用零价铁在高有机负载量下厌氧消化食物废料时抑制过度酸化

minimumrotation.BothdosesofPZVIandSZVIwere0.4gZVI/gVSFWadded.2.3.AnalyticalmethodsTheTS,VS,andpHweremeasuredaccordingtoAPHA(2005).Suspendedsolidswereseparatedfromthedigestereffluentviacentrifugationat3000rpmfor10min,theliquidsupernatantwasfiltratedthrougha0.45-lmmembrane,andSCOD,ammoniaconcentration,ALK,andVFAsweremeasured(Kongetal.,2016).TheSCODwasanalysedfollowingtheHACHmethod.VFAsweredeterminedusingGC(Shimadzu,GC-2014)withaflameionisationdetectorandcapillarycolumn(Stabilwax-DA,30m�0.25mm�0.25lm).Thetemperatureprogramfollowedpreviousmethods(Jiangetal.,2014).3.Resultsanddiscussion3.1.EffectofZVIdosageonexcessiveacidificationinhibitioninFWdigestionwithahighOLRIntheFWADwith10%TS,themixturehadarelativelyhighOLRandlowfluiditytoallowexcessiveacidificationtooccur.ByaddingPZVIorSZVI,acidificationwasreducedsignificantly,andtherecoveryperiodofmethanogenesisvariedbasedonZVIdose.TheaccumulativeCH4productionfromADandtheVFA-to-ALKratio(VFA/ALK)ofeffluentareshowninFig.2.Otherpropertiesoftheeffluent,includingpH,SCOD,andVFAsareshowninS2.Ingeneral,littledifferencewasobservedintheaccumulativeCH4volume(10,000–10,800mL)amongexperimentalgroups,regardlessofthePZVIorSZVIdose,andthecorrespondingCH4yieldwas�380±6mL/gVSFWadded.However,therewasashortlagphasebeforemethanogenesisrecoveryandmaximumCH4productionwhenusingPZVI.Thereactorwith0.4gPZVI/gVShadtheshortestlagphase(30days),withanaccumulativeCH4volumeof�10,500mL.Ingeneral,30daysisarelativelylongtime.ThisoccurredbecauseofthehighTScontent,resultinginapoormasstransferandZVIprecipitationatthebottomofthereactor,slowingthereactionrateofZVIwithexcessiveVFAsinthereactor.TheVFA/ALKisagoodindicatorofADstability,andwhenitislessthan0.3–0.4,thereisminimalriskofacidification(Shahriarietal.,2013;ElbeshbishyandNakhla,2011).ThetotalALKoftheeffluentfromthereactorswithZVIrangedfrom13,000–14,000mgCaCO3/L,andVFA/ALKrangedfrom0.01to0.02(Fig.2).Inthecontrolgroup,themaximumVFA/ALKoftheeffluentwas1.95,althoughitstotalALKwas15,875mgCaCO3/L.Theseresultssuggestedtha