Research And Analysis On The Effectiveness Of The Constructed Wetland System For The Treatment Of Dispersive Rural Domestic Wastewater And Its Influencing Factors

ABR reactor(Anaerobic Baffled Reactor)+ constructed wetland for treatment of rural domestic sewage treatment is necessary for the research of water environment. The process of choice is very important, especially in Suzhou area in “13th Five-Year Plan ”period to be completed 1000 natural villages each year. Constructed wetland has the advantages of low cost, good treatment effect,simple operation etc.These years, domestic and foreign researches on the constructed wetland are mainly focused on how to avoid the clogging of constructed wetland system, construction of composite constructed wetland system, selection of reasonable operating parameters to improve the removal efficiency of constructed wetland and so on. In this paper, 6 groups of different plant type constructed wetlands are constructed, ABR reactor(Anaerobic Baffled Reactor) was used for pretreatment. Simulated actual situation in the outdoor environment, in order to study on the effect of long-term continuous operation of different plant wetland on pollutant removal. Analysis of the effects of environment, plant, microorganism and other factors on the treatment effect of Constructed Wetland. The main research contents and results are as below:(1) The system has run for 16 months since April 2014. Each plant wetland has good removal effect on COD, stable period remained at more than 65%, the best removal effect constructed wetland is cyperus alternifolius wetland, the removal rates of NH4+-N, TN, TP in stable period is62.1%、61.4%、63.7%. The best removal effect constructed wetland is irispseudacorus+ cannaindica wetland, the average removal rate of TN and TP was 2.6% and 3.8% higher than that of 2014. The change of temperature, water temperature, illumination intensity and the removal rate of COD, TN,TP were significantly correlated. The dissolved oxygen in the wetland system mainly comes from inlet water and the plant root system, the secretion capacity of plant root system is limited, therefore,the change of dissolved oxygen and the removal rate of pollutants is not significant.(2) In the process of continuous operation of CW, irispseudacorus and cannaindica interbreeding have stronger environmental resistance, and two kinds of different life cycle of plant hybrid would increase wetland system efficient processing time.When the HL from152L/(m2?d)increase 380L/(m2?d), the removal effect of pollutants in different plants have different degrees of decline, TN removal rate decreased more ammonia removal rate.Plant root growth helps to improve the impact resistance of wetland system, impact resistance performance could be ranked as long-root, middle-root as well as short-root.(3) Hybrid plants wetland microbial quantity and enzyme activity were obviously higher than other wetland plants,which indicated that the diversification of plant growth was suitable for thegrowth and reproduction of microorganism. Ammonifying bacteria dominate in heterotrophic microorganisms, bacteria accounted for 65%~85% of the total number. Urease activity and wetland system were closely related to the removal of nitrogen pollutants and hybrid plants make microbial metabolic activities more exuberant.(4) Adding earthworms can effectively improve the microbial ecological system, which also strengthen the plants and microorganisms and soil enzyme activities. The removal rates of COD,NH4+-N,TN, and TP were increased by 6.7%、4.1%、3.7% and 1.4% after adding earthworms.