Comparative Analysis Of Design Standards Or Regul Ations Of Constructed Wetland (CW) In Differenet Cou Ntries And The Proposal Of CW Norm Of Shannxi Provin CE

As an eco-friendly sewage treatment technology,constructed wetland(CW)has the advantages of less investment,high treatment efficiency and landscape value.It has been accepted as a green technology for wastewater treatment and developed rapidly in the past 20 years.Because of China's vast territory,different provinces have great differences in climate,geography,living habits,economic level and other aspects,Uniform design specifications suitability is weak.At present,Shaanxi Province has not established the relevant design standard.There is an urgent need to work out and set up the design specifications for CWs for the actual situation of Shaanxi Province.If so,it can be used for scientific and reasonable design,construction,management and maintenance of CWs project.In this paper,17 foreign specifications and 16 domestic specifications of constructed wetlands are collected.Through reading and analysis the design process of all aspects of the content,the first draft of design code for Constructed Wetland in Shaanxi Province,namely "technical specification for domestic sewage constructed wetland treatment engineering in Shaanxi Province",was formed.Through the research,the following conclusions and results are obtained:(1)Ireland,Germany and India are the latest in time,India borders on China.Ireland emphasizes pre-design research and customer preferences.Germany pays attention to substrate composition and proportion.In India,the calculation methods of different wetland types are analyzed in detail.Foreign wetland norms are flexible and focus on different aspects.(2)The results show that there are regional differences in the development of constructed wetland,and the best development in East China.These standards promote the application of constructed wetland to a certain extent,but there are also defects.For example,for water quantity and quality,the differences between urban and rural areasshould be taken into account,and the requirements for TN should be appropriately relaxed when considering the reuse of irrigation;the design parameters are affected by many factors,which need to be combined with the actual project operation data;the provisions of "earthworm Dredging","backflashing" and "additional soil layer" are unreasonable.(3)Based on the analysis of topography,climate and water resources in Shaanxi Province,combined with the actual data of water quantity,water quality and plants in Shaanxi Province,the technical specification for domestic sewage constructed wetland treatment project in Shaanxi Province is formed.The standard has been made to meet the requirements for the design,construction,operation,management and maintenance of CWs,which are suitable for the treatment of domestic sewage or the similar wastewater treatment within the scope of Shaanxi Province.It is expected that the work could promote the development and application of CWs technology in Shaanxi Province.