城市污泥中邻苯二甲酸酯(PAEs)的厌氧微生物降解

Anaerobic biodegradation of phthalic acid esters (PAEs) in municipal sludge

邻苯二甲酸酯(PAEs)是城市污泥中普遍存在的一类具有内分泌干扰性作用的有机污染物.研究污泥厌氧生物处理过程中PAEs的微生物降解对保障污泥农用的安全性十分必要.本文以污泥中两种主要的PAEs——邻苯二甲酸二丁酯(DBP)和邻苯二甲酸(2-乙基己)酯(DEHP)为研究对象,通过比较PAEs在污泥厌氧消化系统与发酵产氢系统中降解过程的差异及系统污泥特性的变化,分析不同污泥厌氧生物处理系统中影响PAEs降解的可能因素.结果表明:在污泥厌氧发酵系统中,DBP在6 d内降解率达99.6%,DEHP在整个14 d的培养期间也降解了46.1%;在发酵产氢系统中,在14 d培养过程DBP的降解率仅为19.5%,DEHP则没有明显的降解.与厌氧消化系统相比,PAEs在发酵产氢系统中的降解受到明显抑制,这与发酵产氢过程中微生物量下降、革兰氏阳性菌/革兰氏阴性菌(G+/G-)和真菌/细菌变小及挥发性脂肪酸(包括乙酸、丙酸及丁酸)浓度升高有关.

Phthalic acid esters （ PAEs）, a class of organic pollutants with potent endocrine-disrup- ting properties, are widely present in municipal sludge. Study of PAEs biodegradation under differ- ent anaerobic biological treatment processes of sludge is, therefore, essential for a safe use of sludge in agricultural practice. In this study, we selected two major sludge PALEs, i.e. di-n-butyl phthalate （DBP） and di- （ 2-enthylhexyl ） behaviors in an anaerobic sludge digestion phthalate （DEHP）, to investigate their biodegradation system and a fermentative hydrogen production system. The possible factors influencing PAEs biodegradation in relation to changes of sludge properties were also discussed. The results showed that the biodegradation of DBP reached 99.6% within 6 days, while that of DEHP was 46.1% during a 14-day incubation period in the anaerobic digestion sys- tem. By comparison, only 19.5% of DBP was degraded within 14 days in the fermentative hydro- gen production system, while no degradation was detected for DEHP. The strong inhibition of the degradation of both PALEs in the fermentative hydrogen production system was ascribed to the de- creases in microbial biomass and ratios of gram-positive bacteria/gram-negative bacteria and fungi/ bacteria, and the increase of concentrations of volatile fatty acids （e. g. acetic acid, propionic acid and butyric acid） during the fermentative hydrogen-producing process.