Research On Harmless Treatment Of Rural Organic Waste And Its Effect On Water Environment

The treatment of agricultural organic waste has always been a pain point and difficulty in rural ecological environment governance,especially the impact of waste straw on the water environment is extremely serious.In this paper,it is known through investigation that the water environment in the study area is seriously polluted.It is analyzed that the main pollution source is waste straw,and a high-temperature composting experiment in a sun room is carried out to explore the changes in the physical and chemical properties of each pollution during the composting process.The onedimensional hydrodynamic water quality model simulates the impact of straw and other planting source pollutants on the surrounding water environment before and after treatment,and provides theoretical reference for the governance of the water environment in the study area.The specific conclusions are as follows:(1)Through the 12-month field measurement and analysis of the water quality data of the Helan section of the third drainage ditch in Yinchuan City,Ningxia Hui Autonomous Region,the results show that the pH and ammonia nitrogen in the middle section of the ditch and the Pingluo section have basically reached the national surface.The water environment is Class V water standard,while the CODcr,permanganate index,and TP in the channel have not met the standard for many months,and the months when CODcr and TP exceed the standard are mostly concentrated in March-June and September-November.They are 69mg/L and 0.63mg/L respectively;the months when the permanganate index exceeds the standard are mostly concentrated in September-November,and the maximum content is 71mg/L.(2)Using the single factor evaluation method and the comprehensive index evaluation method,the water environment evaluation of the Helan section of the third drainage ditch is carried out.The results show that the pH and ammonia nitrogen in the ditch are in the light pollution level;the permanganate index is in the medium pollution level,while CODcr and TP are in heavy pollution level.The main sources of pollutants were analyzed as planting sources(returned water from farmland and waste straw),livestock and poultry,aquaculture,and living sources.Among them,the amount of COD entering the ditch in the degraded farmland water was 175.51t/a,and the amount of ammonia nitrogen entering the ditch was 44.46t/a.The amount of TP entering the ditch is 5.62t/a;the amount of COD entering the ditch in the waste straw and residual seedling is 84.22t/a,the amount of ammonia nitrogen entering the ditch is 12.63t/a,and the amount of TP entering the ditch is 1.54t/a;livestock and poultry and In aquaculture,the amount of COD entering the trench is 190.37t/a,the amount of ammonia nitrogen entering the trench is 17.94t/a,and the amount of TP entering the trench is 8.01t/a;the amount of COD entering the trench in the living source is 37.96t/a,and the amount of ammonia nitrogen entering the trench is 37.96t/a.It is 5.4t/a,and the amount of TP entering the trench is 0.96t/a.The main sources of pollutants in the channel are planting sources,livestock and poultry and aquaculture pollution sources.(3)The cow dung and corn stalks were subjected to harmless composting experiments in the sun room according to the ratios of 4:1,3:15 2:1 and 1:1.The results showed that the 4:1,3:1,2:1 ratio of composting effect is better,in which the changes of temperature,pH,moisture content,organic matter,TN are very regular,while P,K and heavy metals in the compost have little change before and after composting,ammonia state Nitrogen gradually decreases in the process of composting,and nitrate nitrogen gradually increases.The heap rot effect of each index in the 1:1 ratio is poor.(4)Based on the one-dimensional hydrodynamic water quality model,the water quality of the channel before and after the treatment of plant source pollutants was simulated,and then the pollutant holding capacity was calculated.Before,the content of CODcr,ammonia nitrogen and TP in the channel continued to increase.After treatment,the reduction effect of CODcr in the channel was better,and the reduction effect of ammonia nitrogen and TP was average;The changes of CODcr,ammonia nitrogen and TP content in the channel are the same as those of Class Ⅳ water.After treatment,the CODcr reduction effect in the channel is better,the maximum reduction efficiency is 23.86%,and the maximum reduction efficiency of ammonia nitrogen and TP is 29.16%and 25.21%,respectively.The reduction efficiency of the material shows a trend of first increasing and then decreasing.