Effect Of P-nitrophenol And Organic Loading Shock On Sludge Activity And Microbial Community In UASB Reactor

Since anaerobic bio-treatment technology has merits of low energy consumption, low sludge output and production of biogas, a kind of green energy, it has already been widly used in treatment of organic waste water throughout the china. Anaerobic bio-treatment devices are often encountered the changes of the components in waste-water and shock of organic loading charge, as in the renewal products or entering of toxic substrates duo to misplay during operation. These changes affect sludge activity and the effluent water quality became poor. Studying the effect of toxicant and organic loading shock on microbic population,especially on methanogens in anaerobic treatment devices are helpful for guiding how to manage the anaerobic treatment devices and to improve waste water treatment efficiency.This paper researched the suitable DNA extraction methods in anaerobic sludge, the effection of the shock of p-nitrophenol and organic loading charge on the sludge activity and diversity of microorganisms in the sludge in the UASB reactor.The main results of this study are as follows:Considering DNA quantity,purity, fragment size and diversity of microorganisms presented,repeated jelly-melt combined with SDS was the best method for DNA extraction compared with ultrosound together with SDS, liquid nitrogen grinding together with SDS and SDS treatment only. Its fragment was the most and Shannon-wienner index was the biggest, which explained it contained the most microorganisms population diversity by PCR-DGGE analyzing.Analyzing the diversity of methenogens in inoculated and matured anaerobic sludge by PCR-RFLP method showed that the diversity of inoculated anaerobic sludge was more than that of matured anaerobic sludge according to the fragments after digestion by HaeIII and RsaI restriction enzymes. Analysis of 16S rDNA sequence in clone libraries showed that the predominant methanogens in mature anaerobic sludge were mainly Methanosaeta sp., Methanomicrobia sp. and Methanothrix sp.,but the predominant methanogens in inoculated anaerobic sludge were Methanospirillum sp., Methanocorpusculum sp. and Methanogenium sp..After the UASB reactor undergoing 20mg/L p-NP and 40mg/L p-NP shock,sludge activities were inhibited, resulting in the rapid decrease of COD_Cr removing efficiency and methane production. Effect by high concentration p-NP shock on anaerobic system was more serious than that by low concentration p-NP. The system tooke 27 days to recovery after high concentration p-NP shock,ll more days longer than by low p-NP shock.Microorganism population diversity was obviously effectted also after p-NP shock by PCR-DGGE analyzing. The impact of p-NP on eubacteria are more serious than on archaea. Chloroflexi, Anaerovibrio sp.and Bacteroide sp. were the speacies whose abundance were affected maximumly. Flavobacteria sp. was the newly appeared bacteria, which may be related with p-NP degradation.The COD_Cr remove efficiency and methane production rate were affected but not very markedly after more 50%, 100%, 150% and 200% organic load charge shock. The system was able to recover very quickly. Eubacteria and archaea diversities did not change greatly based on the PCR-DGGE analysis. The numbers of methanogens were between 9.51×10⁹ and 6.56×10¹⁰cells/g dry sludge by fluorescence real time quantity PCR after organic load charge shock.By MPN method, three kinds of physiology bacteria in anaerobic sludge were counted. The results demonstrated that after p-NP shock the numbers of fermentative bacteria and hydrogen-producing acetogenic bacteria were both only 1% of that befor p-NP shock,but quantity of methane bacteria dropped down to 10% of that befor p-NP shock,indicating that the impact of p-NP shock on eubacteria was bigger than on archaea; Changes of three kinds of physiology bacterial groups were very small after organic loading shock, all keeping in the same order of magnitude.