Development And Aplication Of Assessment System For Ecological Health And Remediation Of Urban Landscape Water Bodies Supplied By Reclaimed Water

The severe shortage of water resources restricted the rapid development of modern cities in China.The recycling of waste water became one of the important ways to solve the problem of water shortage.Reclaimed water has been used as an important source for landscape water supply.The supply amount and proportion in landscape water significantly increased year by year.Due to the quality of the reclaimed water,a large supply amount into the landscape water will change the water quality and raise ecological environmental risks of the urban landscape.In recent,the water quality,ecological risk and health of the urban landscape water bodies,supplied by the reclaimed water,received much attention.Based on above,this study established evaluation index and method of ecological health of the urban landscape water bodies and its used ecological restoration engineering.Firstly,through minoring water quality of urban rivers that supplied by the reclaimed water for a long time,the typical pollutants were identified,including nutrients,heavy metal,colatile organic compounds(VOCs),PAEs,PAHs and PCBs.And the raised ecological environmental risks were evaluated.Obtained results showed that TN,TP,Pb heavy metal and VOCs in urban landscape rivers are out of threshold values.Heavy metals,VOCs and PCBs in urban river water,showed high ecological risk after a long-time supply by reclaimed water.Secondly,the analytic hierarchy method was used to establish a water ecological health evaluation system including 15 indexes,6 criteria,3 levels,which integrates the ecological risk of urban rivers and the indicators of social landscape service functions to show the features including the supplement of reclaimed water and urban landscape water.The evaluation and analysis of the ecological health of the South Hucheng River in Beijing,supplied by reclaimed water for long time,showed that the water ecological health status was able to be accurately reflected by this evaluation system,which belonged to ?higher? level with score 3.52.In South Hucheng River,the diversity of benthic animals is poor and the habitat at the bottom is not conducive to the growth and reproduction of the community.Micro-organic pollutants and heavy metals in South Hucheng River,showed higher potential ecological risks in extreme conditions.Above result suggested that this water ecological health evaluation system can reflect the water ecological health status of South Hucheng River and identify the key problem of this river including the heavy metal,micro-organic pollutants and biological imperfection.Finally,this study established an index and methods to evaluate ecological restoration engineering of the urban rivers and lakes water.The integrated evaluation index and methods included 19 indexes,7 criteria,3 systems,4 levels,focusing on features including important indexes to meet the functional requirements of urban landscape and social impact.The evaluation system was used to evaluate the ecological restoration engineering of Taoranting Lake and Tuchenggou River.Results showed that the restoration project of Taoranting Lake water ecosystem showed a good function on water quality and ecology restoration,which belonged to ?good? and ?general? level with scores 3.53 and 2.92;however,the structure of the water ecosystem in Tuchenggou was basically recovered,but the ecological affinity was too poor,the landscape and social functions was not good,and further improvement was needed.For Tuchenggou River,it was necessary to improve the water quality through ecological restoration project.Meanwhile,it was also significant to build hydrophilic strong and harmonious landscape effects.This study showed that the evaluation system was able to accurately reflect the performance of the ecological restoration project used,and to show the key problem.In this thesis,the two developed evaluation index systems provide the guidance for promoting the water ecological health and water ecological restoration,as well as improving the water ecological environment quality of the landscape water bodies in Beijing.Meanwhile,it can be used as a reference for the improvement of water ecological health and environment quality,and the selection and optimization of ecological restoration projects for urban landscape water bodies supplied by reclaimed water.