Department of Civil Engineering, National Chi Nan University, 1 University Rd, Puli, Nantou 54561, Taiwan E-mail:
Water Sci Technol. 2014;69(11):2357-63. doi: 10.2166/wst.2014.169.
In this study, the biodegradability of nanoscale zero-valent iron (nZVI) dispersants and their effects on the intrinsic biodegradation of trichloroethylene (TCE) were evaluated. Results of a microcosm study show that the biodegradability of three dispersants followed the sequence of: polyvinyl alcohol-co-vinyl acetate-co-itaconic acid (PV3A) > polyoxyethylene (20) sorbitan monolaurate (Tween 20) > polyacrylic acid (PAA) under aerobic conditions, and PV3A > Tween 20 > PAA under anaerobic conditions. Natural biodegradation of TCE was observed under both aerobic and anaerobic conditions. No significant effects were observed on the intrinsic biodegradation of TCE under aerobic conditions with the presence of the dispersants. The addition of PAA seemed to have a slightly adverse impact on anaerobic TCE biodegradation. Higher accumulation of the byproducts of anaerobic TCE biodegradation was detected with the addition of PV3A and Tween 20. The diversity of the microbial community was enhanced under aerobic conditions with the presence of more biodegradable PV3A and Tween 20. The results of this study indicate that it is necessary to select an appropriate dispersant for nZVI to prevent a residual of the dispersant in the subsurface. Additionally, the effects of the dispersant on TCE biodegradation and the accumulation of TCE biodegrading byproducts should also be considered.
本研究评估了纳米零价铁(nZVI)分散剂的生物降解性及其对三氯乙烯(TCE)本征生物降解性的影响。微宇宙研究结果表明，在有氧条件下，三种分散剂的生物降解性顺序为：聚乙烯醇-醋酸乙烯酯-衣康酸共聚物(PV3A) > 聚氧乙烯(20)山梨醇单月桂酸酯(Tween 20) > 聚丙烯酸(PAA)；在厌氧条件下，生物降解性顺序为：PV3A > Tween 20 > PAA。在有氧和厌氧条件下均观察到 TCE 的自然生物降解。在有氧条件下，分散剂的存在对 TCE 的本征生物降解没有显著影响。添加 PAA 似乎对厌氧 TCE 生物降解略有不利影响。添加 PV3A 和 Tween 20 后，检测到更多的厌氧 TCE 生物降解副产物的积累。在有氧条件下，由于添加了更易生物降解的 PV3A 和 Tween 20，微生物群落的多样性得到了增强。本研究结果表明，有必要选择合适的分散剂来防止 nZVI 在地下残留。此外，还应考虑分散剂对 TCE 生物降解性和 TCE 生物降解副产物积累的影响。
