| In recent years,with the implementation of a series of engineering projects such as the construction of new rural and beautiful village,great progress has been made in social and infrastructure in rural areas.But at the same time,environmental pollution and ecological protection,especially in the treatment of rural domestic sewage,has become an urgent problem to be solved.Because of the wastewater in rural areas is characterized by strong dispersibility,wide pollution and varies greatly in quality and quantity,it is difficult to govern.Although there have been many researches on the treatment of rural domestic sewage,many of them have the disadvantages of low efficiency,large infrastructure investment and difficulty in management.Therefore,it is necessary to study a set of sewage treatment technology for the actual situation in rural areas with high efficiency,low investment and easy to manage.This study is based on the project of “Gansu Minsheng Science and Technology---Water,Sewage,Garbage Treatment and Demonstration Project in Rural areas”.Treating sewage in rural areas as the research object,through the comparison between iron filter and ordinary filter,the treatment effect of biological iron method and land treatment technology on rural domestic sewage was studied.The results prove that:(1)As the pretreatment process,the tower circulation filter has a good effect on the removal of pollutants.This creates favorable water conditions for the land treatment system.There is no significant difference in the removal rate of COD polyurethane and iron+polyurethane filters.The removal rate of COD can reach more than 80% under the four conditions of circulation flow rate of 15L/h?30L/h?45L/h and 60L/h.The removal efficiency of the two fillers is not good for ammonia nitrogen and total nitrogen,and the removal rate is below 50%.However,the removal rate of iron+polyurethane is higher than that of polyurethane.In the removal of phosphorus,the removal effect of iron+polyurethane was much better than that of polyurethane.Different HRT has certain effect on removal of COD and ammonia nitrogen,but no significant changes in phosphorus removal.With the experiment,the optimal cyclic flow rate and the optimal HRT were determined to be 45L/h and 3h respectively.(2)The filling method in the land treatment system has certain effect on the treatment effect.On the removal of COD and ammonia nitrogen,the ordinary gravel still has good effect.The addition of sponge iron has strengthened the physicochemical and biochemical effects of soil,especially with the combination of polyurethane,which has a good strengthening effect on the removal of phosphorus.The surface load has a great influence on the removal of COD.Despite the addition of sponge iron,the removal rate of ordinary gravel in COD will decrease with the increase of surfaceload.Due to the role of microorganism,the COD removal rate of polyurethane will increase slowly over time.The surface load has a little effect on ammonia nitrogen,but the removal effect of compound filling soil treatment system on ammonia nitrogen is better than that of ordinary coarse grit stone land treatment system.In respect of phosphorus removal,the addition of sponge iron for phosphorus has a strong resistance to impact load action,especially in the combination of polyurethane and sponge iron reactor,on phosphorus removal effect is stable.(3)The tower circulation filter and land treatment system have different functions.The tower circulation filter is mainly pretreated with the raw water,while the land treatment system is further processed with the effluent of the tower circulation filter.After the two systems are processed,the effluent can meet the requirements of sewage treatment in rural areas.Because of the system has low infrastructure cost,convenient operation and maintenance,low energy consumption and can make full use of land resources in rural areas,there is a wide application prospect in the treatment of decentralized domestic sewage in rural areas. |
PDF Full Text Request