A Study On Constructed Wetland Restoration Of Shen-fu Irrigation Channel's Sewage

As a kind of ecological technology, constructed wetland which is used in the treatment of municipal sewage has springed up for the recent thirty years in developed countries. For its advantage on low investment, high quality effluent, high resistant ability, easy operating, low construction and running costs, easy maintenance, high removal rate of NH₄⁺-N, organically combining sewage treatment with ecological construction and creating urban landscape when treating sewage, constructed wetlands are gradually accepted by more and more countries. For determining the ecological restoration solutions of Shen-Fu irrigation channel, and in answer to the overall objective of ecological restoration , Firstly, the subject investigated the field conditions, and then did the on-site sample analysis and constructed wetland simulation studies at last. The studies tested how the structure, base materials and hydraulic retention time to affect the treatment efficiency of COD, NH₄⁺-N and TP,and finally preliminary determined the technical plan of Shen-Fu irrigation channel constructed wetland.The conclusions of the study were as follows:(1)When Hydraulic Retention Time (HRT) was 1 day and Hydraulic loading was 30cm/d, the removal rates of COD, NH₄⁺-N and TP could reach 85%, 55% and 60% above. The water quality can reach the standards of<The reuse of urban recycling water-water standard for scenic environment use> (GB/T 18921-2002) and the Grade B standards of<Discharge standard of pollutants for municipal wastewater treatment plant> (GB 18918-2002). The COD can reach the Gradeâ…¤standards of<Environmental Quality Standards of Surface Water> (GB 3838-2002) but NH₄⁺-N and TP can not.(2)When adding active sludge which contains lots of nitrobacteria into the experiment system, the removal rate of NH₄⁺-N went down obviously in the early boot time. After the system run some time, the quantity of nitrobacteria and nitrification capacity are both enhanced in each constructed wetland unit as the temperature went up, and the difference between the nitrobacteria system and no nitrobacteria system just narrowed little by little.(3)There was a strong effect of removing TP when choosing industrial byproduct-water granulated slag- as the constructed wetland's ground substance.(4)Different pollutants have different removal rates between subsurface flow constructed wetland and vertical flow constructed wetland, but it was not obvious. The vertical flow constructed wetland had a little advantage on the remove of NH₄⁺-N and TP. While it came to COD, the advantage just almost disappeared.The experiment result indicates that the surface flow constructed wetland and vertical flow constructed wetland technology can effectively remove the COD, NH₄⁺-N and TP in sewage, and it is feasible to use wetland technology to restore the Shen-Fu irrigation channel's sewage as a core technology.