Dynamic characteristics of soluble microbial products in a granular sludge reactor

Abstract

Soluble microbial products constitutes a major fraction of organic matters in biological wastewater treatment effluent, severely challenging downstream deep purification treatment processes. Effective control of soluble microbial products necessitate a full understanding on soluble microbial products properties in biological bioreactors, including the rapidly developing aerobic granular sludge systems. Here, we provide insights into the contents and composition dynamics of soluble microbial products during start-up and steady state of aerobic granular sludge. The effluent concentrations of soluble microbial products in the aerobic granular sludge reactor increased rapidly from 22.1 mg/L to 32.1 mg/L during the initial sludge granulation stage and declined drastically to 11.7 mg/L during granules maturing. The polysaccharides was dominant composition of soluble microbial products, which was decreased from 90% to 40% during granulation process. The ultimate effluent soluble microbial products content was lower than that in a floccular sludge reactor, indicating a higher effluent quality of the aerobic granular sludge system. This work highlights the superiority of aerobic granular sludge in improving effluent quality and implies a necessity to control soluble microbial products at the initial granulation process which has been overlooked before.