[Treatment characteristics of saline domestic wastewater by constructed wetland]

A series of experiments were conducted to evaluate the feasibility of using constructed wetland (CW) to remove pollutants from saline domestic sewage. The experimental results indicated that the effects of salinity on the contaminant removal were insignificant when the influent salinities of the CWs were less than or equal to 1.5%. For the influent salinity of 0%, 0.5%, 1.0% and 1.5%, the average removal rates of the CWs were found to be above 68.3% for COD and above 66.1% for NH4(+) -N. When the influent salinity was increased to 2.0%, the individual numbers of microorganisms in the CW reduced obviously. It was similar to the change of the soil enzyme activity in the CW. Then the removal efficiency of the CW also dropped significantly. The average removal rate of COD and NH4(+) -N dropped to 52.9% and 50.3%, respectively. The effects of HRT on the treatment performance of CW under the saline condition of 1.5% were also investigated in this study. And the results showed that nitrogen removal was more greatly affected by HRT than organic matter removal. The NH4(+) -N removal efficiency in CW decreased from 65.1% -78.2% to 47.1% when the HRT of the CW varied from 3-5 d to 2 d.