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Biological treatment is currently a favorable option to treat wastewater due to its environmentally friendly methods and minimal toxic by-products. The majority of biological wastewater treatment uses bacteria as treatment agents, which are known to have excellent capabilities for removing various pollutants. Researchers have extensively explored the use of extracellular polymeric substances (EPSs) generated by bacteria in wastewater treatment. This review focuses on the sources of EPSs, factors influencing their production, and their role in wastewater treatment. Bacterial species, nutrient availability, pH, temperatures, and the presence of toxins were mentioned to be the factors influencing EPS production by bacteria in wastewater treatment. Produced EPSs by bacteria may promote the aggregation, adsorption, decolorization, and degradation of pollutants. This review highlights the challenges of discovering new potential bacterial species and complex EPS extraction methods, as well as the importance of mass production for larger-scale applications. [ABSTRACT FROM AUTHOR]

Population growth and rapid industrial expansion has contributed to substantial amount of waste generation that subsequently lead to increased demand for landfill sites. Leachate is a harmful substance that leaks from the landfill site consisting of vast amounts of organic and inorganic pollutants, and collected at the bottom of the site. Thus, we explored the potential of optimizing ferrous sulfate heptahydrate or copperas and lime in the coagulation treatment of leachate. Different formulations of copperas to lime (80:20 and 60:40) were employed for leachate treatment. This study evaluated the effect of initial pH 3-8, coagulant dosage 1,000-6,000 mg/L and coagulation time 15-75 min on leachate treatment. Finding showed that the hybrid coagulant of 60C:40L successfully achieved optimum removal of turbidity, color and suspended solids of about 89%, 91% and 96%, respectively, at pH 5, coagulant dosage of 5,000 mg/L, coagulation time of 30 min, and sedimentation time of 60 min. It was also found that the Freundlich isotherm model was the best to describe the adsorption mechanism for the studied coagulant. The findings of this research are vital for the development of sustainable and cost-effective leachate treatment in the future. [ABSTRACT FROM AUTHOR]

Implementation of biofloc technology (BFT) system in aquaculture industry shows high productivity, low feed conversion ratio, and an optimum culture environment. This study was divided into two phases. The first phase involved maintaining the water quality using the optimum carbon-to-nitrogen ratio by manipulating pH in culture water. The second phase examined the performance of harvesting biofloc (remaining phytoplankton and suspended solids in the system) using chicken eggshell powder (CESP). This study showed that pH 7 to 8 were the best biofloc performance with high removal percentage of ammonia (>99%) with a remaining ammonia concentration of 0.016 mg L-1 and 0.018 mg L-1, respectively. The second phase of this study was performed to determine the optimal formulation and conditions of using CESP as a bio-flocculant in harvesting excess biofloc. The use of eggshell showed a higher harvesting efficiency of more than 80% under the following treatment conditions: 0.25 g L-1 of eggshell dosage; with rapid and slow mixing rates of 150 and 30 rpm, respectively; 30 min of settling time; settling velocity of 0.39 mm s-1 and pH of 6 to 7. Therefore, the results indicated that biofloc would be the best green technology approach for sustainable aquaculture wastewater and the CESP is an organic matrix that environmental-friendly bio-coagulant for biofloc harvesting. [ABSTRACT FROM AUTHOR]