Coagulant with UV-AOPs

15 Pages·2017·1.97 MB·English

applied
sciences
Article
Removal of Algae, and Taste and Odor Compounds
by a Combination of Plant-Mineral Composite
(PMC) Coagulant with UV-AOPs: Laboratory
and Pilot Scale Studies
YirgaWelduAbrha1,2,HominKye1,MinhwanKwon1,DooraeLee1,KihoKim1,YoumiJung1,
YongtaeAhn1andJoon-WunKang1,*
1 DepartmentofEnvironmentalEngineering(YIEST),YonseiUniversity,1Yonseidae-gil,
Wonju,Gangwon-do26493,Korea;[email protected](Y.W.A.);[email protected](H.K.);
[email protected](M.K.);[email protected](D.L.);[email protected](K.K.);
[email protected](Y.J.);[email protected](Y.A.)
2 DepartmentofLandResourceManagementandEnvironmentalProtection,MekelleUniversity,
P.O.Box231,Mekelle,Ethiopia
* Correspondence:[email protected];Tel.:[phone];Fax:[phone]
(cid:1)(cid:2)(cid:3)(cid:1)(cid:4)(cid:5)(cid:6)(cid:7)(cid:8)(cid:1)
(cid:1)(cid:2)(cid:3)(cid:4)(cid:5)(cid:6)(cid:7)
Received:3August2018;Accepted:27August2018;Published:1September2018
FeaturedApplication:Theproposedcombinedplant-mineralcompositecoagulantwithUV-AOPs
can be applied to remove taste and odor compounds and its precursor (algae) in the drinking
watersystem.
Abstract: Theseasonaloccurrenceofalgaebloomsinsurfacewatersremainsacommonproblem,
suchastasteandodor(T&Os),theriskofdisinfectionby-products(DBPs),anddisturbancetowater
treatmentsystems. Thecoagulationefficiencyofplant-mineralcomposite(PMC)coagulantfollowed
byUV-basedadvancedoxidationprocesses(UV-AOPs;UV/H O andUV/Cl )wasevaluatedfor
2 2 2
removalofalgae,turbidity,dissolvedorganicmatters,andtasteandodorcompoundsinlab-scale
andpilot-scaletests. Inthelab-scaletest, coagulationprocesswith20mg/LofPMCshowshigh
removal efficiency of turbidity (94%) and algae (99%) and moderate removal efficiency of UV
254
(51%)andgeosmin(46%). Thepilottestresultsalsoshowgoodremovalefficiencyofturbidity(64%),
chlorophyll-a(96%). AfterPMCcoagulationprocess, themajorwaterfactors, whichaffectedthe
performanceofUV-AOPs(i.e.,UVtransmittance(85–94%),andscavengingfactor(64,998–28,516s−1)),
were notably improved, and further degradation of geosmin and 2-methylisoborneol (2-MIB)
was achieved in both lab-and pilot-scale tests of the UV-AOPs. The UV/H O process shows
2 2
higherremovalefficiencyofgeosminand2-MIBthantheUV/Cl processbecauseofthepHeffect.
2
TheresultsconfirmedthatthePMC-basedcoagulationfollowedbyUV/H O processcouldbean
2 2
effectiveprocessfortheremovalofalgae,geosmin,and2-MIB.
Keywords: advanced oxidation process; algae; coagulation; geosmin; 2-MIB; plant-mineral
compositecoagulant
1. Introduction
Harmful algae bloom problems are becoming more serious with increasing frequency and
quantityintheaquaticenvironment[1]. EspeciallyindrinkingwatersourcesinKorea,theproblemis
significantbecauseoftheimpactoftheharmfulalgalonthewatertreatmentperformance[2]. Analgal
bloomeventresultsinthereleaseofgeosmin,2-methylisoborneol(2-MIB)andtasteandodor(T&O)
Appl.Sci.2018,8,1502;doi:10.3390/app8091502 www.mdpi.com/journal/applsci
Appl.Sci.2018,8,1502 2of15
compoundsfromthealgalcellsduringandafterbloomevents. Thetoxicand/orodorousmetabolites
producedbythesebloomsimpactthedrinkingwaterquality. Odorsoforganiccompoundsproduced
byalgaearecharacterizedasearthyandmusty/camphorous. Odorsofsuchcompoundscanbeeasily
sensedbythehumannoseevenatextremelylowconcentrations,e.g.,concentrationsaslowas4.0and
8.5ng/Lforgeosminand2-MIB,respectively[3].
Various mitigation methods for algae and T&O problems have been examined, including
coagulation,filtration,potassiumpermanganate,chlorineandozonetreatments[4–6]. Amongthose
processes,thecoagulationstageisrecommendedforremovalofalgaetoensureminimalimpacton
subsequentprocessesandpreventthereleaseofthetoxicorT&Ocompoundsfromcelldestruction[7].
However,someofthemostcommonlyusedcoagulants(e.g.,aluminumsalts)havedisadvantages,
suchasproductionofharmfulsludgeandresidualsinthetreatedwater, whichcanbeharmfulto
humanhealth[8,9].
Inpractice,owingtothevariabilityinwaterqualityandlowdegradabilityofcertaincompounds,
achieving the desired water quality by using a single conventional method for removal of algae,
geosmin,and2-MIBisdifficult. Implementationofnontoxicandeasy-to-usetreatmentmethodsto
protectdrinkingwaterfromalgal-bloom-relatedproblemsisneeded. Therefore,thewaterindustryis
exploringalternativestoreplaceAl-basedcoagulantsandwaystostrengthenmethodsthatcombine
coagulationandadvancedoxidationprocesses(AOPs). Oneeffortthathasbeenmadeinthiscontext
istheinvestigationoftheuseofanewcoagulantthatisbasedonaplant–mineralcomposite(PMC)
for water treatment [10], which was selected to reduce the aluminum sludge and residuals and
evaluatedfortreatmentofalgaeanddissolvedorganicmatters(DOMs)inalab-scalebatchsystem
andapilot-scaleflowingsystem(109m3/h). Thepilotfacilitywasinstalledatawaterintakestation
fromHan-riverinKorea. ThePMC-basedcoagulantconsistsofmixturesofindigenousplantextracts
(e.g., Camellia sinensis, Quercus acutissima, and Castanea crenata) and minerals (e.g., loess, quartz
porphyry, and natural zeolite) [10]. In reservoir water treatment, PMC performance was found
tobeeffectiveinremovingchlorophyll-a(88–98%),phytoplankton(84–92%)andzooplankton[11].
Moreover,about70%removalefficiencyofturbidityandsuspendedsolidswasalsoreportedinthe
reservoir water [11]. In the present study, the algae and its metabolite removal efficiencies in the
drinkingwatersystemofPMCbasedcoagulationprocesswereevaluated. Forthecasethatrequired
higherremovalefficiencyofT&Ocompounds,UVbasedAOPs,i.e.,UV/H O andUV/Cl processes,
2 2 2
were also evaluated as a following processes of the PMC coagulation process. The geosmin and
2-MIBremovalefficienciescouldbeenhancedthroughseveraloptionslikesimultaneousapplication
ofvariousAOPs,achievingsafetyandsubsequentsuitabilityofthedrinkingwater[12,13]. UV-based
AOPs are well-established processes which have been implemented worldwide and have distinct
benefitsforsimpleinstallationandsmallfootprint.
Theaimofthisstudywas(1)toevaluatethePMCforremovalofalgae,turbidity,dissolvedorganic
matterandmechanismofcoagulation;(2)toevaluatethecombinationprocessofPMCcoagulation
withUV-basedAOPstoremoveT&Ocompounds.
