Water Quality Improvement Projects In Harbin Section Of Songhua River Based On Capacity Expansion

China is in industrialization development stage at present, and with large population density, only using the successful pattern and experience of developed countries in river harnessing for reference is difficult to achieve the expected target. Therefore, faced with the increasingly serious problem of river pollution, to research and develop water quality improvement projects in rivers which are scientific and rational and suitable in china is important.Harbin was selected for case study in this paper. Through analyzing the water environment and water pollution, and comprehensively evaluating the problems of Harbin urban rivers, the Harbin section of Songhua River and Hejia ditch were selected as research objects. According to different water environment and functional localization of different rivers, the water quality improvement projects in rivers was discussed considering local conditions and different rivers.Firstly, Harbin section of Songhua River was studied, chose COD and NH3-N as characteristic factors. The one-dimensional water environmental capacity model.was used to calculate the water environment capacity. The result showed that the water environment capacity was dynamically changed in different months; the total actual water environment capacity of COD and NH3-N were 1061398 t and 66880 t respectively from January to October. Secondly, modified TMDL was proposed when water environmental capacity was not enough. The wetland eco-purification function was put into use in capacity total content control and pollution load allocation: for upper reaches and branch, used backward induction method to set the water quality target, according to pollutants reduction requirements; for sewage outlet which needed to reduce large amount of pollutants, in icebound season(January to March), improved the pollutants emission requirements; in summer(April to October), used the eco-purification function of coastal wetland to purify the sewage and then the effluent could be discharged into Songhua River. In result, the target of pollution control, water quality improvement, expansion of water environmental capacity and recovery of water ecological function could be achieved.With the target of water environment restoration of Hejia ditch, proposed the landscape environmental water supplement scheme, industrial pollution control and river ecological restoration. Two water supplement schemes were proposed, which were reclaimed water from Pingfang sewage treatment plant located in the upstream of the west of Hejia ditch with Songhua River, and only reclaimed water. Through comparing the above two water supplement schemes, using reclaimed water as the main water source was suggested, and the total landscape environmental water supplement was 140.2 thousand m3/d. Rainwater resources potential calculation method was used to calculate the amount of rainwater collection of Hejia ditch collection area in rainy season(June to September). It was calculated that the total amount of rainwater collection in rainy season was 28422.5 thousand m3, and average rainwater collection was 233.0 thousand m3 / d. In turn, the third water supplement scheme was proposed. In summer, the reclaimed water could be replaced by rainwater, which was beneficial to cost saving and reducing the pressure of the sewage plant.Hejia ditch is one of the main sewage rivers in Harbin, the industrial pollution control along Hejia ditch is very important to water quality improvement. Harbin Hanan Green Food Industrial Park located in the upstream of Hejia ditch was selected for case study. A food wastewater treatment method by integrating wastewater reuse and resource utilization was proposed. Three treatment scenarios were investigated, including total treatment, separated treatment and resource utilization. Cost-Benefit Analysis method was used to calculate the cost and benefit of each cubic meter wastewater treatment, for purpose of providing decision-making basis for the implementation of the food wastewater resource utilization. And the benefits of the above three methods were-2.45 yuan, 0.84 yuan and 3.79 yuan respectively. Resource utilization method provide d the potato-processing enterprises which discharged 500 to 600 m3/d wastewater in the Industrial Park with a total benefit of 1895 to 2274 yuan/d.