深型复合垂直流人工湿地对模拟污水处理厂尾水中PBDEs的去除研究

研究以四溴联苯醚(BDE-47)为目标污染物,构建了两套深型复合垂直流人工湿地小试系统(IVCW,总基质层高=180 cm)。在固定水力停留时间(HRT=3d)和水力负荷(0.3 m/d)条件下,分析测定其对BDE-47(进水浓度=25μg/L)的分段去除率,并探讨PBDEs加入对IVCW系统常规净化效果与基质微生物的影响。批实验结果表明,运行3个月后, IVCW对模拟污水中BDE-47去除率达到99.9%。与对照组相比, BDE-47处理组对氨氮的去除率由72.3%提高至82.9%,但对硝态氮的去除率显著下降,由53.0%降至28.1%,化学需氧量(COD)去除率由88.1%降至82.3%。IVCW各单元基质中BDE-47的残留量沿水流方向逐渐递减,在距离入流最近的下行流上层单元中BDE-47含量最高(约0.01μg/g);但BDE-47的加入导致基质微生物脱氢酶活性明显降低。微生物特征脂肪酸分析结果表明,实验组与对照组下行流单元微生物群落组成差异明显,分别以具有耐受型较强的微生物如革兰氏阳性厌氧菌和快速生长的好氧型革兰氏阴性菌为主。探究IVCW对BDE-47的去除潜力及迁移转化规律...

REMOVAL OF PBDEs FROM SIMULATED EFFLUENT OF WASTEWATER TREATMENT PLANT BY DEEP INTEGRATED VERTICAL FLOW CONSTRUCTED WETLAND

Two pilot-scale deep integrated vertical flow constructed wetland systems (IVCW, total matrix height=180 cm) were constructed with tetrabrominated diphenyl ethers (BDE-47) as target pollutants. Under the conditions of fixed hydraulic retention time (HRT=3d) and hydraulic loading rate (0.3 m/d), the step-by-step removal rate of BDE-47 (influent concentration=25 μg/L) was analyzed, and the effects of polybrominated diphenyl ethers (PBDEs) on the conventional purification efficiency and substrate microorganisms of IVCW systems were discussed. The batch experimental results showed that after three months of operation, the removal rate of BDE-47 in simulated effluent of wastewater treatment plant by IVCW reached 99.9%. Compared with the control group, the removal rate of ammonia nitrogen in BDE-47 treatment group increased from 72.3% to 82.9%, but the removal rate of nitrate nitrogen decreased from 53.0% to 28.1%. Meanwhile, the removal rate of chemical oxygen demand (COD) decreased from 88.1% to 82.3%. The residual amount of BDE-47 in the substrate of each unit of IVCW decreased gradually along the flow direction, and the content of BDE-47 was the highest in the upper unit of downstream flow, which was close to the inflow (0.01 μg/g). A significant decrease in substrate microbial dehydrogenase activity was resulted due to BDE-47 involvement. Correspondingly, microbial fatty acid profile analysis showed that there was a significant difference in microbial community composition of the down-flow units between the experimental and the control groups, which were dominated by more tolerant anaerobic Gram-negative bacteria and fast-growing aerobic Gram-negative bacteria, respectively. The removal potential of BDE-47 and its migration and transformation mechanisms in IVCW could provide useful reference and a feasible scheme for the removal of refractory organic pollutants by ecological engineering systems.