Effects of dissolved oxygen on performance and microbial community structure in a micro-aerobic hydrolysis sludge in situ reduction process. (1st March 2016)

• Record Type: Journal Article
• Authors: Niu, Tianhao; Zhou, Zhen; Shen, Xuelian; Qiao, Weimin; Jiang, Lu-Man; Pan, Wei; Zhou, Jijun
• Is Part Of: Water research. Volume 90(2016)
• Page Start: 369
• Page End: 377
• Publication Date: 2016-03-01
• Subjects: Sludge reduction -- Microbial community -- Micro-aeration -- Sludge process reduction activated sludge (SPRAS) process -- Wastewater treatment; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2015.12.050
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: A sludge process reduction activated sludge (SPRAS), with a sludge process reduction module composed of a micro-aerobic tank and a settler positioned before conventional activated sludge process, showed good performance of pollutant removal and sludge reduction. Two SPRAS systems were operated to investigate effects of micro-aeration on sludge reduction performance and microbial community structure. When dissolved oxygen (DO) concentration in the micro-aerobic tank decreased from 2.5 (SPH ) to 0.5 (SPL ) mg/L, the sludge reduction efficiency increased from 42.9% to 68.3%. Compared to SPH, activated sludge in SPL showed higher contents of extracellular polymeric substances and dissolved organic matter. Destabilization of floc structure in the settler, and cell lysis in the sludge process reduction module were two major reasons for sludge reduction. Illumina-MiSeq sequencing showed that microbial diversity decreased under high DO concentration. Proteobacteria, Bacteroidetes and Chloroflexi were the most abundant phyla in the SPRAS. Specific comparisons down to the class and genus level showed that fermentative, predatory and slow-growing bacteria in SPL community were more abundant than in SPH . The results revealed that micro-aeration in the SPRAS improved hydrolysis efficiency and enriched fermentative and predatory bacteria responsible for sludge reduction. Graphical abstract: Highlights: Effects of micro-aeration on sludge reduction and microbial community were studied. The micro-aerobic sludge reduction process, SPRAS, reduces observed yield by 68.3%. Flocs disintegration and cell lysis were two major mechanisms for sludge reduction. Illumina-MiSeq sequencing showed increasing microbial diversity with micro-aeration. Micro-aeration in SPRAS enriched fermentative, predatory and slow-growing bacteria.