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Addition of iron materials for improving the removal efficiencies of multiple contaminants from wastewater with a low C/N ratio in constructed wetlands at low temperatures
- Zhao, Zhimiao, Xu, Chenglong, Zhang, Xiao, Song, Xinshan
- Environmental science and pollution research international 2019 v.26 no.12 pp. 11988-11997
- Thauera, Thiobacillus, bacteria, carbon, carbon nitrogen ratio, chemical oxygen demand, chromium, constructed wetlands, copper, denitrification, heavy metals, ion exchange, iron, kinetics, microbial communities, nitrates, nitrogen content, operating costs, pollution control, temperature, wastewater, wastewater treatment
- Constructed wetlands (CWs) are widely used in wastewater treatment. Wastewater generally contains multiple contaminants. In this study, CWs were applied to treat wastewater with a low COD/TN ratio and containing heavy metals. Iron-based material was added in CWs to enhance the treatment efficiency. The contaminant removal efficiency was positively correlated with the dosage of iron-based material. Considering the operation cost, we added 1 g of iron-based material in CW and realized the multi-contaminant removal efficiency after 4-day treatment at low temperature: 99.51% of Cu(II), 87.22% of Cr(VI), 65.62% of TN, and 60.23% of COD. Microbial community analysis and kinetic analysis predicted that the removal mechanism involved ion exchange and microbial denitrification. Specific bacteria were found in CWs with iron-based material, such as Thiobacillus spp. and Thauera spp., indicating that the nitrate removal in the denitrification process was triggered by carbon sources and that Fe²⁺ worked as both the electron donor and the adjuster of the abundances of specific bacteria. The addition of iron-based material into CWs was a green option to improve the pollutant removal performance.