Groundswell -Compost Process
description
Transcript of Groundswell -Compost Process
� ProcessingCitytoSoilcollectionswiththeGroundswellCompostingProcess
processing City to Soil collections with the Groundswell Composting process
CompostingfacilitieshavebeenestablishedinGoulburnMulwareeCouncilandLachlanCouncilonexistinglandfillsites.Anon-farmcompostingsitelocatedintheSydneyWaterCatchmentforPalerang/Queanbeyancouncilcollectionshasbeenlicensedandwillbeoperationalsoon.FoodscrapsandgardenwastecollectedthroughtheCitytoSoilcollectionsinGoulburnMulwareeCouncilandLachlanCouncilarebeingcompostedusingtheGroundswell’sCompostingProcessoutlinedbelow.
TheGroundswellCompostingProcesshasbeendesignedtomeetthefollowingcriteria:
requireminimalnewmachineryorinfrastructure
abletouseexistinglandfillorfarmmachinery(e.g.smalltractorwithbladeorfrontendloader)
abletooperateinexposedsiteswithnopowerandminimalwater
minimallabourandmachineryrequirement
simplestep-by-stepprocessthatcanbemanagedbyexistingwastemanagementorfarmlabourwithoutexpertcompostingknowledge
abletooperateconsistentlywithseasonallyvariablefeedstocks
abletoeffectivelymanageconcernsaboutputresciblesincludingodour,verminandbirds
producethehighestqualitybiologicallyactivecompostpossiblewithzerophysicalcontaminationthatmeetsagriculturalmarketrequirements.
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This document describes the composting process being used by four NSW councils to transform their residential food and garden waste into a high quality, high nutrient, and biologically active composted product as part of the Groundswell project.
GroundswellisathreeyearprojectwhichissupportedbytheNSWEnvironmentTrustUrbanSustainabilityProgram.Theprocesshassubsequentlybeentrialledandadoptedbyagrowingnumberofcouncilsandfarmerstocompostbiosolids,cardboard,commercialpetfoodwaste,manures,papersludge,nappiesandwaterweeds.
InstrumentaltothesuccessoftheGroundswellprojecthasbeenthedevelopmentofasimplebuteffectivecompostingprocessusingabio-techproductfromaQueenslandcompanycalledVitalResourceManagement(VRM).Thebio-techproductisatwopartinoculantthatwhenproperlyusedandmanaged,createsstability,predictability,consistencyandnoodouratanystageofthecompostingprocess.CombinedwiththeuseofcompostableBiobagsforthecollectionoffoodscraps,whichactivelydehydratefoodscraps(includingmeat)andensurefoodarrivesatthecompostingsiteinanaerobicstate,theentireCitytoSoilprocessisodourfreefromkitchentofinishedproduct.
c o m p o s t i n g p r o c e s s
� ProcessingCitytoSoilcollectionswiththeGroundswellCompostingProcess
Summary of Composting ProcessTheCitytoSoilfeedstockofcombinedkitchenandgardenwastecreatessomespecialopportunitiesandrisksforsuccessfulcomposting.Thehighernutrientandmoisturelevelspresentinthefoodscraps,combinedwithpotentiallychallengingingredientssuchasmeatscrapsprovidesaperfectfeedstocktoproduceamicrobiallyrich,highnutrientproductifcorrectlyprocessed.ThespecificsoftheVRMactivatedcompostingprocess(technicallymoreofafermentativeprocess)areoutlinedbelow.Inessence,thecompostingprocesshasbeendevelopedforsimplicity,cost-effectivenessandefficiencywhileensuringapremiumcompostproduct.
Thecompostingprocessisattractingsignificantinterestduetoitslowlabour,plantandwaterrequirements.Thekerbsidecollectedfoodscrapandgardenwastefeedstockisnotshreddedpriortoprocessing.Thisremovestherequirementforshreddingequipmentonsite.Additionally,thefermentativeprocessreducesthenumberofturnstojustonceduringthe8-��weekcompostingprocess.Thisresultsinacheaper,cleanerendproductwithlessphysicalcontamination.
Theprojectisalsochallengingassumptionsthattheprocessingoffoodissynonymouswithverminandodourissuesandneedstooccurindoorsorinvessel.
