CSIR-National Environmental Engineering Research Institute (NEERI), Worli, Mumbai, India.
CSIR-National Environmental Engineering Research Institute (NEERI), Worli, Mumbai, India.
Chemosphere. 2018 May;199:569-584. doi: 10.1016/j.chemosphere.2018.01.059. Epub 2018 Feb 1.
This study investigated the occurrence, removal and influence of plant-operating conditions on removal mechanisms of 83 VOCs in different treatment units of a CETP in Mumbai, treating industrial waste on primary and secondary level. A mass balance approach was used to predict VOC removal by volatilization, stripping, weir drop, adsorption, and biodegradation. Results indicate that ∼17% of VOCs were removed by stripping in equalization tank and ∼8% were removed by weir drop in primary clari-flocculator respectively. Biodegradation was the dominant mechanism in aeration tank and was relatively poor for hydrophobic compounds which were more vulnerable to removal by stripping. Stripping rates could be reduced by increasing the active biomass concentration and using fine pore diffusers to reduce the air/effluent ratio. Decrease in Henry's constant and compound concentration can shift the main removal mechanism from stripping to biodegradation. Results also show considerable agreement between measured (71.2%) and predicted (67.1%) total removal, especially in aeration tanks. Equalization tanks (actual, 20.5%, predicted, 16.9%), primary clari-flocculator (actual, 14.2%, predicted, 7.7%), and secondary clarifier units (actual, 29.5%, predicted, 16.8%) showed fairly acceptable differences in measured and predicted removal. The effect of other mechanisms on VOC removal need to be further explored owing to their major contribution to VOC removal. This study is the first attempt in understanding the mechanisms behind the removal of VOCs in each treatment unit, especially equalization tanks and clarifier units, which have been severely underestimated till date.
本研究调查了在孟买的 CETP 的不同处理单元中，植物运行条件对 83 种 VOC 去除机制的发生、去除和影响，该 CETP 主要处理工业废水的一、二级处理。采用质量平衡法预测通过挥发、汽提、堰降、吸附和生物降解去除 VOC。结果表明，在均衡罐中，约有 17%的 VOC 通过汽提去除，在一级澄清池通过堰降去除约 8%。在曝气池，生物降解是主要的去除机制，对于疏水性化合物，其去除机制相对较差，更容易受到汽提的影响。通过增加活性生物量浓度和使用细孔扩散器来降低空气/废水比，可以降低汽提速率。亨利常数和化合物浓度的降低可以将主要的去除机制从汽提转变为生物降解。测量值（71.2%）和预测值（67.1%）之间的总去除率有相当大的一致性，特别是在曝气池中。均衡罐（实际，20.5%，预测，16.9%）、一级澄清池（实际，14.2%，预测，7.7%）和二级沉淀池（实际，29.5%，预测，16.8%）之间的测量值和预测值的去除率存在相当大的差异。需要进一步探索其他机制对 VOC 去除的影响，因为它们对 VOC 去除的贡献很大。本研究首次尝试了解每个处理单元中 VOC 去除背后的机制，特别是均衡罐和澄清池单元，这些单元迄今为止一直被严重低估。
