Research On Treatment Of Siraitia Grosvenori Processing Wastewater By External Circulation Anaerobic Reactor

As the main origin of siraitia grosvenori,Guangxi discharges lots of siraitia grosvenori processing wastewater into the environment every year.This kind of wastewater with high organic matter concentration,acidity belongs to the high concentration organic wastewater areas and is suitable for treatment by anaerobic process.But right now,the report about treatment of siraitia grosvenori processing wastewater is only found to use UASB technology in China,while other anaerobic treatment processes are not been reported in literature.The experiment was did with external circulation anaerobic reactor which was self-made and siraitia grosvenori processing wastewater diluted.In this paper,the condition during the start-up was investigated.The experiment results showed that,when the organic load was increasing from 1.29 kgCODcr/(m3·d)to 7.411 kgCODcr/(m3·d)with the reaction temperature of(35 ± 1)degrees and HRT=26h,only 40 days the start-up was finished under the condition of circulation not started.At the moment,the removal rate of CODcr reached 95.6%,and the concentration of VFA was low to 2.33mmol/L,and the concentration of alkalinity reached 34.3mmol/L,and the biogas production reached 24.9L/d,including methane ratio reaching as high as 71.6%,and the methane production reached 17.9L/d,and the reactor could produce 0.441 m3gas per every as1 kg CODcr removed.At the same time,the granular sludges with certain mechanical strength and dense and good settling behavior had been formed in the reactor.The dominant archaea in the mature granular samples were Coccus and Chain-like bacteria using scanning electron microscope.Entered the normal processing phase,continuing through into siraitia grosvenori processing wastewater.The results indicated that without activating the circulation system,the CODcr removal rate,pH value of effluent,basicity and Gas production per kg COD of reactor decreased gradually with the increment of inflow water volume,while the density of VFA increased gradually.On the condition of inflow water volume increased from 0.3L/h to 1.25L/h,the removal of CODcr rate decreased from 92%to 63%;pH value of effluent reduced from 7.3 to 6.6;basicity of effluent reduced from 34.07mmol/L to 21.95mmol/L;Gas production per kg COD gradually decreased from 0.441m3/d to 0.303m3/d;VFA was up from 2.35mmol/L to 7.05mmol/L.After opening the external circulation,through the comparison of reactor effect and removal rate on different condition of inflow water volume and circulating volume condition,the best operating effect of reactor was on the condition of inflow water volume of 0.92L/h,and circulation reflux volume of 1.18L/h.What's more,its removal rate of CODcr reached to 86.4%,and pH value of effluent was up to 7.3;effluent volatile acid declined to 2.41mmol/L;basicity was up to 34.68mmol/L;the biogas production has reached 0.72m3/d in which 74.9%was methane.The gas production per kg COD was up to 0.502m3/d at most.External circulation running could promptly improve the property of reactor and adjust the reactor into its best operating status so that enhance the operating efficiency of reactor.Through the study of characteristics of cozymaseF420,EPS,VSS,VSS/SS value and SVI value of sewage sludge by operating circulation test,the results showed that biological indicators of after-circulating sewage sludge were better than the measured value in the 45th running day,in which cozymaseF420,EPS,VSS,VSS/SS value respectively increased 0.39?mol/gVSS,9.7mg/gVSS,5mg/L,and 5%.Meanwhile,SMA was measured after the start-up and operation with external circulation of reactor,that SMA was 0.348[LCH4/(gVSS·d)]after the operation of reactor,0.04[LCH4/(gVSS·d)]higher than the value of 0.308[LCH4/(gVSS·d)]at the end of the start-up of reactor;however,the SVI declined by 9.27mL/g,which indicated that activity and sedimentation property of granular sludge at the end of operation enhanced.After the operation with external circulation,the biofacies of granular sludge was relatively abundant,mainly with methane streptobacteria,coccus,brevibacterium,tumor tissue associated on bacteria surface.