Ozonation of municipal wastewater effluent containing metal sulfides and metal complexes: Kinetics and mechanisms.
Ozonation of municipal wastewater effluent containing metal sulfides and metal complexes: Kinetics and mechanisms.
复制标题
DOI：
10.1016/j.watres.2018.01.042
复制
发表时间：
2018-05
期刊：
影响因子：
12.8
通讯作者：
B. Thalmann;U. von Gunten;R. Kaegi
中科院分区：
文献类型：
--
作者：
B. Thalmann;U. von Gunten;R. Kaegi
臭氧氧化可用于缓解城市污水处理厂排放的有机微污染物对水环境的污染。金属的毒性也存在于污水处理厂的污水中，强烈依赖于它们的形态。因此，了解污水处理厂出水臭氧化过程中金属形态的变化对评估可能的负面影响至关重要。本文研究了臭氧与三种金属硫化物（ZnS、CuS和CdS）及Cu（II）、Cd（II）、Ni（II）、Zn（II）、Mg（II）和Pb（II）的金属乙二胺四乙酸（EDTA）/氨氯乙酸（NTA）配合物的反应动力学和化学计量学。在化学计量因子为2.6 - 3.9摩尔臭氧/摩尔硫化物和pH 8> 104M-1s-1的表观二级速率常数的情况下，在WWTP流出物的臭氧化过程中，预期硫化物的完全氧化和相应金属的伴随释放，以增强微污染物的减少。在pH 8时，金属-EDTA络合物与臭氧反应的表观二级速率常数范围为42 M − 1s − 1至2.0 × 104 M − 1s − 1，其增加顺序为Cd（II）<Cu（II）<Mg（II）<Ni（II）<Zn（II）。约40%的Cd（II）-EDTA加标到污水处理厂的污水被氧化在典型的特定臭氧剂量为0.5 - 0.7 gO3/gDOC。对于其他金属-EDTA络合物，氧化的部分显著更高。通过扩散梯度薄膜（DGT）法测定的污水处理厂出水中的生物可利用部分增加臭氧化过程中，由于金属离子的氧化释放。藻类毒性（莱茵衣藻）与CuS/CdS加标污水处理厂的污水测试显示，在各自的媒体对铜和镉的高耐受性。仅在Cu浓度高于10 μ M时观察到毒性反应，该浓度高于典型的WWTP流出物浓度。臭氧化后的生物后处理通常会降低金属的生物利用度，从而降低毒性。因此，生物后处理可作为保护受纳沃茨下游生态的额外屏障。
Ozonation can be applied to mitigate the discharge of organic micropollutants from municipal wastewater treatment plants (WWTPs) to the aquatic environment. The toxicity of metals also present in WWTP effluents strongly depends on their speciation. Therefore, knowledge on the change of the metal speciation during ozonation of a WWTP effluent is essential to assess possible negative impacts. The kinetics and the stoichiometries of the reactions of ozone with three metal sulfides (ZnS, CuS and CdS) and metal-ethylenediaminetetraacetate (EDTA)/nitriloriacetic acid (NTA) complexes of Cu(II), Cd(II), Ni(II), Zn(II), Mg(II) and Pb(II) were investigated. With a stoichiometric factor of 2.6–3.9 moles of ozone per mole of sulfide and apparent second-order rate constants at pH 8 > 104M−1s−1, a complete oxidation of the sulfides and a concomitant release of the respective metals is expected during ozonation of a WWTP effluent for enhanced micropollutant abatement. The apparent second-order rate constants at pH 8 for the reactions of metal-EDTA complexes with ozone ranged from 42 M−1s−1to 2.0 × 104M−1s−1and increased in the order Cd(II) < Cu(II) < Mg(II) < Ni(II) < Zn(II). Approximately 40% of Cd(II)-EDTA spiked to a WWTP effluent was oxidized at typical specific ozone doses of 0.5–0.7 gO3/gDOC. For the other metal-EDTA complexes a significantly higher fraction was oxidized. The bioavailable fraction determined by the diffusive-gradient thin films (DGT) method in the WWTP effluent increased during ozonation, due to the oxidative release of the metal ions. Algal toxicity (chlamynomodas reinhardtii) tests with CuS/CdS spiked WWTP effluent revealed a high tolerance toward Cu and Cd in the respective media. A toxic response was only observed at Cu concentrations above 10 μM, which is above typical WWTP effluent concentrations. Biological post-treatment after ozonation generally reduced the bioavailability of the metals, which resulted in a lower toxicity. Therefore, the biological post-treatment serves as an additional barrier to protect the downstream ecology of receiving waters.