Study Of Microbial Diversity In The Different Phase Space And Performance On Upflow Anaerobic Sludge Blanket (UASB) Startup Treating Swine Wastewater

As large amounts of wastewater from piggery farm are mostly discharged directly to environment without appropriate recycle and treatment today, that brings about a serious pollution. At present, anaerobic biological treatment is mainly a high efficient process for treating high concentration organic wastewater. There are manyways such as anaerobic filter (AF), upflow anaerobic sludge bed (UASB), hybrid anaerobic reactor (UASB+AF), two-stage anaerobic digestion process, upflow anaerobic sludge bed reactor (USR), etc. As the source of improved-innovation in sewage reactor today, UASB is one of the most important research areas in wastewater treatment last decade. Along with biological development and advancement of microorganismapplication, microorganism is playing more important role in wastewater treatment.Current studies focus on microorganisms of granule sludge to better understand the associations of microorganisms for engineering development of reactor performance stability. The treatment capacity and stability of anaerobic system are controlled by the reactor startup playing an important role in the formation process of aerobic granular sludge, however. Along with the development of molecular biotechnology,16S rRNA sequencing technology enables much broader application on microbial flora diversity to enhance microbial ecology. This paper studied microbial diversity in the different phase space and performance on UASB startup treating swine wastewater from the idea of livestock environmental protection concepts to provide a theoretical basis for the enhancement of anaerobic reactor start-up technology in large-scale pig farms. Dispersion of organicpollutants in UASB was studied by monitoring wastewater samples total solids (TS), total suspended solids (TSS), volatile solids (VS), volatile suspended solids (VSS), pH and COD characterized in four ways:total (CODtot), suspended solids (CODss, the difference between total and filtered sample), colloidal (CODcol, the difference between filtered and soluble samples) and soluble (CODsol) in different phase space(under gas-liquid-solid heights) of UASB reactor during start-up. With the method of 16S rRNA technology, the microbial community structure and biodiversity of different phase space on UASB treating swine wastewater to study the internal processing mechanism during startup. The conclusions of this study are as follows:(1) The experiment results indicated that the reactor could obtainsteady statewithin 96 days under ambient temperatureby adopting the way of continuous water intake at room temperature. The start-up process had experienced four stages of hydraulic retention time. The removal rate of COD could reach above 80% and gas yield was 0.8998 L/L·d. COD removal rate and the gas production ratevaried greatly,depending on thedecrease of hydraulic retention time during startup, but after operation for some timegetting back to normal. Organic load rateconstantlyincreased during in tests and could reach 10.95kgCOD/(m3·d) at the end of startup.(2) The COD changes in different phase space of UASB reactor during startup seemed irregular, but the removal rate of CODss, CODcol and CODsol would increase with the height of reactor when to close the stability which obtained maximizing in the position of the outlet. However, COD removal efficiency had a lower part under gas-liquid-solid separater and the removal rate of CODtot could reach above 80%.(3) The sludge concentration changes in different phase space of UASB reactor during startup was characterized bythe highestat the bottom of reactor, up to 50-60 g/L, and no significant difference among the rest of phase space(P> 0.05). Suspended solidscharacterized bysignificantly increased (P< 0.05) in outlet than inlet indicated UASB reactorcould play an active role inexclusion of suspended solids.(4) The bacteroidetes was dominant in the swine wastewater and anaerobic sludge of Anaerobic Baffled Reactor (ABR). ABR also contained the other main bacteria, methanogens. Microbes from UASB reactor inlet of swine farm wastewater and the inoculation of anaerobic sludge was characterized by few changes in dominant bacteriaclassification, only by differences in quantity. Wherever stage was, therewas the very striking similarity ofmicrobial variety in different phase space of UASB reactor during startup. A large fluidity of water in the UASB reactor at the early stage of startup led to differentstrainin different space. In addition, the experiment showed thatMethanocorpusculaceae appeared in the early stage of start-up exclusively as predominant bacteria, thereafter,washed outside the reactor, which was concluded that Methanocorpusculaceae only attach to worse settleabilitysludge. But after the startup, Methanosaetaceaewasmainly enriched in the bottom of reactor, which explained that this bacteria concentrated on the composition of granular sludge.