Study On The Application Of Under Soil Field Treatment System In Rural Sewage Treatment

Rural sewage treatment is getting more and more attention in China,but traditional urban sewage treatment technology is not suitable for rural sewage.It is required to develop sewage treatment technology that conforms to the characteristics of rural sewage from the aspects of economy,stability and applicability.The commonly used ecological treatment technology and biological treatment technology have certain disadvantages,which cannot be fully applied to rural areas.Therefore,several technologies can be combined to form a new sewage treatment technology.Under this test adopts the sewage treatment technology under soil field.This process has the advantages of less investment,simple process,low operation cost,stable treatment effect and convenient management and maintenance,and is suitable for rural sewage treatment.Its application research is of great significance in rural sewage treatment.Analysing the transformation law of rural sewage.Exploring the best operation parameters of the land treatment system and mechanical filter.Studying the effect of backflushing on the process,verify the feasibility and practicability of this technology in the aspect of rural sewage.From April to July 2018,the transformation law of rural sewage was studied.The water consumption per capita in the town is 18.75L/(person·d),with a daily variation coefficient of 1.08,a time variation coefficient of 1.20,and a total variation coefficient of 1.30.The seasonal change law of sewage with less water and higher pollutant concentration in spring,more water and lower pollutant concentration in summer was obtained.And the daily variation pattern of waste water,more sewage quantity from 9 to 13,19 to 21,and less sewage quantity from 22 to the next day of 4.Optimize the denitrification capacity of land treatment system.The water intake of the system is 150m~3/d,and the hydraulic load is 0.67m3/(m~3·d).Under the different condition of anoxic/aerobic section length and the reflux ratio,studying the ammonia nitrogen,TN removal ability of this system.Determine the 1-4#exposure trachea had closed,5-9#had opened,11-12#trachea closed and reflux ratio under the condition of 200%have the best treatment effect,57.4%removal rate of TN and56.5%removal rate of ammonia nitrogen.This process increases the coagulation step to strengthens its phosphorus removal ability.PAC coagulant was selected in this experiment.By studying the effect of phosphorus removal efficiency under different feeding methods and dosages.It was determined that when the feeding method was post-placement and the dosage was50mg/L,the TP removal rate was 70.4%,and the water outlet TP concentration was0.42mg/L,which reached the emission standard.According to the disposal of mud by land treatment system and phosphorus removal efficiency of the mechanical filter,the optimal operating conditions were determined,including 15 min of air flush,15 days of backflush cycle of the land treatment system,and 5min of air flush,10min of gas-water combined recoil,10min of water flush and 2 days of flushing cycle of the mechanical filter.