Experiment Study On The EGSB-SBR Composite Process In Treating Juice Wastewater And Physicochemical Properties Of Anaerobic Granules

With the sustainable and rapid development of juice industry, environmental pollutioncaused by juice wastewater, an emerging industry wastewater, has become increasinglyprominent in China. At present, juice wastewater has become the second largest pollutionsources of Weihe River immediately following the paper wastewater.In this paper, based on the actual treatment conditions of the juice wastewater,anaerobic-aerobic combined technology with the core of anaerobic biotechnology to treatcondensed fruit juice wastewater was studied.The characteristics and regulations of using EGSB-SBR combined technology to treatreal fruit juice wastewater was studied in this paper on the basis of successful startup ofEGSB reactor, the completion of the second quick starting EGSB reactor and thedomestication of EGSB reactor，and the technical problems of acidic fruit juice wastewaterstable operation under the conditions of low-alkali was solved by controlling the refluxratio; At the same time, the variation of physico-chemical parameters, such asmicroorganisms in anaerobic granular sludge, the methanogenic activity and mechanicalstrength were examined at every stage, especially determination of mechanical strength foranaerobic granular sludge was improved and regulated and the factors affecting its sizewere deeply analyzed and summarized. Through the research in this paper, theory guide isexpected to be provided for practical project, and finally exploring a recyclable technologypath which can economically and effectively solve the industry wastewater.Through long-term biological systems operation and related experiments as well astheoretical research, the main conclusions of this paper are as follows:（1） After174days of operation, the volume load of EGSB reactor was upgraded from0.33kgCOD·m^-3·d^-1to13.1kgCOD·m^-3·d^-1; gas production reached100L·d^-1, CODremoval rate remained stably at more than90%. At higher granular sludge concentrationand sludge organic loading conditions, after16days of running the reactor by enhancinghydraulic load and organic load alternately, the volume load was upgraded from2.27 kgCOD·m^-3·d^-1to11kgCOD·m^-3·d^-1, COD removal rate reached92%; gas production80L·d^-1. Fast second start of EGSB reactor was achieved;（2） The domestication of anaerobic reactor for concentrated fruit juice wastewater canbe successfully achieved by ramping up the ratio of the juice wastewater in glucosewastewater. By controlling the reflux ratio at3:1, EGSB reactor can effectively treat fruitjuice wastewater at low alkalinity conditions without adding NaHCO3and can stably rununder high load conditions;（3） When treating condensed fruit juice wastewater with combined technology, atstable operation stage, EGSB average influent COD, BOD5and SS were respectively5968mg·L^-1,2130mg·L^-1,1020mg·L^-1; SBR effluent were respectively131mg·L^-1,10.8mg·L^-1,50.2mg·L^-1, the COD, BOD5, SS removal rates of which were96%,99.5%and95.1%.The effluent COD reached B-class emission standards of Shaanxi Province “emissionstandards for condensed fruit juice processing industrial"（DB61/421-2008）, while BOD5,SS reached its A-class emissions standards;（4） With gradual reduction of pH in feed liquor of low alkalinity acidic juicewastewater, the methanogenic activity of anaerobic granular sludge decreased significantly,acid resistance of granular sludge was domesticated, and dominant species in the reactorgradually changed. The mechanical strength of granular sludge varied with the change ofreactor running conditions, which can reflect the actual running condition in reactor asimportant quality parameters of anaerobic granular sludge.（5） With the method of screening the anaerobic granular sludge samples and thenmeasuring the mechanical strength, the problems of poor accuracy and reproducibility inthe present compression experiment existing in the practical operation process were solved.By determining and comparatively analyzing mechanical strength of anaerobic granularsludge samples from different sources, it was found that there was a certain positivecorrelation between the mechanical strength of anaerobic granular sludge and the size ofthe reactor as well as hydraulic loading used; furthermore, the mechanical strength ofanaerobic granular sludge had a close relationship with its major metals （Ca, Fe, Mg）content.