2. MaterialsandMethods
2.1. ReagentsandMaterials
All reagents used were of analytical grade, unless mentioned otherwise. Geosmin (>97%)
and 2-MIB (>98%) dissolved in methanol were purchased from Dalton Pharma Services (Toronto,
ON,Canada)anddilutedindeionizedwaterforfurtheruse. Sulfuricacid(98.08%)andhydrogen
peroxide (H O ; 30 wt % solution) were purchased from Kanto Chemical Co., Inc. (Tokyo, Japan)
2 2
andSigma-AldrichKorea(Seoul,Korea),respectively. HCl(30%)andsodiumchloride(>99%)were
purchasedfromDuksanChemicalCo.,Ltd. (Ansan,Korea). ThePMC-basedcoagulantthatconsisted
ofsilicate(20%),barleystone(20%),loess(10%),kaolin(3%),sericite(3%),andzeolite(4%)andextracts
Appl.Sci.2018,8,1502 3of15
fromchestnut(6.5%),sawtoothoak(6.5%),greenteaplant(6.5%),persimmon(6.5%),ashtree(6.5%),
andpine(6.5%)volume%wasfromMCEKoreaandK-water(Hongseong-gun,Korea).
2.2. ExperimentalProcedure
2.2.1. Lab-ScaleExperiment
Rawwaterwascollectedatthepilotplantsite(HanRiver, SouthKorea). Therawwaterwas
storedat4◦Cimmediatelyaftercollection. Thejartestexperimentwasconductedat22to25◦C.
Anabaena sp. (AG10279) was obtained from the Korean Type Culture Collection (KTCC).
Anabaena sp. was cultured in a 250 mL Erlenmeyer flask with a BG-11 media and under culture
conditionsofaconstanttemperatureof25◦C,lightexposurefor12h(150µmol·m−2·s−1)anddark
intervalsfor12hwithashakingspeedof150rpm. Toexaminethealgaeremovalefficiencyofthe
PMC-basedcoagulant,aknownamountofAnabaenasp. culturewasmixedwithrawwatercollected
from the Han River. A water sample for lab-scale tests was prepared by injecting Anabaena sp.,
intotherawwatercollectedfromtheinfluentofthepilotsystem. Toensurestablealgaeconcentration,
wemonitoredtheopticaldensityat680nm(OD )ofthetestwaterusingaspectrophotometer[14].
680
TheOD ofthesamplesolutionwasstableafter6h,andtheinitialconcentrationofchlorophyll-a
680
wasmeasuredas97.1mg/m3. OtherparametersofthetestedwaterarelistedinTable1.
Table1.Waterqualityparametersofrawwaterusedinthelab-scaleandpilot-scaletests.
Parameters Lab-ScaleTest FirstPilot-ScaleTest SecondPilot-ScaleTest
Turbidity(NTU) 4.6 1.1 15.6
DOC(mg/L) 3.4 0.9 0.8
UV254(cm−1) 0.034 0.015 0.027
pH 7.8 6.9 6.7
chlorophyll-a(mg/m3) 97.1 0.5 0.7
134.6ng/Lgeosmin 100.0ng/Lgeosmin 100.0ng/Lgeosmin
Targetchemicals
159.0ng/L2-methylisoborneol(2-MIB) 80.0ng/L2-MIB 80.0ng/L2-MIB
Thecoagulationprocesswasconductedusingaprogrammablejartestertodeterminetheoptimum
doseofPMCfortheremovalofalgae,turbidity,andorganicmattersfromtheincidentwaterofthepilot
system. ThePMCwasaddedto1Lofrawwaterina1Lbeaker. TheadditionofPMCwasfollowed
byrapidmixingat140rpmfor1min,thenslowmixingat40rpmfor59min. Theseconditionswere
determinedtosimulatethepilot-system. Afterallowingthecontentsinthebeakertosettlefor30min,
samplesforwaterqualitymeasurementswerecollectedfromapproximately3cmbelowthewater
surface. Varying PMC-based coagulant dose, with five levels (0, 5, 10, 20, 40, and 70 mg/L) were
evaluatedforalgalcells, turbidity, dissolvedorganiccarbon(DOC),andUV removal. Thezeta
254
potentialsofthecoagulatedsampleswithvaryingdosesofcoagulantwerealsomeasured.
Thephotodegradationexperimentswerecarriedoutusingabench-scalequasi-collimatedbeam
apparatus[15]equippedwithtwo11-Wlow-pressurelamps(Philips,Amsterdam,TheNetherland),
whichprimarilyemitlightat253.7nm. A50mLgeosminand2-MIBaliquotwasplacedinaPetridish
atadepthofabout0.786cm[15–17]. Thesolutionwasstirredusingacross-shapedstirringbarwitha
diameterof1cmtoensurethatitwashomogenouslyexposedtoUVlight,andthesolutioniswell
mixedinthesystem. TheUVirradiance(mW/cm2)wasdeterminedusingtheperoxideactinometry
methodwithacalibratedradiometerequippedwithaUV254detector(UVXRadiometer;UVP,Upland,
CA,USA)attheheightofthesurfaceofthePetridish[15,17]. Theaverageincidentirradianceacross
thesurfaceofthesolutionwasdeterminedusingaPetrifactorandareflectionfactor[15].
2.2.2. Pilot-ScaleExperiment
Pilot-scaleexperimentswereconductedinawatertreatmentplant(WTP)intakestationduring
late spring (April and May) and summer (July), which takes raw water from Han-river in Korea.
Appl. Sci. 2018, 8, x FOR PEER REVIEW 4 of 15
2.2.2. Pilot-Scale Experiment
Appl.Sci.2018,8,1502 4of15
Pilot-scale experiments were conducted in a water treatment plant (WTP) intake station during
late spring (April and May) and summer (July), which takes raw water from Han-river in Korea. To
eTxoamexianme itnheet choeacgoualgautiloanti oenffeicffiiecniecnyc oyf oPfMPMC-Cb-absaesde dcocaogaugulalnant taat tppiliolot-ts-sccaalele ((110099 mm33//hh),) ,vvaaryryiningg ddoosseess
ooff tthhee PPMMCC--bbaasseedd ccooaagguullaanntt ((00, ,1100, ,2200, ,3300,, aanndd 4400 mmgg//LL) )wwereer eeevvaaluluaatetded fofor rchchlolororopphhyylll-la-a, ,tuturbrbididitiyty, ,
aanndd UUVV22554 4rermemovoavla. lO. Onlninlien echchlolroorpophhylyl-lla- acoconncecnentrtartaitoino nmmeaesausurermemenetn twwasa scacarrrireided oouut tuussiningg aa PPLLCC
aauuttoommaattiicc ccoonnttrrooll ssyysstteemm ((NNaammyyaannggjuju, ,KKoorreeaa)).. TThhee ccoonncceennttrraattioionnss ooff cchhlolorroopphhyyllll--aa iinn tthhee rraaww wwaatteerr
rraannggeedd ffrroomm 22..33 ttoo 115566 mmgg//mm3.3 .
AAfftteerr tthhee PPMMCC--bbaasseedd ccooaagguulalatitoionn pprroocceessss, ,ththee ttrreeaatteedd wwaatteerr wwaass bbrraanncchheedd ttoo ccoonndduucct ttthhee UUVV
AAOOPPss eexxppeerriimmeennttss. .TThhee ffllooww rraattee iinn UUVV ssyysstteemm wwaass aarroouunndd 11..88 mm33//hhr,r ,aanndd ggeeoossmminin, ,22--MMIIBB wweerree
ssppiikkeedd iinnttoo tthhee ininfflluueenntt ooff ththee UUVV rreeaacctotorr.. TThhee UUVV rreeaacctotorr wwaass aa LLPPAA1155 ssyysstteemm wwitihth oonnee loloww-p-prreessssuurree
aammaalglgaamm llaammpp rraatteedd aatt 887711..88 mmJJ//ccmm2.2 .TThhe ecoconntatammininanant taanndd ooxxididaannt t(i(.ie.e.,. ,hhyyddrrooggeenn ppeerrooxxididee aanndd
cchhlloorrininee)) stsotockck sosloultuiotinosn ws wereer ienjiencjetecdte idntion tthoet hUeVU inVfliuneflnut epniptep tihpreotuhgrho usegphasreaptea irnajteectiinojnec ptioorntsp. Tohrtes .
eTffhlueeenfflt usaemntpslainmgp plionrgt pwoarst swuaffsicsiuefnfitlcyie fnatrl ydfoawrndsotwrenamstr efraommf rthome inthjeectiniojenc tpioorntsp toor tesntsouerne stuhraet tthhaet
stthreeasmtr ewamas wwaesllw melilxmedix bedefobreefo rreearcehaicnhgi ntghet hseamsapmlipnlgin pgoprot ratnadn dthtahta trereppreresesenntatatitvive essaammppleless wweerree
ccoolllleecctteedd. .TThhee sscchheemmaattiicc ddeessiiggnn ooff tthhee ccoommbbiinneedd ttrreeaattmmeenntt iiss sshhoowwnn iinn FFiigguurree 11..