FeedstockTheCitytoSoilfeedstockincludessourceseparatedhouseholdkitchenandgardenwaste.Allfoodscrapsincludingmeat,bones,dairyproductsandfatareincluded.
Householdersinparticipatingtownshavereceivedvented6litreMaxAirkitchenbench-topfoodscrapbinsandayear’ssupplyofcompostablebiobags.ThebiobagsandMaxAirbinsminimiseodoursbyallowingthecontentstobreathe.Whenthebiobagsarefull,theyaretiedclosedandplacedintheCitytoSoil�40Lwheeliebin(MGB)alongwithanygardenwaste.
InGoulburnMulwareethe�40litreMGBsarecollectedmonthly.InCondobolin,thecollectionisfortnightly.
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stage 1: picking
Feedstockisdelivereddirectlyontothecompostingsite/hardstandarea.Wherepossiblethetruckshouldspreadthematerialoutoverawideareatofacilitatepickingandspraying.Thematerialarrivespre-mixedwithfoodscrapsneatlycontainedinBiobagswhicharestillintactbutvisiblydehydrated.Thereisusuallynoodouratpointofdelivery.Occasionallyandseasonally,theremaybesometemporaryodoursduetolawnclippingswhichmayhaveslumpedinthebaseofMGBsandturnedanaerobic.Thisseemstochangequitequicklyonceonsite.Ifodourisnoticeableorunacceptableatthisearlystage,thematerialcanbesprayedwithdilutedinoculantspriortopicking.
Thefirsttaskinthecompostingprocessistopickthroughthefeedstockbyhandtoremoveanyphysicalcontamination.Anicefeatureofthebiobagsisthattheyensurethefoodscrapsarriveattheprocessingsitesomewhatdehydrated,neatlycontainedandinanaerobicstatewithnoodour.Evenwithamonthlycollectionthebagsarerobustenoughtoremainintactduringthecollectionandcompactionprocess.
Typicalcontaminationremovedatthisstageincludesthebottles,cansorplasticbags.Thebiobagsoffoodscrapsgointothecompostingprocessintact.
Onceanyphysicalcontaminationisremoved,thefeedstockissprayedwiththeVRMPhotonCompostingsolutionsandanappropriateamountofnonorde-chlorinatedwater.
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stage 2: inoculating
ThecompostinginoculantisacombinationofVRMPhotonStarterCulture®andVRMPhotonSeedingAgent®.TheVRMPhotonStarterCultureandVRMPhotonSeedingAgenthasbeenspecificallyselectedtomeetthefeedstockrequirementsofacombinedfoodandgardenwastecollection.
Dilutionratesare�litreofstartercultureand�litreofseedingagentdilutedinaminimumof�0litresofwaterforevery�0cubicmetersofgreenwaste.(i.e.,�00mlsofeachproductforeachcubicmeteroffeedstock)
Bothproductsshouldbedilutedinwaterattheaboveratespriortoapplication.Ideallythecompostingsolutionshouldbeappliedunderpressureusingafullconesprayoratomiser(e.g.ayellowpressurenozzle)asexposureofthesolutiontooxygenkick-startstheoxidisationprocesswhichkick-startsbiologicalactivitywhilethefinedropletsizemaximisessurfacecoverage
Thepilesshouldbequitewetbeforecovering(ideally40%–60%,min�0%moisturetomax80%moisture)-wetterthanwouldnormallybeassociatedwithopenwindrowcomposting.Ifextrawaterneedstobeaddedtothepilesthedilutionratecanbeincreasedbyincreasingtheamountofwatertheinoculantsaremixedwith.Inpractice,acombinedfoodscrapandgardenwastecollectionisreasonablymoistandshouldonlyrequireasmallamountofadditionalwater.(Forexample,inGoulburnMulwareeCouncil,�000litresisusuallyaddedtoeach�00tonnebatchoffoodscrapsandgardenwaste,regardlessofseasonalvariation,InCondobolin,wheretheclimateisdryer,approximately�50-�00litresofwaterisappliedtoeach�0tonnebatchoffeedstock).
