生物滴滤床法降解二氯甲烷废气的因素影响特征

二氯甲烷作为溶剂广泛应用于制药行业，其挥发性废气对人类健康和大气环境的危害极大。本文采用生物滴滤床对某制药厂浓度范围在0.02~2g/m³的二氯甲烷废气进行了为期132天的中试规模实验。在适宜的停留时间、温度、喷淋量和pH等实验条件下，控制适当的进气浓度可得到高效去除效率并且废气出口浓度达标。实验揭示了生物膜内生物降解是过程的限制因素，结果表明，在喷淋量为1200L/h、进气浓度范围为0.45~0.65g/m³时该生物系统去除效率最高可达98.9%，最大去除负荷可达EC_max=155.25g/(m³·h)。随着进气浓度的增加，去除负荷随之增大，而去除效率下降，废气出口浓度超标，表明生物滴滤系统已处于反应控制。此外，间歇实验表明，该生物系统具有良好的稳定性。指出生物滴滤床的设计、运行取决于当地的二氯甲烷废气排放标准。

Influence character of factors for the removal of dichloromethane from waste gases using a biotrickling filter

Dichloromethane as a solvent has been widely used in the pharmaceutical industry. But the emitted waste gas containing dichloromethane is harmful to both human health and atmospheric environment. In this paper, a 132-day pilot scale experiment was carried out for the removal of dichloromethane from waste gas with the concentration range of 0.02~2g/m³ in a pharmaceutical factory using a biological trickling filter. The removal efficiency of dichloromethane from waste gas can reach the highest by controlling the appropriate intake concentration and the outlet concentration of dichloromethane in waste gas meets emission standard under the optimum operating conditions, including residence time, temperature, spray volume and pH. The biodegradation in the biofilm is the limiting step in the process. The experimental results show that when the spray volume is 1200L/h and the inlet concentration range is 0.45—0.65g/m³, the maximum removal efficiency and maximum removal load of the biological system can reach 98.9% and 155.25g/(m³·h), respectively. With the increase of inlet gas concentration, the removal load increases, while the removal efficiency decreases and the outlet concentration of dichloromethane in waste gas exceeds the standard, which indicates that biological trickling system belongs to reaction control. The intermittent operation shows that the biological system has good stability. The design and operation of the biological trickle filter depend on the local standards for dichloromethane emission.