Extracellular polymeric substances production kinetics of 13 sludge isolates using wastewater sludge as raw material and its flocculation potential.

The kinetics of batch fermentation of 13 extracellular polymeric substances (EPS) producing bacterial strains (9Bacillus, 2Serratiaand 2Yersinia) were carried out using sterilized sludge as a raw material. The most ofBacillus(µmax: 0.11–0.27 h−1),Serratia(µmax: 0.23–0.27 h−1) andYersinia(µmax: 0.18–0.19 h−1) strains had capability to grow and produce EPS (1.36–2.12 g/L) in the sterilized sludge. In general, EPS production was mixed growth associated for all the bacterial strains cultivated independently.Bacillussp. 7,Serratiasp. 2 andYersiniasp. 2 produced higher concentration (1.95–2.12 g/L) of EPS than the other remaining bacterial strains. Protein and carbohydrate contents of EPS remained constant during fermentation. Broth EPS (B-EPS) exhibited high kaolin flocculation activity (≥75%) in most of the cases exceptBacillussp. 1,Bacillussp. 5 andBacillussp. 9, respectively. In general, high flocculation activities (FAs) (≥75%), were attained using 1.31–1.70 mg B-EPS/g kaolin, 0.45–0.97 mg protein/g kaolin and 0.11–0.21 mg carbohydrates/g kaolin. The study suggests that further systematic exploration is required for optimizing the process of EPS production. EPS produced in the sludge can potentially be used for different water and wastewater treatments. [ABSTRACT FROM PUBLISHER]