Analysis Of Spatial And Temporal Characteristics And Pollution Restoration In Feicui Lake

With the continuous development of China's economy,the problem of water environment pollution has become increasingly prominent.In order to explore the changes of water quality and eutrophication in lakes?library?,and to strengthen the research on its application and management,the typical non-closed polluted water is taken as the research basic.From August,2018 to January 2019,through sampling and monitoring in field,the spatial and temporal variation characteristics during three water periods were analyzed,and the intrinsic relationship between environmental factors was carried out by means of correlation analysis,correlation analysis and eutrophication evaluation.According to the characteristics of water pollution,it is proposed to use the repair technology such as enhanced coagulant dosing and bottom of microporous aeration to repair the polluted water.The main research contents and conclusions are as follows:?1?Analysis of temporal and spatial variation characteristics of water environment showed that WT,pH,turbidity,SS decrease gradually,while DO and SD increase gradually;COD_Cr and COD_Mn meet the ClassV and?standard of Surface Water,the proportion of TP below the?standard is 77%,TN is almost all lower than the V standard,and the Chl-a showed a significant seasonal difference.In the vertical direction,the vertical concentration difference of each environmental factor gradually decreases;There are local and bottom layer anoxic phenomena in the water,and the difference of TN and TP have large variations in each water period,which may be related to the presence of algae light layer in water,which may be related to the presence of algae true light layer in water;In the horizontal direction,the concentration distribution of TN and TP indicates that the exogenous pollution in the southern main lake has a certain influence on the hanges of nitrogen and phosphorus concentrations in the research area.The Chl-a in the abundant period is gradually decreasing from the northeast to the south,but not in the dry period.Differences,overall,the water quality of the water changes significantly during the abundant period and medium period,and there is no significant difference in the dry period.?2?Correlation analysis showed that the correlation between Chl-a and SS,TP was the highest in physical and chemical indicators(r_0i=0.776;r_0i=0.748);Correlation analysis of Person showed that Chl-a and WT,TP?r=0.759,P<0.01;r=0.728,P<0.01?have a very significant positive correlation and a significant negative correlation with SS?r=-0.748,P<0.01?.The results of comprehensive nutritional status index?TLI?and nutritional status index?EI?showed that The water was in mild or moderate eutrophication during the monitoring period.The contribution of TN and TP in the two eutrophication evaluations was close to 45%,while the difference in Chl-a ratio was the largest,and the difference was 6.2%.It belongs to the phosphorus control lake.?3?The coagulation test of contaminated raw water was carried out by using common coagulant.The results showed that PAC had the best coagulation effect,and the removal rate of water turbidity,SS and TP was up to 96.4%,92.0%and 85.0%;The effect of DIA and PAC have obvious effects on removing algae after enhanced coagulation.The removal rate of Chl-a is up to 91.8%,the flocculation sedimentation rate is nearly doubled after intensive coagulation,and the compactness is obviously improved.From the economic point of view;when PAC and DIA are both 20mg/L,the reinforced coagulant can achieve good algae removal,Chl-a removal rate is 74.5%.?4?Micro-aeration aeration testi in field showed that when the aeration flux is 4m³/h,the reaction period is 12h,and the running time is 50d,DO concentration is obviously improved and?DO of vertical is reduced;Bottom aeration improved the exchange rate of vertical flow and vertical flow in water,but disturbance caused a phased impact on the migration and transformation of nutrients such as turbidity and nitrogen and phosphorus.At the end of the test,COD,TN,NH₃-N and TP of the overwatein were reduced by 11.1%,14.2%,23.2%and 23.1%,respectively,and the sediment layer was reduced by6%,21.6%,35.9%and 28.2%in the aeration group.Compared with the control group,COD,TN,NH₃-N and TP of the overwater are reduced by 22.5%,31.8%,39.7%,9.7%,sediment layer decreased by 3%,34.3%,49.4%and 17.6%.Aeration can effectively remove NH₃-N,but the effect of TP removal is not ideal.In general,method of single aeration has limitations in the practical application of shallow water in cities.Aeration needs to be combined with chemical,biological microbial dosing,and sediment passivation to achieve greater effectiveness.