Hydrogen sulphide emission from two large pig-finishing buildings with long-term high-frequency measurements

SUMMARYHydrogensulphide(HS)isacommontoxicairpollutantandisemittedfromdecomposingmanureatanimalfacilities.However,therehavebeenonlyafewstudiesofHSemissionsfromanimalbuildings,especiallythoseinvolvinglong-term,high-frequencymeasurements.Inthecurrentstudy,HSemissionsfromtwo,1000-headpig-finishingbuildingsinIllinois,USA,weremonitoredwithahigh-frequencymeasurementsystemfor6monthsin1997duringtwo,partial,pig-growthcycles.Airsamplestreamswerecontinuouslytakenfromthepitheadspace,andthepitandwallfanexhaustair.HydrogensulphideconcentrationwasmeasuredateachlocationwithHSconvertersandsulphurdioxide(SO)analysersduring16or24samplingcyclesperday,resultingin4544samplingcyclesand219daysofreliabledata.Buildingventilationratewasthesummationofpitfanandwallfanairflowrates.Airflowratesoftheunderfloormanurepitfansweremeasureddirectlywithfull-sizeimpelleranemometersorcalculatedfromairflow voltagerelationshipsofthefans.Airflowratesofthewallfanswerecalculatedfromfanoperationanddifferentialstaticpressuredataandfanperformancecurves.MeanHSemissionwas059kg dayperbuilding,074g dayperm ofpitsurfacearea,or63g dayperanimalunit(AU 500kganimalweight).ThedeterminationofHSemissionperAUwasrestrictedto193dayswhenbuildingoccupancywasatleast700pigsperbuilding.HighertemperaturesandbuildingventilationratesresultedinsignificantlyhigherHSemissionsperAU.INTRODUCTIONHydrogensulphide(HS)isoneofseveralnoxiousgasesemittedbylivestockconfinementfacilities.Itisgeneratedfromanaerobicfermentationofmanure.Usually, the concentration of HS is very low inanimalhousescomparedwithothergaseouspollu-tantslikecarbondioxide(CO)andammonia(NH).ThemeanHSconcentrationwasabout127µg m inatypicallyventilatedpigbuildingandabout396µg mafter the ventilation was shut off for 6 hours(Muehling 1970) (Cited volumetric concentrationsfromoriginalpublicationswereconvertedtomassconcentrations assuming 20 C and 1013 10 Paatmosphericpressure.)ThemeanHSconcentrationin