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Title:The feasibility and microbial community dynamics of using down flow hanging sponges (DHS) reactor in treating high strength soft drink wastewater
Author(s):Liao, Junhui
Advisor(s):Liu, Wen-Tso
Department / Program:Civil & Environmental Eng
Discipline:Environ Engr in Civil Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Down-flow hanging sponge (DHS)
High strength wastewater
Organic removal efficiency
Soft drink wastewater
Abstract:The feasibility of using a standalone down-flow hanging sponge (DHS) reactor to treat high organic strength soft drink wastewater was investigated by operation over 700 days. At the same time, the microbial compositions were characterized and related to reactor performance. Synthetic wastewater at a concentration of 3000 mg/L chemical oxygen demand (COD) was directly fed to two identical DHS reactors operated in parallel. The effluent from these two reactors was then combined and fed to a third DHS reactor identical as the first two in physical scale. The first two DHS reactors were operated with a hydraulic retention time (HRT) of 15.3 hours and an organic loading rate of 4.9 kg COD/m3 sponge volume/day, and achieved > 90% organic matters removal efficiency. The third reactor consistently achieved a final effluent COD < 60 mg/L. It was observed that in the first two reactors, the organic matters removal efficiency could be correlated with parameters like effluent pH, volatile fatty acid (VFA) concentrations and biomass content. Lower organic removal efficiency was correlated with lower pH and higher VFA concentration in the effluent. Higher organic removal efficiency was correlated to less suspended solid (SS) in the effluent and higher biomass concentration retained in the reactor. Extracellular polymeric substance (EPS) produced by retained biomass could capture ammonia that was not used for microbial growth. Excessive EPS production was speculated as a cause that triggered biomass sloughing, which led to reduction in biomass in the reactor and decreases in organic removal efficiency. In addition, the removal capacity at different parts of the reactor was different, and > 60% of organic and nitrogen species contents were removed at the upper part of the reactor. The microbial community analyses together with redundancy analysis revealed that the community structures could be distinguished based on the locations of individual sponges taken along the reactor. Also, microbial community structures were continuously shifted during the entire operation period and a feeding accident influenced the community structures significantly. In general, at the end of the operation period, OTUs in phylum Proteobacteria were more abundant in the reactor with good organic removal efficiency (>90%) than that with poor efficiency (<50%). In contract, OTUs related to Bacteroidetes was observed to be more abundant in the reactor with poor organic removal efficiency. OTUs closely related to Tolumonas auensis, and Rivicola pingtungensis had higher abundance in the upper part communities than middle and lower part of the reactor with good organic removal efficiency and these OTUs were likely targeting the major components in the feeding substrate. In addition, the lower abundance of these OTUs in the upper part of the reactor with poor organic removal efficiency than that with good efficiency might also indicate the importance of these OTUs in treating the soft drink wastewater tested in this study.
Issue Date:2016-06-23
Rights Information:Copyright 2016 Junhui Liao
Date Available in IDEALS:2016-11-10
Date Deposited:2016-08

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