Biopolymers Production by Mixed Culture and Their Applications in Water and Wastewater Treatment.

Thirteen extracellular polymeric substances (EPS) producing bacterial strains were cultivated (as pure/mixed culture) in sterilized sludge (suspended solids: 25 g/L). The mixed culture produced higher concentrations of EPS (4.9 g/L) as compared to that of the pure culture (2.7-3.7 g/L). The harvested EPS were examined for their flocculation performance (turbidity removal and dewatering) in jar tests using kaolin suspensions with Ca2+. Broth (B-EPS) revealed high kaolin flocculating activity (91.2%) at very low concentrations (0.8 mg B-EPS/g kaolin) and it was comparable to the chemical polymer, Magnafloc-155 (90.4% at 0.2 mg/g kaolin). B-EPS also exhibited very good flocculation performance (turbidity removal %) in river water (93.5%), municipal wastewater (91.7%) and brewery wastewater (81.8%). The study revealed that the mixed culture consortium could be used for the production of highly efficient flocculants.

Rice mill wastewater treatment in microbial fuel cells fabricated using proton exchange membrane and earthen pot at different pH.

Performance of microbial fuel cells (MFCs), fabricated using an earthen pot (MFC-1) and a proton exchange membrane (MFC-2), was evaluated while treating rice mill wastewater at feed pH of 8.0, 7.0 and 6.0. A third MFC (MFC-3), fabricated using a proton exchange membrane (PEM), was operated as control without pH adjustment of the acidic raw wastewater. Maximum chemical oxygen demand (COD) removal efficiencies of 96.5% and 92.6% were obtained in MFC-1 and MFC-2, respectively, at feed pH of 8.0. MFC-3 showed maximum COD removal of 87%. The lignin removal was 84%, 79%, and 77% and the phenol removal was 81%, 77%, and 76% in MFC-1, MFC-2, and MFC-3, respectively. Maximum sustainable volumetric power was obtained at feed pH of 8.0, and it was 2.3 W/m(3) and 0.53 W/m(3), with 100 ohm external resistance, in MFC-1 and MFC-2, respectively. The power was lower at lower feed pH. MFC-3 generated lowest volumetric power (0.27 W/m(3)) as compared to MFC-1 and MFC-2. More effective treatment of rice mill wastewater and higher energy recovery was demonstrated by earthen pot MFC as compared to MFC incorporated with PEM.