequent experiments. An atomic absorption spectrophotometer was used to analyze the concentrations of Ca 2+ , Mg 2+ , Na + , and K + ions(Yildirim & Akarsu, 2010 ). According to research (Krishnamurthy et al., 2021; Rahman et al., 2014 ), struvite is a slow-release crystal fertilizer that works well and may be administered to crops as soon as they are planted. The concentration of heavy metals in the produced struvite is the first and most crucial factor in determining whether or not it may be utilized as fertilizer(Uysal et al., 2010 ). According to this study, the concentration of heavy metals (As, Ni, Cr, Zn, and Cu) was below the AAS instrument's detection limit. It is therefore possible to use the struvite generated in this work as fertilizer. Finding the fertilizing efficacy of struvite by comparing it to inorganic fertilizer (NPK) was the second task that was carried out. Phosphate phosphorus determination Ammonium nitrogen determination 2.5 Fertilizer Efficiency Evaluation For the evaluation of the fertilizing efficiency of struvite crop trial experiment was conducted by planting maize seed. In order to plant maize seeds, twenty-four plastic pots were prepared. Each pot was filled with an equal amount of correctly mixed soil from a common area. Accordingly, five treatments each with four replicates and a control were constructed. In the first, there was no chemical fertilizer added as a control; in the second, there were 8 grams of NPK (chemical fertilizer) according to the common agricultural practice of the area, in the third, there were eight grams of struvite; in the fourth, there were twelve grams of struvite; in the fifth, there were sixteen grams of struvite; and in the sixth, there were twenty grams of struvite. When struvite was applied, the dosages were 1, 1.5, 2, and 2.5 times that of NPK (Liu et al., 2013 ). Both NPK and struvite were applied on the planting day. Because struvite is a slow-release cristal fertilizer(Rahman et al., 2014 ). The fertilizing effect of Struvite was assessed in comparison to the control and fertilizers. 2.6 Comparison with Conventional Fertilizers The plants were harvested after two months, and measurements and records were made of the dry biomass of the maize, the number of leaves, the maximum width and length of the leaves, and the height of the stem. Following three days of drying at 70 o C in an oven, the entire plant was weighed to measure its dry weight(Nilsson & Li, 2007 ). To determine whether there was a significant difference in the mean value of the variables, the experiment's data were examined using the mean and standard deviation in conjunction with a one-way ANOVA(Kassa et al., 2018 ) 3 Results and discussion 3.1 Chemical composition of struvite The chemical composition of the produced struvite was analyzed, and the results are shown in the Table 3 :1. 3:1 the chemical composition of the produced struvite no parameters concentration mg/l Concentration (%) 1 Magnesium(Mg 2+ ) 234.9 2.58 2 Calcium(Ca 2+ ) 29685.4 11.77 3 Sodium(Na + ) 0.061 0.05 4 Potassium( K + ) 0.073 0.06 5 Phosphate(PO 4 3− -p) 245.7 2.66 6 Ammonium nitrogen 121.3 1.01 The findings highlight the elemental concentrations of key components, including magnesium (Mg²⁺), calcium (Ca²⁺), phosphate (PO₄³⁻-P), ammonium nitrogen (NH₄⁺-N), sodium (Na⁺), and potassium (K⁺). These values provide insight into the composition and potential utility of the struvite as a slow-release fertilizer. Magnesium (Mg²⁺) The concentration of magnesium in the produced struvite was 234.9 mg/L, contributing to 2.58% of the total composition. Magnesium is an essential component of struvite and plays a crucial role in its crystallization process. This concentration indicates that magnesium from dolomite was effectively utilized in the precipitation reaction. Studies have shown that sufficient magnesium is critical for efficient struvite formation, as it reacts with ammonium and phosphate to form the crystal lattice(Le Corre et al., 2009 ). Calcium (Ca²⁺) Calcium was present at a significantly higher concentration of 29685.4 mg/L, constituting 11.77% of the total composition. This high calcium concentration suggests the possibility of co-precipitation of calcium compounds, such as calcium phosphate, alongside struvite. Excess calcium in the system can interfere with struvite formation and reduce its purity by forming competing precipitates. This phenomenon has been observed in other studies, particularly when using calcium-rich dolomite as a magnesium source(Rahman et al., 2014 ). Phosphate (PO₄³⁻-P) The phosphate content of the struvite was 245.7 mg/L, representing 2.66% of the total composition. Phosphate is a critical nutrient in struvite and is responsible for its utility as a phosphorus-rich fertilizer. The recovery of phosphate in this study demonstrates the effectiveness of dolomite as a reagent for struvite precipitation. These findings align with previous research, which underscores the role of phosphate in the crystallization process and its recovery potential from wastewater(Song et al., 2007 ). Ammonium Nitrogen (NH₄⁺-N) The ammonium nitrogen concentration in the struvite was 121.3 mg/L, making up 1.01% of the total composition. Ammonium ions are essential for the formation of struvite crystals, as they combine with magnesium and phosphate in stoichiometric proportions. The recovery of ammonium nitrogen indicates the dual nutrient recovery capability of this process, making struvite an attractive option for sustainable wastewater treatment. Sodium (Na⁺) and Potassium (K⁺) Sodium and potassium were present in trace amounts, with concentrations of 0.061 mg/L (0.05%) and 0.073 mg/L (0.06%), respectively. Their low concentrations suggest minimal interference with the struvite precipitation process. These elements may originate from the dolomite or wastewater but are not significant contributors to the struvite composition. 3.2 The purity of the produced struvite According to several researchers (Korchef et al., 2011; Liu et al., 2013 ; Rahman et al., 2014 ; Yesigat et al., 2022), the ideal chemical composition of pure struvite is magnesium ammonium phosphate hexahydrate (MgNH₄PO₄·6H₂O), which appears as a white crystalline solid. This ideal form assumes a 1:1:1 molar ratio of magnesium, phosphorus, and nitrogen. However, the struvite recovered in this study deviates from this pure form both in appearance and chemical composition. The product obtained was brownish in color and contained 1.01% nitrogen, 2.66% phosphorus, 0.06% potassium, 2.58% magnesium, and a significantly high 11.77% calcium content. The presence of elevated calcium levels indicates substantial co-precipitation of metallic ions particularly calcium during the recovery process, which adversely affects the purity of the struvite. As a result, the final product cannot be classified as pure struvite. Nevertheless, it is worth noting that the recovered material is free from detectable concentrations of heavy metals, which are known to pose risks to plant and human health. This absence of toxic elements makes the product safe for further testing in agricultural applications. Despite its impurity, the chemical composition of the synthesized struvite suggests a strong potential as a slow-release fertilizer. It retains essential nutrients such as phosphorus, magnesium, and ammonium nitrogen key elements for plant growth. Moreover, the study underscores the viability of using dolomite as an economical and effective source of magnesium for struvite precipitation, reinforcing its practicality for sustainable nutrient recovery from wastewater. 