Cause Analysis And Treatment Measures Of Endogenous Hydrogen Sulfide Pollution In Reservoir

Water source reservoir plays an important role in China’s water supply system,and its water quality directly determines the quality of water supply.Exogenous input and endogenous release are the two main reasons for the deterioration of reservoir water quality.At the moment when exogenous pollution has been paid attention to and gradually improved,endogenous pollution has gradually become the main factor affecting reservoir water quality due to its concealment and complexity of treatment.The existing treatment technology of endogenous pollution of water body is mainly aimed at rivers and shallow lakes.It is not suitable for reservoirs with large water surface and deep water,and the economic cost is large.As a novel layered water intake method,underwater control curtain has the advantages of simple structure,flexible disassembly and low cost.It has been widely used in the treatment of reservoir discharge water temperature and reservoir eutrophication.This technology has a broad application prospect in solving the problem of internal pollution in reservoirs.However,there is a lack of research on the application effect of this technology in endogenous pollution,and the layout form,operation mode and other relevant technical details in endogenous pollution control.In view of the above problems,taking a typical water source reservoir in Northeast China as the research object,this paper analyzes the characteristics of its internal pollution and the causes of the typical pollutant hydrogen sulfide.According to the causes of its water quality problems and referring to the relevant principles of the underwater control screen,an underwater isolation screen is designed,which is a targeted device for the internal pollution of the reservoir.Using this device,a comprehensive treatment scheme for the internal treatment of the reservoir is designed.Relevant research results are as follows:(1)Study on the current situation of water environment in reservoir and its basin.Based on the history of the reservoir and the data of field investigation and monitoring,the current water environment of the reservoir is analyzed.The results show that the water body of the reservoir is generally in good condition and can be maintained at the class II water quality standard most of the time.Remarkable achievements have been made in the treatment of water environment in the basin.The pollution load of point source and non-point source can meet the requirements of warehousing water quality.The water quality of warehousing rivers meets the standard,and there is basically no risk of deterioration of reservoir water quality due to exogenous input.(2)Study on the causes of hydrogen sulfide-problem in reservoir.At present,the main water quality problem of the reservoir is the frequent escape of hydrogen sulfide in the middle and late stage of thermal stratification.Through the vertical monitoring results of water quality in front of the dam in the non ice sealing period of the reservoir and the determination of the content of relevant pollutants in the sediment,it is found that the values of S,Fe,Mn and other elements in the sediment of the reservoir are high,which is the material source of the internal pollution problem of the reservoir.The reservoir is a stable layered reservoir.The phenomenon of water temperature stratification in summer leads to the lack of dissolved oxygen content in the bottom water body,which is conducive to the generation and release of sulfide.At the same time,the existence of water temperature stratification structure also hinders the transportation of sulfide to the upper layer.The gradual disappearance of water temperature stratification in the middle and later stages of thermal stratification makes it possible to release the sulfide accumulated in the bottom water body,resulting in the concentrated outbreak of sulfide problem in the reservoir.(3)Design and effect research of underwater isolation screen.Aiming at the problem of endogenous hydrogen sulfide escape in the reservoir,an underwater isolation screen device is designed to ensure the water quality of the reservoir intake.The device can intercept the inferior water body at the bottom of the reservoir,transport the water body to the surface oxygen enriched area,and promote the up-down exchange of the water body.Its effect is verified by using the hydrodynamic module and convection diffusion module in Mike21 model and mike3 model.The verification results show that,The isolation screen has a good effect in intercepting inferior water bodies and transporting water bodies to oxygen enriched areas,but it has no obvious effect in promoting the mixing of upper and lower water bodies.(4)Study on comprehensive treatment scheme of reservoir water quality problems.Based on the verification of the underwater isolation screen,the advantages and disadvantages of the existing endogenous pollution control technologies and the applicability of relevant technologies in the reservoir are analyzed.Finally,a comprehensive treatment plan for the endogenous pollution of the reservoir is determined based on the combination of underwater isolation screen,sediment dredging and oxygenation and aeration.The scheme has the advantages of low cost and can prevent secondary pollution in the treatment process,It can provide reference for the endogenous pollution of other reservoirs.