Fouling evaluation in a MBR for dairy effluent treatment

Abstract

A submerged membrane bioreactor was used in the treatment of dairy wastewater, and three different sludge retention time (SRT) were evaluated. High removal efficiencies of organic matter, apparent color, and nutrients were observed for all the three conditions. However, the membrane fouling was considerably intense, and the concentration of soluble microbial products (SMP) and extracellular polymeric substances (EPS) and the critical flux of the system were analyzed for a better understanding of the reasons. Contrary to what other authors noticed, it was not possible to establish any relation between SMP concentration and fouling rate. In contrast, the EPS seem to have some influence on this phenomenon. The critical flux results justified the strong fouling observed, as almost all the measured values were below the established operational flux. The SRT of 60 d was selected as the best among the three evaluated because it resulted in lower EPS concentration and higher values of critical flux.

Keywords:

• Membrane bioreactor
• Dairy industry effluent
• Fouling
• Sludge retention time
• Soluble microbial products
• Extracellular polymeric substances
• Critical flux

Acknowledgments

The authors thank PAM Membranas Seletivas Ltda. for supplying the membranes, CNPq—The National Council for Scientific and Technological Development, and FAPEMIG—Foundation for Research Support of the State of Minas Gerais for their permanent support.