Characteristics And Mechanisms Of PCP Anaerobic Biodegradation

Effect of carbon source (glucose, pyruvate, yeast extract) and electron donor (H2) on anaerobic degradation of pentachlorophenol (PCP) was investigated. Gas chromatograph-mass (GC-MS) analysis of the intermediate products in PCP catabolism was carried out. Differences of bacterial community in the anaerobic systems were detected by terminal restriction fragment length polymorphism technique (T-RFLP). The bacterial diversity in the anaerobic sludge of PCP was studied by the 16s rRNA cloning and sequencing method. The operation conditions of applying expanded granular sludge bed (EGSB) reactor for the treatment the PCP wastewater was also studied. Results are shown as follows:1. Compared with carbon-free system, the supplementation of different carbon sources and H2 may greatly enhance the degradation of PCP. When glucose, pyruvate, yeast extract and H2 were added, the removal efficiencies of PCP were 71%, 74%, 51% and 56%, respectively,. In contrast, without carbon addition, only 17.64% of PCP was removed. Different glucose concentrations could affect the degradation of PCP. Among them, the addition of 2 g/L glucose showed an obvious promotion.2. GC-MS analysis showed that, the intermediate products of PCP degradation, 2,3,4,5-TeCP, 2,3,4,6-TeCP, 2,3,5-TCP, 3,5-DCP and 2,4-DCP could be detected. It is indicated that under the condition of anaerobic biodegradation, the dechlorination reaction gradually happened and the PCP was mineralized.3. The analysis of T-RFLP showed that bacterial community structures were different under different treatment conditions. It was speculated that some microorganisms phylogenetically affiliated with the genus Clostridium, Frankia and Desulfitobacterium existed in the PCP-degradating systems.4. 16S rDNA sequencing method was used to investigate the bacterial diversity in the anaerobic sludge of PCP. It is indicated that 38 clones could be divided into 11 phylotypes. TM7 was the dominant component of the biodegradation bacterial community, followed by Betaproteobacteria, Firmicutes, Bacteroidetes, Planctomycetes, Verrucomicrobia and OP11. TM7 inferred as PCP- degradating microorganisms by the phylogenetic analysis results.5. Under the conditions of 80 mg/L PCP and 4500mg/L COD in influent, effluent recycle ratio 10, and hydraulic retention time 18 h, PCP and COD could be degraded efficiently. Keywords: Pentachlorophenol, Anaerobic Biodegradation, Cometabolism, T-RFLP, 16S rRNA clone library, EGSB reactor...