污染物排放波动特征及对排污许可限值的影响

受生产活动变化的影响,企业的污染物排放具有一定的波动性,制定基于不同时间周期的污染物排污许可限值,是完善企业污染物排放监管的需要。以铁岭市企业在线监测数据为基础,采用短周期排放量与长周期排放量的比值β,研究了企业行业特征和规模对不同周期污染物排放量的影响。结果表明,行业对β值具有重要的影响,铁岭市屠宰行业、煤炭行业和污水处理厂COD日排放量与年排放量的比值β平均值分别为2.82、2.61和1.65,NH-N排放量Cr MDL 3的β平均值分别为2.9、3.49和2.59,表明污水处理厂相比屠宰行业和煤炭行业具有更强的稳定性。从企业规模来看,MDL企业规模较小时,由于生产稳定性差β值波动较大;企业规模较大时,β值趋于稳定。因此,制定不同周期的企业排污许可限值时,应基于不同的行业特征和企业规模给出不同的参考比值。

Fluctuation of Pollutant Discharge from the Enterprises and its Effects on the Discharge Permit Limits

Pollutant discharge of the enterprises shows a distinct fluctuation due to the production cycle.It is very necessary to give different temporal discharge permit limits to improve the supervision of the polluters.On the basis of the online pollutant monitoring data of several enterprises in Tieling City,the effects of the industry characteristics and size of the enterprises on the fluctuation of different temporal pollutant discharge amount are studied by application of β value,the ratio of short-term to longterm discharge amount.The results show that β value is greatly affected by the industrial characteristics.With regard to the three industries of slaughter,coal mining and wastewater treatment plant (WWTP),the average βMDL,the ratio of daily to annual discharge amount,is 2.82,2.61 and 1.65 respectively for CODCr,and 2.9,3.49 and 2.59 for NH3-N,indicating that WWTP is more stable than the other two industries.It is also found that the β value shows greater fluctuation when the enterprise size is small,but gets more stable when it is over a certain size.Therefore,it is very important that the industry characteristics and size of the enterprises should be taken into consideration when different temporal discharge permit limits are formulated.