| Hangzhou West Lake plays a great role as the main landscape water in China.Longhong stream is one of the natural supply sources of West Lake,Due to the influence of the non-point source pollution of the surrounding tea garden,the concentration of nutrients in the water exceeds the standard,which has a great influence on the water quality in West Lake.Therefore,it is necessary to effectively control the Longhong stream which can solve the eutrophication problem of the West Lake from the source.The main work and achievements are as follows:?1?Through the investigation and long-term water quality monitoring of Longhong stream,The water area is large and the inlet and outlet are narrow,existing dead water,the water is weak acid,and the content of dissolved oxygen is high,and the water is characterized by"low phosphorus and high nitrogen".?2?According to the characteristics of river channel,the project adopts the technology of combining multi-strengthened biological denitrification in ponds with the biochemical and chemical synergistic effects of the pond chain combination,through the multi-level ecological corridor,composite ecological floating bed,biological zeolite in the water for physics,chemistry,biology multiple purification to improve water quality.?3?After a year's monitoring of the water quality of Longhong stream,the demonstration project had a good effect on the improvement of water quality.The average removal rates of COD,TP,TN,NO3--N,and NH4+-N in water were 23.59%,45.20%,27.64%,23.34%,and 14.06%,respectively.In different seasons,the purification effect is different.In summer,the purification effect of water is better,and the treatment effect is poor in winter.This may be related to the growth state of plants and the activity of microorganisms in water.?4?The removal efficiency of nitrogen in each treatment unit was compared.The results show that the water when the initial concentration of TP was 9.08 mg·L-1,TN is about 24.53 mg·L-1,a strain of Myriophyllum after 24 days of absorption,removal of TP and TN were 69.09%and 51.6%,the total amount of absorption is 6.08 mg and 6.45mg.When the initial concentration of TN is about 60 mg·L-1,after 108 hours of purification,the removal rate of TN by 70 g ceramsite is 93.30%,and the denitrification efficiency of the upper growing plant is higher.After 96 hours of purification,the removal rate of 3 g stereoscopic elastic filler to TN was 87.16%.After 120 g of zeolite was purified for 132 hours,the removal rate of TN by surface zeolite was 91.15%,the removal rate of TN by deep zeolite was 85.75%,and the denitrification efficiency of surface zeolite was higher than that of deep zeolite.By comparing the rate of denitrification of each treatment unit,it was found that the rate of denitrification from high to low is stereoscopic elastic filler,ceramsite,zeolite and plant.?5?The microbial diversity of four groups of membrane carriers,water and sediment were studied by high throughput sequencing technology.The results showed that in the four groups of membrane carriers,the microbial abundance and diversity on the stereoscopic elastic filler were the largest and the plants were the smallest.The microbial diversity of the influent was better,while the microorganisms in the effluent were more homogeneous.A total of 41 samples were detected in the experiment,mainly Proteobacteria,a total of 816 genera were detected.Enterobacter,Acinetobacter and Pseudomonas with denitrifying phosphorus removal can be detected and occupied the most. |
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