The Research And Simulation Of Self-purification Ability In Typical Urban River

Due to the rapid development of urbanization, urban r iver has been severely polluted and destructed, and the self-purification ability of water gradually disappeared, so the ecological restoration of water environment is urgently needed. The self-purification ability of water must be regained to ensure the ecological restoration of water. The boundary of urban river is complicated, the definition of self-purification ability is difficult, so we must use artificial measures or water conservancy projects to improve the self-purification ability in order to ensure the rational development and utilization of self-purification ability. At home and abroad on the implementation of ma ny urban river channel regulation project, the effect of governance is often unpredictable. The model of water environment is needed for simulation of the effect of the governance to the management of next work for guidance and scheme optimization, and the engineering effect after evaluation, in order to achieve the purpose of promotion engineering experience.This paper takes suzhou Guangdu garden urban river as the research object to determine the corresponding self-purification parameters of water through the indoor and outdoor simulation experime nt, and studied the changes of self-purification capacity under different engineering measures. And water quality model was established according to actual condition, the changes of NH3-N, CODcr, TP of water was simulated based on the self-purification parameters from experiment, compared with the measured values for calibration and verification, and to evaluate the effect after the engineering measures to implement, the results show that:The water self-purification ability of water can be enhanced by artificial water cycle, areation and filtration. The established water quality model can well reflect the water quality changes in study area, the simulation results of deterministic coefficient is good, is more than 0.7. The simulation analysis indicates that the artificial measures can improve the water quality and cut down the pollution load. The decrease of CODcr, NH3-N and TP could be cut down by 6.8%、9.8% and 10.1% through artificial water cycle, by 4.2%, 6.3%, 17.8% through artificial aeration, by 12.3%, 18.9% and 9.5% through filtration in dry season. The restoration projects indicated that the decrease of CODcr, NH3-N and TP could be cut down by 15.7%, 29.8% and 21.3%. While in rainy season, the decrease of CODcr, NH3-N and TP could be cut down by 31.5%, 22.1%, 17.3% through artificial water cycle, by 23.5%、16.7%,18.9% through artificial aeration, by 41.3%,43.5% and 10.2% through filtration, by11.2%,52.4% and 14.7% through the restoration project. The maximum reduction of CODcr(41.3%) appeared in filtration purification filter in the rainy season, the maximum reductions of NH3-N(52.4%) appeared in the comprehensive improvement project in the rainy season; while the maximum reductions of TP(21.3%) is under the condition of the comprehensive improvement project in the dry season.To sum up, the water self-purification ability can be improved and the pollution of NH3-N, CODcr, TP can be cut down to a certain extent after the implement of different engineering measures. Among them, the comprehensive improvement project can complete all pollutant reduction effectively during the dry season.To insure the long-term maintenance of the comprehensive ecological restoration engineering, the water quality must be detected on a regular basis in future.