FFiigguurree 11.. SScchheemmaattiicc ddeessiiggnn ooff tthhee ccoommbbiinneedd ttrreeaattmmeenntt,, ppllaanntt--mmiinneerraall ccoommppoossiittee ((PPMMCC)) ccooaagguullaattiioonn
ttrreeaattmmeenntt ffoolllloowweedd bbyy UUVV--bbaasseedd aaddvvaanncceedd ooxxiiddaattiioonn pprroocceesssseess ((UUVV--AAOOPP)) ttrreeaattmmeenntt..
22.3.3. .AAnnaalylyssisis
TTuurrbbiiddiittyy wwaass mmeeaassuurreedd uussiinngg aa HHaacchh 22110000 NN TTuurrbbiiddiimmeetteerr ((HHaacchh CCoommppaannyy, ,LLoovveelalanndd, ,CCOO, ,
UUSSAA)). .AA ttoottaall oorrggaanniicc ccaarrbboonn ((TTOOCC)) aannaallyyzzeerr ((DDoonngg--iill SSHHIIMMAADDZZUU CCoorrpp.,. ,SSeeoouull, ,KKoorreeaa)) wwaass uusseedd ttoo
mmeeaassuurree tthhee DDOOCC ooff ssaammpplelessa aftfetrerfi fltirltartaiotinonth trhoruoguhgah cae lcluelllousleoasec eatacetetamtee mmbermanbera(npeo r(eposirzee :si0z.4e5: 0µ.4m5) .
µAms)p. eAct rsoppehctortoopmhoetteorm(eCtaerry (C50arPyr o5b0e P,Vroabriea, nVAaruiastnr aAliuasPtrtay,liLat dP.t,yM, Letldbo., uMrneelb,Aouursntera, lAiau)swtraasliua)s ewdatso
umseeda stuor metehaesuUrVe 2th54e oUfVsa25m4 opfl essamafptelresfi altfrtaetri ofinltrtahtriooung thhraomugehm ab mraenmeb(praonree s(ipzoer:e0 s.4iz5eµ: m0.4).5 AµmpH). Am petHer
m(Tehteerr m(TohFeisrhmeor SFciieshnetirfi cSIcniecn.,tSifiincg aInpco.r,e ,SSininggaappoorree, ),Swinhgicahpowraes), cawlihbircahte dwdaas ilcyaulisbirnagtesdta nddaailryd suosfipngH
s4ta.0n,d7a.0r,dasn odf 1p0H.0 ,4w.0a, s7.u0s, eadndto 1m0.e0a, swuares tuhseedp Htoo mftehaesuwrae ttehres apmHp olef st.hAe wmaicteror sscaomppelwesa. sAu smedicrtoosccooupnet
wthaes aulsgeadl cteol lcso.uAntz ethtae- paolgtaeln tcieallls&. Ap azretitcal-epositzeentainala l&y zpearr(tOictlseu skizaeE alencatlryozneirc s(OCtos.u,kLat dE.,leOctsraoknai,cJsa Cpaon., )
Lwtda.s, uOsseadkato Jadpeatenr)m winaes uthseedz ettoa dpeotteernmtiianleo tfhteh zeectoaa pgoutleanntti.al of the coagulant.
TThhee ccoonncceennttrraattiioonnsso fogf egoesomsimniann dan2-dM 2IB-MwIeBr ewdeerteer mdeinteerdmuisniendg augsiansgc har ogmaast ocghrraopmhaetqougirpappehd
ewqiuthipapePdo lawriisthQ ai oPno-tlraarpis mQa sisosnp-tercatpro mmeatsesr s(TphecetrrmomoFeitsehr e(rTShceiernmtiofi cF,iWshaelrt hSacmie,nMtifAic,,U WSAal)t.hSaempa, rMatiAon,
UoSfAdi)f. fSeerepnatractoiomnp oofu dnidffserwenats caocmhipeovuendduss winags aacJh&iWeveCdP u-Ssiinlg5 aC JB&MWS CcPo-lSuiml 5n C(Ble nMgSt hc:ol3u0mmn; (ilnetnegrtnha:l
3d0i amm; eitnetre:rn0.a2l5 dmiamm;efitelrm: 0t.h2i5c kmnmes;s :fi0lm.2 5thµimck;nAesgsi:l e0n.2t5T eµcmhn; oAloggilieenst, STaenchtanoClloagraie,sC, ASa,nUtaS AC)l.arTah, eCGAC,
UoSvAen).t Temhep GerCa touvreenw taesmhpeeldraatutr4e0 w◦Casf ohrel2dm ati n4,0i n°Ccr feoars e2d mbiyn,7 in◦cCremasine−d1 btyo 72 °0C0 ◦mCi,nw−1 htoic 2h0w0 a°Cs,h welhdicfohr
w2ams ihne.lHd efoliru 2m maitna. cHoenlsiutamn taflt oa wcornastteanotf f1lomwL ramtei no−f 11 mwLas muisne−d1 waasst huesecda rarsie trhgea csa.rTriheer sgpalsi.t Tvheen tswplaits
voepnetn wedasf oorp3enmeidn faofrt e3r mthien ianfjteecrt itohne. iTnhjeecteiloenct. rTohnei melpecatcrtoino nimizpataicotn iomnoizdaetsiowne mreoadsefso wlloewres :aiso fnolsloouwrsc:e
itoenm spoeurracteu treemopfe2r3a0tu◦rCe; othf 2e3t0ra °nCs;f tehrel itnreantesfmerp leinraet utermeopfer2a8t0ur◦eC o;fs o2l8v0e °nCt;d seollavyentitm deeloafy5 timmien o;ef l5e cmtrionn;
eelencetrrgoyn oenfe7r0geyV o.fT 7h0e eVfu.l Tlshcea fnumll sacsasns pmeacstrsa swpeecrterao bwtaerinee odbtaatianemda asts a-t om-achssa-rtog-echraatrigoes rcaatnior sacnagni rnagngfrionmg
f5ro0mto 5305 t0oa 3m50u atmodue ttoe rdmetienremaipnep raoppprrioapterimatea smseasssfeosr fsoerl eseclteecdteido niomn omnoitnoitroinrigng[1 [81]8.].
AcolorimetricmethodforthedeterminationofperoxidasewithN,N-diethyl-p-phenylenediamine
(DPD)wasusedtodeterminetheconcentrationsofH O andchlorineusingaDR/2500spectrophotometer
2 2
Appl. Sci. 2018, 8, x FOR PEER REVIEW 5 of 15
A colorimetric method for the determination of peroxidase with N,N-diethyl-p-
Apphpel.nSycli.e2n0e18d,i8a,m15i0n2e (DPD) was used to determine the concentrations of H2O2 and chlorine usi5nogf 1a5
DR/2500 spectrophotometer (Hach, Loveland, CO, USA) at 530 nm. The spectrophotometer was
calibrated using 10 mL of water sample as a blank. A 10 mL water sample pipetted into a sample cell.
