2012ConstructedWetlandsWithFloating

Thisarticlewasdownloadedby:[T.R.Headley]On:18November2012,At:21:03Publisher:Taylor&FrancisInformaLtdRegisteredinEnglandandWalesRegisteredNumber:1072954Registeredoffice:MortimerHouse,37-41MortimerStreet,LondonW1T3JH,UKCriticalReviewsinEnvironmentalScienceandTechnologyPublicationdetails,includinginstructionsforauthorsandsubscriptioninformation::AnInnovativeStormwaterTreatmentTechnologyT.R.Headleyab&C.C.TannercaHelmholtzCentreforEnvironmentalResearch,Leipzig,GermanybWetlandsCompetenceCenter,BAUEREnvironment,Muscat,SultanateofOmancNationalInstituteofWaterandAtmosphericResearch(NIWA),Hamilton,NewZealandAcceptedauthorversionpostedonline:17Nov2011.Versionofrecordfirstpublished:15Oct2012.Tocitethisarticle:T.R.Headley&C.C.Tanner(2012):ConstructedWetlandsWithFloatingEmergentMacrophytes:AnInnovativeStormwaterTreatmentTechnology,CriticalReviewsinEnvironmentalScienceandTechnology,42:21,2261-2310Tolinktothisarticle:::2261–2310,2012Copyright©Taylor&FrancisGroup,LLCISSN:1064-3389print/1547-6537onlineDOI:10.1080/10643389.2011.574108ConstructedWetlandsWithFloatingEmergentMacrophytes:AnInnovativeStormwaterTreatmentTechnologyT.R.HEADLEY1,2andC.C.TANNER31HelmholtzCentreforEnvironmentalResearch,Leipzig,Germany2WetlandsCompetenceCenter,BAUEREnvironment,Muscat,SultanateofOman(Currentaddress)3NationalInstituteofWaterandAtmosphericResearch(NIWA),Hamilton,NewZealandThetreatmentofurbanstormwaterposesnumeroustechnicalandoperationalchallenges,particularlyduetotheintermittentandhighlyvariablenatureofhydrologicandpollutantinputs.Floatingemergentmacrophytetreatmentwetlands(FTWs)areahybridiza-tionofpondsandwetlandsthatofferpotentialadvantagesfortreat-mentofthesehighlyvariableflows.FTWsutilizerooted,emergentmacrophytesgrowingonamatorraftfloatingonthesurfaceofthewaterratherthanrootedinthesediments.Thus,theycantoleratethewidelyfluctuatingwaterdepthstypicalofstormwatersystems,withouttheriskoftheplantsdrowning.Therootshangbeneaththefloatingmatandprovidealargesurfaceareaforbiofilmattach-ment.TheauthorsprovideareviewoftheFTWconcept,structure,function,andtreatmentefficiencyreportedtodateanddiscussthepotentialadvantagesofthisemergingtechnologyforstormwaterapplications.Althoughstilllimited,theavailabledatafrommeso-cosmandpilotstudiesonremovalofkeypollutantssuchasor-ganicmatter,suspendedsolids,nutrients,andmetalsshowsthattheycansignificantlyenhanceperformanceofpondsystems,andprovidesimilarorbetterperformancethansurfaceflowwetlandsforarangeofpollutedwaters.FurtherstudiesareneededtoverifytheapparentpotentialofFTWstreatingstormwateratfullscale.AddresscorrespondencetoC.C.Tanner,NationalInstituteofWaterandAtmo-sphericResearch(NIWA),P.O.Box11-115,Hamilton3251,NewZealand.E-mail:[e-mail]2261Downloadedby[T.R.Headley]at21:0318November20122262T.R.HeadleyandC.C.TannerKEYWORDS:constructedwetland,emergentmacrophyte,float-ing,hydroperiod,performance,pond,treatment,urbandrainageINTRODUCTIONArtificiallyconstructedpondsandwetlandshavebecomewidelyacceptedasurbanstormwatertreatmentdevicesoverthepasttwodecadesandareincreasinglybeingintegratedintowatersensitiveurbandesignpractices(Carletonetal.,2001;Croweetal.,2007;KadlecandWallace,2009;Mel-bourneWater,2002;Weissetal.,2007).Thisgrowingpopularityhasbeenlargelyduetothefactthatpondandwetlandbasedsystemsoffertheadvantagesofprovidingarelativelypassive,low-maintenanceandopera-tionallysimpletreatmentsolutionwhilepotentiallyenhancinghabitat,recre-ational,andaestheticvalueswithintheurbanlandscape(Knightetal.,2001;LeeandLi,2009;Rousseauetal.,2008).However,anumberoflimitationshaveemergedwiththeapplicationofwetlandandpondsys-temsforstormwatertreatment.Forexample,althoughpondsaregener-allyeffectiveatattenuatinghydraulicsandremovingcoarsesuspendedsediments,theyarelesseffectiveatremovingfinerparticulatesanddis-solvedcontaminants(AucklandRegionalCouncil,2004;Revittetal.,2008;Scholesetal.,2008;U.S.EnvironmentalProtectionAgency,2008).Toen-hancetreatmentcapabilities,wetlandsareoftenusedincombinationwithponds.Wetlandsystemswithhorizontalsubsurfaceflowgenerallyhavelim-itedapplicationforstormwatertreatmentduetothehydrauliclimitationsoft