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Effect of hydraulic retention time on performance of an anoxic–aerobic sequencing batch reactor treating saline wastewater
Wang, Z. C.; Gao, M. C.; Ren, Y.; Wang, Z.; She, Z. L.; Jin, C. J.; Chang, Q. B.; Sun, C. Q.; Zhang, J. & Yang, N.
Abstract
The effects of hydraulic retention time on the
performance and microbial community structure of an
anoxic–aerobic sequencing batch reactor treating saline
wastewater were investigated. The average removal efficiencies
of chemical oxygen demand and ammonia nitrogen
decreased from 90 and 85 % to 68 and 71 % with the
decrease in hydraulic retention time from 17 to 9 h,
respectively. No obvious accumulation of nitrate nitrogen
and nitrite nitrogen in the effluent was found. The contents
of polysaccharide and protein in extracellular polymeric
substances increased with the decrease in hydraulic retention
time. The polysaccharide/protein ratio decreased from
1.18 to 1.11 with the decrease in hydraulic retention time
from 17 to 9 h. The increase in extracellular polymeric
substances with the decrease in hydraulic retention time led
to the increase in sludge volume index. The specific
ammonium oxidation rate, specific nitrite oxidation rate,
specific nitrate reduction rate, and specific oxygen uptake
rate increased with the decrease in hydraulic retention time.
The diversity indices of microbial community decreased
from 2.69 to 2.39 with the decrease in hydraulic retention
time from 17 to 9 h. The α-proteobacteria were the dominant
groups under hydraulic retention time of 17, 14, 11,
and 9 h, which constituted 46, 30, 40, and 40 % of the
whole microbial community, respectively.
Keywords
Hydraulic retention time; Sequencing batch reactor; Extracellular polymeric substances; Microbial activity; Microbial community structure
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