3.3 The fertilizing efficiency of struvite Following two months, the maize plants were harvested, and the dry biomass, number of leaves, maximum leaf breadth and length, stem height, and stem circumference were measured and recorded in Table 3 :2. Table 3 :2 plant growth parameters for different treatments Treatments Parameters Steam height (cm) Steam width(cm) Dry Biomass(gram) No of leaf Max.leaf width(cm) Max.leaf length(cm) control 1 90 7.5 38.4 11 7 75 2 100 6.5 33.6 14 6 65 3 110 7 47.8 13 7 70 4 105 6.5 37.5 14 5 85 8 gram fertilizer 1 195 9.8 173.1 16 10 90 2 120 8 146.9 15 9 70 3 190 9 158.6 15 10 100 4 140 9.5 161.8 16 8 80 8 gram struvite 1 190 10 169.4 17 12 105 2 200 9.5 170.5 17 10 100 3 185 9 149.7 16 9 94 4 191.7 9.5 163.2 16.7 10.3 99.7 12 gram struvite 1 190 10 143.3 17 11 108 2 180 9 161.9 17 10 95 3 185 9 171.7 16 9 90 4 190 8.5 131.9 16 9 100 16 gram struvite 1 160 11 189.1 17 12 105 2 190 10 176.3 16 10 94 3 185 11 169.5 17 9 105 4 180 9 193.1 17 9 100 20 gram struvite 1 180 11.5 161.5 17 11 95 2 190 10.5 130.8 16 10 85 3 190 11 167.6 17 12 100 4 200 10.5 175.3 17 10 105 3.4 Statistical Analysis The analysis of the experimental results of the pot experiment was done by one-way ANOVA. Results of multiple comparisons of Dry Biomass, number of leaf, leaf length, leaf width, steam circumference and steam height between different treatment groups was done by using the Least Significant Difference (LSD) test. The dependent variables are Dry Biomass, number of leaf, maximum leaf length, maximum leaf width, steam circumference, steam height, and the treatments include a control, 8 gram fertilizer, 8 gram struvite, 12 gram struvite, 16 gram struvite and 20 gram struvite. Significant differences at the 0.05 level were marked with an asterisk (*). 3.4.1 Dry biomass (gram) All struvite treatments (8 g, 12 g, 16 g, and 20 g) and the 8 g fertilizer treatment significantly increased dry biomass compared to the control. The mean difference was − 120.8 for 8 g fertilizer (p < 0.001) and − 142.7 for 16 g struvite (p < 0.001), confirming greater biomass production with fertilizer and struvite application. No significant differences were observed between 8 g fertilizer and 8 g struvite, and only a slight reduction in biomass was noted for 8 g fertilizer compared to 12 g struvite (-7.9, p = 0.413). Aside from the 16 g dose (-29.8, p = 0.005), no significant differences were found among 8 g, 12 g, and 20 g struvite treatments. Overall, fertilizer and struvite treatments enhanced dry biomass, with the control consistently performing worse. These findings suggest that 8 g of struvite is the optimal dosage for biomass formation. 3.4.2 Number of leaf All treatments (8 g fertilizer and all struvite dosages) significantly increased the number of leaves compared to the control (p < 0.001). The highest increases were with 8 g, 16 g, and 20 g struvite, with a mean of 3.750 more leaves. The 8 g fertilizer treatment also significantly increased the number of leaves by 2.500 (p < 0.001). Struvite treatments (8 g, 12 g, 16 g, and 20 g) were all better than the control in inducing leaf formation with mean differences ranging from 3.500 to 3.750 (p < 0.001). No significant differences were observed among struvite dosages, an implication that using more than 8 g of the dose does not further enhance leaf count. These findings confirm struvite as an effective and green fertilizer alternative, with 8 g determined as the optimal dose for leaf maximization. 3.4.3 Maximum Leaf length All struvite treatments (8 g, 12 g, 16 g, and 20 g) significantly enlarged leaf length compared to the control (p < 0.05), with mean differences ranging from − 22.500 cm to -27.250 cm. The 8 g fertilizer treatment significantly had shorter leaves than all the struvite treatments except for 20 g struvite, which did not differ significantly (p = 0.073). Compared to 8 g fertilizer, dosages of 8 g, 12 g, and 16 g struvite significantly increased leaf length (-13.250 cm to -16.000 cm). Struvite dosages were not significantly different from each other, indicating that dosing above 8 g does not influence leaf length more. Due to diminishing returns with increasing dosages, 8 g of struvite is the optimum for leaf length enhancement. These findings indicate struvite as a viable alternative to conventional fertilizers for plant growth promotion. 3.4.4 Maximum Leaf width All treatments significantly increased leaf width compared to the control (p < 0.05), the largest of which was observed in 20 g struvite (4.500 cm, p 0.05). Although 20 g struvite presented the greatest mean difference (1.500 cm), it was not significant (p = 0.069), indicating that the increase in struvite dosage does not have a significant influence on leaf width. Struvite has a consistent effect in increasing leaf width, showing its potential as a source of nutrients. Because there were no significant differences among dosages, 8 g struvite can be the ideal dosage for leaf width increase 3.4.5 Steam height Stem height also increased significantly with all treatments compared to control (p < 0.001). Stem height was highest with 8 g struvite (90.425 cm), followed by 20 g struvite (88.750 cm). Stem height with 8 g fertilizer was boosted by 60.000 cm but much lower compared to 8 g (-30.425 cm, p = 0.021) and 20 g struvite (-28.750 cm, p = 0.028). There were no significant differences among intermediate dosages of struvite (12 g, 16 g, and 20 g), indicating a plateau effect. Low dosages of struvite, particularly 8 g, were effective in promoting stem height, suggesting it is sufficient for optimal growth. The results indicate struvite as a via ble substitute for traditional fertilizers. 3.4.6 Steam circumference Stem circumference increased much more with all treatments than in the control (p < 0.001), with greatest growth at 20 g struvite (4.000 cm). The 8 g fertilizer treatment significantly smaller stem circumference than 16 g (-1.175 cm, p = 0.020) and 20 g struvite (-1.800 cm, p = 0.001), while no differences were significant between 8 g fertilizer and lower dosages of struvite (8 g and 12 g). 20 g struvite treatment was significantly better than 8 g (p = 0.008) and 12 g struvite (p = 0.001), though there were no differences between 16 g and 20 g, which suggests a plateau effect. However, 16 g struvite also had greater stem circumference compared to the control, 8 g fertilizer, and 12 g struvite. These results reveal struvite's effectiveness in optimizing stem circumference with 16 g being the optimal dosage for balancing growth and resource use, hence struvite as an effective alternative to conventional fertilizers. 3.5 Limitations and practical challenges In conducting a crop trial experiment, it is essential to begin with a thorough analysis of the initial soil properties, particularly its chemical composition. Understanding the baseline concentrations of key macronutrients especially nitrogen (N) and phosphorus (P) prior to the application of struvite is critical. This initial data serves multiple purposes: it helps in assessing the direct contribution of struvite to soil nutrient enrichment, and it also provides insight into the soil's nutrient retention and absorption capacity. Such baseline measurements form the foundation for evaluating the effectiveness of struvite as a fertilizer. Unfortunately, due to the unavailability of appropriate analytical equipment in our laboratory, we were unable to perform the necessary pre-treatment soil analysis. This limitation is acknowledged as a constraint in fully quantifying the nutrient dynamics and evaluating the precise impact of struvite application in our experimental setup. As previously discussed, dolomite rock was utilized as the magnesium source for struvite precipitation in this study. However, it is important to note that the specific dolomite rock used contained a higher concentration of calcium compared to magnesium. This imbalance significantly influenced the struvite formation process. Chemical analysis of the precipitated struvite revealed that the elevated calcium content interfered with the crystallization process, leading to reduced purity of the final product. The presence of excess calcium can compete with magnesium during precipitation, resulting in the formation of unwanted byproducts such as calcium phosphates, which compromise the structural integrity and fertilizing efficiency of struvite. This issue represented one of the major challenges encountered during the experimental phase of the research. To overcome this limitation and enhance the purity of struvite produced from dolomite-based systems, further investigation is required. Future research should focus on strategies to minimize calcium interference such as selective pre-treatment of dolomite, controlled precipitation conditions, or alternative low-calcium magnesium sources to optimize struvite recovery and ensure its effectiveness as a sustainable fertilizer. 