The Bioaugmentation Technology Of Prydine Under Anoxic Conditions

Enhanced biodegradation technology of pyridine under anoxic condition was elucidated in this paper through both batch experiments and continuous experiments.Batch experiments were carried out to study the influence of different operating parameters, (like initial pH values, nitrate concentrations, pyridine concentrations, different electron acceptors and so on,) applied on the process of pyridine biodegradation. The results indicated that pyridine could be mineralized in the anoxic or anaerobic conditions, accompanied by the release of ammonia. However, in the anoxic condition, the pyridine biodegradation was significantly enhanced, probably due to the presence of the electron acceptor, i.e., NO3--N. Pyridine was degraded optimally at initial pH 7.5-8.0. High concentration of nitrate or pyridine had an inhibitory effect on the anoxic degradation of pyridine.In continuous experiments, the combined anoxic-aerobic process consisted of an anaerobic baffled reactor (ABR) and a moving-bed biofilm reactor (MBBR) was operated for nearly one year to investigate the performance of pyridine biodegradation and nitrification in this integrated system. The NH4+ released from pyridine biodegradation in ABR was nitrified completely into NO3--N in MBBR, which was then recirculated to ABR, serving as the electron acceptor for pyridine biodegradation. The results further verified the pyridine biodegradation was enhanced with the existence of nitrate nitrogen under anoxic conditions. With the effluent recirculation rates increased from 0 to 400%, pyridine biodegradation in ABR was improved significantly, probably due to the high availability of nitrate and the mitigation of the toxic effects over the biomass at relatively high recirculation rates. In addition, the residual pyridine in ABR effluent was proved to have negative impact on the nitrification effect of MBBR by the verified experiment.High-throughput sequencing technology was applied to study the microbial community structure of the ABR for examining the important role of various microbes played in the process of pyridine biodegradation. The results demonstrated that Paracoccus, Thiobacillus and Paludibacter were the dominant species during former stage of the anoxic degradation system. In addition, this paper made a comparative difference analysis of the microbial community structure and diversity between the two groups of anoxic condition and anaerobic condition during the later stage. The results showed that the microbial community structure under anoxic conditions was relatively more complex, and diversity was higher.