Research For Qian Tang River Micro-polluted Oligo Carbon Water Nitrogen Demonstration Engineering

The diversion total nitrogen of Qiantang river water exceeded2mg/L all the time, so the nitrogen removal research of Qiantang river water for nitrate nitrogen must be aimed at. The technology of the Qiantang River high nitrogen water treatment and engineering demonstration build the technical subjects important part of improving the water quality and aquatic vegetation of West Lake in Hangzhou, lowering nitrogen completion of the demonstration project is the aquatic vegetation on the premise of building technology and the necessary preparations, West Lake aquatic vegetation restoration, an important foundation to build and maintain.The works to reduce the total nitrogen content in the Qiantang River diversion as the core objective, integrated use of biological nitrogen removal, multi-Tong artificial wetlands and other biological-ecological technology, through the integration of engineering and technical1500m3/d of water diversion total nitrogen reduced by40%more or less and reach the Class IV surface water environmental quality standards. Through multi-Tong, the main topic-artificial wetland coupled system run debug system effluent total nitrogen, reducing the role of biological ecological system, ensure the system water reach the quality of surface water Class Ⅳ water standards; study different hydraulic loading system denitrification effect and system strengthening measures modified plants pond startup, commissioning, strengthen commissioning stage, the focus of the commissioning phase of pH, DO, temperature, hydraulic retention time of denitrification, and problems in the debugging process. The following conclusions:1. From2007to2012, the Qiantang water TN concentration between2-4mg/L of nitrate nitrogen to total nitrogen ratio of between38.42%-84%, and an average of about70%.2. Start-up phase, the system at a lower temperature, pH value between7-9, dissolved oxygen about4mg/L, the modified plants pond for TN is negative; system water for TN only10%.3. Under different hydraulic retention time, the modified water pond and the effluent of the system effected. The best nitrogen hydraulic retention time for TN removal of system water effected were HRT=1.9-3.8h. When HRT=1.9h, the removal effect of TN was best.4. Modified plants pond the best reaction temperature is25℃, the residence time of 2.5h more optimal pH value at between7.2-7.6; wetlands optimum temperature is30℃.5. Better nitrogen removal system, the dissolved oxygen was stratified distribution anaerobic layer hypoxia layer, and aerobic layer stratified obvious:in the surface water depth of20cm, the DO value of aboutl.8-3.2mg/1; depth50cm, about0.5-1.8mg/1; depth70cm, its dissolved oxygen dropped to0mg/1;6. When the system for Nitrogen removal was affected best, the modified aquatic pond pH was in7.2-7.6.