4 Conclusion All things considered, the study demonstrates that struvite is a highly effective and sustainable fertilizer, significantly enhancing various plant growth parameters such as dry biomass, number of leaves, leaf breadth, leaf length, stem height, and stem circumference compared to the control. At higher concentrations, struvite outperformed conventional fertilizers; however, dosages beyond 8 g did not result in additional notable benefits, indicating a plateau effect. The 8 g dose emerged as the most effective and economical option, ensuring optimal plant growth while promoting resource efficiency. It is important to note, however, that the struvite recovered in this study deviates from the pure form both in appearance and chemical composition. The product was brownish in color and contained 1.01% nitrogen, 2.66% phosphorus, 0.06% potassium, 2.58% magnesium, and a notably high 11.77% calcium content. The elevated calcium concentration indicates substantial co-precipitation of metallic ions, particularly calcium, during the recovery process, which negatively impacts the purity of the struvite. Consequently, the final product cannot be classified as pure struvite. Despite this, the findings highlight the potential of recovered struvite, even in its impure form, to serve as a viable and sustainable alternative to chemical fertilizers, contributing to improved plant health and environmental sustainability. Declarations Ethics approval not applicable Consent to participate not applicable Consent for publication not applicable Funding There is no funding Conflict of interest : The authors have no relevant financial or non-financial interests to disclose Availability of data and materials: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request Acknowledgment The authors would like to express their sincere appreciation to Arba Minch University for providing the opportunity and necessary support to undertake this research. Special thanks are extended to the dedicated Water Quality Experts at Arba Minch University for their valuable guidance, technical assistance, and commitment throughout the experimental work References Cordell, D., Drangert, J. O. & White, S. The story of phosphorus: Global food security and food for thought. Glob. Environ. Change . 19 (2), 292–305. https://doi.org/10.1016/j.gloenvcha.2008.10.009 (2009). 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The determination of fertilizer quality of the formed struvite from effluent of a sewage sludge anaerobic digester. J. Hazard. Mater. 181 (1–3), 248–254. https://doi.org/10.1016/j.jhazmat.2010.05.004 (2010). Vanlauwe, B., Asten, P. J. A., Van, Group, O., Blomme, G. & International, B. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of Sub-Saharan Africa. Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of Sub-Saharan Africa , January . (2014). https://doi.org/10.1007/978-3-319-07662-1 Yetilmezsoy, K., Ilhan, F., Kocak, E. & Akbin, H. M. Feasibility of struvite recovery process for fertilizer industry: A study of financial and economic analysis. J. Clean. Prod. 152 , 88–102. https://doi.org/10.1016/j.jclepro.2017.03.106 (2017). Yildirim, M. Dissolution Kinetics of Icel-Aydincik Dolomite in Hydrochloric Acid . 127–132. (2008). Yildirim, M. & Akarsu, H. Preparation of magnesium oxide (mgo) from dolomite by leach-precipitation-pyrohydrolysis process. Physicochemical Probl. Mineral. Process. 44 , 257–272 (2010). Zhou, Y., Zhu, Y., Zhu, J., Li, C. & Chen, G. A Comprehensive Review on Wastewater Nitrogen Removal and Its Recovery Processes. Int. J. Environ. Res. Public Health . 20 (4). https://doi.org/10.3390/ijerph20043429 (2023). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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-7406473","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":511945022,"identity":"d5c56d19-5192-4cd1-beec-fe49815dec99","order_by":0,"name":"Melsew Endalew Berihun","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA40lEQVRIiWNgGAWjYFAC5gYGBjYGGX725gNAnoQMEVoYwVp4JHuOJYC08BCvxeBGjgGIS1iLbntj4+OCMjuQls+vbtRY8DCwHz66AZ8WszMHm41nnEvmkTzzdpt1zjGgw3jS0m7g1XIjsU2at42Zh+947jbjHDagFgkeM/xa7j9s/83bVs/DcCDnmXHOP2K03GBsY+ZtO8wjcCKH+XFuGzFaziQ2S/OcOw4KZDPm3D4JHjaCfjl++OBnnrJqOWBUPv6c860OyDh8DK8WZMAmASaJVQ4CzB9IUT0KRsEoGAUjBwAAu+5IXhV2nh4AAAAASUVORK5CYII=","orcid":"","institution":"Arba minch university","correspondingAuthor":true,"prefix":"","firstName":"Melsew","middleName":"Endalew","lastName":"Berihun","suffix":""},{"id":511945023,"identity":"3be96013-6bbf-4167-b000-e617a933446a","order_by":1,"name":"knife Kassa","email":"","orcid":"","institution":"Arba minch university","correspondingAuthor":false,"prefix":"","firstName":"knife","middleName":"","lastName":"Kassa","suffix":""},{"id":511945024,"identity":"71259b07-f7a0-4010-bbc2-7d487553a2dc","order_by":2,"name":"Assen Yimam Mohammed","email":"","orcid":"","institution":"Arba minch university","correspondingAuthor":false,"prefix":"","firstName":"Assen","middleName":"Yimam","lastName":"Mohammed","suffix":""}],"badges":[],"createdAt":"2025-08-19 08:53:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7406473/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7406473/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91859898,"identity":"d4394f73-3326-4041-9ec7-60ccdf84940a","added_by":"auto","created_at":"2025-09-22 12:26:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":912378,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7406473/v1/ea413414-221e-4bc8-adb3-3522a27bfe16.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Assessing the purity and fertilizing potential of struvite derived from domestic wastewater using dolomite rock as a magnesium source","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eAgricultural productivity in Africa is strongly dependent on the availability and efficient use of fertilizers, especially phosphorus-based fertilizers. As the continent\u0026rsquo;s population grows and the demand for food rises, the need to restore and maintain soil fertility has become increasingly urgent (Ludemann et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). However, access to conventional fertilizers in many African countries remains limited due to high costs, inadequate infrastructure, and reliance on imports(Vanlauwe et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). These challenges contribute to declining soil fertility and stagnant crop yields across large areas of Sub-Saharan Africa. To address this, there is a pressing need for sustainable and locally available alternatives to conventional fertilizers.