Oncethepilesarewetandinoculatedtheyarepiledintowindrowsandfullycoveredwithdurable,waterproofpolytarpsweigheddownwithtyresorotherheavyobjectsthatwillnotdamagethetarps.Toassistwithwaterreticulationthroughthepile,windrowsshouldhavean‘M’profileandsmallerpilesshouldhaveaflattopandasmalldiporhollowinthemiddle.Thisassistscondensationtodripbackintothepile.Highinternaltemperaturesdrivemoisturetotheoutsideofthepileandstepsshouldbetakentoensurecondensationontheinnersurfaceofthetarpdoesnotdripdownthesidesandoutofthepile.Goodcontactbetweenthetarpandthepilehelps.Morerecentlyon
largersiteswehavestartedusingtarpswithahemreinforcedwith��/�”waterpipeandeitherclampsorsandbagstokeepthetarpstightandtocounteractstrongwinds.
Broadlyspeakingtheinoculantcontainscombinationsofaerobicandanaerobicbacteria,specialfungiandyeasts.Thecompostingprocessismoreaccuratelydescribedasafermentativeprocess.Specificmicrobesareincludedthatactivelybreakdownfats,meatsandotherdifficultproductsthatmightchallengeaconventionalaerobiccompostingprocess.Withincertainlimits,thespecificbalanceofcarbontonitrogeninthefeedstockisnotvitaltothecompostingprocessbecausetheinoculantscontainbothcarbonfixingandnitrogenfixingbacteria.
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Odourproducedbysulphurreducingbacteriawhichpredominateinconventionalanaerobicprocessesisaddressedbytheinclusionofphotosyntheticbacteriaandpurplenon-sulphurbacteriaintheinoculantmix.Thesebacteriaconsumethesulphurreducingbacteriaandalsocompetefortheirfoodsource.Thepurplenon-sulphurbacteriarequireanaerobicconditionstoflourishandoutcompetethesulphurreducingbacteria.Unlikethesulphurreducingbacteria,thepurplenonsulphurbacteriaareinhibitedbysunlight.Coveringthepileshelpstocreatetheconditionsforthepurplenon-sulphurbacteriatoflourish.
Collectivelythesecompostingsolutionsprovidearangeofsignificantadvantages.
therequirementtoturnpilesisreducedasthemicrobialpopulationdoesnotrequireventilation.
carbonretentionisconsiderablyhigherthaninregularcomposting.
odourisgreatlyreducedandinmostinstanceseliminatedalltogether.Wehavefoundthatthereisnoissuewithodouratanystageofthecompostingprocess.
therequirementtocoverpileswithpolytarpssignificantlyincreasesthethermalandmoistureefficiencyofthepiles,reducingbothwaterrequirementsandrunoff.
AdditionalinformationonVRMcanbefoundat:www.vrm.com.au
Thecoveredpilesareleftforfourtosixweeks.Duringthefirstdayortwothetemperatureclimbstoaround65-70°Casaflushofaerobicactivitytakeplace.Bytheendofthefirstweekthetemperaturestabilisesataround50-55°C.Thisearlyaerobicflushofactivityprovidesthefirstoftwoopportunitiesforpasteurisation.Ifwellmanaged,thesetemperaturesareevenachievedontheoutsideofthepiles.AccordingtotheAS4454standards,compostmustreachandholdatemperatureof55°Cforthreedaystoachievepasteurisationrequirements.Iftheexpectedtemperaturesareachievedthroughoutthepile,theGroundswellcompostingprocessexceedsthepasteurisationrequirementsoutlinedinthestandard.
Inassociationwiththestabilisationoftemperaturearound55°C,thepHleveldropstoaround�.5-4.5asthefermentativebacteriacolonisethepiles.Thepilesshouldremainquitewet,andthecolourquickly
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changestoauniformblackcolour.Additionally,rayfungiandactinomycesquicklystarttoinfiltratethepilesandcanbeobservedasgreyfilamentsorpowderyflakes.Ifthesegreypowderyflakesandfilamentsarepredominating,itcanbeanindicationthatthepileistoodry,socheckmoisturelevelsandapplyde-chlorinatedornon-chlorinatedwaterasrequired.
Evidenceofsecondarycompostingprocessescanusuallybeobservedontheoutersurfaceofthepileswherethereismoreoxygenandthetemperatureiscoolerthroughthepresenceofslaters,nativecockroachesandotherlargersoilbiology.
