过硫酸盐活化方式对水厂二级出水中有机物和抗生素抗性基因的去除效能与机制

分别采用纳米零价铁(nZVI)和超声(US)技术对过硫酸盐(PS)进行活化,探究PS、nZVI/PS和US/PS 3种预氧化工艺对城市污水厂二级出水中不同类型抗生素抗性基因(antibiotic resistance genes, ARGs)和溶解性有机物(dissolved organic matter, DOC)的去除效能与机制。结果表明:最佳PS和nZVI投加量为4,2 mmol/L,US最佳功率为40 kHz,经过PS、nZVI/PS和US/PS预氧化反应后,二级出水中ARGs(tetA、tetC、sulⅠ、sulⅡ),intⅠ1及16S rRNA的浓度分别为104.38~106.82,104.02~105.97,104.02~106.98 copies/mL;在最佳反应条件下DOC去除率分别为11.2%、17.2%和15.3%;其中,nZVI/PS对ARGs和DOC的去除效果最好。3种预氧化过程中均有OH·和SO₄-·参与反应,相较于PS和US/PS,nZVI/PS预氧化过程中产生的SO₄-·和OH·含量最多,且SO₄-·在反应体系中的浓度最高。因此,nZVI/PS预氧化方式可作为后续处理二级出水中ARGs和DOC的有效去除方法。

MECHANISMS AND EFFICIENCY OF REMOVAL OF ORGANIC MATTER AND ANTIBIOTIC RESISTANCE GENES IN SECONDARY EFFLUENT OF WATARPLANTS BY DIFFERENT PERSULFATE ACTIVATION METHODS

This paper used iron nanoparticles(nFe) and ultrasound(US) to activate persulfate(PS), then explored the removal efficiencies of PS, nFe/PS and US/PS in pre-oxidation processes on antibiotic resistance genes(ARGs) and dissolved organic matter(DOC) in secondary effluent, and discussed their removal mechanisms. The results showed that the optimal dosages of PS, nFe and US were determined to be 4 mmol/L, 2 mmol/L and 40 kHz, respectively. After PS, nFe/PS and US/PS pre-oxidation reactions, concentrations of ARGs(tetA, tetC, sulⅠ, sulⅡ), intⅠ1 and 16 S rRNA were 104.38~106.82, 104.02~105.97 and 104.02~106.98, respectively. Under the optimal reaction conditions, the removal rates of DOC were 11.2%, 17.2% and 15.3%, respectively. Among them, nFe/PS had the best removal effect on the above-mentioned ARGs and DOC. In the three pre-oxidation processes, OH· and SO₄-· all participated in the reaction. Compared with PS alone and US/PS combined processes, the content of OH· and SO₄-· generated was the highest in the pre-oxidation of nFe/PS, and the concentration of SO₄-· was the highest in the reaction system. Therefore, the nFe/PS pre-oxidation method could be used as a subsequent treatment to effectively remove ARGs and DOC in the secondary effluent.