Study On Sewage Treatment With Constructed Rapid Infiltration

Constructed rapid infiltration(CRI) system is a new type of land treating technology which is based on the traditional rapid infiltration(RI), because of better infiltration media replacing the natural soil, as a result, the hydraulic loading can be increased and the occupying land area can be minished.On the basis of the confirmation of the media configuration,wet/dry ratio and hydraulic loading by the prior preparatory experiments, the aim of this experiment is to study the performance of the constructed rapid infiltration(CRI) treating the sewage. This article mainly studies the CRI performance in the different wet/dry ratio, hydraulic loading and aeration, while the mechanism including height, time transformation and the clogging is also researched. Finally, we ascertain the optimal control index.In the wet/dry ratio experiment, we research the performance of the system under the refered three W/D ratios when the hydraulic loading is 0.1m/d, the results indicate the the 1d:3d is the optimal ratio, the average effluent concentration of COD, TN, TP is 46 mg/L, 26.7 mg/L, 1.0mg/L respectvely, and the removal rate of COD, TN, TP is 84.3%,57.7%,85.1% respectively. For the removal of COD, ratio should be chosen under the consideration of abundant nutritional materials and aerobic recovery; W/D ratio is contrary to the removal rate of TN, smaller ratio and longer drying time favor the removal of nitrogen; W/D ratio has no relation to the removal of TP, we estimate that the TP removal is concerned with the wet time and the soil adsorption capacity.In the hydraulic loading experiment, we research the performance of the system under the refered four hydraulic loadings when the W/D ratio is 1d:3d, the results indicate the the 0.1m/d is the optimal loading and the removal rate of COD, TN, TP is 84.2%, 57.8%,84.9% respectively. When the hydraulic loading rises from 0.1m/d to 0.14m/d, hydraulic loading is contrary to the removal rate of COD and TN; hydraulic loading has no relation to the removal of TP.In the aeration experiment, we research the performance of the system under three ways, the results indicate that aeration through plants has no meaning to the removal of COD; plants have an obvious significance to the removal of nitrogen and phosphorous.In the mechanism experiment, we research the height, time transformation of the system. The results suggest that (1) 70cm height soil is suitable and the surface 20cm contributes great for the pollutants removal, SS, a lot COD and the other pollutants...