(THhaecnh, ,oLnoev eDlaPnDd ,fCreOe, cUhSlAor)inate5 P30ownmde.rT hPeillsopwec twroapsh aodtodmedet earnwd amscixaelidbr wateedll.u Asifntger1 0admdLinogf w25a tµerLs (a1m gp/lLe
paseraobxliadnaks.eA st1o0ckm sLowluattieorns)a omf ppleerpoixpiedtatesde irnetaogaensat,m thpele cchellol.rTinhee nc,oonnceenDtPraDtiofrne emchealosruinreedP oinw mdegr/LPi.l lFoowr
wthaes Had2Ode2,d thaned chmloixreindew reelsl.uAlt fwterasa dddivinidge2d5 bµyL t(w1go/ [L19p–e2r1o]x.i dasestocksolution)ofperoxidasereagent,the
chlorineconcentrationmeasuredinmg/L.FortheH O ,thechlorineresultwasdividedbytwo[19–21].
2 2
3. Results and Discussion
3. ResultsandDiscussion
3.1. PMC for Algae and Organic Matters Removal, Lab-Scale
3.1. PMCforAlgaeandOrganicMattersRemoval,Lab-Scale
Figure 2 shows the removal efficiency of algae and turbidity as a function of varied PMC-based
Figure2showstheremovalefficiencyofalgaeandturbidityasafunctionofvariedPMC-based
coagulant dose from 0 to 70 mg/L at 22 to 25 °C. Overall, the degradation tendencies of algae and
coagulantdosefrom0to70mg/Lat22to25◦C.Overall,thedegradationtendenciesofalgaeand
turbidity were similar. The removal efficiencies of both algae and turbidity tended to increase with
turbidityweresimilar. Theremovalefficienciesofbothalgaeandturbiditytendedtoincreasewith
increasing PMC dose up to 20 mg/L, with further increase in the PMC dose decreasing the algae and
increasing PMC dose up to 20 mg/L, with further increase in the PMC dose decreasing the algae
turbidity removal efficiency. The highest removal of algae was found to be 98% at 20 mg/L PMC. For
and turbidity removal efficiency. The highest removal of algae was found to be 98% at 20 mg/L
the case of turbidity, the removal efficiency was around 94% at 20 mg/L PMC, but it was decreased
PMC.Forthecaseofturbidity,theremovalefficiencywasaround94%at20mg/LPMC,butitwas
to 83.4% at 70 mg/L PMC. It was implied that particles repelled each other due to the strong
decreasedto83.4%at70mg/LPMC.Itwasimpliedthatparticlesrepelledeachotherduetothestrong
electrostatic repulsion forces caused by adsorbed polycations, as reported earlier in [22]. The algae
electrostaticrepulsionforcescausedbyadsorbedpolycations,asreportedearlierin[22]. Thealgae
removal efficiencies achieved with the PMC were approximately 10 to 19% higher than those
removalefficienciesachievedwiththePMCwereapproximately10to19%higherthanthosereported
reported in previous work using Al-based [2].
inpreviousworkusingAl-based[2].
Residual chlorophyll-a
Residual turbidity
100 5
)
3
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)
g/ U
m 80 4 T
N
a ( y (
yll- 60 3 dit
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chl 40 2 al t
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si R
e
R 0 0
0 20 40 60 80
PMC dose (mg/L)

Figure2.Concentrationofchlorophyll-aandresidualturbidityafterremovalwithvaryingdosesof
Figure 2. Concentration of chlorophyll-a and residual turbidity after removal with varying doses of
thePMC-basedcoagulant(0,5,10,20,40,and70mg/L).
the PMC-based coagulant (0, 5, 10, 20, 40, and 70 mg/L).
FFiigguurree 33 sshhoowwss tthhee rreemmoovvaall eefffificciieennccyy ooff UUVV225544 aanndd DDOOCC aass aa ffuunnccttiioonn ooff iinniittiiaall ddoossee ooff tthhee PPMMCC..
UUVV225544 aanndd DDOOCC aarree ppaarraammeetteerrss ffoorr mmoonniittoorriinngg tthhee ddiissssoollvveedd oorrggaanniicc mmaatttteerr ((DDOOMM)) rreemmoovvaall aanndd
ccoonnttrroolllliinngg ccooaagguullaanntt ddoosseess iinn wwaatteerr ssuuppppllyy ssyysstteemmss ffoorr tthhee rreemmoovvaall ooff TTOOCC [[2233]].. TThhee iinniittiiaall UUVV225544
aanndd iinniittiiaall ccoonncceennttrraattiioonn ooff DDOOCC wweerree 00..003344 ccmm−−11 aanndd 33.4.4 mmgg/L/,L r,ersepsepcetcivtievleyl.y .
IInn tthhee ccooaagguullaattiioonn pprroocceessss,, tthhee rreemmoovvaall eefffificciieennccyy ooff bbootthh ppaarraammeetteerrss,, ii..ee..,, UUVV225544 aanndd DDOOCC,,
iinnccrreeaasseedd wwiitthh iinnccrreeaassiningg PPMMCC ddooses e(F(iFgiugruer e3)3. )A.tA 2t0 2m0gm/Lg P/MLCPM, thCe, UthVe25U4 Van25d4 DaOndC DreOmCovreamls owvearles
wfoeurnedf otou nbde 5t1o%b ean5d1% 14a%n,d re1s4p%e,ctrievseplyec. tTivheel hy.igThheer UhiVgh25e4 rreUmVo2v5a4lr eefmficoiveanlcieefsfi cthieannc tihese tDhOanCt rheemDoOvaCl
irnedmiocavtaelsi nthdaict ahteysdtrhoapthhoybdicro apnhdo bliacragne dalraormgeatairco mcoamtipcocuonmdpso wunedres wpreerfeeprerneftiearlelny tiraelmlyorveemdo vveiad tvhiae
cthoeagcuoalagtuiolant ipornopcerossc e[s2s4[]2. 4G].hGerhnearonuato uett aetl. a[l2.5[2] 5a]lsaols roerpeoprotertde dthtahta stmsmalall laalilpiphhaatitcic ccoommppoouunnddss ddoo nnoott
absorbUVlightbecausetheylackconjugateddoublebonds,andthereforearenotdetectedthrough
UV measurements. Thisfindingisinagreementwiththoseofpreviousstudies[25–27].
254
Appl. Sci. 2018, 8, x FOR PEER REVIEW 6 of 15
Appl. Sci. 2018, 8, x FOR PEER REVIEW 6 of 15
absorb UV light because they lack conjugated double bonds, and therefore are not detected through
abUsoVrb25 4U mVe alisguhrte bmeecnautss. eT thhiesy f ilnadckin cgo insj uing aatgerde edmoeunbtl ew biothn dthso, saen dof t phreervefioorues asrteu dnioets d[2e5te–c2t7e]d. through
UApVpl2.5S4 cmi.2e0a1s8u,8r,e1m50e2nts. This finding is in agreement with those of previous studies [25–27]. 6of15
A (cm-1)
254
A2D54O (Cc m(m-1g)/L)
0.05 4
DOC (mg/L)
0.05 4
0.04
3
0.04 )
-1(cm)54-1A(cm)25400..000023..0023 23 2C (mg/L)DOC (mg/L
A2 1O
0.01 D
1
0.01
0.00 0
0.00 0 20 40 60 800
0 20 PMC 4d0ose (mg/L6)0 80
PMC dose (mg/L)

Figure 3. Removal of UV254 and dissolved organic carbon (DOC) at the laboratory-scale using varying
FFiiggduuorrseee s33 ..o RRf etehmmeoo PvvMaall Coo-ffb UUaVsVe22d554 4 caoannadgd dudilsaissnsotol v(l0ve,ed 5d ,o o1rrg0g,a a2nn0ici,c 4cca0ar, rbabonondn (7(DD0O OmCCg))/ aLat)t .t thhee llaabboorraattoorryy--ssccaallee uussiinngg vvaarryyiinngg
dosesofthePMC-basedcoagulant(0,5,10,20,40,and70mg/L).
doses of the PMC-based coagulant (0, 5, 10, 20, 40, and 70 mg/L).
