� 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.

� ProcessingCitytoSoilcollectionswiththeGroundswellCompostingProcess

stage 1: picking

Feedstockisdelivereddirectlyontothecompostingsite/hardstandarea.Wherepossiblethetruckshouldspreadthematerialoutoverawideareatofacilitatepickingandspraying.Thematerialarrivespre-mixedwithfoodscrapsneatlycontainedinBiobagswhicharestillintactbutvisiblydehydrated.Thereisusuallynoodouratpointofdelivery.Occasionallyandseasonally,theremaybesometemporaryodoursduetolawnclippingswhichmayhaveslumpedinthebaseofMGBsandturnedanaerobic.Thisseemstochangequitequicklyonceonsite.Ifodourisnoticeableorunacceptableatthisearlystage,thematerialcanbesprayedwithdilutedinoculantspriortopicking.

Thefirsttaskinthecompostingprocessistopickthroughthefeedstockbyhandtoremoveanyphysicalcontamination.Anicefeatureofthebiobagsisthattheyensurethefoodscrapsarriveattheprocessingsitesomewhatdehydrated,neatlycontainedandinanaerobicstatewithnoodour.Evenwithamonthlycollectionthebagsarerobustenoughtoremainintactduringthecollectionandcompactionprocess.

Typicalcontaminationremovedatthisstageincludesthebottles,cansorplasticbags.Thebiobagsoffoodscrapsgointothecompostingprocessintact.

Onceanyphysicalcontaminationisremoved,thefeedstockissprayedwiththeVRMPhotonCompostingsolutionsandanappropriateamountofnonorde-chlorinatedwater.

4 ProcessingCitytoSoilcollectionswiththeGroundswellCompostingProcess

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.

5 ProcessingCitytoSoilcollectionswiththeGroundswellCompostingProcess

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.

6 ProcessingCitytoSoilcollectionswiththeGroundswellCompostingProcess

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.

7 ProcessingCitytoSoilcollectionswiththeGroundswellCompostingProcess

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.

8 ProcessingCitytoSoilcollectionswiththeGroundswellCompostingProcess

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