Preliminary Study On Influencing Factors And Prevention Techniques Of Deteriorated Water Quality Of Waterstorage Pond In Guanzhong Area

The waterstorage pond is a soil and water conservation project that accumulates rainwater in low-lying rural areas in northern arid regions.While exerting its soil and water conservation efficiencies such as the gully protection plateau,it can also provide scarce wetland landscapes for the area.In the 1990s,due to the rise of various rainwater harvesting projects,their traditional functions were limited,and the existence value of the waterstorage ponds was weakened.In addition to the closed water bodies,shallow water levels and small areas,the lack of management and The intrusion of foreign pollutants reduced the self-purification capacity of the water body,and most of the existing waterstorage ponds had serious water eutrophication and even been abandoned.Since 2016,the Shaanxi Provincial Department of Water Resources has included the ecological restoration and remediation of rural waterstorage ponds into the province's“Thirteenth Five-Year Plan”for soil and water conservation.However,the new and renovating waterstorage ponds have repeatedly experienced black and odorous water bodies.According to the survey,the black and odor rate of newly built and renovated water bodies of the waterstorage ponds in the surrounding area of Yangling Demonstration Zone in Guanzhong area has reached46%.These phenomena not only restrict the development of rural society,but also cause the rural water ecological environment to deteriorate continuously.Therefore,it is imperative to understand the causes of the deterioration of the water body of the waterstorage pond and its changing rules fundamentally,and take corresponding measures to carry out the restoration and remediation work according to local conditions.This study aims at the black and odor problem of water bodies during the renovation and restoration of waterstorage ponds in Guanzhong area,taking the typical representative waterstorage ponds around Yangling District as the research object,based on the existing research on the evaluation,analysis and restoration of polluted water bodies The results,on the basis of clarifying the types of waterstorage pond construction and pollution sources,analyzed the different factors that may cause the deterioration of water quality,and studied different types of purification measures.The main conclusions are as follows:?1?Investigations and studies have shown that the water quality of the waterstorage ponds in the study area is inferior to surface water,with varying degrees of pollution.The pollutants are mainly nitrogen compounds.The sources of pollutants mainly include domestic sewage,farm wastewater,and different The confluence of surface runoff on the mat surface,the implementation of anti-seepage at the bottom of the waterstorage pond,and the configuration of sewage treatment facilities are more important for improving the water environment of the waterstorage pond.In addition,with the related restoration and management measures of the internal water body,the improvement effect of the water body will be better.?2?Under the test conditions,the inclined plate can significantly reduce the suspended matter in the sediment.When the discharge flow is small?the discharge flow is 25L/min,the length of the sedimentation tank is 1m?,the inclined tube sedimentation tank and the ordinary sedimentation There is no obvious difference in the sedimentation efficiency of the pool,and there is no significant change with the increase of the length of the pool;when the discharge flow is large?the discharge flow is 95L/min and 160L/min?,the inclined plate sedimentation tank is in different pool length conditions The efficiency of sinking sand is generally higher than that of ordinary sand sink;inclined pipe sand sink is better than ordinary sand sink in removing coarse particles larger than 0.01mm in different pool lengths and different discharge flows in high sand flow,and the inclined plate sinks The special structure and placement method of the sand pond have reduced the water flow rate to a certain extent,and can effectively deposit coarse particles and suspended matter in the sand pond.?3?The three plants showed a good purification effect on the total nitrogen in the water body,the average removal rate was as high as 56.37%,and the average removal rate for NH₃-N was as high as 73.87%.The main removal of NH₃-N by the Canna and Acorus group The pathways including ammonia volatilization,root absorption and nitrification.The main removal route of NH₃-N in the Siberian iris group is ammonia volatilization and nitrification.The main reason for the removal rate of NH₃-N in the control group up to 60.55%is ammonia volatilization;The variation of NO₃^-–N concentration in the plant-floating bed group is mainly related to the difference in the degree of nitrification reaction of the water bodies and the absorption efficiency of plants in each test group.The removal efficiency of TP in the water bodies of the two pollutant sources by the canna group and the water calamus group was 55.42%and58.32%,respectively.The removal efficiency was much greater than that of the control group?15.57%?,while the TP concentration of the Siberian iris group at the end of the experiment was not Significant differences.Among the plants,Acorus calamus is suitable for the purification of water sources of point source and non-point source pollution.The canna root rots in the heavily polluted water body due to the developed root system to produce secondary pollution.It is not suitable for the purification of water source polluted by point source pollution.Poor growth adaptability in the water source of the pollution source is not suitable for promotion as a floating bed plant for remediation of polluted water in the waterstorage pond.?4?Chemical reagents with different concentrations have different effects on water pollutants and other elements.For calcium oxide,the principle of removing total phosphorus in water is basically the same as calcium peroxide,the only difference is Calcium peroxide is a strong oxidant.It reacts with water to produce oxygen,which can increase the dissolved oxygen content in the water body.It has the effect of changing the microenvironment of the water body,enhancing the aerobic microbial activity,and promoting the nitrification reaction of the water body.Therefore,within a certain concentration range The removal efficiency of pollutants with strong oxidizing calcium peroxide is higher than that of calcium oxide,and its water purification benefit exceeds calcium oxide,and the unit price is only about20RMB/kg.