Study On Remediation Effect And Evaluation System Of Typical Black Odor Water In Xiangtan

At present,the rectification of black odor water has become a hotspot in the country and has become one of the problems that undermine the urban water environment in China.The research on the evaluation of urban black odor water remediation has not yet formed a complete theoretical system,which makes it impossible to accurately judge whether the remediation plan is reasonable,whether the remediation measures are effective,and thus the direction of remediation is not clear,resulting in unsatisfactory remediation effect.Establishing a sound and effective remediation effect evaluation system will help to grasp the key and core of urban black odor water remediation,and will play an important role in regulating the remediation effect of urban black odor water.Taking the black odor water treatment project completed in Xiangtan City as an example,this paper selected 7 typical black odor water bodies as the main research objects,among which the Great Wall first-class canal and the Qiuzi Dam were heavy black odor water,the Great Wall second-class canal,Yuhu Lake,Nanyang Canal,Ailao Canal and Qili Chong Ditch were mild black odor water.All of the black odor water had direct sewage discharges and were mostly in densely populated areas of residents,the rural non-point source pollution was serious.After the initial rectification,the physical and chemical indicators of water quality of the water bodies have improved significantly,and the senses have also been significantly improved.In order to further comprehensively evaluate the multi-index and multi-level evaluation of the remediation effect,on the basis of the theory that the urban black odor water body remediation effect evaluation has not yet been formed,this study summarized and drew on the water environment quality evaluation and the river remediation project post-evaluation,used the evaluation method in river ecosystem health assessment,through the construction ideas of “selecting indicators,determining indicator survey methods,index empowerment,establishing evaluation criteria,and determining grades”,screened 14 representative indicators(transparency,dissolved oxygen(DO),redox potential(ORP),ammonia nitrogen(NH3-N)from five aspects: water quality physical and chemical indicators,water ecological environment,water function benefits,management indicators and social livelihood benefits Land cover green coverage rate,shore line hardening rate,bank protection ecology,submerged plant coverage rate,water function satisfaction rate,interception and emission reduction rate,surrounding water system connectivity rate,rationality of remediation plan,management organization system soundness,public Satisfaction)from five aspects: water quality physical and chemical indicators,water ecological environment,water function benefits,management indicators and social livelihood benefits and then completed the design of the index system including the target level A,the criterion level B,and the indicator level C(The water quality physical and chemical indicators are the determination indicators,which can directly determine whether the remediation effect evaluation results are qualified).Fully used the advantages of the expert evaluation method(Delphi)and the analytic hierarchy process(AHP),the indicators empowered by the "expert evaluation-analytic hierarchy process";determined the evaluation criteria of the indicator layer from the highest to the lowest level I,Class II,III,IV,and V;according to the matter-element extension model,this paper constructed the classic domain,the domain and the object to be evaluated the element matrix,the degree of correlation was calculated,and the evaluation level was determined.The system was applied to the typical black and odorous water body remediation project in Xiangtan City.The evaluation results were as follows: Great Wall first-class canal(II),Great Wall second-class canal(III),Yuhu Lake(I),Nanyang Canal(II),Ailao Canal(Unqualified),Qilichong Ditch(II)and Qiuzi Dam(Unqualified).By assigning the evaluation standard interval,and then calculating and verifying by the fuzzy probability evaluation method,the evaluation results are all within the level allowable range,and the results are accurate.Finally,the influencing factors of the evaluation results were identified.The factors that affects the remediation effect were the physical and chemical indicators of water quality(transparency,dissolved oxygen,ammonia nitrogen),land green coverage,interception and emission reduction rate and public satisfaction.The identified influencing factors were tracked and evaluated to suggest improvements in the remediation plan.