\u003c/p\u003e\u003cp\u003ePhosphorus (P) is an essential macronutrient for plant development, playing a central role in photosynthesis, energy transfer, and root formation(Cordell et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). The primary source of phosphorus used in fertilizer production is phosphate rock, a finite and non-renewable resource(Cordell et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Globally, phosphate rock reserves are highly concentrated, with more than 70% located in Morocco and Western Sahara alone(Jasinski, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The uneven geographical distribution and diminishing quality of phosphate rock pose serious threats to long-term global food security and make phosphorus a potentially critical resource in the coming decades (Cordell \u0026amp; White, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eRecovering phosphorus from wastewater presents a sustainable alternative that can help close the nutrient loop, reduce environmental pollution, and preserve natural phosphate rock reserves(Petzet \u0026amp; Cornel, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Domestic wastewater, in particular, contains considerable quantities of phosphorus and nitrogen, which if not properly managed, can lead to eutrophication of water bodies(Liu et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Rahman et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Smith et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1999\u003c/span\u003e). One of the most promising technologies for nutrient recovery is the precipitation of struvite (magnesium ammonium phosphate hexahydrate \u0026ndash; MgNH₄PO₄\u0026middot;6H₂O), which can be harvested from wastewater under controlled condition(Le Corre et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Mart\u0026iacute; et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eStruvite is recognized for its slow-release properties, making it an efficient and environmentally friendly fertilizer that minimizes nutrient losses and enhances nutrient uptake by crops(Johnston A.E.* \u0026amp; Richards, 2003). Conventional struvite production typically requires the addition of commercial magnesium salts such as MgCl₂ or MgSO₄, which can be cost-prohibitive for widespread use in low-income regions(Yetilmezsoy et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). In contrast, dolomite rock (CaMg(CO₃)₂), a naturally occurring and widely available mineral, presents a cost-effective alternative magnesium source for struvite precipitation(Rahman et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Utilizing dolomite aligns with resource-efficient strategies suited for decentralized wastewater treatment systems, particularly in developing regions.\u003c/p\u003e\u003cp\u003eHowever, to ensure the agricultural suitability and environmental safety of struvite produced from dolomite, it is essential to assess its chemical purity and fertilizing sufficiency. This study aims to evaluate the quality and nutrient release potential of struvite precipitated from domestic wastewater using dolomite rock as a magnesium source. The findings will contribute to the development of low-cost, sustainable fertilizer alternatives while promoting integrated waste management and resource recovery in the African context.\u003c/p\u003e"},{"header":"2 Materials and Methodology","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Description of the study area\u003c/h2\u003e\u003cp\u003eThe research was carried out at Arba Minch, the city of South Ethiopia Regional state. With its network of springs and close vicinity to Lake Abaya and Lake Chamo, Arba Minch, which translates to \"Forty Springs,\" is well-known for its plentiful natural water resources. According to National Meteorology Agency of Ethiopia the area is situated geographically at 6\u0026deg; 2˝ N 37\u0026deg; 33˝ E, and its elevation is 1,390 meters above sea level. Approximately 17.37\u0026deg;C is the mean minimum temperature and 30.30\u0026deg;C is the mean maximum temperature. December saw the lowest recorded mean minimum temperature of 15.13\u0026deg;C and the highest recorded at 32\u0026deg;C.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Dolomite dissolution\u003c/h2\u003e\u003cp\u003eFor struvite precipitation, dolomite rock served as a supply of magnesium(Rahman et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). 2M hydrochloric acid (HCl) was used to dissolve the crushed and dried dolomite in a 25% solid-to-liquid ratio after it had been sieved through a 425\u0026micro;m sieve. For ten minutes, the dissolution process was conducted with continuous stirring at a speed of 200 rpm to guarantee that the dolomite was completely dissolved(Yildirim, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). The solution was then placed in a thermostatically controlled water bath (KOTTER MANN) for 30 minutes at 80 degrees Celsius to release the calcium and magnesium ions(Yildirim \u0026amp; Akarsu, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAfter cooling, any remaining particles were filtered out of the resultant solution using a 0.45\u0026micro;m pore size WHAT-MAN filter paper, and stored for subsequent experiments\u003c/p\u003e\u003cp\u003eAccording to (Saldi et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2021\u003c/span\u003e),the following reaction may happen when dolomite is dissolved in 2M hydrochloric acid:\u003c/p\u003e\u003cp\u003eCA Mg (CO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e + 4H\u003csup\u003e+\u003c/sup\u003e = Ca\u003csup\u003e2+\u003c/sup\u003e + Mg\u003csup\u003e2+\u003c/sup\u003e + 2H\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e.\u003c/p\u003e\u003cp\u003eAn atomic absorption spectrophotometer was used to analyze the concentrations of Ca\u003csup\u003e2+\u003c/sup\u003e, Mg\u003csup\u003e2+\u003c/sup\u003e, Na\u003csup\u003e+\u003c/sup\u003e, and K\u003csup\u003e+\u003c/sup\u003e ions (Yildirim \u0026amp; Akarsu, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Struvite precipitation process\u003c/h2\u003e\u003cp\u003eThe dolomite solution prepared earlier was mixed with the wastewater in varying ratios to investigate its efficiency in nutrient recovery through struvite precipitation. The pH of the mixtures was adjusted to 8.0 (Darwish et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Le Corre et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Zhou et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) using 1M sodium hydroxide (NaOH) to create optimal conditions for struvite formation. The mixture was stirred continuously by using orbital shaker at a stirring speed of 76rpm (Darwish et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Ohlinger, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) for 25 minutes (Darwish et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) to allow for sufficient interaction between the dolomite solution and the wastewater.\u003c/p\u003e\u003cp\u003eIn order to separate the solid precipitates, the mixtures were filtered through a 0.45\u0026micro;m pore size WHAT-MAN filter paper after the reaction had been allowed to settle for six hours(Etter et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Nutrient recovery percentages were computed by analyzing the filtrate for residual amounts of (NH\u003csub\u003e4\u003c/sub\u003e-N) and (PO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e3\u0026minus;\u003c/sup\u003e -p). The production of the solid precipitate (struvite) was measured by weighing it after it had been dried in the sunlight(Etter et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Characterization of the struvite\u003c/h2\u003e\u003cp\u003e2M hydrochloric acid (HCl) was used to dissolve the crushed and dried struvite in a 25% solid-to-liquid ratio after it had been sieved through a 425\u0026micro;m sieve. For ten minutes, the dissolution process was conducted with continuous stirring at a speed of 200 rpm to guarantee that the dolomite was completely dissolved(Yildirim, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). The solution was then placed in a thermostatically controlled water bath (KOTTER MANN) for 30 minutes at 80 degrees Celsius to release the calcium and magnesium ions(Yildirim \u0026amp; Akarsu, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAfter cooling, any remaining particles were filtered out of the resultant solution using a 0.45\u0026micro;m pore size WHAT-MAN filter paper, and stored for subsequent experiments. An atomic absorption spectrophotometer was used to analyze the concentrations of Ca\u003csup\u003e2+\u003c/sup\u003e, Mg\u003csup\u003e2+\u003c/sup\u003e, Na\u003csup\u003e+\u003c/sup\u003e, and K\u003csup\u003e+\u003c/sup\u003e ions(Yildirim \u0026amp; Akarsu, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAccording to research (Krishnamurthy et al., 2021; Rahman et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), struvite is a slow-release crystal fertilizer that works well and may be administered to crops as soon as they are planted.