Biosafety and Removal Potential of Pollutants in Wastewater by the Microbial Flocculant from Marine Bacterium Obtained from Umlalazi Catchment, RSA

Abstract Bioflocculants have been reported to be successfully used in the removal of pollutants and dye decolourization from wastewater as they (pollutants) have negative impact on both humans and aquatic life if not properly treated. Thus, the potential removal rate of a microbial flocculant produced by the marine bacterial strain of Bacillus safensis KX94275.1 from uMlalazi estuary, Mthunzini area, KZN for pollutants from wastewater samples and dyes from different dye solution was investigated. B. safensis produced a non-toxic microbial flocculant showed margin of safety in both breast cancer cells and normal cells with 87% and 96% cell survival after treatment with maximum dosage of bioflocculant solution of 100 µg/µL, respectively. Functional groups such as amino, carboxylic and hydroxyl group were revealed with FT-IR spectrum to be possessed by the microbial flocculant produced. Above 65% of microbial flocculant was attained when the flocculant was subjection to 700 oC using the thermogravimetric analyser. A produced bioflocculant was aqua-solvable and have no inhibitory effect in bacteria tested. This heat-stable and cation-dependent (Ba2+) bioflocculant removed more than 85% dye from different dye solutions, such as basic fuchsine (93%), congo red (87%), crystal violet (90%) and methylene blue (93%), using 0.4 mg/mL optimum dosage concentration at neutral pH. This wide pH (3-12) tolerant bioflocculant showed improvement on both domestic and coal mine wastewaters for the removal of biochemical oxygen demand with 66% and 99%, chemical oxygen demand with 48% and 93%, phosphate with 61% and 59%, total nitrogen with 69% and 68% and sulphide with 71% and 83% removal rate, respectively, and flocculation rate of 91% (domestic) and 95% (coal mine) wastewater. Thus, the application of the bioflocculant on wastewater treatment indicated the tremendous prospective in replacing risky traditional flocculating agents frequently utilized for purification of wastewater.