Effects of cattail biomass on sulfate removal and carbon sources competition in subsurface-flow constructed wetlands treating secondary effluent.
Sulfate is frequently found in the influent of subsurface-flow constructed wetlands (SSF CWs) used as tertiary treatments. To reveal the effects of plants and litters on sulfate removal, as well as the competition for organic carbon among microorganisms in SSF CWs, five laboratory-scale SSF CW microcosms were set up and were operated as a batch system with HRT 5 d. The results showed that the presence of Typha latifolia had little effect on sulfate removal in CWs, with or without additional carbon sources. Cattail litter addition greatly improved sulfate removal in SSF CWs. This improvement was linked to the continuous input of labile organic carbon, which lowers the redox level and supplies a habitat for sulfate reducing bacteria (SRB). The presence of SRB in cattail litter indicated the possibility of sulfate removal around the carbon supplier, but the quantity of microbes in cattail litter was much lower than that in gravel. Stoichiometry calculations showed that the contribution of SRB to COD removal (21-26%) was less than that of methane-producing bacteria (MPB) (47-61%) during the initial stage but dominated COD removal (42-65%) during the terminal stage. The contributions of aerobic bacteria (AB) and denitrification bacteria (DB) to COD removal were always lower than that of SRB. It was also observed that the variations in COD: S ratio had a great influence on the relative abundance of genes between SRB and MPB and both of them could be used as good predictors of carbon competition between SRB and MPB in CWs.
Key Laboratory of Yangtze Water Environment of Ministry of the State Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Department of Landscape Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences Prague 16521, Czech Republic.
Yi
Y
Chen
Key Laboratory of Yangtze Water Environment of Ministry of the State Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. Electronic address: weny@tongji.edu.cn.
Yue
Y
Wen
Key Laboratory of Yangtze Water Environment of Ministry of the State Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Junwei
J
Zhou
Key Laboratory of Yangtze Water Environment of Ministry of the State Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Zhiru
Z
Tang
Key Laboratory of Yangtze Water Environment of Ministry of the State Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Ling
L
Li
Key Laboratory of Yangtze Water Environment of Ministry of the State Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Qi
Q
Zhou
Department of Landscape Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences Prague 16521, Czech Republic.
Jan
J
Vymazal
D001419:Bacteria / Q000378:metabolism; D018533:Biomass; D002244:Carbon / Q000737:chemistry / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S; D013431:Sulfates / Q000737:chemistry / Q000378:metabolism*; D032401:Typhaceae / Q000502:physiology*; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism; D018508:Water Purification / Q000379:methods*; D053833:Wetlands
D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D014874:Water Pollutants, Chemical; D002244:Carbon
Carbon competition; Cattail litter; Subsurface flow constructed wetlands (SSF CWs); Sulfate; Sulfate reducing bacteria (SRB)