\u003c/p\u003e\u003cp\u003eThe concentration of heavy metals in the produced struvite is the first and most crucial factor in determining whether or not it may be utilized as fertilizer(Uysal et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). According to this study, the concentration of heavy metals (As, Ni, Cr, Zn, and Cu) was below the AAS instrument's detection limit. It is therefore possible to use the struvite generated in this work as fertilizer. Finding the fertilizing efficacy of struvite by comparing it to inorganic fertilizer (NPK) was the second task that was carried out.\u003c/p\u003e\u003cp\u003ePhosphate phosphorus determination\u003c/p\u003e\u003cp\u003eAmmonium nitrogen determination\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.5 Fertilizer Efficiency Evaluation\u003c/h2\u003e\u003cp\u003eFor the evaluation of the fertilizing efficiency of struvite crop trial experiment was conducted by planting maize seed. In order to plant maize seeds, twenty-four plastic pots were prepared. Each pot was filled with an equal amount of correctly mixed soil from a common area. Accordingly, five treatments each with four replicates and a control were constructed. In the first, there was no chemical fertilizer added as a control; in the second, there were 8 grams of NPK (chemical fertilizer) according to the common agricultural practice of the area, in the third, there were eight grams of struvite; in the fourth, there were twelve grams of struvite; in the fifth, there were sixteen grams of struvite; and in the sixth, there were twenty grams of struvite.\u003c/p\u003e\u003cp\u003eWhen struvite was applied, the dosages were 1, 1.5, 2, and 2.5 times that of NPK (Liu et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Both NPK and struvite were applied on the planting day. Because struvite is a slow-release cristal fertilizer(Rahman et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The fertilizing effect of Struvite was assessed in comparison to the control and fertilizers.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e2.6 Comparison with Conventional Fertilizers\u003c/h2\u003e\u003cp\u003eThe plants were harvested after two months, and measurements and records were made of the dry biomass of the maize, the number of leaves, the maximum width and length of the leaves, and the height of the stem. Following three days of drying at 70\u003csup\u003eo\u003c/sup\u003eC in an oven, the entire plant was weighed to measure its dry weight(Nilsson \u0026amp; Li, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). To determine whether there was a significant difference in the mean value of the variables, the experiment's data were examined using the mean and standard deviation in conjunction with a one-way ANOVA(Kassa et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2018\u003c/span\u003e)\u003c/p\u003e\u003c/div\u003e"},{"header":"3 Results and discussion","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Chemical composition of struvite\u003c/h2\u003e\u003cp\u003eThe chemical composition of the produced struvite was analyzed, and the results are shown in the Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e3\u003c/span\u003e:1.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003e3:1 the chemical composition of the produced struvite\u003c/h3\u003e\n\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\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=\"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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eno\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eparameters\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003econcentration mg/l\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eConcentration (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMagnesium(Mg \u003csup\u003e2+\u003c/sup\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e234.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.58\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCalcium(Ca \u003csup\u003e2+\u003c/sup\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e29685.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e11.77\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSodium(Na\u003csup\u003e+\u003c/sup\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.061\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.05\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\u003ePotassium( K\u003csup\u003e+\u003c/sup\u003e )\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.073\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePhosphate(PO\u003csub\u003e4\u003c/sub\u003e \u003csup\u003e3\u0026minus;\u003c/sup\u003e -p)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e245.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.66\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAmmonium nitrogen\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e121.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.01\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\u003eThe findings highlight the elemental concentrations of key components, including magnesium (Mg\u0026sup2;⁺), calcium (Ca\u0026sup2;⁺), phosphate (PO₄\u0026sup3;⁻-P), ammonium nitrogen (NH₄⁺-N), sodium (Na⁺), and potassium (K⁺). These values provide insight into the composition and potential utility of the struvite as a slow-release fertilizer.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMagnesium (Mg\u0026sup2;⁺)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe concentration of magnesium in the produced struvite was 234.9 mg/L, contributing to 2.58% of the total composition. Magnesium is an essential component of struvite and plays a crucial role in its crystallization process. This concentration indicates that magnesium from dolomite was effectively utilized in the precipitation reaction. Studies have shown that sufficient magnesium is critical for efficient struvite formation, as it reacts with ammonium and phosphate to form the crystal lattice(Le Corre et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2009\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cb\u003eCalcium (Ca\u0026sup2;⁺)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eCalcium was present at a significantly higher concentration of 29685.4 mg/L, constituting 11.77% of the total composition. This high calcium concentration suggests the possibility of co-precipitation of calcium compounds, such as calcium phosphate, alongside struvite. Excess calcium in the system can interfere with struvite formation and reduce its purity by forming competing precipitates. This phenomenon has been observed in other studies, particularly when using calcium-rich dolomite as a magnesium source(Rahman et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cb\u003ePhosphate (PO₄\u0026sup3;⁻-P)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe phosphate content of the struvite was 245.7 mg/L, representing 2.66% of the total composition. Phosphate is a critical nutrient in struvite and is responsible for its utility as a phosphorus-rich fertilizer. The recovery of phosphate in this study demonstrates the effectiveness of dolomite as a reagent for struvite precipitation. These findings align with previous research, which underscores the role of phosphate in the crystallization process and its recovery potential from wastewater(Song et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cb\u003eAmmonium Nitrogen (NH₄⁺-N)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe ammonium nitrogen concentration in the struvite was 121.3 mg/L, making up 1.01% of the total composition. Ammonium ions are essential for the formation of struvite crystals, as they combine with magnesium and phosphate in stoichiometric proportions. The recovery of ammonium nitrogen indicates the dual nutrient recovery capability of this process, making struvite an attractive option for sustainable wastewater treatment.