Research Of Transforming 2,4-Dichlorophenol By Microbial Electrolysis

The processing craft of nondegradable toxic 2,4-dichlorophenol was limited to its low efficiency and high cost. In this study, bioelectrochemical system consisted of conventional anaerobic treatment and electrochemical system was developed to treat 2,4-dichlorophenol wastewater. As a result, a purpose of high efficiency and economic was successfully achieved.The two-chamber microbial fuel cell reactors was firstly start up with the anodes domesticated together in ambient temperature, and the seed sediment was taken from the intersection of the Songhua River and the Ash Creek. Considering the different operation ways of MFC and BES, bio-anode domestication strategies aiming at the BES was designed by measuring the anodic polarization curve. The measured internal resistances of started-up BES showed that the internal resistances of bio-cathode with glucose of 1000mg/L as the co-substrate, non-glucose co-substrate as the co-substrate and abio-cathode were 37.38Ω,44.25Ωand 56.7Ω,respectively.Then factors affecting the performance of bio-cathode were analyzed. Removal rate of 2,4-dichlorophenol with the concentration of 200mg/L was found to be 98.5% when the following conditions were used: a pH of 6.5~7, concentration of glucose 1000mg/L, apply voltage of 0.7V and operation time of 48h. The lowest voltage of the reducing of 2,4-dichlorophenol was decreased from 0.5V to 0V when the micro-organisms were seeded, so the energy consumption was greatly reduced. The reduction potentials of 2,4-dichlorophenol on bio-cathode and abio-cathode were -0.37V and -0.4V, respectively, through the result of cyclic voltammetry curves.Microbial community structure on cathodes in different conditions were also analyzed. It was found that Swine manure pit bacterium,Pseudomonas aeruginosa strain,Dysgonomonas wimpennyi,Bacterium C111 were the dominant microorganisms in open circuit condition, Enterococcus aquimarinus strain , Swine manure pit bacterium,Clostridiaceae bacterium were the dominant microorganisms in MFC condition, Swine manure pit bacterium, Enterococcus aquimarinus strain ,Dysgonomonas wimpennyi,Clostridia bacterium were the dominant microorganisms in glucose of 1000mg/L condition, while Enterococcus aquimarinus strain ,Dysgonomonas wimpennyi , Pseudomonas aeruginose were the dominant microorganisms in condition of non-glucose co-substrate.Finally, through the results of HPLC and cyclic voltammetry curves of cathodes in different conditions, also some relevant literature, the transformation paths of 2,4-dichlorophenol on different bio-cathodes were all as followed: 2,4-dichlorophenol was firstly reduced to 2-Chlorophenol or 4- Chlorophenol, then they were converted to phenol.