3.2. Zeta Potential of PMC
33..22.. ZZeettaa PPootteennttiiaall ooff PPMMCC
The zeta potential of the test water at varying PMC-based coagulant doses was determined to
invTTehhsteei gzzaeettteaa tpphooett eemnnetticiaahlla oonffi sttmhhee otteef sstttu wwrbaaidtteeirrty aa tta nvvdaarr ayyliignnagge P PrMMemCCo--vbbaaasls.ee Wdd ccitoohaa gginuucllraaennatts didnoogss eePssM wwCaa ssd ddoseeettee frrrmmomiinn ee0dd t ottoo 7 0
iinnvvmeegsst/tiLigg,a atthteee t tzhheeet amm peeoccthehanantniiaissmlm w oaofs f tiutnurcbrrbeidiadistieytdy a fnarnodmd a la−gl2ag6ea. e3r emrmeVmo vtooav l+a. 2lW.7.1Wit hmi tihVn ci(nrFecigarseuiarnsegi 4n P)g.M TPhCMi sdC coosdueol dsfre obfmer oe 0mx ptol0a i7tn0oe d
m70gbm/yL tg,h t/heL eh, zitgehhtealy zp epottoaesnpittoiivateel nwcthaiaaslr ignwec arosefa itsnhecedr Pe faMrsoeCmd s−ft2roo6cm.k3 sm−olV2u6 tti.o3o +nm2 (7V+.414t mo.8V6+ 2 m(7FV.i1g)u.m TreVh 4e() Fi.s iTogheuilrsee ccto4rui)c.l dpT obhieins et xcwopaulasl idfnoebuden d
bexytp otlh abeie nh aeirdgohbulyyn dtph o2es0ih–t4iigv0he m lcyhgpa/Lrog sPeiMt iovCfe t hdcheo asPreMg, ewCoh sfitctohhc erkaP snMogleCu tiisso tconlco (ks+e4s 4oto.l8u t6th imeo noVp()+t. i4Tm4hu.e8m 6is moPeMVle)Cc.tT drhioces peiso foionertl e twhctear saic lfgopauoeni nadtn d
twoa tbuserf boauirdoniudtynt dor e2bm0e–oa4vr0oa mul, nig.de/L.2, 0P2–0M4 0mCm gd/goL/s (eLF, PiwgMuhriCceh d4 ro)a.s neT,ghweis hi sri ecchslourslate n itgnoed tihicseac toleopsst etimhtoautt mhthe Peo McphtCiam rdguoems ne ePfouMrtr Ctahldeiz oaasltegioafoner actnohdue ld
taulgrbbaeei dthaintey dm rteaumjrobroi dvreaitmly, oir.evem.a, lo2 mv0 aemlc,hgi.a/eLn., i(2sFm0igm ougfr /aelL g4()aF.e iT gahunirdse rt4eu)sr.ubTlithd iiisntydr eiisncua ctlotesain gtdhuialcata tttiehosnet hcpharoatrcthgeeess cn [he2au8r]tg.r eaAlnitze tauhtteiro aPnlMi zcaoCtu idoldno se
bcoehu tihlgdeh bmeera ttjhohera mnre am2j0oo rvmraeglm /mLo,ev ctahhlaemn rieescvmhea ronsfai salm lgoafo eft haaenlg das oetulaurntbidiodntiu tyrcbh iinadr icgtoyea igfnruoclmoata igonunelg apatritooivcneep stsro o[ 2cpe8os]s.s Ai[t2itv8 t]eh. eAc oPtuMtlhdCe lPdeMoadsCe to
hdiogrsehesethra ibtghihlaieznra tt2iho0an nm o2gf0 /Ltmh, etg h/peLa rr,tetihvcleeersrs.ea vTl ehorefs atplhaoer ftsitcohlleeusts iocoolnuu tlcidoh narrecgpheea lfr rgeoeamcfhr on ometghaneterigv, aeot witvoie npgtoo tspoit oisvstiert oicvnoegu cleodlue lcledtarodles attadot ic
rtoesrrteeapsbutiallisbziioalitnzi oafnotir oconef sot chfaetuh pseeapdrta ibrcytlie ctslh.e esT .ahTdesh operapbreatidrct lipecsole lcysoccuaotluidol dnresr pe[2ep2le ]le. aeMcahoch roeotohtvheerer,r, , oaowlwgianieng gb titooo- cssottrrloloonnigdg see alleerccett krroonssottwaattniicc to
rreeppcauurllrssyiioo nnne ffgooarrtccievesse ccsaauuursfsaeecdde b bcyyh atthhrgeee aasdd asstoo mrrbboeesddt pppHooll yyleccvaatetiiloosn n[s2s 9[[2]2.22 T]]..h MMusoo, rrteehooevv heeirrg,, haa llagglaageea ebb iirooe--mccooollvllooaiildd essf faairrceeie kknnncooiewws nno ftt ooth e
ccaaPrrrrMyy Cnnee cggaaantt iibvveee asstuutrrriffbaaucceete ccdhh ataorrgg theesse aamtt emmchoossattn ppisHHm llsee ovvfee cllssh [[a22r99g]]e.. TnThehuuutssr,,a ttlhhizeea hhtiiioggnhh aaanllggdaa mee rureetmmuaoolvv aaatllt reeafffcfiitccioiieennn bcciieeetssw ooeffe ttnhh eteh e
PPMMneCCg cacatainnv bebleye a acttthrtaribirbguuetedted da tlogto athete ha emnmde cethhcahen apinsomissimst iovsfeo clfyh cachrhgaaerrg gneeednu etcruoatmlrizapaliotzinaoetnino atnsn doa nfm dthumetu PuaMtlu aCattl-rbaaatctstreiaodcn tc ibooenatgwbueelteawnn tet he(ine.e .,
nthezegeanoteilvigteeal,ty ibv acehrllyaerycg hseatdor ngaeelgd, aaaen ldagn alodee atshnse)d [p1tho0e]s.i tpivoesiltyi vcehlayrgchedar cgoemdpcoomnepnotsn eonf ttshoe fPtMheCP-bMasCe-db acsoeadgucolaangtu (lia.en.t,
z(ie.eo.l,itzee,o bliatrel,ebya srtloeynes,t oannde, laonedssl)o [e1s0s]). [10].
20
20
) 10
V
)m10
V
(mal ( 0
al nti 0 20 40 60 80
entiote -10 20 PMC 4d0ose (mg/L6)0 80
pota p-10 PMC dose (mg/L)
t
ta Ze -20
e
Z -20
-30

-30

FigFuigreur4e. E4.f fEefcfteoctf oPfM PCM-bCa-sbeadsecdo acgouaglaunltandto dseos(0e, (50,, 150, ,1200, ,2400, ,4a0n, dan7d0 7m0g m/Lg/)Lo)n oZn eZtaetpao pteontetniatli.al.
Figure 4. Effect of PMC-based coagulant dose (0, 5, 10, 20, 40, and 70 mg/L) on Zeta potential.