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSodium (Na⁺) and Potassium (K⁺)\u003c/b\u003e\u003c/p\u003e\u003cp\u003eSodium and potassium were present in trace amounts, with concentrations of 0.061 mg/L (0.05%) and 0.073 mg/L (0.06%), respectively. Their low concentrations suggest minimal interference with the struvite precipitation process. These elements may originate from the dolomite or wastewater but are not significant contributors to the struvite composition.\u003c/p\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.2 The purity of the produced struvite\u003c/h2\u003e\u003cp\u003eAccording to several researchers (Korchef et al., 2011; Liu et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Rahman et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Yesigat et al., 2022), the ideal chemical composition of pure struvite is magnesium ammonium phosphate hexahydrate (MgNH₄PO₄\u0026middot;6H₂O), which appears as a white crystalline solid. This ideal form assumes a 1:1:1 molar ratio of magnesium, phosphorus, and nitrogen. However, the struvite recovered in this study deviates from this pure form both in appearance and chemical composition. The product obtained was brownish in color and contained 1.01% nitrogen, 2.66% phosphorus, 0.06% potassium, 2.58% magnesium, and a significantly high 11.77% calcium content.\u003c/p\u003e\u003cp\u003eThe presence of elevated calcium levels indicates substantial co-precipitation of metallic ions particularly calcium during the recovery process, which adversely affects the purity of the struvite. As a result, the final product cannot be classified as pure struvite. Nevertheless, it is worth noting that the recovered material is free from detectable concentrations of heavy metals, which are known to pose risks to plant and human health. This absence of toxic elements makes the product safe for further testing in agricultural applications.\u003c/p\u003e\u003cp\u003eDespite its impurity, the chemical composition of the synthesized struvite suggests a strong potential as a slow-release fertilizer. It retains essential nutrients such as phosphorus, magnesium, and ammonium nitrogen key elements for plant growth. Moreover, the study underscores the viability of using dolomite as an economical and effective source of magnesium for struvite precipitation, reinforcing its practicality for sustainable nutrient recovery from wastewater.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.3 The fertilizing efficiency of struvite\u003c/h2\u003e\u003cp\u003eFollowing two months, the maize plants were harvested, and the dry biomass, number of leaves, maximum leaf breadth and length, stem height, and stem circumference were measured and recorded in Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e3\u003c/span\u003e:2.\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 \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e3\u003c/span\u003e:2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eplant growth parameters for different treatments\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\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\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTreatments\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"7\" nameend=\"c8\" namest=\"c2\"\u003e\u003cp\u003eParameters\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSteam height (cm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSteam width(cm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eDry Biomass(gram)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo of leaf\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eMax.leaf width(cm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eMax.leaf length(cm)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e\u003cb\u003econtrol\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e38.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e75\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e33.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e65\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e110\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e47.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e70\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e105\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e37.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e85\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e\u003cb\u003e8 gram fertilizer\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e195\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e173.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e90\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e120\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e146.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e70\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e158.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e140\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e161.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e\u003cb\u003e8 gram struvite\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e169.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e105\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e200\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e170.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e185\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e149.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e94\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e191.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e163.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e99.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e\u003cb\u003e12 gram struvite\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e143.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e108\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e180\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e161.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e95\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e185\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e171.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e90\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e131.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e\u003cb\u003e16 gram struvite\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e160\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e189.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e105\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e176.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e94\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e185\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e169.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e105\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e180\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e193.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e\u003cb\u003e20 gram struvite\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e180\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e11.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e161.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e95\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e130.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e85\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e167.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e200\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e175.