Possiblity Of The Agricultural Uitilization Of Rural Domestic Sewage And Its Influence On Soil And Crop Production

With the development of rural economy and improvement of infrastructure,the discharge of rural domestic sewage also increases.Meanwhile,the domestic sewage is rich in nitrogen and phosphorus.If it is discharged into natural water without proper treatment,it will inevitably cause water eutrophication.From the perspective of resource utilization,the nitrogen and phosphorus in domestic sewage can be a necessary nutrient for crop growth.It can reclaim the resources in the sewage while absorbing the sewage.It is an effective way to solve the current pollution discharge of domestic sewage in rural areas.This article through the investigation and indoor and outdoor two parts of the experiment to examine the feasibility of domestic sewage utilization.Analyzed the feasibility of agricultural resource utilization of domestic sewage,and explored the ecological impact that may occur in the process of it.Investigating the accumulation,migration and transformation of surfactant,salt,nitrogen and phosphorus in soil during the utilization of rural domestic sewage.The focus is on soil physical and chemical properties and microbial populations,crop yield and quality,and the impact on groundwater.The main conclusions are as follows:(1)Test rural sewage contains a certain amount of nitrogen and phosphorus nutrients.COD,surfactant(LAS),heavy metals and other pollutants have a low content,and the salt content is not high.All the water quality indicators can achieve the "Water Quality Standard for Farmland Irrigation"(GB5048-2005)in the requirements.At the same time,the questionnaire survey found that most of the farmers in Anji County have a high degree of recognition and acceptance of agricultural uitilization of rural domestic sewage.It is feasible to promote the agricultural uitilization of rural domestic sewage in Anji County,because it already has a good foundation.(2)Indoor short-term application of domestic sewage or simulated domestic sewage containing LAS at a low concentration has not yet had a significant impact on the soil-crop system.At the same time,the soil-crop system can effectively absorb the pollutants such as organic matter,nitrogen and phosphorus in domestic sewage through physical,chemical and biological effects.In terms of soil physical and chemical properties,the physical and chemical properties of LAS affected 0?20cm soil more than 20?40cm.In crop yield,the water content of ipomoea aquatica increases with increasing LAS concentration,so as to achieve the effect of increasing yield.But there is no significant difference was found in the quality indicators of ipomoea aquatica.In the soil microorganisms,short-term test LAS has obvious effects on bacteria in the soil,but has no obvious effect on fungi and actinomycetes.However,with the increase of LAS concentration,the adsorption of nitrogen and phosphorus decreased and the vertical leaching loss increased,which led to the increase of nitrogen and phosphorus in the leachate and led to the risk of eutrophication.Therefore,in practical application,it is necessary to regularly monitor the content of surfactants in domestic sewage so as to reduce the environmental risks.(3)After 467 days of field trials,no significant effect of COD,ammonia nitrogen,total nitrogen and total phosphorus concentrations in leachate of 20?40cm soil depth was observed using different load of anaerobic tank effluent irrigation,indicating that the soil-crop system could Effectively absorb nitrogen and phosphorus in domestic sewage and other pollutants.At the same time,it has little influence on the basic physical and chemical properties of the soil,no risk of soil salinization,and to a certain extent,increase the amount of soil microorganisms,thereby affecting the activity of microorganisms in the soil and further improving the soil quality.Under the reasonable choice of irrigation hydraulic load,the moderate utilization of domestic sewage will not have a negative impact on the yield,agronomic traits and quality of crops,and the nitrogen,phosphorus and other nutrients contained in domestic sewage can to some extent Increase crop yields.The best hydraulic load of this test is 0.002 m3/m2 · d.Under the hydraulic load of this test,groundwater is basically not polluted,but with the increase of hydraulic load and the increase of the concentration of pollutants in domestic sewage,the potential risk of contamination of groundwater still exists.