Appl. Sci. 2018, 8, x FOR PEER REVIEW 7 of 15
AAppppll.. SSccii.. 22001188,, 88,, x1 5F0O2R PEER REVIEW 77 ooff 1155
3.3. pH and Alkalinity
3.3. pH and Alkalinity
The changes in solution pH and alkalinity after coagulation with various PMC-based coagulant
3.3. pHandAlkalinity
doTsehse a crhea snhgoews nin i nso Fluigtuiorne 5p.H T hane din aitlikaall pinHit yo fa fttheer rcaowag wulaatteiro nw wasi tahp vparorixoiumsa PteMlyC 7-b.8a. sTehde c joaarg tueslat nwt as
docsoensT dahureecc tshehdaon wwgientsh ini vn aFsriogyluiunrtgeio d5n.o TpsehHse aoinnf ditthiaaell kP paMHliCn oi-tfby tahaseeft drea rcwocoa wagguaultaelanr ttwi,o aanns wda pitthpher voeaxffriemioctau tosefPl yPM M7C.8C-.b Tdahosseee dj aocrno t aethgsteu wlpaHanst of
cdoontshdeesu tcaetrseetd ws whaoittwehr n vwaianrys Fienivggau dlruoeast5ee.sd oT. fhI tte hwiena PistM ioabClsp-ebHravseoedfd ttchhoeaatrg tauhwlea ntwets,a tat enwrdaw ttehares peaHfpfe pdcrteo coxrfie mPaMsaetdCel yadfot7es.8re .aodTnd htiheteijo apnrH ote fos tfth e
wthaePs MtecsCotn -wbdaaustceetdre dwcoawasgi etuhvlaavlnuatra. ytIeinndcg.r eIdta sowisnaegss otohbfest ehPreMvePCdM tdhCoa-stbe ta hdseee cdtreecsato sawegdau ttleharne p tp,HHa nd adencrtdhe aeaslekedfafl eiancfttiteoyrf aoPdf MdthiCtei otdneos ots few tohanete r.
PthMeTChpe-Hb paHosef ddt hecceoraetgeassuteladwn tato.t eIanrpcpwrreaoasxsiienmvgaa tlteuhlaey t Pe7dM.0. CaIt t dthwoesa eos pdotebicmsreeuramvsee PddM tthhCea- tbpatHhsee adtn ecdso taawglkuaaltlaeinnrtit pdyH oosfed ,te hwcerh etiaecsshet diwndaafitcteearr.t es
Tadhtdeh iapttiHo tn hdeoe fcartlehkaeaslPeindMi ttCoy -abcpoapsnersoduxmciompatagitouenllya n o7ft. .0tI hanetc trhPeeaM soiCnp gtcimothauegmuPl MaPnMCt Cdis-o bslaeessedsd et chcroaeanags euthdlaatnth toe dfp oaHsleu,a mwn-dhbiaacslhke adinl idcnhiicteaymteoisfc al
tthhaectot aetghstuew laaanlktteasr l[.i3nT0iht,3ye1 ]pc.o Hnsduemcrpetaisoend otof tahpep rPoMxiCm actoealygu7l.a0nat titsh eleossp ttihmaunm thPaMt oCf- baalusemd-bcoasaegdu lcahnetmdoicsael,
wcohaigcuhlainndtsic [a3t0e,s31th].a tthealkalinityconsumptionofthePMCcoagulantislessthanthatofalum-based
chemicalcoagulants[30,31].
pH
pHAlkalinity (mg/L as CaCO )
3
9.079..50 Alkalinity (mg/L as CaCO3) 302350O)3aCO)3
7.5 25 CC
6.0 20Caas
pHpH46..5034..05 12501105mg/L as y (mg/L
3.0 10 y (nit
1.5 5nitali
1.50.0 5 0aliAlk
k
0.0 0 20 40 60 800 Al
0 20 PMC d40ose (mg/6L0) 80
PMC dose (mg/L)

Figure 5. Effect of coagulant dose on pH and alkalinity with varying doses of the PMC coagulant (0,
FFiigg5uu, rr1ee0 ,55 2.. 0EE,f f4ffee0cc, tta oonffd cc o7o0aa ggmuugllaa/nLnt)t. d doossee oonn ppHHa anndda alklkaalilninitiytyw witihthv vaaryryininggd dosoesseso fotfh teheP MPMCCco caogauglualnatn(t0 (,05,,
150, ,1200, ,2400, ,4a0n, adn7d0 7m0 gm/gL/)L.).
3.4. PMC for Geosmin and 2-MIB Removal
33..44.. PPMMCC ffoorr GGeeoossmmiinn aanndd 22--MMIIBB RReemmoovvaall
The geosmin and 2-MIB removal efficiencies of the different PMC doses were investigated. In
theTT chhoeea gggeueoolassmtmioiinnn apanrnoddc 2e2-s-MsM, IPBIBMr erCem-mboaovsvaeladle fecfiofcfaiicgeinuecnlaiceniset osw foatfhs teihndejei fdcfteiefrfdeen ruetpnP ttM oP C7M0dC mo sdgeo/sLswe. sTe hrweee irrneevm einsotvviegasal tteiegfdfai.cteIiendn.t chIyne of
tchoega gecoousalmagtuiionlan atinpodrno 2pc-erMosscI,BePs isnM, cPrCMe-abCsae-sdbe adwseictdoh a cignouacrlgaeunalstainwntg aw sthaiens PjienMcjteeCcdt deudop suept ion to 7b 0o70tmh m gp/groL/Lc..eT Tshsheees r r(eFemmigoouvvraeal l6 ee).ff fifTichciieee nnreccmyy ooovff al
ggeeeoofssfmmiciiinenn aacnnydd o 22f-- MgMeIIoBBs miinniccnrr eeaaanssdeedd 2 ww-MiittIhhB ii nnatcc rr2ee0aa ssmiinnggg/L tthh oeef PPPMMMCCC dd wooassees iiannp bbpoortothhx ippmrrooaccteeelssyss ee4ss6 ((%FFii ggauunrrdee 3667))..% TT,h hreee srrpeemmecootivvvaaelll y.
eeffffiTicchiieeen nrcceyym oooffv ggaeel ooessfmmficiiinne naacnniddes 22 w--MMerIIBBe haattig 22h00e mmr fggo//rLL g ooefof PsPmMMiCnC wtwhaaasns a afpopprp r2roo-xMxiimmIBaa.t teTelhlyyi s44 6w6%%a saa nandtdt r3i37b7%u%t,e ,rdree stspope etchctteiiv vfelelaylty.t. er
TThhseet rrrueecmmtuoorvveaa all needfffif isccoiieelunnbcciiileeissty ww oeefrr geee hhoiisggmhhieenrr tffhooarr ngg ee2oo-MssmmIBiinn [ 1tt]hh. aann ffoorr 22--MMIIBB.. TThhiiss wwaass aattttrriibbuutteedd ttoo tthhee ffllaatttteerr
ssttrruuccttuurree aanndd ssoolluubbiilliittyy ooff ggeeoossmmiinn tthhaann 22--MMIIBB [[11]]..
200
Geosmin (ng/L)
)200
L
)g/ Ge2o-sMmIBin ( (nngg/L/L))
ng/LB (n151050 2-MIB (ng/L)
B (MI
MI2- 100
2-or 100
r n
min oosmi 50
se50
oG
e
G 0
0 5 10 20 40 70
0
0 5 PM10C dos2e0 (mg/L4)0 70
PMC dose (mg/L)
Figure6.Trendsingeosminand2-methylisoborneol(2-MIB)removalbyPMCprocess esatthelab-scale
Figure 6. Trends in geosmin and 2-methylisoborneol (2-MIB) removal by PMC processes at the lab-
(initialgeosminconcentration=134.58ng/L;initial2-MIBconcentration=159.02ng/L;PMCdose:0,
Figsucarele 6(.i nTirtieanl dgse oinsm geino scmonince anntrda t2i-omn e=t h13y4li.s5o8b nogr/nLe;o inl i(t2i-aMl 2I-BM) IrBem coonvcaeln btrya PtiMonC = p1r5o9c.0e2s snegs/ aLt; PthMe Cla db-ose:
5,10,20,40and70mg/L).
sca0l,e 5 (,i n1i0t,i a2l0 g, e4o0s amnidn 7c0o nmcegn/Ltr)a. tion = 134.58 ng/L; initial 2-MIB concentration = 159.02 ng/L; PMC dose:
0, 5, 10, 20, 40 and 70 mg/L).
