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Impact of food to microorganism ratio and alcohol ethoxylate dosage on methane production in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor
- Nie, Yulun, Tian, Xike, Zhou, Zhaoxin, Li, Yu-You
- Frontiers of environmental science & engineering 2017 v.11 no.6 pp. 6
- acclimation, alcohols, cell structures, membrane bioreactors, methane, methane production, microorganisms, organic acids and salts, sludge, wastewater
- The effects of food to microorganism (F/M) ratio and alcohol ethoxylate (AE) dosage on the methane production potential were investigated in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor (SAnMBR). The fate of AE and its acute and/or chronic impact on the anaerobic microbes were also analyzed. The results indicated that AE had an inhibitory effect to methane production potential (lag-time depends on the AE dosage) and the negative effect attenuated subsequently and methane production could recover at F/M ratio of 0.088–0.357. VFA measurement proved that AE was degraded into small molecular organic acids and then converted into methane at lower F/M ratio (F/M<0.158). After long-term acclimation, anaerobic microbe could cope with the stress of AE by producing more EPS (extracellular polymeric substances) and SMP (soluble microbial products) due to its self-protection behavior and then enhance its tolerance ability. However, the methane production potential was considerably decreased when AE was present in wastewater at a higher F/M ratio of 1.054. Higher AE amount and F/M ratio may destroy the cell structure of microbe, which lead to the decrease of methane production activity of sludge and methane production potential.