Moisturelevelsduringthefermentationprocessshouldfallnolowerthan�0%withanoptimummoisturelevelof40%-60%butnohigherthan80%whereadequateleachatecontrolsareinplace.Ideally,thesurfaceofthepile(underthetarps)shouldremainmoist.
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stage 3: turning and respraying
After4-6weeks,thepilesareuncovered,spreadandre-examinedtoremoveanyphysicalcontaminationthatmighthavebeenmissedatthebeginningoftheprocess.BythisstagethepileshaveslumpedbyaboutathirdandtheBiobags,foodscrapsandsmalleritemshavedisappeared.Smallerpiecesofcontamination,aswellasthosethatmayhavebeenenclosedintheBiobagsbecomeeasiertoseeasthecomposthastakenonauniformtextureanddarkcolour.
Thecompostisthenmixed,re-wet,resprayedwiththeinoculants,re-piled,recoveredandleftforanother4to6weekperiod.Asimilarearlyspikeintemperature(around65-70°C)followedbyalongerperiodataround50-55°CandanassociatedpHlevelof�.5-4.5canbeexpectedduringthesecondfermentationstage.Thisprovidesthesecondopportunityforpasteurisationandensuresmaterialthatwaspreviouslyontheoutsideofthepilehasbeenre-incorporatedandprocessed.
stage 4: maturation & storage
After8-��weeks,dependingonprocesscontrolandparticlesizeoftheoriginalfeedstock,temperaturesshouldslowlycomedownandpHshouldreturntoneutral.Thecompostcanbelefttomature.Pilesshouldbekeptcoveredandnotallowedtodryout.Ideally,pilesshouldnotdropbelow40%moisture.
Theendproductispredominantly‘chocolatebrownie’innaturewithsomelonger,coarser,butsignificantlysoftenedparticulate.Itisusuallytoofineorsofttoputthroughashredderorgrinderbutissuitableforascreening(e.g.flipscreen)process.Arotatingdrumtrommelwitha�6mmmeshresultsinanexcellentfinishedproduct.Largerparticlesthatarescreenedfromthecompostcaneitherbereprocessedintothenextcompostbatchorstockpileduntilashredderorgrinderbecomesavailable.
Anylastremainingphysicalcontaminantsshouldberemovedpriortoscreeningorfinalprocessing.Tofacilitatestabilisation,pilescanbescreenedandlefttomature.
Undercorrectstorageconditions,thelongerthepilesarelefttomature,thebetterthecompostbecomes.WehaveobservedtheCationExchangeCapacityoffinishedcompostincreasefrommid�0sto7�afterstorageforseveralmonths.
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About the MaxAir IITM bins and BiobagsTM
TheGroundswellprojectutilisedtheMaxAirIIsystemwhichcombinesa6litreventedplasticbucketandrollsof�0litrecompostablebags.ThecombinedMaxAirbucketandbagsaredesignedtopreventodoursandputrificationoffoodwastebyretainingfoodscrapsinanaerobicstate.Thebreathabilityofthebagsandbucketpromotesventilationandevaporationofmoisture,resultinginaweightreductionofupto�5%infivedaysand40%insevendays.Initialtrials,researchandmarkettestingindicatehighlevelsofhouseholderacceptanceoftheproduct.TheMaxAirbinsandBioBagsarecurrentlyusedinover�00municipalitiesglobally.
TrialsundertakenbytheGroundswellProjectTeaminearly�008testedtheperformanceoftheMaxAirBinsandBiobagsinamonthlycollectionscenario.Inthistrial,compostablebagswerefilledwitharangeof‘highrisk’foodscrapsincludingfishcarcasses,meat,left-oversandrottenfruitandvegetables.Bagswerethenplacedinanumberof�40litreMGBswithvaryingamountsofgardenwaste.Binsweremonitoredovera4weekperiod.Atnostageduringthetrialwereoffensiveodoursdetectedinsideoremanatingfromthebins.Thecompostablebagsappeartoassistgreatlyinkeepingfoodscrapsaerobic.OdourswereconsiderablylessthanmightbeexpectedfromputrefyingfoodwasteenclosedinplasticbagsinresidualwasteMGBs.
