A Pilot Experiment On Rural Domestic Wastewater Treatment Using Combined ABR-Constructed Wetland System

At present,the anaerobic treatment technology was often applied to the treatment of rural domestic wastewater in domestic and abroad. This kind of treatment technology is low efficient and can't meet the needs of recycle. Furthermore, a lot of deficiencies exist in traditional technology of constructed wetland for domestic wastewater treatment, for example, it occupies much more ground than traditional treatment project, and can not be loaded with high-concentration wastewater. Common problems with clogging and mosquito breeding encountered in operation happened etc. Combined ABR-constructed wetland process was tested in practical engineering to study weather it can conquer the defects of single wastewater treatment process mentioned above.The running effects of combined system with anaerobic baffled reactor and constructed wetland (ABR-CW) for domestic wastewater treatment from April 2006 to March 2007,including CODCr removal, ammonia removal, phosphorus removal and the role of the plants, were described in this paper. The results revealed the average removal rate of CODCr and ammonia (NH3-N) of ABR-CW was 78.9% and 88.55%, respectively, in summer and autumn with HRT (hydraulic retention time) about 50 hours. However, the average removal rat of CODCr was 56.6%, and that of NH3-N remained above 47%, without changing the daily treatment capacity. The removal rate of phosphorus remained above 83.6%, and 92.3% in summer as a result of the absorption of the plants in CW due to the use of special substrate. So the removal of phosphorus mostly attributed to the adsorption of substrate of CW. The adsorption capability of substrate did not reach saturation, but the data showed a downtrend. The effects of the plants in CW are remarkable to NH3-N removal, but unapparent to phosphorus removal.Practice shows that the treatment system has better effect which can mainly be observed in the following aspects:1. ABR reduced the loading of constructed wetland;Consequently,the establishment area is decreased. 2. There is a large reduction in suspended substance in wastewater after the ABR process,it decreased the possibility of clogging during the constructed wetland process. 3. Rational plant disposition in constructed wetland increases plant biomass to raise the treatment efficiency. 4. Beautifying the environment for this landscape engineering meets the need of construction socialism new village. For the test is conducted in Tianjin, this system is sensitive to temperature, so the research also shows that temperature is a key factor in restricting the treatment effect.