The Research Of Total Point Source Main Pollutant Distribution Method And Method’s Application Based On The Environmental Capacity

As the receiving water body of sewage discharged by Harbin city people’s life and production, municipal sewage treatment plants and other outfalls are located at the Songhua River in Harbin, and their sewage loads would have an important impact on the Songhua River in Harbin. Therefore, it is significant to develop a reasonable total amount pollution allocation scheme to control the emission of sewage discharged by industries along the river reach. In this study, the total amount water pollution allocation type is selected based on water environmental capacity; the method of trial and error of WASP7.3 is used to simulate and calculate water environmental capacity of 5 control reaches of the Songhua River in Harbin in the target year 2015; and then, the concept of the largest quarterly pollution load derived from the US TMDL Water Quality management model is referenced for the allocation of total water pollutants of “watershed- generalization control reaches”; and then, the total amount of water pollutants in 2015 that needs to be reduced or is the remaining capacity of emission, which comes from each jurisdiction and each pollution source(each industrial source), is distributed based on the integration of environmental Gini coefficient and the proportional allocation method. The results are as follows:(1)The verification and validation results are satisfactory on the phase of modeling. The modeling results of water environmental capacity of 5 control reaches of the Songhua River in Harbin in the target year 2015 using the method of trial and error of WASP7.3 are: COD, NH3-N in water environment capacity are 490030.18t/a, 47972.83 t/a, respectively; in 1 ~ 4 quarters, COD’s quarterly water environment capacity are 36551.15 t /quarter, 124173.74 t /quarter, 237879.72 t / quarter and 91425.62 t /quarter, respectively; NH3-N’s quarterly water environmental capacity are 4316.95 t / quarter, 9463.47 t / quarter, 23781.00 t /quarter and 10411.83 t / quarter, respectively.(2) Total allocation results of each control reach of the Songhua River in Harbin in 1 ~ 4 quarters in 2015, namely the largest quarterly pollution load, are calculated based on the model of quarterly water environmental capacity of COD, NH3-N. Results show that: all of largest quarterly pollution loads of COD, NH3-N basically present 3rd quarter > 2nd quarter > 4th quarter > 1st quarter; all of river control units have available assimilative capacity; but, in 1st quarter, all of water pollution loads in 1st reach and 2nd reach exceed the corresponding water environmental capacity.(3) On the basis of the distribution of the total amount of water pollutants coming from each control reach, the proportional allocation method is used to distribute the total amount of water pollutants coming from each jurisdiction and each sewage enterprise. At the same time, the environmental Gini coefficient is used to evaluate the fairness of the secondary distribution. All environmental Gini coefficient calculations are less than 0.2. Therefore, according to those assign weights in the text, the proportional allocation of the total amount of water pollutants of COD, NH3-N, which come from each jurisdiction and each sewage enterprise, is reasonable and strongly equity.