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\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\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Statistical Analysis\u003c/h2\u003e\u003cp\u003eThe analysis of the experimental results of the pot experiment was done by one-way ANOVA. Results of multiple comparisons of Dry Biomass, number of leaf, leaf length, leaf width, steam circumference and steam height between different treatment groups was done by using the Least Significant Difference (LSD) test. The dependent variables are Dry Biomass, number of leaf, maximum leaf length, maximum leaf width, steam circumference, steam height, and the treatments include a control, 8 gram fertilizer, 8 gram struvite, 12 gram struvite, 16 gram struvite and 20 gram struvite. Significant differences at the 0.05 level were marked with an asterisk (*).\u003c/p\u003e\u003cdiv id=\"Sec15\" class=\"Section3\"\u003e\u003ch2\u003e3.4.1 Dry biomass (gram)\u003c/h2\u003e\u003cp\u003eAll struvite treatments (8 g, 12 g, 16 g, and 20 g) and the 8 g fertilizer treatment significantly increased dry biomass compared to the control. The mean difference was \u0026minus;\u0026thinsp;120.8 for 8 g fertilizer (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and \u0026minus;\u0026thinsp;142.7 for 16 g struvite (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), confirming greater biomass production with fertilizer and struvite application.\u003c/p\u003e\u003cp\u003eNo significant differences were observed between 8 g fertilizer and 8 g struvite, and only a slight reduction in biomass was noted for 8 g fertilizer compared to 12 g struvite (-7.9, p\u0026thinsp;=\u0026thinsp;0.413). Aside from the 16 g dose (-29.8, p\u0026thinsp;=\u0026thinsp;0.005), no significant differences were found among 8 g, 12 g, and 20 g struvite treatments.\u003c/p\u003e\u003cp\u003eOverall, fertilizer and struvite treatments enhanced dry biomass, with the control consistently performing worse. These findings suggest that 8 g of struvite is the optimal dosage for biomass formation.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section3\"\u003e\u003ch2\u003e3.4.2 Number of leaf\u003c/h2\u003e\u003cp\u003eAll treatments (8 g fertilizer and all struvite dosages) significantly increased the number of leaves compared to the control (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The highest increases were with 8 g, 16 g, and 20 g struvite, with a mean of 3.750 more leaves. The 8 g fertilizer treatment also significantly increased the number of leaves by 2.500 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003cp\u003eStruvite treatments (8 g, 12 g, 16 g, and 20 g) were all better than the control in inducing leaf formation with mean differences ranging from 3.500 to 3.750 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). No significant differences were observed among struvite dosages, an implication that using more than 8 g of the dose does not further enhance leaf count.\u003c/p\u003e\u003cp\u003eThese findings confirm struvite as an effective and green fertilizer alternative, with 8 g determined as the optimal dose for leaf maximization.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section3\"\u003e\u003ch2\u003e3.4.3 Maximum Leaf length\u003c/h2\u003e\u003cp\u003eAll struvite treatments (8 g, 12 g, 16 g, and 20 g) significantly enlarged leaf length compared to the control (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), with mean differences ranging from \u0026minus;\u0026thinsp;22.500 cm to -27.250 cm. The 8 g fertilizer treatment significantly had shorter leaves than all the struvite treatments except for 20 g struvite, which did not differ significantly (p\u0026thinsp;=\u0026thinsp;0.073).\u003c/p\u003e\u003cp\u003eCompared to 8 g fertilizer, dosages of 8 g, 12 g, and 16 g struvite significantly increased leaf length (-13.250 cm to -16.000 cm). Struvite dosages were not significantly different from each other, indicating that dosing above 8 g does not influence leaf length more.\u003c/p\u003e\u003cp\u003eDue to diminishing returns with increasing dosages, 8 g of struvite is the optimum for leaf length enhancement. These findings indicate struvite as a viable alternative to conventional fertilizers for plant growth promotion.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section3\"\u003e\u003ch2\u003e3.4.4 Maximum Leaf width\u003c/h2\u003e\u003cp\u003eAll treatments significantly increased leaf width compared to the control (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), the largest of which was observed in 20 g struvite (4.500 cm, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). No differences were detected between struvite treatments (8 g, 12 g, 16 g, and 20 g) or between 8 g fertilizer and any level of struvite (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Although 20 g struvite presented the greatest mean difference (1.500 cm), it was not significant (p\u0026thinsp;=\u0026thinsp;0.069), indicating that the increase in struvite dosage does not have a significant influence on leaf width.\u003c/p\u003e\u003cp\u003eStruvite has a consistent effect in increasing leaf width, showing its potential as a source of nutrients. Because there were no significant differences among dosages, 8 g struvite can be the ideal dosage for leaf width increase\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec19\" class=\"Section3\"\u003e\u003ch2\u003e3.4.5 Steam height\u003c/h2\u003e\u003cp\u003eStem height also increased significantly with all treatments compared to control (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Stem height was highest with 8 g struvite (90.425 cm), followed by 20 g struvite (88.750 cm). Stem height with 8 g fertilizer was boosted by 60.000 cm but much lower compared to 8 g (-30.425 cm, p\u0026thinsp;=\u0026thinsp;0.021) and 20 g struvite (-28.750 cm, p\u0026thinsp;=\u0026thinsp;0.028). There were no significant differences among intermediate dosages of struvite (12 g, 16 g, and 20 g), indicating a plateau effect. Low dosages of struvite, particularly 8 g, were effective in promoting stem height, suggesting it is sufficient for optimal growth. The results indicate struvite as a via ble substitute for traditional fertilizers.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec20\" class=\"Section3\"\u003e\u003ch2\u003e3.4.6 Steam circumference\u003c/h2\u003e\u003cp\u003eStem circumference increased much more with all treatments than in the control (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), with greatest growth at 20 g struvite (4.000 cm). The 8 g fertilizer treatment significantly smaller stem circumference than 16 g (-1.175 cm, p\u0026thinsp;=\u0026thinsp;0.020) and 20 g struvite (-1.800 cm, p\u0026thinsp;=\u0026thinsp;0.001), while no differences were significant between 8 g fertilizer and lower dosages of struvite (8 g and 12 g).\u003c/p\u003e\u003cp\u003e20 g struvite treatment was significantly better than 8 g (p\u0026thinsp;=\u0026thinsp;0.008) and 12 g struvite (p\u0026thinsp;=\u0026thinsp;0.001), though there were no differences between 16 g and 20 g, which suggests a plateau effect. However, 16 g struvite also had greater stem circumference compared to the control, 8 g fertilizer, and 12 g struvite.\u003c/p\u003e\u003cp\u003eThese results reveal struvite's effectiveness in optimizing stem circumference with 16 g being the optimal dosage for balancing growth and resource use, hence struvite as an effective alternative to conventional fertilizers.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec21\" class=\"Section2\"\u003e\u003ch2\u003e3.5 Limitations and practical challenges\u003c/h2\u003e\u003cp\u003eIn conducting a crop trial experiment, it is essential to begin with a thorough analysis of the initial soil properties, particularly its chemical composition. Understanding the baseline concentrations of key macronutrients especially nitrogen (N) and phosphorus (P) prior to the application of struvite is critical. This initial data serves multiple purposes: it helps in assessing the direct contribution of struvite to soil nutrient enrichment, and it also provides insight into the soil's nutrient retention and absorption capacity. Such baseline measurements form the foundation for evaluating the effectiveness of struvite as a fertilizer.