6533b7d1fe1ef96bd125d576

RESEARCH PRODUCT

Effect of substrate composition on the stability and microbial community of an anaerobic expanded granular sludge bed reactor treating printing solvent mixtures of ethanol and glycol ethers

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Abstract The performance and microbial community analysis of an expanded granular sludge bed reactor (EGSB) treating wastewater polluted with mixtures of ethanol and glycol ethers –such as 1-ethoxy-2-propanol (E2P) and 1-methoxy-2-propanol (M2P)– were evaluated. The results showed good EGSB performance during start-up (100% of ethanol) in terms of global removal efficiency (RE > 95%). When glycol ethers were added, an initial adaptation period was observed of ~20 days. While the RE of M2P became complete, the RE of E2P reached only 65%. The proportion of glycol ethers was gradually increased and at the end of this study only a binary mixture of E2P and M2P was fed. In the last stage, the global RE dropped to 80% and a partial degranulation of the sludge bed occurred, revealing the importance of acetate-yielding compounds as co-substrate for maintaining the granular structure of the sludge. Microbial community analysis showed a relation between the substrate utilized in the reactor and the developed microbial populations, such as Methanosaeta, an acetate consumer, and Methanomethylovorans, a methanol consumer, which were the predominant microorganisms in the archaeal population; the predominant bacterium found was Geobacter, an ethanol consumer; this and Methanosaeta are synthropic partners.