Treatment of Rural Domestic Wastewater by Aerated Constructed Wetland
|Course||Utilization of Agricultural Resources|
|Keywords||Constructed Wetland Rural Domestic Wastewater Aeration Removal efficiency|
Constructed wetland is a practical way for domestic sewage treatment in rural aera in China because of its low construction and operation cost. However, the pollutant removal efficiency is rather low, comparing to the conventional methods, owing to the low dissolved oxygen supply, which presently becomes the bottleneck in the application to wastewater treatment.In order to increase the efficiency of pollutant removal, three intensifying measures, e.g. continuous aeration, intermittent aeration and tidal flow, are introduced in the experiment for the purpose of oxygen enrichment in constructed wetland. The results run as follows:Continuous aeration, intermittent aeration and tidal flow had great influence on COD removal efficiency, and the outflow concentration of COD was 47.09 mg/L, 44.84 mg/L and 48.80 mg/L,respectively, when influent concentration was 508.04 mg/L, whil ethe concentration of COD was 64.52 mg/L in the wetland without aeration.The outflow concentration of TN was decreased from 24.09 mg/L in common wetland to 19.07 mg/L,18.13 mg/L and 18.92 mg/L in the wetlands with continuous aeration, intermittent aeration and tidal flow, respectively, when influent concentration was 75.22 mg/L. Further research showed that nitrification/denitrification process could account for nitrogen removal.Wetland with artificial aeration had great influence on TP removal. Compared to the conventional wetland with an outflow of 3.019 mg/L, the wetlands with continuous aeration, intermittent aeration and tidal flow had the TP concentration of 2.305 mg/L,2.155 mg/L, and 2.164 mg/L while influent concentration was 9.788 mg/L. Experiment also demonstrated that adsorption of phosphorus onto substrates could account for nitrogen removal mechanism.Urease and phosphase activity in the media of constructed wetland presented an remarkable realation to the removal of TN, TP and COD in wetlands, indicating the importance of biological acitivity.