Study On High-efficiency Utilization Technology Of Paddy Field In Rural Dispersed Domestic Sewage Treatment Tail-water

In recent years,the urbanization process in southern Jiangsu has accelerated,and the level of rural human settlements has continuously increased.The increasing recycling of domestic sewage has become an urgent ecological problem.In the rural areas,there is a large amount of farmland,which can be used as a wetland system to dissipate the dewatered domestic sewage treatment tail water.The high-efficiency utilization technology of rice fields for the development of rural decentralized domestic sewage treatment tail water can not only solve the problem of a large number of tail water discharge into rivers polluting rural ecological environment,but also provide an important scientific basis for the realization of livable villages.In this study,the spatial and temporal distribution of tail-water in the distributed domestic sewage treatment in Luodun Village of Changshu City,the distribution of villages and the physical and chemical properties of the tail water were mainly investigated.The experiment on the growth characteristics of rice under the continuous irrigation of tail water was carried out,and different tail water irrigation was studied.Dynamic changes of tiller,changes in plant biomass,changes of nitrogen,phosphorus and potassium in various organs of plants,changes in yield and changes of available nitrogen,phosphorus and potassium in paddy soils.The research results are as follows:(1)There are 10 large villages in Luodun Village,with a total of 1,504 households.The whole village has 28 small-scale distributed domestic sewage treatment facilities according to the main rivers,and the annual discharge water volume is about 245,280 cubic meters.(2)The rural dewatering domestic sewage treatment tail water in Luodun Village shows that the spring and summer water saving is significantly higher than that in the autumn and winter seasons,showing three peaks in one day,6-7 o'clock,11-12 o'clock,18-19 o'clock.(3)After the domestic sewage is treated by the distributed treatment device,the tail water still contains a large amount of nitrogen and phosphorus substances,the total nitrogen content is 14.32mg/L,and the total phosphorus content is 1.22mg/L,which only meets the sewage discharge level.The B standard is far higher than the surface water standards of the five types of surface,and the discharge into the surrounding rivers will still cause environmental pollution problems.(4)With the increase of tail-water input,its nitrogen input equivalent is increasing,which can promote the increase of rice tiller in the short term,but when the nitrogen input equivalent of tail water exceeds 300kg/ha,the effective number of tillers is instead Showing a downward trend.(5)In terms of rice plant biomass,as the input of tail water increases,the amount of dry matter increases continuously.The nitrogen input equivalent in tail water is 300kg/ha,and its biomass is the largest.(6)In the distribution of nitrogen,phosphorus and potassium in various organs of rice plants,with the increase of tail water input,it can promote the accumulation of nitrogen,phosphorus and potassium in various organs of rice plants.The nitrogen input equivalent in tail water is 300kg/ha,its organs have the highest nitrogen,phosphorus and potassium contents.(7)In terms of rice yield formation,the increase of tail water input has the greatest influence on the effective panicle number and 1000-grain weight,showing an increasing trend.The nitrogen input equivalent in tail-water is 300kg/ha,and the highest yield is 11442.38kg./ha,equivalent to the yield of conventional fertilization treatment.(8)In terms of the accumulation of available nitrogen,phosphorus and potassium in paddy soil,the content of available nitrogen,phosphorus and potassium in the soil increased with the increase of tail-water input,indicating that the continuous tail-water input can provide more for rice plants.The nutrients that promote their growth.(9)When the nitrogen input equivalent of 300 kg/ha in the tail water is 8.7 m3/mu per day,the rice growth can be optimized.At this time,Luodun Village needs to support 77 acres of farmland to absorb the amount of tail water produced.