| Influence of non-point pollution on the water quality appears obviously after effective control and management of point pollution. The researches from many countries and zones indicated that non-point pollution is the principal causation inducing eutrophication. It is very difficult to prevent and control non-point pollution because non-point pollutants have some characteristics of dispersive origin, variety of contaminants and concentrations, strong randomization, and lots of influence factors. Pollutants from cities and agricultural zones through rainstorm runoff goes into water bodies, becomes main orgin of non-point pollution. Therefore, it is very important to effectively control rainstorm runoff for preventing non-point pollution. Hilly areas of purple soil lies in the most forward edge of the upper reaches of Yangtze River's Green Belt. The density is large, the rural towns develop fast. The waste water discharge unorderly, pile up at random because of lacking the pipeline and process system, then move to the downstream water body through the runoff. Waste water of rural town have higher pollution load in the catchment, causing much pressure to the adjacent place or the water environment.So far, simulation research is the main approach to control runoff, few field experiments are reported. Compared infiltration tank with other ecological treatment techniques, it has advantages of highly hydraulic loading, and low floor area. Owing to characteristics of runoff pollution in rural township, it needs to further study on the possibility of pollution control through medium infiltration, influence factors, construction manner, and management measures.The adsorption capabilities of single medium and mixed media of bentonite, zeolite, and sand to phosphorous were analyzed using static and dynamics adsorption experiments, and the removal effect of phosphorous in runoff is preliminarily studied using the constructed infiltration tank. The achievements were summarized as follows.1. The static sorption experiments showed that bentonite has the best adsorption capacity for phosphorous. The mixed media has better adsorption effect than zeolite and sand, decreases the desorption rate, and thus reduces the risk of secondary pollution. The maximum theoretical adsorption amounts of bentonite, zeolite and sand are 250.00 mg·kg-1, 76.34 mg·kg-1 and 71.43 mg·kg-1, respectively. The maximum theoretical adsorption amounts of two mixed and three mixed media are 210.12 mg·kg-1, 200.15 mg·kg-1, respectively.2. The column experiments showed that the infiltration coefficient is a key influence factor on the retention time of waste water and the removal rate of total phosphorous. All of the mixed media have high removal efficiencies with above 82%, especially the removal efficiencies of two types containing bentonite are above 96%. All mediums have good removal effect efficiency (above 94%) for phosphate except sand (64.06%). In consideration of the infiltration coefficient and removal rate, taking the mixed medium as the filter material is good choice. Chemical mechanism plays an important role in removing phosphorus by mixed mediums.3. The pilot cell experiment results indicated that the removal efficiency for phosphorous with infiltration tank is affected by rainfall condition, such as rainfall amount, strength, and interval. The high shock loading efficiently decreases the removal rate for phosphorous, and there is a high relationship between the removal rate and rainfall interval. The removal rate decreases with the use time increasing, which need be studied in the future.
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