Effect Of Sulfuide Concentration On Biochemical Efficiency And Biodesulfurization By Oxidization

Sulfide not only can inhibit anaerobic biochemical reaction but also can generate stronginhibiting effect on subsequent aerobic treatment.Therefore,the influence of sulfideconcentration on anaerobic and aerobic biological efficiency and their concentration thresholdhas been studied in anerobic baffled reactor and biological contact oxidation reactor,then thefeasibility of relieve anaerobic inhibition has been investigated by changing pH and addingFeCl2,and a Thiobacillusthioparus strain which was used to explore the appropriate operatingconditions of sulfur wastewater treatment by biological oxidation also has been screenededfrom the biofilm of aerobic reactor.Concluded as follows:(1)The influencing law of sulfide concentration on anaerobic biological efficiency:whenthe influent sulfide concentration was less than20mg/L,sulfide could promote anaerobicbiological efficiency and the removal rate of COD rose from76.23%to81.57%;80mg/L wasthe turning point of weak inhibition and strong inhibition;120mg/L was the turning pointwhether anaerobic system could be operated normally and the removal rate of COD was only29.67%.(2)The solutions to relieve anaerobic inhibition of sulfide: the anaerobic inhibition ofsulfide could be relieved by increasing pH when it was not higher than8and adding moderateFeCl2when ρ(Fe/S) was between3/4and1/2can obviously relieve the inhibition of sulfide.(3) The influencing law of sulfide concentration on aerobic biological efficiency: whenthe influent sulfide concentration was less than15mg/L,sulfide has no effect on aerobicbiological efficiency and the indices have little change such as the removal rate ofCOD(80%);60mg/L was the turning point of weak inhibition and strong inhibition;150mg/Lwas the turning point whether aerobic system could be operated normally and the removalrate of COD was only20.48%.(4) The influencing law of sulfide concentration on nitration efficiency: when theinfluent sulfide concentration was less than10mg/L,sulfide has no effect on nitration and theindices have little change such as the removal rate of NH3-N(71%) and the μAofnitrobacteria(0.76/d);40mg/L was the turning point of weak inhibition and strong inhibition;100mg/L was the turning point whether nitration could be operated normally andthe removal rate of NH3-N was only22.69%and the μAof nitrobacteria was0.347/d.(5) The appropriate operating conditions of sulphur removal by biological oxidization:therelationship between influent sulfide concentration and best DO is y=0.00396x+0.42418;the removal rate of sulfide could reach90%when HRT was2～3h and pH was7～8;theparticle diameter of elemental sulfur which was generated in aerobic reactor was1～2μm andits surface had many flocculent material under electron microscopy.