Evaluation Of Utilizing Biological Purification Water Quality Engineering Of Beijing South-to-North Water Transfer Reservoirs

The Middle Route of the South-to-North Water Transfer Project is a water transfer project with a large scale and a wide span in China.Its operation has effectively alleviated the current situation of water shortage in cities along the water conveyance,and greatly improved the ecological environment of the water-receiving areas of Hebei,Henan,Tianjin and Beijing.As the reservoir of the South-to-North Water Diversion in Beijing,the Daning Reservoir,the Yizhuang Regulation Pool and the Tuancheng Lake Regulation Pool are gradually playing an important role in regulating storage and transportation,optimizing allocation into Water,etc.,when an emergency occurs on the South-to-North Water Diversion Main Line.In the case of the situation,the emergency water supply in the storage pool will be urgently switched to ensure the safety of the water supply in the urban area.Therefore,the water quality in the storage pool should be kept stable at the moment and reach the standard.At present,the three reservoir pools have not begun to supply water to the surrounding water plants in a regular manner.The water body has poor fluidity and long water storage period.In order to maintain stable water quality,the three tanks are biologically manipulated.The filter-feeding fish,squid,is introduced into the water body.Its unique sputum structure can filter plankton in the water.The plankton absorbs nitrogen,phosphorus and other nutrients in the water to maintain its own growth and purify the water.Enhance the ability of the reservoir to resist algal blooms.Based on the existing amount of plankton,according to the “Measures for the Evaluation of Reservoir Fish Productivity” formulated by the Ministry of Water Resources,fish productivity calculations are carried out for the three reservoir pools,and then the amount of the harvest is estimated based on the recovery rate,combined with previous experience.As well as consulting with relevant fishery experts,the Daning Reservoir has been planted with 40,000 catties of fish(mainly carp)in 2018.The Yizhuang regulating pool has not been put into operation in 2018 due to abnormal algae in 2017.In 2018,the City Lake Regulating Pool put a total of 18,000 catties of fish(mainly carp).The water ecological monitoring of the three reservoirs is continuously monitored.The on-site rapid measurement indicators include temperature,dissolved oxygen and transparency.The laboratory physical and chemical indicators include total nitrogen,total phosphorus,ammonia nitrogen,permanganate index,chlorophyll a,and ecological indicators.There are phytoplankton and zooplankton,and the stability of water quality is judged according to the change of monitoring indicators,and the water quality in 2017 is collected by means of single factor evaluation,correlation analysis,factor analysis and nutritional status evaluation,and 2018 The monitoring data are compared and combined with the data of fish caught.It can be concluded that:(1)The water quality of the Daning Reservoir is good.The total nitrogen monitoring data in 2018 is basically no more than 1 mg/L.The ammonia nitrogen content meets the Class I surface water standard.The total phosphorus content meets the Class III surface water standard for most of the period.Permanganic acid The salt index is between 3 mg/L and 4mg/L.From the analysis results,the water quality indicators of the Daning Reservoir are stable and the water quality is more stable than that in 2017.(2)The monitoring data of Yizhuang Regulation Pool in 2018 indicates that the water quality is relatively stable,the total nitrogen content is below 1.0mg/L for most of the time,and the ammonia nitrogen content meets the Class II surface water standard for the whole year.The total phosphorus content is in Class II to Class IV.Between the surface water standards,the transparency is significantly improved,the algae changes normally,and the nutritional status is stable in the middle nutrient type.(3)The total nitrogen content of the Tuanchenghu regulating pool is currently stable at around 1 mg/L.The ammonia nitrogen content can reach the surface water class I standard in the second half of 2018.The total phosphorus content has a small increase compared with 2017,but most of it The period meets the standard of surface water III,and the permanganate index decreases compared with 2017,and the algae density is slightly higher.(4)According to the fish survey situation,the fish growth status of the Daning Reservoir is the best,and the size of the fish caught is large,indicating that the fish have high utilization rate of plankton in the reservoir,and the reservoir condition is suitable for fish growth.Combined with the changes in water quality,it can be seen that the implementation of biological manipulation in the Daning Reservoir is an effective means to maintain water quality safety,and should continue to be implemented to make the ecological circulation of the reservoir develop benign;the Yizhuang adjustment pool has a small pool capacity,no large buildings are covered,and the bottom of the pool is a hard-structured structure with a single ecological structure.It is not suitable for normal fish growth,and other means of purifying water quality should be sought.The fish growth status of the Chenghu regulating pool is general.Although the bottom of the pool is a hard-structured structure,the regulating pool has bridges,islands,pavilions and other building facilities,which creates a good environment for the growth of fish.It should be further monitored the water ecological changes in the pool.