Appl.Sci.2018,8,1502 8of15
From the results in Figure 6, it was found that PMC coagulation process could remove some
geosminand2-MIB,andPMCshowshigherremovalefficiencyofgeosmin(46%)and2-MIB(37%)than
otherchemicalcoagulantreportedinpreviousstudies[32,33]. AfterthePMCcoagulation,theresidual
geosminand2-MIBwasfoundtobeabout73.63and99.85ng/L,respectively. However,theaverage
thresholdofgeosminand2-MIBconcentrationsisapproximately10ng/L[34],thusfurtherremovalof
geosminand2-MIBisstillneeded. Therefore,toenhancetheremovalefficiencyofthesecompoundsa
PMC-basedcoagulationprocessfollowedbyAOPprocesswascarriedout.
3.5. UV/H O andUV/Cl forT&ORemoval,Lab-Scale
2 2 2
ThisstudyinvestigatedtwodifferentUVbasedAOPs, i.e., UV/H O andUV/Cl processes,
2 2 2
to enhance the geosmin and 2-MIB removal efficiencies after the PMC-based coagulation process.
Bothoftheprocessesareknowntogeneratehydroxylradical(•OH),whichreactsnon-selectivelywith
awiderangeoforganicandinorganiccompounds,bythephotolyticdecompositionofH O ,HOCl,
2 2
andOCl− [35]asfollowingequations:
H O +hv→2•OH, (1)
2 2
HOCl+hv→•OH+Cl•, (2)
OCl− +hv→O•− +Cl•, (3)
O•− +H O→•OH+OH−. (4)
2
For the case of the UV/Cl process, it is known that there are formation of reactive chlorine
2
species(i.e.,Cl•,Cl −•,andClO•),butitwasreportedthatOH•isaprimarilyradicalspeciestothe
2
degradationoftaste-and-odorcompoundsascomparedtoreactivechlorinespecieswhichareformed
intheUV/Cl process[36].
2
Treatment in the presence of algae species using oxidation processes has drawbacks such as
undesirabletoxinsandtasteandodorcompounds[37,38];therefore,theAOPswereappliedafterthe
coagulationprocesswiththeoptimumPMCdose,i.e.,20mg/L.Inaddition,sinceAOPsperformance
issignificantlyaffectedbyDOCandUV level[39],higherperformanceofAOPsisexpectedafter
254
thecoagulationwiththePMC-basedprocess.
Figure 7 shows the geosmin and 2-MIB removal with the UV/Cl and UV/H O processes.
2 2 2
UVdoseswerevariedasaround200,and700mJ/cm2,andoxidantdosewas5mg/L.TheinitialpH
ofthetestwaterwasapproximately6.9,butitwasincreasedto7.4aftertheinjectionof5mg/LofCl
2
becauseofthebasicpHofsodiumhydrochloricacidsolutionandlowbuffersystemoftestedwater
(alkalinity=27.5mg/LasCaCO ). NopHchangewasobservedaftertheinjectionofH O .
3 2 2
In both processes, the removal efficiency of geosmin and 2-MIB increased as UV dose
increased. The removal of geosmin and 2-MIB in the processes could be explained by the •OH
formation and reaction with those compounds. It is known that geosmin and 2-MIB are not
photo-reactivecompounds[12]buthighlyreactivewith•OH(k =7.8×109 M−1·s−1 and
OH,geosmin
k =5.1×109M−1·s−1)[40].
OH,2-MIB
Atthesame UVdoseof700mJ/cm2, theUV/H O process showshigherremovalefficiency
2 2
(87.2%ofgeosminand71.4%of2-MIB)thanUV/Cl process(62%ofgeosminand38%of2-MIB).
2
This result could be explained by the speciation of free chlorine (HOCl and OCl−) with pKa
7.5. At the condition of pH higher than 7.5, OCl− is the predominant species, and it is known
that the •OH scavenging rate by OCl− (kOH,OCl− = 8.80 × 109 M−1·s−1) is much higher than
H O (k =2.7×107M−1·s−1)andHOCl(k =8.46×104M−1·s−1[41];therefore,itis
2 2 OH,H2O2 OH,HOCl
reportedthattheremovalefficiencyofgeosminand2-MIBintheUV/H O processcouldbehigherat
2 2
pHabove7thantheUV/Cl process[36].
2
Betweenthetwocompounds,geosminremovalefficiencywashigherthan2-MIBinbothprocesses.
Thisisbecausegeosminhashigherreactivitywith•OHthan2-MIB.
AAppppll.. SSccii.. 22001188,, 88,, 1x5 F02OR PEER REVIEW 99 ooff 1155
100
Geosmin
2-MIB
80
)
%
( 60
al
v
o
m 40
e
R
20
0
2) 2) 2) 2)
m m m m
c c c c
J/ J/ J/ J/
m m m m
0 0 0 0
0 0 0 0
2 7 2 7
( ( ( (
Cl2 Cl2 O 2 O 2
V/ V/ H 2 H 2
U U V/ V/
U U

Figure 7. Trends in geosmin and 2-MIB removal by the UV/Cl , and UV/H O processes at the
2 2 2
lFaibg-sucrael e7(. inTirteianldgse oins mgeinoscmonince nantrda t2io-Mn:I1B3 4r.e5m8onvga/lL b;yin itthiael U2-VM/CIBl2c, oanncde nUtrVat/iHon2O:12 5p9r.o0c2enssge/sL a;tU tVhed olasbe-:
0s,c2a0le0 ,(iannitdia7l0 g0emosJm/cinm c2o;nCclendtorastei:o5n:m 1g34/.L5;8H ngO/L; dinoistiea:l5 2m-MgI/BL c;oinnicteianltrpaHti:o6n.:9 1).59.02 ng/L; UV dose: 0,
2 2 2
200, and 700 mJ/cm2; Cl2 dose: 5 mg/L; H2O2 dose: 5 mg/L; initial pH: 6.9).
3.6. CoagulationTestinPilotScale
3.6. Coagulation Test in Pilot Scale
Thepilot-scalePMC-basedcoagulationexperimentswereconductedwithvaryingdosesofPMC
The pilot-scale PMC-based coagulation experiments were conducted with varying doses of PMC
(from 10 to 40 mg/L) at 109 m3/h flow rate. The algae removal performance of the PMC-based
(from 10 to 40 mg/L) at 109 m3/h flow rate. The algae removal performance of the PMC-based
coagulantinthepilot-scaletestsisshowninFigure8. Thechlorophyll-aremovalefficienciesinthe
coagulant in the pilot-scale tests is shown in Figure 8. The chlorophyll-a removal efficiencies in the
pilot-scaletestswerefoundtobefrom78.0–96.0%,80.0–98.7%,90.0–99.6%and78–95%(depending
pilot-scale tests were found to be from 78.0–96.0%, 80.0–98.7%, 90.0–99.6% and 78–95% (depending
ontheperiodofexperiment)atPMC-basedcoagulantdosesof10,20,30,and40mg/L,respectively
on the period of experiment) at PMC-based coagulant doses of 10, 20, 30, and 40 mg/L, respectively
(Figure8). Theremovaltrendsofalgaeandturbidityweresimilar. ThecoagulationprocesswithPMC
(Figure 8). The removal trends of algae and turbidity were similar. The coagulation process with PMC
showedgoodalgaeremovalefficienciesinthepilot-scaletests.
showed good algae removal efficiencies in the pilot-scale tests.
