A^(2)O工艺污水处理厂微生物气溶胶逸散特征及暴露风险评价

Emission characteristics and exposure risk assessment of microbial aerosols from WWTP with AO treatment process

监测了北京市某A^(2)O工艺污水处理厂不同工艺段逸散出的微生物气溶胶的浓度和粒径分布情况,统计了各工艺段所有采集样本污染程度和可吸入颗粒占比,分析了影响各工艺段微生物气溶胶浓度和可吸入颗粒数变化的因素.同时,计算了各工艺段暴露风险值,判断微生物气溶胶对不同人群的危害性.结果表明,各工艺段微生物气溶胶均有不同程度的释放,浓度变化范围在107~37139 CFU·m^(-3)之间,其中,生物池释放浓度最低,为107~624 CFU·m^(-3),一直处于清洁等级;板框脱水间释放浓度最高,为3329~37139 CFU·m^(-3),粉尘颗粒较多是造成板框脱水间微生物气溶胶浓度极高的重要原因.各工艺段可吸入颗粒(<4.7μm)占比为42.30%~93.36%,其中,污泥处理单元吸入风险较高,可吸入颗粒占比为83.52%~93.36%.板框脱水间细菌气溶胶对人体存在非致癌风险(HQ>1),需引起重视.

The concentration and particle size distribution of microbial aerosol emitted from different process units of an A^(2)O process wastewater treatment plant in Beijing were monitored. The pollution levels and the proportion of inhalable particles were evaluated statistically for all samples from each process to identify and analyze the factors affecting the microbial aerosol concentration and inhalable particles quantity. Based on the calculation of exposure risk value, the harmful effects of microbial aerosol on environment and different population were characterized. The results showed that the microbial aerosols were detected from all treatment stages with the concentration varied from 107 to 37139 CFU·m^(-3). The bioaerosols concentration near biological treatment process was the lowest level ranging from 107 to 624 CFU·m^(-3), ranking as clean level. Due to the large amount of dust around, the highest concentration range of 3329~37139 CFU·m^(-3) was detected from the process of plate and frame filter press dewatering.The inhalable particles(<4.7 μm) of process units ranged from 42.30% to 93.36%. Meanwhile, the inhalable particles ranged from 83.52% to 93.36%, indicating a potential risk in sludge treatment unit. the dewatering process should require more attention for its non-carcinogenic risk to humans(HQ>1).