TheBioBaghasaveryhighpenetrationbarrieragainstbacteria,viruses,sporesandmould.BioBagsalsoensuresaferandmorehygienicconditionsforwastecollectorsandcompostingfacilities.BioBagsarefullycompostableandcertifiedaccordingtotheEuropean
StandardEN��4��andtheUSstandardASTMD6400,whichiscompatiblewith
theAustralianStandardAS4454.
VRM Inoculants and Odour ManagementCompostingisgenerallyunderstoodaseitheranaerobicoranaerobicprocess.OneoftheremarkablecharacteristicsoftheVRMPhotonCompostinginoculantsusedintheGroundswellCompostingProcessisthelackofodourproducedeventhoughitisessentiallyatwophasestaticpilesystem.Inovertwoyearsofcontinuousprocessingofcombinedfoodscrapsandgardenwaste,thecompostingsitesatGoulburnandCondobolinhaveneverproducedanodourproblemoranynoticeableodour.Thissituationhasbeenreplicatedatmorethansevenothercouncilsiteswithevenmorehigh-riskmaterialsincludingbiosolidsandcommercialfoodwaste.TheGroundswellCompostingProcessrecruitsmicrobiologythatarebothaerobicoranaerobicorboth.
TheVRMInoculantsincludeEffectiveMicroorganisms(EM)whichareusedaroundtheworldtotreatsewerage,wastewater,foodwaste,municipalwaste,andimprovingorrehabilitatingagriculturalsoil.TogetherwitharangeofotherformulationsallculturedinAustralia,VRMInoculantsincludeseedpopulationsofpurplenonsulphurbacteriaandotherphotosyntheticorganisms.TheVRMinoculantsalsocontainfamiliesoffungi,(egactinomyces),yeasts,andotheraerobicandfermentingbacteria(e.g.lactobacillus,cyanobacterandrayfungi).ThekeyfamiliesofbacteriaresponsibleforthemanagementofodourintheGroundswellCompostingProcessarephotosyntheticbacteriaingeneralandpurplenonsulphurbacteriainparticular.
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thepile.Purple-non-sulphurbacteriadirectlycompetewithsulphurreducingbacteriaforsulphate,donotproducesulphidecompoundsandcanbeculturedinthecompostingpilewithoutdifficulty.
Theresultisacomplexinterdependencyofbiologicalfamilieswhicheachcreatetheconditionsforthe
othersandprotectagainstthedominantbiologicalprocessinthepilebecomingputrefactiveorodorous.Theprocessisperhapsmoreeasilyunderstoodasakintoasilageprocess.
TheGroundswellCompostingProcessisattractingsignificantinterestfromothercouncilsandprocessors.Tohelpbuildtheknowledgebaseaboutthisnewapproachtocomposting,theNSWDECCWhascontractedanodourstudytoascertainexactlywhatemissionscomeoffthepiles.Theresultfromthisstudywillbeavailableinearly�0��.
For updates and more information on the Groundswell project go to: www.groundswellproject.blogspot.com
Written by Simone Dilkara, 2010. Graphic design/illustration by Carolyn Brooks
This work is licensed under the Creative Commons Attribution 3.0 Unported License and can be reproduced providing the Groundswell project is acknowledged as the original source.
The Groundswell Project was assisted by the NSW Government through its Environmental Trust
Thephotosyntheticbacteria(whichperformphotosynthesisanaerobically)areintegraltotheGroundswellCompostingProcessbecausetheysupportprocesseswhichtransformputrefactivesubstancessuchahydrogensulphideintousefulorbenigncompoundssuchasoxygen,water,hydrogenperoxideorcarbondioxide.Intherightconditions,somephotosyntheticbacteriausetheheat(ratherthansunlight)generatedinthepileasenergyandhydrogenfromhydrogensulphide,methanegas,indol,skatole,methylmercaptansandotherorganicacidsandcompoundsproducedduringthedecompositionoforganicsubstances.Creatingtheconditionsforphotosyntheticbacteriatoflourishduringcompostingsimultaneouslybreaksdownodourproducingcompoundssuchashydrogensulphide,out-competessulphurreducingbacteriaandgeneratesoxygenwithin