Fate of Pharmaceuticals in the Environment and in Water Treatment Systems - Chapter 14 doc

331
14
Treat ment of Antibiotics
in Swine Wastewater
Craig D. Adams
14.1 INTRODUCTION
The formation and occurrence of antibiotic-resistant bacteria (especially pathogens)
intheenvironmentareofsignicantconcerntosociety,andarethespecicfocusof
thescienticandregulatorycommunities.InanimalagricultureintheUnitedStates
andelsewhere,antibioticsareprovidedtoswinefortherapeuticreasons,aswellasfor
growthpromotion.Manyantibioticsthatarefedtoorinjectedintoswinemaypass
throughtheswineunmetabolizedand,therefore,endupintheswinemanurethatis
passed into the treatment system. Accordingly, it is of considerable interest that an
economicalandeffectivemeansoftreatingtheseantibioticspreventorminimize
theirintroductionintotheenvironmentduringtheireldapplication(Figure 14.1).
Contents
14.1 Introduction 331
14.2 Typical Manure Handling Systems for Swine 332
14.2.1 Interior Storage 332
14.2.2 Exterior Storage and Treatment 333
14.2.3 Multicell Lagoon Systems 334
14.2.4 Anaerobic Digestion 334
14.3 Sorption of Antibiotics in Swine Lagoons 336
14.4 Hydrolysis of A ntibiotics in Lagoons 337
14.5 Biological Treatment of Antibiotics in Conventional Swine Treatment
Systems 337
14.5.1 Anaerobic Biodegradation 338
14.5.2 Aerobic Biodegradation 339
14.5.3 Inhibition of Anaerobic Biodegradation by Antibiotics in
Swine Lagoons 339
14.6 Chlorine Treatment for Antibiotics in Swine Wastewater 340

14.6.1 Antibiotic Removal 340
14.6.2 Simultaneous Disinfection 342
14.6.3 Comparison of Selected Classes of Antibiotics 345
14.7 Other Treatment Approaches 345
14.8 Concluding Remarks 346
References 347
© 2008 by Taylor & Francis Group, LLC
332 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems
14.2 TYPICAL MANURE HANDLING SYSTEMS FOR SWINE
Swinemanureisamixtureofurineandfeces,whichoftencontainssignicantcon-
centrations of antibiotics and hormones. Swine manure may typically contain only
10to20%solidsand,therefore,isgenerallyinslurryform.Thus,swinemanuregen
-
er
ally cannot be handled using solids handling equipment. Lagoon slurry is usually
dischargedthroughdirectlandapplicationtocroplands.Whiletheslurryhassig
-
ni
cant nutrient value, it may also contain antibiotics, hormones, antibiotic-resistant
organisms, as well as excessive phosphorus and other problematic contaminants.
Land application of liquid slurry from anaerobic lagoons or storage basins, and
anaerobic digesters, is typically achieved by using irrigation-type equipment. These
systems include stationary spray guns, sprinkler systems, and controlled ooding.
14.2.1 INTERIOR STORAGE
Swinemanurefromconnedproductionfacilitiesisoftenstoredineitherinterior
(underoor) or exterior (lagoon) storage basins (Miner et al., 2000). The underoor
basin or pit is located directly beneath the slatted oor of the building housing the
swine (
Figure 14.2). The swine manure, along with excess food and other solids,
fallsorisperiodicallyrinseddownintotheunderoorpit.Maximumstoragetime

inatypicalunderoorpitmayrangefrom5to12months(Mineretal.,2000).Ven
-
ti
lation of the underoor pits is critical to remove noxious gases such as hydrogen
suldeandammonia,aswellascarbondioxideandmethane,fromtheconnement
building.Priortoremovalfromthepit,themanuremustbeagitatedtohomogenize
itsothatallofitcanbecompletelyremovedfromthepit,andtoensurethatthe
FIGURE 14.1 Sludgepumpusedtotransferlagoonslurryfromlagoontoadjacentelds.
© 2008 by Taylor & Francis Group, LLC
Treatment of Antibiotics in Swine Wastewater 333
removed manure has uniform nutrient characteristics. Agitation is usually achieved
usingpumpsplacedinmultiplelocationsalongthepitwall(Mineretal.,2000).The
dischargefromunderoorstorageisgenerallyappliedtosurroundingeldsasafer
-
tilizer, although it is usually nonoptimal relative to nutrient p:n ratios.
14.2.2 EXTERIOR STORAGE AND TREATMENT
Analternativetoanunderoorstoragebasinistheexteriorstoragebasin,commonly
referredtoasa“lagoon.”Occasionally,exteriorstorageofmanureisinsteadaccom-
pl
ishedbyusingatanklocatedoutsidethebuilding;thisisfarlesscommon,how-
ev
er,thantheuseofalagoon.Generally,swinemanureiscollectedusingaslatted
oordesign,andthenperiodically(e.g.,twiceperday)ushedwithwatertomoveit
from the building.
Inthesimplestdesign,themanureowstoasingle-ortwo-stagelagoonforstor
-
age
and treatment, followed by periodic land application. A variation of this system
rstprovidesforliquid-solidseparation,afterwhichthesolidsmaybecomposted
andtheliquidpassedtoalagoonforstorageandtreatment,priortolandapplication

