Ecological Restoration Of Three Kinds Of Polluted Water Bodies In Rural Area Of Ningxia

As a necessary resource in people’s production and life,the importance of water is self-evident.As the country with the highest water consumption in the world,China’s water pollution problem is becoming increasingly prominent in today’s increasingly severe contradiction between water supply and demand.Although the total amount of water resources in China is large,the per capita disposable amount is small,and the distribution of time and space is even more uneven.Ningxia Hui Autonomous Region is located deep in the northwest inland of China,with scarce annual precipitation and scarce water resource utilization.Therefore,it is of great significance to carry out ecological restoration of polluted water bodies and promote the recycling and utilization of water resources in Ningxia.This article focuses on the ecological restoration of three different types of polluted water bodies in rural areas of Ningxia,and studies their ecological restoration effects,in order to provide some reference for the local water environment governance and water ecological restoration work in Ningxia.1.In order to reduce the impact of tail water from small urban sewage treatment plants on natural water bodies,a composite ecological treatment system was constructed using a combination process of ecological ditches and ecological stabilization ponds to deeply treat the tail water of Zhenbeibao Sewage Treatment Plant in Xixia District,Yinchuan,Ningxia.A study was conducted on the water quality and microbial community structure along the process of the composite ecological treatment system from April to October 2021.The research results show that the combination process of ecological ditches and ecological stabilization ponds has a good removal effect on pollutants in tail water,with average removal rates of phosphate,nitrite nitrogen,and ammonia nitrogen reaching 39.66%,58.28%,and 70.72%,respectively.The effluent quality meets the Class IV standard of the Surface Water Environmental Quality Standard(GB3838-2002).There is high microbial diversity within the system.As the concentration of pollutants along the system decreases,the overall richness and diversity of microorganisms also show a downward trend.The dominant bacteria in the system were Proteobacteria,Firmicutes,Bacteroidota,Actinobacteria and Cyanobacteria.The dominant bacterial classes were Gammaproteobacteria,Alphaproteobacteria,Bacilli,Bacteroidia and Actinobacteria.There were differences in microbial communities between ecological ditches and ecological stable ponds(P<0.05).Environmental factor correlation analysis shows that phosphate has the greatest impact on the composition of microbial communities in the system,followed by p H and nitrite nitrogen.The combination process of ecological ditches and ecological stabilization ponds is used to treat the tail water of sewage plants,which is simple in construction and has significant effects,and has certain promotion and application prospects.2.In order to improve the water quality of polluted rural small and medium-sized rivers,a comprehensive ecological restoration project of ecological restoration of the main river channel and purification of the bypass ecosystem was implemented in Pingerzhigou,Xixia District,Yinchuan,Ningxia.A study was conducted from April to August 2021 on the water quality and microbial community structure along the main river channel of Pingerzhigou;A study was conducted from June to September 2022 on the water quality status downstream of the main river channel of Pingerzhigou.In 2021,the average removal rate of phosphate in rivers was 97.59%,the average removal rate of nitrite nitrogen was 74.00%,and the average removal rate of ammonia nitrogen was86.83%;In 2022,the average removal rate of phosphate in the downstream of the river was 79.02%,the average removal rate of nitrite nitrogen was 68.6%,and the average removal rate of ammonia nitrogen was 76.67%.After the implementation of ecological restoration projects in the main rivers,the nitrogen and phosphorus content along the river has shown a significant downward trend,and the final effluent can meet the Class III standard for surface water environmental quality.The overall richness and diversity of microbial communities in the main river channels show a decreasing trend,which is consistent with the changes in water quality along the way.The dominant bacterial phyla in river water were Proteobacteria,Firmicutes,Bacteroidota,Actinobacteria and Cyanobacteria.The dominant classes are Gammaproteobacteria,Bacteroidia,Bacilli,Alphaproteobacteria and Actinobacteria.The microbial community structure in various regions along the river has a certain degree of stability,but there are differences between the upstream and downstream(P<0.05).Environmental factor correlation analysis shows that water temperature has the greatest impact on the composition of microbial communities in river water bodies,followed by phosphate and ammonia nitrogen.3.In order to study the purification effect of the bypass rice field ecosystem on the water quality of the Pingerzhigou River,a study was conducted in August 2021 on the water quality status,microbial communities in water and soil within the bypass rice field system.After entering the bypass paddy field,the concentration of pollutants in the river water shows a significant downward trend,with an average removal rate of61.11% for phosphate,56.07% for nitrite nitrogen,and 31.2% for ammonia nitrogen.The dominant bacteria in the water bodies of the by-pass paddy field ecosystem were Proteobacteria,Bacteroidota,Actinobacteria,Firmicutes and Cyanobacteria.The dominant classes are Gammaproteobacteria,Bacteroidia,Actinobacteria,Alphaproteobacteria and Bacilli.The dominant bacterial phyla in the soil of the by-pass paddy field ecosystem were Proteobacteria,Chloroflexi,Actinobacteria,Firmicutes and Bacteroidota.The dominant bacterial classes are Gammaproteobacteria,Alphaproteobacteria,Anaerolineae,Bacteroidia and Acidimicrobiia.The relative abundance of dominant phyla and dominant phyla of microorganisms entering and exiting the water in the bypass rice field ecosystem has changed,with a significant increase in the relative abundance of Actinomycetes(P<0.05).The correlation analysis of environmental factors shows that salinity has the greatest impact on the composition of microbial communities in the bypass rice field ecosystem,followed by p H and phosphate.For rural rivers with complex pollution sources and relatively poor water quality,a comprehensive ecological restoration plan combining ecological restoration of main river channels and purification of bypass ecosystems can achieve good ecological restoration results.4.In order to purify the tail water of pond aquaculture,a composite ecological ditch system consisting of different types of ecological ditches connected and coupled was constructed in the rice fish co cultivation cycle water aquaculture model.A study was conducted in 2020 and 2021 on the water quality status along the composite ecological ditch of Kehai Biotechnology Co.,Ltd.in Helan County,Yinchuan,Ningxia.The results showed that in 2020,the average removal rate of phosphate,nitrite nitrogen,and ammonia nitrogen in pond aquaculture tail water was 96.21%,91.27%,and 94.75%,respectively.In 2021,the average removal rate of phosphate,nitrite nitrogen,and ammonia nitrogen from pond aquaculture tail water was 68.96%,61.36%,and 51.92%,respectively;After the paddy field is drained and purified,it can meet the Class IV standard for surface water environmental quality.The overall water quality of pond aquaculture tail water and rice field backwater has been significantly improved after being purified by a composite ecological ditch system.The use of a composite ecological ditch system can achieve the recycling of water for pond aquaculture and rice field irrigation,which has strong applicability in arid and water deficient areas such as central and western China.