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Published on: October 15, 2015
The influence of different sludge concentrations on its dewaterability during bioleaching
Wenfeng Yang1, Liyuan Zeng2, Weihao Zhang3
1College of Chemistry and Environmental Engineering, Jiujiang University, Jiujiang 332005, China and Jiujiang Key Laboratory of basin management and ecological protection, Jiujiang University, Jiujiang Jiangxi, 332005, China E-mail: yqy46901@163.com; School of Resource and Environmental Sciences, Hubei Biomass-Resource Chemistry and Environmental Biotechnology Key Laboratory, Wuhan University, Wuhan Hubei, 430079, China.
Bioleaching effectively enhances sewage sludge dewaterability. The optimal concentration for improved dewatering was 10 g·L-1, with tightly bound extracellular polymeric substances (EPS) playing a key role.
Area of Science:
- Environmental Science
- Biotechnology
- Water Treatment
Background:
- Bioleaching is an efficient technology for improving sewage sludge dewaterability.
- Understanding the impact of sludge concentration on bioleaching is crucial for optimizing this process.
Purpose of the Study:
- To investigate the effect of different sludge concentrations on bioleaching-induced sludge dewaterability.
- To elucidate the underlying mechanisms of bioleaching's influence on sludge dewaterability, focusing on extracellular polymeric substances (EPS).
Main Methods:
- Bioleaching was performed on sewage sludge at concentrations ranging from 5 to 30 g·L-1.
- Key parameters monitored included pH, oxidation-reduction potential (ORP), capillary suction time (CST), and specific resistance to filtration (SRF).
- Fractionation and analysis of extracellular polymeric substances (EPS) including slime EPS (S-EPS), loosely bound EPS (LB-EPS), and tightly bound EPS (TB-EPS) were conducted.
Main Results:
- Sludge buffering capacity increased with concentration, inhibiting bioleaching efficiency.
- Optimal dewaterability enhancement was achieved at a sludge concentration of 10 g·L-1, with maximum improvement at pH 2.11.
- The ratio of S-EPS to TB-EPS significantly influenced dewaterability; higher TB-EPS correlated positively with improved dewatering, while increased protein and DNA in S-EPS correlated negatively.
Conclusions:
- Sludge concentration is a critical factor affecting bioleaching efficiency and sludge dewaterability.
- The composition and structure of EPS, particularly the ratio of S-EPS/TB-EPS, are key mechanisms driving bioleaching-induced dewaterability improvements.
- Targeting TB-EPS reduction and managing S-EPS content can optimize bioleaching for enhanced sludge dewatering.
