污泥中温厌氧消化过程中多溴联苯醚的生物降解研究

Biodegradation of Polybrominated Diphenyl Ethers in Mesophilic Anaerobic Digestion of Sewage Sludge

摘要: 多溴联苯醚(PBDEs)是城市污泥中普遍存在的一种持久性有机污染物，其残留浓度与生态风险近年来受到广泛关注，但关于污泥处置过程中PBDEs归宿的研究相对较少。本文通过建立小型规模实验装置，连续运行60天，考察了典型城市污泥中温厌氧消化过程中PBDEs的生物降解过程，并初步分析了导致PBDEs降解的微生物群落组成。结果表明：经过两个泥龄阶段(40天)的运行，厌氧消化反应达到稳定状态。污泥中主要的PBDEs同系物BDE-209的质量呈现先增加后减少的趋势，在整个厌氧消化过程中，降解率达67.5%。其它PBDEs同系物则在第III泥龄阶段均表现出增加的趋势，特别是三种九溴化合物BDE-206、207和208。根据九溴化合物的增加量及其化合物分子结构，发现BDE-209脱溴降解主要发生在邻位和间位溴原子上，同时也有其它含溴化合物的生成。通过16S rDNA高通量测序技术测定表明，污泥厌氧消化过程中微生物群落组成丰度较高，多样性较大，其中脱卤球菌科(Dehalococcoidaceae)有可能在PBDEs的降解中起到一定作用。这为进一步分离筛选和培养污泥中厌氧降解PBDEs的优势菌种提供了依据。

Abstract: As persistent organic pollutants, polybrominateddiphenyl ethers (PBDEs) were frequently de-tected in sewage sludge worldwide. The occurrence of PBDEs as well as the irpotential environ-mental risk was widely concerned in recent years. However, few studies were conducted on the fate of PBDEs during the disposal of sewage sludge. The present study developed a small-scale anaerobic digestion reactor to explore the degradation of PBDEs in sewage sludge in 60 days. Meanwhile, the microbial structure in sludge was analyzed, aiming to further identify the responsible species for the degradation. Results showed that the mesophilic anaerobic digestion reaction reached to equilibrium after two sludge age running (40 days). The mass of BDE-209, a main component of PBDEs in sewage sludge, increased in the first sludge age and then decreased in the following two ages with a degradation rate of 67.5%. For all other PBDE congeners, the mass increased dramatically in the third sludge age, especially for three nona-brominated congeners BDE-206, 207, and 208. Based on mass changes and chemical structures of three nona-brominated congeners, the debromination of BDE-209 is more likely to occur in meta- and ortho-position of bromine rather than para-position. Other degradation products containing bromine are also expected. High-throughput sequencing results indicated that the microbialspecies in anaerobic sewage sludge is diverse, of which dehalococcoidaceae could be contributed more to the degradation of PBDEs. The findings could provide help in the isolation and culture of strains for degradation of PBDEs in sludge.