合流制溢流污染调蓄池设计容积数值模拟

Numerical Simulation of Design Volume of Combined Sewer Overflow Storage Tank

按照现有规范计算雨水调蓄池的容积,无法对调蓄后的截污效果进行有效评估。以SWMM为计算工具,通过数值模拟,可以针对具体的流域分析降雨强度、调蓄池容积对污染物的截留效果。以深圳市龙岗区某流域为研究对象,设定不同强度的初期降雨深度,模拟不同初雨径流流量过程和污染物冲刷过程,并对6种污染物(COD、SS、TN、TP、BOD_(5)、NH_(3)-N)累积收集量和调蓄池容积的关系进行数值模拟。结果表明,初雨雨量的差异性对污染物冲刷峰值和总量不具有倍数关系;初期冲刷效应按照递减排序为TN>COD>BOD_(5)>NH_(3)-N>SS,TP没有明显的初期冲刷效应;调蓄容积不低于浓度峰值对应的容积,综合考虑多个污染物的控制效果后可以适当放大;本案例中,调蓄池污染物浓度在峰值之后呈现先快后慢的下降趋势,当调蓄容积不超过10 000 m;时,收集效率仍然较高。调蓄池的主要控制对象和目标值不同时,需要综合考虑后确定调蓄容积。

It is impossible to evaluate the sewage interception performance accurately after storage if the volume of the storage tank is calculated according to the existing design codes.The effect of rainfall intensity and storage tank volume on pollutant interception in a specific watershed was analyzed through numerical simulation of SWMM.Initial rainfall depth with different intensities was set,and the flow process and pollutant flush process of different initial rainfall runoff in a watershed of Longgang District,Shenzhen were simulated.In addition,the relationship between the accumulated collection amount of six pollutants (COD,SS,TN,TP,BOD_(5) and NH_(3)-N) and the storage tank volume was calculated through numerical simulation.The difference of initial rainfall had no multiple relationships between the peak value and the total amount of pollutants.The flush effect of initial rainfall in descending order was TN,COD,BOD_(5),NH_(3)-N and SS,and the initial rainfall had no obvious flush effect on TP.The storage capacity should not be less than the volume corresponding to the peak concentration,and it could be appropriately amplified after considering the control efficiency of multiple pollutants.In this case,the concentration of pollutants in the storage tank decreased rapidly at first and then slowed down after the peak value.When the storage capacity was less than 10 000 m^(3),relatively high collection efficiency was still obtained.When the main control object and target value of the storage tank are different,the storage volume should be determined after a comprehensive consideration.