Experimental Study On The Treatment Of Rural Domestic Sewage By Modified Soil Infiltration Device

At present,most of the rural areas in China lack effective collection and treatment facilities for domestic sewage.In some areas,sewage is directly discharged without any treatment,causing serious pollution to environmental sanitation.Compared with urban domestic sewage collection and treatment,the source of sewage in rural areas is scattered and small,and it lacks the necessary technical and economic support.It is unreasonable to directly adopt the urban sewage treatment mode.Therefore,it is of great social significance and application value to research and develop wastewater treatment technology with low cost,good treatment effect and suitable for small water volume and distributed treatment.Although the traditional soil percolation system has a good treatment effect on organic matter and total phosphorus,it is considered to be very suitable for sewage treatment technology in rural areas.However,due to the large area of the system,the nitrogen removal t is poor and easy to block and other issues have limited the promotion and application of this technology.In view of these shortcomings,this paper proposes an improved soil infiltration system that replaces part of the soil with leachate system with fly ash,and systematically studies the treatment effect of improved soil infiltration system on rural domestic sewage.1.According to the proposed research idea of the improved soil percolation system suitable for rural sewage treatment,the up-and-down splitting method is used for the percolation treatment,and the corresponding filter layer structure and parameters are given.2.Ten sets of start-up period tests were carried out.The analysis of the test results showed that the comprehensive start-up time of COD,total nitrogen,ammonia nitrogen and total phosphorus was based on the start-up period of the COD with the longest stable treatment effect.For 25 d.After the system was started,the removal efficiency of COD,ammonia nitrogen,total nitrogen and total phosphorus reached 83%,81%,39% and 90% respectively.3.Eight groups of hydraulic load tests were carried out.The results show that the system has the best treatment effect under the hydraulic load of 8cm/d.The removal effects of COD,ammonia nitrogen,total nitrogen and total phosphorus are 85.13%,85.58%,43.17% and 94.16%,respectively.4.Ten groups of flow ratio test was carried out.The results show that the proper split ratio is the key to improve the nitrogen removal efficiency of the system.When the split ratio(upper inlet: lower inlet water)is 2:1,COD,ammonia nitrogen,total the removal rates of nitrogen and total phosphorus were 82.36%,80.07%,63.78% and 89.93%,respectively.Compared with the unsplit operation,the total nitrogen removal rate was significantly improved,and the removal rates of COD,ammonia nitrogen and total phosphorus were decreased.Compared with the addition of biological matrix to the system to improve the denitrification effect,the shunting process is simple to construct,and the nitrogen removal effect of the system can be significantly improved without increasing the operating cost of the system.