Study On Riparian Ecological Engineering For River Water Quality Improvement In Urban Section Of The Yitong River

River is one of the important components of urban ecosystem, which is of vital importantsignificance to the coordinate development among city, economy and environment. In recentyears, due to excessively water use in the city, the urban river flowrate was decreased sharply,some of urban river were even cutoff. However, dams have often been built in urban riverowing to city landscape construction, result in the river ecosystem service, such as selfpurification of water quality, getting worse and worse. Loss of natural characteristic of river isone of the normal and significant problems for the urban river. So it is urgent to carry out theriver restoration engineering in future.To deal with this problem, this study have investigated the hydrological characteristicsand water quality of Yitong river by collecting data and field investigation, which is a typicalpolluted one in the Northeast of China. This ecological engineering was designed based on thethought of near nature, multi-function, high efficiency and sustainability,4natural ponds ofthe east bank of Yitong river under the downstream of Ziyou bridge were selected to be theproject area to conduct the ecological engineering, according to the result of terrainexploration and Yitong river,physical condition. The aims of the engineering were simplifiedas follow: increasing the water self-purifying capability, decreasing the pollution andenvironment risk.The related technical parameters of the engineering are as follow: a total water area offour ponds in experimental area from south to north is45000m2, storage capacity is about40000m3, the inflow of water is about9000m3/d, residence time of water is4.5days,hydraulic loading is0.2m3/m2·d. The whole project started in April2014and completed inJune2014. According to the monitoring data of the ecological engineering from June toSeptember2014, the removal rate of COD was54%~94%and the average influent andeffluent COD are116.16mg/L,28.01mg/L respectively. The average removal rate of COD isabout76%. If the treatment of water is9000m3/d on average, the removal of COD is793.35kg/d and142.74t/year. The content of COD have reached the surface water standard of classIV in June and July. The removal rate of ammonia nitrogen is more than20%. In addition, thesystem provides the habitat for aquatic organisms, with improving the function of biodiversityconservation.This ecological engineering use ecological net sludge technology with low energy, lowcost, low maintenance cost. The completed project not only have improved the river waterquality and regional environment quality, beautified the urban landscape water and provided a leisure entertainment places for residents living around, but also have made environmentaleducation popularization and improved awareness of the public environmental protection.