Abstract
Low-energy cost wastewater treatment is required to change its current energy-intensive status. Although promising, the direct anaerobic digestion of municipal wastewater treatment faces challenges such as low organic content and low temperature, which require further development. The hydrolysis-aerobic system investigated in this study utilized the two well-proven processes of hydrolysis and aerobic oxidation. These have the advantages of efficient COD removal and biodegradability improvement with limited energy cost due to their avoidance of aeration. A pilot-scale hydrolysis-aerobic system was built for performance evaluation with actual municipal wastewater as feed. Results indicated that as high as 39–47% COD removal was achieved with a maximum COD load of 1.10 kg/m3·d. The dominant bacteria phyla included Proteobacteria (36.0%), Planctomycetes (15.4%), Chloroflexi (9.7%), Bacteroidetes (7.7%), Firmicutes (4.4%), Acidobacteria (2.5%), Actinobacteria (1.8%) and Synergistetes (1.3%), while the dominant genera included Thauera (3.42%) and Dechloromonas (3.04%). The absence of methanogens indicates that the microbial community was perfectly retained in the hydrolysis stage instead of in the methane-producing stage.
Highlights
IntroductionWastewater treatment accounts for a large amount of the energy load in society as a whole
Wastewater treatment accounts for a large amount of the energy load in society as a whole.It is estimated that 3–4% of total U.S electricity is consumed for the movement and treatment of water and wastewater [1]
Stage I was a start-up with an average chemical oxygen oxygen demand demand (COD) load of 0.14 kg/m3 ·d
Summary
Wastewater treatment accounts for a large amount of the energy load in society as a whole. It is estimated that 3–4% of total U.S electricity is consumed for the movement and treatment of water and wastewater [1]. A similar situation could be observed in other developed and developing countries. High energy consumption creates a large carbon footprint, accelerating global warming. As wastewater production increases due to population and economic growth, the energy-water burden becomes heavier for the future, undermining social sustainability. It is of great importance to reduce energy costs during the treatment of wastewater
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