\u003c/p\u003e\u003cp\u003eUnfortunately, due to the unavailability of appropriate analytical equipment in our laboratory, we were unable to perform the necessary pre-treatment soil analysis. This limitation is acknowledged as a constraint in fully quantifying the nutrient dynamics and evaluating the precise impact of struvite application in our experimental setup.\u003c/p\u003e\u003cp\u003eAs previously discussed, dolomite rock was utilized as the magnesium source for struvite precipitation in this study. However, it is important to note that the specific dolomite rock used contained a higher concentration of calcium compared to magnesium. This imbalance significantly influenced the struvite formation process. Chemical analysis of the precipitated struvite revealed that the elevated calcium content interfered with the crystallization process, leading to reduced purity of the final product. The presence of excess calcium can compete with magnesium during precipitation, resulting in the formation of unwanted byproducts such as calcium phosphates, which compromise the structural integrity and fertilizing efficiency of struvite.\u003c/p\u003e\u003cp\u003eThis issue represented one of the major challenges encountered during the experimental phase of the research. To overcome this limitation and enhance the purity of struvite produced from dolomite-based systems, further investigation is required. Future research should focus on strategies to minimize calcium interference such as selective pre-treatment of dolomite, controlled precipitation conditions, or alternative low-calcium magnesium sources to optimize struvite recovery and ensure its effectiveness as a sustainable fertilizer.\u003c/p\u003e\u003c/div\u003e"},{"header":"4 Conclusion","content":"\u003cp\u003eAll things considered, the study demonstrates that struvite is a highly effective and sustainable fertilizer, significantly enhancing various plant growth parameters such as dry biomass, number of leaves, leaf breadth, leaf length, stem height, and stem circumference compared to the control. At higher concentrations, struvite outperformed conventional fertilizers; however, dosages beyond 8 g did not result in additional notable benefits, indicating a plateau effect. The 8 g dose emerged as the most effective and economical option, ensuring optimal plant growth while promoting resource efficiency.\u003c/p\u003e\u003cp\u003eIt is important to note, however, that the struvite recovered in this study deviates from the pure form both in appearance and chemical composition. The product was brownish in color and contained 1.01% nitrogen, 2.66% phosphorus, 0.06% potassium, 2.58% magnesium, and a notably high 11.77% calcium content. The elevated calcium concentration indicates substantial co-precipitation of metallic ions, particularly calcium, during the recovery process, which negatively impacts the purity of the struvite. Consequently, the final product cannot be classified as pure struvite.\u003c/p\u003e\u003cp\u003eDespite this, the findings highlight the potential of recovered struvite, even in its impure form, to serve as a viable and sustainable alternative to chemical fertilizers, contributing to improved plant health and environmental sustainability.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eEthics approval not applicable\u003c/p\u003e\n\u003cp\u003eConsent to participate\u0026nbsp;not applicable\u003c/p\u003e\n\u003cp\u003eConsent for publication\u0026nbsp;not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003eThere is no funding\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e: The authors have no relevant financial or non-financial interests to disclose\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u0026nbsp;\u003c/strong\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to express their sincere appreciation to Arba Minch University for providing the opportunity and necessary support to undertake this research. Special thanks are extended to the dedicated Water Quality Experts at Arba Minch University for their valuable guidance, technical assistance, and commitment throughout the experimental work\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCordell, D., Drangert, J. O. \u0026amp; White, S. The story of phosphorus: Global food security and food for thought. \u003cem\u003eGlob. Environ. Change\u003c/em\u003e. \u003cb\u003e19\u003c/b\u003e (2), 292\u0026ndash;305. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gloenvcha.2008.10.009\u003c/span\u003e\u003cspan address=\"10.1016/j.gloenvcha.2008.10.009\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2009).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCordell, D. \u0026amp; White, S. 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A Comprehensive Review on Wastewater Nitrogen Removal and Its Recovery Processes. \u003cem\u003eInt. J. Environ. Res. Public Health\u003c/em\u003e. \u003cb\u003e20\u003c/b\u003e (4). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/ijerph20043429\u003c/span\u003e\u003cspan address=\"10.3390/ijerph20043429\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"pure Struvite, dolomite rock, domestic wastewater, fertilizing efficiency, optimal dose, nutrient recovery, sustainable fertilizer","lastPublishedDoi":"10.21203/rs.3.rs-7406473/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7406473/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe fertilizing efficiency of struvite recovered from domestic wastewater by using dolomite rock as a magnesium source was assessed in a pot experiment. The objective of this study was to ascertain the ideal dosage and a sustainable fertilizer efficacy of the recovered struvite. The resulting product was brownish in color and chemically different from pure struvite; it had 1.01% nitrogen, 2.66% phosphorus, 0.06% potassium, 2.58% magnesium, and a high 11.77% calcium content, indicating considerable calcium co-precipitation that impacted the purity of the product.\u003c/p\u003e\n\u003cp\u003eTo measure the growth response based on stem height, stem circumference, leaf number, leaf width, and dry biomass, maize plants were fed with different doses of struvite (8, 12, 16, and 20 g). According to the findings, an 8 g dose considerably increased plant growth, surpassing larger doses and exhibiting a plateau effect. The recovered struvite, in spite of its impure state, turned out to be a viable and efficient substitute for traditional fertilizers. This study emphasizes how nutrient recovery from wastewater can help promote environmentally friendly agricultural practices.\u003c/p\u003e","manuscriptTitle":"Assessing the purity and fertilizing potential of struvite derived from domestic wastewater using dolomite rock as a magnesium source","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-11 11:52:46","doi":"10.21203/rs.3.rs-7406473/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2284ef02-01f2-407f-96aa-07ef1fca4e52","owner":[],"postedDate":"September 11th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":54373026,"name":"Biological sciences/Ecology"},{"id":54373027,"name":"Earth and environmental sciences/Ecology"},{"id":54373028,"name":"Earth and environmental sciences/Environmental sciences"},{"id":54373029,"name":"Biological sciences/Plant sciences"}],"tags":[],"updatedAt":"2025-09-22T12:26:13+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-11 11:52:46","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7406473","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7406473","identity":"rs-7406473","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}