Heavy metals removal from wastewater using extracellular polymeric substances produced by Cloacibacterium normanense in wastewater sludge supplemented with crude glycerol and study of extracellular polymeric substances extraction by different methods

摘要

Extracellular polymeric substances synthesis by Cloacibacterium was affected by different concentrations of glycerol in the medium. The concentration of EPS in 72 h fermentation was increased from 13 g/L with no external carbon supplementation to 21.3 +/- 0.7 g/L with 2% (w/v) crude glycerol addition. Physical and chemical extraction methods (heating, centrifugation and ethylene diamine tetra-acetic acid (EDTA)) were used in this study and their performance to extract EPS was compared. A significant variation in concentration of extracted B-EPS (broth-EPS) by heating (20.8 +/- 0.5 g/L) and centrifugation (21.3 +/- 0.7 g/L) extraction methods was not observed. However, in case of extraction with EDTA (5 g/L), the B-EPS concentration extracted was 25.5 +/- 0.9 g/L, which exhibited high flocculation activity of 95.3 +/- 0.5% at optimum dose of 23.1 mg B-EPS/g kaolin. Moreover, Ni removal efficiency of 80% from primary treated wastewater was achieved using 35 mg/L of B-EPS extracted by centrifugation method. (C) 2016 Elsevier Ltd. All rights reserved.