| Now in China,traditional total amount control cannot adapt to water quality improvement to support environmental management.Water quality targets can be achieved under total control strategy with environmental capacity.However,its application is limited in rivers absence of natural runoff and almost without water environmental capacity,especially in urban rivers with high development strength.Beiyunhe river basin belongs to upstream of Haihe river basin.It is typical water shortage urban river in north China which has both crisis of water resource shortage and water environment pollution.It is very difficult to find suitable technological method to improve water quality of this kind of river basin.In this thesis,Beijing part of this seriously polluted river basin was selected as the object area,looking for pollutants amount controlling technology base on different water quality goals in near and far future.This study aims at easing the contradiction between water resource shortage and water environment pollution in Beiyunhe river basin,and providing reference solution for water pollution control of urban river basin in north China.This thesis investigated and evaluated the status of water environment and pollution source discharge of Beiyunhe river basin,experimentally researched mechanism of ammonia nitrogen conversion and sediment pollutants release,measured land bearing capacity and assessed spatial distribution suitability of livestock and poultry breeding,built water quality model to quantitatively characterize the relation between pollutants discharge and water quality,made out short term,medium term and long term water quality targets,laid out scenarios of pollution control for different targets,simulated and predicted the water quality improvement effects of different scenarios,and then came up with the technology proposal of total amount control of this river basin.Main conclusions of this thesis can be summarized as follows:?1?The current situation of water environment of Beiyunhe river basin is serious and not optimistic because of very high pollutants discharge amount.In base year of 2013,water quality seriously exceeded the standard and the main pollutants were NH3-N,COD,BOD5 and TP.In 2013,emissions of NH3-N and COD in Beiyunhe river basin are 12.1and 123.7 thousand tons respectively.The emission components of NH3-N and COD are2%,11%,81%,6%and 3%,19%,57%,20%respectively according to the environmental statistics caliber of industrial,agricultural,domestic and urban non-point sources.Domestic discharge,in which domestic wastewater treatment plants took the biggest holding,was most important sources in the river basin.For agricultural sources,livestock and poultry breeding took the biggest holding.Spatially,domestic discharge mainly distributed in Liangshuihe sub basin,Wenyu mainstream and agricultural in Fenghe sub basin,Beiyunhe mainstream,Shahe sub basin.?2?NH3-N was the pollutant which was most seriously exceeded standard and most difficult to meet the standard in Beiyunhe river basin.Static test using the tail water of two typical domestic wastewater treatment plants showed that the conversion of ammonia was a result of joint action of both nitrification of nitrobacteria and assimilation of algae.The nitrification rate is 0.21 d-1 during suitable temperature condition.The relationship between the synthesis degradation coefficient of ammonia and water temperature can be expressed by the formulaK?28?0.41?1.06?7?t-20?8?.?3?The nutrients are very rich in sediments of Beiyunhe river basin,its release rate was significantly affected by hydraulic condition.Sediment release played important role to restrict water quality improvement.In sediment of Qinghe tributary,the content of ammonium and phosphorus is 104 and 144 mg/kg respectively.The release patterns of sediment pollutants are generally the same in still water and low flow of 0.05m/s.An increase of flow rate brought about faster release rate,as well as significantly increased the dissolved oxygen content in the water,which can greatly promote the nitrification and then reduced the concentration of ammonia.Besides,a fast water flow will disturb the sediment and then increase the content of particulates in water body.Adsorption of phosphorus will be improved and the concentration of phosphate will decrease then.?4?Pollution control of livestock and poultry breeding was one of the key factors of water quality improvement of Beiyunhe river basin.The scale and spatial arrangement of breeding should be optimized according to land bearing capacity.Calculation and comparative analysis of theoretical and actual land bearing capacity showed that the breeding scale should be cut down in Shahe sub basin,Wenyu mainstream et al,as well as in Changping district,Haidian district because the actual capacity exceeded theoretical capacity,but additional breeding scale still can be allowed in Fenghe sub basin,Xiaozhonghe sub basin et al,as well as Tongzhou district,Shunyi district because of land bearing capacity margin.Suitability assessment on 234 breeding enterprises in Beiyunhe river basin by way of analysis hierarchy process showed that the percentage were 1.7%,31.06%,66.38%,0.85%of score 0-30,30-60,60-80,80-100 respectively.Enterprises with very poor and very good suitability were both few,and those with suitability score under 60 should be shut down gradually.?5?Because pollutant discharge amount exceeded environmental capacity a lot,amount control strategy based on phased water quality targets should be taken in near future,and strategy based on environmental capacity in far future gradually.The One-dimensional water quality model of Beiyunhe river basin by MIKE 11 was established,with simulation error controlled iną15%.The water environmental capacity of NH3-N and COD were simulantly calculated as 2.228 and 40.998 thousand tons respectively,under the condition of class V water quality achievement of Yulinzhuang section.Phased water quality targets were set as that eliminating black odorous water bodies in short term2020,significantly improving water quality in medium term 2025,and basically reaching water quality standard in long term 2030.?6?In order to achieve phased water quality targets,simulant prediction of effect of pollution control scenarios showed that water quality improvement and then meeting the standard would be a long and tough task.Based on weak,medium,strong population control proposals,as well as discharge control projects of industrial,agricultural,domestic and urban non-point sources,it was set that 9 conventional scenarios,2strengthen scenarios,3 capacity increase scenarios,and 6 combined strengthen scenarios.4 indicator sections,which named central Tugou bridge,Houweigou bridge,Beiyunhe 1#,Beiyunhe 2#,were selected to be assessment section to predict and evaluate the effect of single and combined scenarios.The result showed that for target of 2020,by weak population control proposal,emission amount into river of NH3-N and COD must be limited under 3957 tons and 62.0 thousand tons respectively,and reduce 67%and 50%respectively comparing to the base year 2013;for target of 2025,by weak population control proposal,emission amount into river of NH3-N and COD must be limited under2665 tons and 47.6 thousand tons respectively,and reduce 78%and 61%respectively comparing to 2013;for target of 2030,in order to reach the standard,medium population control proposal together with high strengthen water save proposal and key sub basin strengthen control proposal must be all conducted during the 5 years to control emission amount into river of NH3-N and COD under 1429 tons and 39.3 thousand tons respectively,and reduce 88%and 68%respectively comparing to 2013,in addition,water circulation proposal and ecological water supply proposal should be conducted to enlarge the environment capacity.The demanded total discharge amounts of different terms were distributed to each sub basins and administrative districts in Beiyunhe river basin for basis of environmental decision making and pollution control examination. |
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