Figure9showstheturbidityandUV databeforeandafterPMCcoagulationprocess. Theraw
254
Figure 9 shows the turbidity and UV254 data before and after PMC coagulation process. The raw
waterturbiditywasvariedfrom1.6to11.8turbidity(NTU).Theturbidityremovalefficienciesinthe
water turbidity was varied from 1.6 to 11.8 turbidity (NTU). The turbidity removal efficiencies in the
pilot-scaletestswerefoundtobefrom33.3–41.4%,41.2–77.4%,48.3–84.0%and36.7–78.9%(depending
pilot-scale tests were found to be from 33.3–41.4%, 41.2–77.4%, 48.3–84.0% and 36.7–78.9%
on the period of experiment) at PMC doses of 10, 20, 30, and 40 mg/L, respectively (Figure 9a).
(depending on the period of experiment) at PMC doses of 10, 20, 30, and 40 mg/L, respectively (Figure
Additionally, the average UV removal efficiencies in the pilot-scale tests were approximately
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9a). Additionally, the average UV254 removal efficiencies in the pilot-scale tests were approximately
35.6–45.7%, 41.4–48.9%, 36.7–62.4%, and 42.6–57.6% (depending on the period of experiment) at
35.6–45.7%, 41.4–48.9%, 36.7–62.4%, and 42.6–57.6% (depending on the period of experiment) at PMC
PMC doses of 10, 20, 30, and 40 mg/L, respectively (Figure 9b). Moreover, the turbidity removal
doses of 10, 20, 30, and 40 mg/L, respectively (Figure 9b). Moreover, the turbidity removal efficiency
efficiencyofthecoagulationprocessincreasedasthelevelofturbidityincreased. Eventhoughthe
of the coagulation process increased as the level of turbidity increased. Even though the turbidity
turbidityremovalefficiencywasnotashighasthelab-scaletest,theturbiditylevelaftertreatment
removal efficiency was not as high as the lab-scale test, the turbidity level after treatment was low.
waslow.
TheoptimumPMC-basedcoagulantdosewas20mg/Lforalllevelsofturbidityinthelab-scale
tests. However, the optimum dose for the pilot-scale tests was varied depending on the level of
turbidityfrom20–30mg/L,whichis10mg/Lhigherdosethanthelab-scale. Themaximumlevelsof
turbidityofthetestwaterwere4.6and11.8NTUforthelab-scaleandpilot-scaletests,respectively.
FurtherincreaseinPMCdose(40mg/L)decreasestheturbidityremovalefficiency. Thisindicates
theoccurrenceofchargereversalwhichcausestheparticlesinthetestwatertobepositivelycharged
duringthecoagulationprocessandthereforetheparticlesstarttorestabilizeathighPMCcoagulant
doses. Similarly,chemicalcoagulants,suchaspolyaluminiumchloridehavebeenreportedtodecrease
turbidityremovalefficienciesat dosesabovethe respectiveoptimumdoses [42–44]. Theturbidity
Appl.Sci.2018,8,1502 10of15
removalwashigherinthelab-scalethanthepilot-scaletestattheoptimumdoseofPMC(20–30mg/L).
Forinstance,incaseoftheturbidityof4.7NTU,theremovalefficiencyinthelabscalewas93.4%but
theobtainedvaluefromthepilot-testswasapproximately70.2%. Eventhoughtheturbidityremoval
efficiencywasnotashighasthelab-scaletest,theturbiditylevelaftertreatmentwaslow.Theoptimum
PMCdosesdifferencefortheturbidityremovalefficiencyinthelab-scaletestandpilot-scaletests
couldbeduetothedifferencesinthewatermatrices. Therefore,aPMCdoseof30mg/Lwasusedfor
tAhpeplr. eSmci. o20v1a8l, 8o, fxb FoOtRh PTE&ERO RcEoVmIEpWo u ndsinthepilot-scaletests. 10 of 15
Before coagulation
After coagulation
Removal
160 100
140
80
) 120
3
m
g/ )
m 100 60 %
a ( al (
- 80 v
yll o
h m
p 60 40 e
r R
o
l
h
C 40
20
20
0 0
6 8 9 7 9 0 4 5 3 8 1 2 9 0 5 8 5 9 0 1
Date / / / 1 1 2 2 2 / 2 / / / 1 1 1 / 1 2 2
5 5 5 5 5 5 5 5
/ / / / / / / / / / / /
4 4 4 4 4 4 5 5 7 7 7 7
PMC Dose 10 mg/L 20 mg/L 30 mg/L 40 mg/L

Figure8.Concentrationsofchlorophyll-abeforeandaftercoagulationusingthePMC-basedcoagulant
Figure 8. Concentrations of chlorophyll-a before and after coagulation using the PMC-based
inthepilot-scaletests(PMCdose:10,20,30,and40mg/L).
coagulant in the pilot-scale tests (PMC dose: 10, 20, 30, and 40 mg/L).
3.7. UTVh/eH o2pOt2imanudmU PVM/CCl2-bParsoecdes csoiangPuillaotnSt cdaolese was 20 mg/L for all levels of turbidity in the lab-scale
tests. However, the optimum dose for the pilot-scale tests was varied depending on the level of
Theoxidationofgeosminand2-MIBintheUV/H O andUV/Cl processeswasevaluatedafter
2 2 2
turbidity from 20–30 mg/L, which is 10 mg/L higher dose than the lab-scale. The maximum levels of
thePMCcoagulationprocesswithPMCdoseof30mg/L.FortheUVbasedAOPs,backgroundwater
turbidity of the test water were 4.6 and 11.8 NTU for the lab-scale and pilot-scale tests, respectively.
characteristicsaresignificantlyimportantforremovalefficiencyoftargetcompounds. Asmentioned
Further increase in PMC dose (40 mg/L) decreases the turbidity removal efficiency. This indicates the
in Section 3.6, after coagulation process using PMC, the water quality was notably increased as
fooclclouwrres:ncDeO oCf c(h1a.3rg→e r0e.v8emrsga/l Lw)h,iUchV cau(s0e.s0 6t9h5e →par0t.i0c2le7s2 incm th−e1 )t,easnt dwtauterrb itdoi tbye (p31o.s1it→ive1ly5 .c6hNarTgUed).
254
Tdourpirnegd tichtet choeapgeurlfaotriomna pnrcoecoefssU aVn-dba tsheedreAfoOreP sth,teh peasrctaicvleens gsitnargt ftaoc troerstcaobuillidzeb aeta hniginhd PicMatCo rcofoargu•lOanHt
wdoasteesr. bSaicmkgilraorulyn,d cdheemmaicnadl (cso−a1g)u. Tlahnetss, casuvechn gains gpfoalcytoalrusmwienrieumm eachsulorreiddeb ehfoarvee abnedenaf treerptohretePdM tCo
decrease turbidity removal efficiencies at doses above the respective optimum doses [42–44]. The
treatment(FigureS1). Asexpected,thescavengingfactorwasnotablydecreasedafterPMCtreatment
(t6u4r9b9id8i→ty r2e8m51o6vsa−l 1w).asT hheigUheVr tirna nthsem liatbta-snccaelew tahsanin tchree apsieldot(-8sc5a→le t4e%st )a.tT thhies ocpotuimldubme edxopslea oinf ePdMbCy
(20–30 mg/L). For instance, in case of the turbidity of 4.7 NTU, the removal efficiency in the lab scale
thedecreasedDOCandUV afterthePMCprocessbecauseDOMsarethemainwaterconstituents
254
cwoanss i9d3e.4re%d binutt htheee sotbimtaaintieodn voafl•uOe Hfrosmca vthene gpinilgotr-atetsetss inwansa tauprpalrowxaimtearste[l1y6 7].0M.2%or. eEovveenr, trhemouogvha lthoef
turbidity removal efficiency was not as high as the lab-scale test, the turbidity level after treatment
turbiditycouldincreasetheperformanceofUVbasedAOPsbecauseturbiditycausingparticlescan
was low. The optimum PMC doses difference for the turbidity removal efficiency in the lab-scale test
and pilot-scale tests could be due to the differences in the water matrices. Therefore, a PMC dose of
30 mg/L was used for the removal of both T&O compounds in the pilot-scale tests.