Performance Of The Multiple Patterns-based Subsurface Flow Constructed Wetland System Combined With New Type Of Pretreatment Technology

With the rapid development of urbanization in China, a large number of untreated or partially treated sewage directly discharged into the water column, leading to serious water pollution and water scarcity. Water protection is becoming a urgent problem. Currently, a large number of sewage treated technology requires higher operating costs, skilled management. As a heavily populated and lowly enconmic area, the Three Gorges reservoir area presents shortage of land and skilled management and technology operators in many areas. As a low-power/high efficiency, low running costs and easy management of ecological wastewater treatment process, the constructed wetlands are widely used in town sewage treatment by gradually. The constructed wetland has some shortcoming such as large area needed, easy clog. Different wastewater treatment process with a combination of constructed wetlands for sewage treatment methods more widely used, combined process can avoid the shortcomings of constructed wetland for the treated seawage, and is suitable for our present conditions of domestic wastewater treatment plant.In this study, acidification precipitation tank and activated sludge process for the pre-process and combination with the constructed wetland technology for wastewater treatment. Continuous monitoring with more than 11 months on the built sewage treatment with processing and analysis water quality indicators as TOC, COD, BOD5, TP, TN, AN and TSS, the conclusions as follows:1,Combined pre-activated and sludge-corrrdor constructed wetland has more removal capabilies than combined pre-acidification process, its effluent can reach standards of GB 18918-2002; Pre-activated sludge treatment capacity is stronger than the pre-acidification and sedimentation tanks, pre-activated sludge process used for treatment of domestic sewage can reduce the load of the influent with wetland, stable water quality of the influent of the wetland. 2,The presence of plants can reduce the effluent pollutant concentration, Windmill grass has slightly higher removal ability than Water iris in terms of TOC, COD, BOD5 and TSS. Water iris has better removal ability on the TP, TN and AN. Wetlands with coal cinder has better ability for pollutant removal than that with gravel. However, there is no significant difference for nitrogen removal. So, coal cinder can be used to removal phosphorus and organic matter.3,HLR,HRT,season and the type of substrate of wetlands have significant effects on removal of pollutants, however, water levels and vegetation types hve little effect on the performance of the system. The type of pre-process technology can significantly affect the concentrations of organic matter and nitrogen. When selecting the activated sludge as a pre-feed technology, coal cinder as substrate, windmill grass as plant in the constructed wetland system performed at low HLR and long HRT and high temperature (summer), higher pollutantants removal can realize.