(Miner et al., 2000).
Inamoresophisticatedsystem,thewastefromthebarnismixedandpumped
into an anaerobic digester. Methane generated in the process provides for energy
recovery.Theefuentfromtheanaerobicdigesterisoftenpumpedintoananaerobic
lagoon for storage and treatment, followed by land application (Miner et al., 2000).
Avarietyoflagoonsystemsareusedforswinewastewatertreatment.Alagoon
system may be a single cell, or may contain multiple cells in series. Generally,
lagoons are not aerated and are, therefore, anaerobic. In some cases an aerated cell
isusedforenhancingammoniaremoval.
FIGURE 14.2 Insideaswinebarnatatypicalconcentratedanimalfeedoperation.
© 2008 by Taylor & Francis Group, LLC
334 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems
Inastandardanaerobiclagoon,swinemanureisstoreduntilthetimeofyearthat
is amenable for eld application, that is, when the nutrients are needed and the ground
isnotfrozen.Additionally,sometreatmentofthemanureisachievedinthelagoon
andthequalityoftheslurrychangeswithtime.Ingeneral,solidsaredecreased,which
makestheslurrymuchmoreamenabletoeldapplication(Mineretal.,2000).Key
differences between an anaerobic digester and an anaerobic lagoon for swine waste
treatment are that lagoons have no temperature control and cannot capture methane
for energy recovery (unless appropriately covered). Depending on the region, in the
colder winter months, anaerobic activity in a lagoon may be very low relative to that
inthewarmersummermonths.Astemperaturesincreaseduringthetransitionfrom
winter to summer, the excess stored organic matter may cause enhanced anaerobic
activity until stored organic loads are reduced (Miner et al., 2000).
14.2.3 MULTICELL LAGOON SYSTEMS
Two-andthree-celledlagoonsystems,inseries,arealsousedatsomefacilities.
Typically,therstcellisoperatedasinasingle-cellsystem.Mostsolidsareretained
intherstcell,whichprovidesforadditionalsolidsdecomposition.Inthenalcell,
algaeoftenmaythrive,allowingbetterslurrytreatment(Mineretal.,2000).Addi
-

tionally, aeration is sometimes added to the nal cell to improve efuent quality.
Multicelledsystemsaremorecommonwhenthelagoonwateristobeusedasthe
ushingwaterforthebarns.
Asanexampleoftypicaltreatmentparameters,characteristicsofswinebarn
wastewaterintwodifferentlagoonsystemsstudiedbyQiangetal.(2006)arepre
-
s
e
nted in Table 14.1. For L
agoonSystemA,comparisonoftheinuent(A-INF)and
efuent (A-EFF) from the rst of two anaerobic cells showed a signicant reduction
insolublechemicaloxygendemand(SCOD)anddissolvedorganiccarbon(DOC),
while ammonia, alkalinity, pH, and UV adsorption all in
creased(Table14.1).C
om-
parisonoftheinuentintothesecond(overow)cellanditsbulkconcentration(A-
OV)(whichisperiodicallylandapplied),showedafurtherreductionofSCODand
COD,aswellasammonia(Table14
.1).
As
econdtwo-celllagoonsystemwasalsostudied(LagoonB)thatwassimilarto
Lagoon System A, except that the rst cell of the lagoon was aerated. Similar treat
-
me
nt was achieved for SCOD and DOC. However, a much lower ammonia concen-
tr
ationwasachievedintheefuentoftherst(aerated)cell(B-EFF),whichhelped
achieve a very low nal ammonia concentration (B-OV) in the second (nonaerated)
cell. The slurry from this second cell is periodically land applied.
14.2.4 ANAEROBIC DIGESTION

Swine manure is also amenable to treatment in an anaerobic digester. An anaerobic
digester is enclosed so as to capture product gases (e.g., hydrogen sulde, ammonia,
methane,andcarbondioxide)andtoallowefcienttreatmentoftheswinewaste.
However,becausethislevelofefcientwastetreatmentisnotrequiredintheUnited
States for CAFO wastes, the perceived cost associated with anaerobic digesters
haslimitedtheiruseforswinemanuretreatmentintheUnitedStates.Theuseof
© 2008 by Taylor & Francis Group, LLC
Treatment of Antibiotics in Swine Wastewater 335
TABLE 14.1
Mean Physical-Chemical Properties of Wastewaters from Two Swine Lagoons
Properties
Lagoon A
Raw Waste from
Barn (AINF)
Lagoon A
Bulk Slurry from
1st (Anaerobic)
Cell (A-EFF)
Lagoon A
Bulk Slurry from
2nd (Anaerobic)
Cell (A-OV)
Lagoon B
Raw Waste from
Barn (BINF)
Lagoon B
Bulk Slurry from
1st (Aerated)
Cell (B-EFF)
Lagoon B Bulk

Slurry from 2nd
(Anaerobic) Cell
(B-OV)
pH 7.5 8.1 8.3 7.4 8 8.5
Soluble COD (mg/L) 1102 302 145 104 248 126
Dissolved Organic Carbon (mg/L) 385
117 73 359 80 42.7±5.2
Ammonia-N (mg/L) 141 390 165 120 20 14
Nitrate-N (mg/L) 2.9 3.8 3.7 3.2 3.97 3
Nitrite-N (mg/L) ND* ND* 0.6 ND* ND* 0.1
Alkalinity (mg/L) 513 1405 620 539 723 2351
Total Dissolved Solids (mg/L) 1370 2510 1360 1430 1570 680
Conductivity (uS) 2060 3760 2035 2140 2350 1030
UV
254 nm
(m
-1
) 1.8 2.2 1.1 1.7 1.5 0.7
Specic UV Absorbance (L/mg-m) 0.5
1.9 1.6 0.5 1.8 1.5
Source: Qiang et al., Ozone Science and Engineering 26, 1–13, 2006. (With permission.)
*
ND = Not Detected
© 2008 by Taylor & Francis Group, LLC
336 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems
anaerobicdigestersmayincrease,however,asmoreemphasisisplacedonenergy
recovery,odorcontrol,andmoreeffectivewastetreatmentthanisprovidedbyopen
storagebasinsorlagoons.
14.3 SORPTION OF ANTIBIOTICS IN SWINE LAGOONS
Sorption of antibiotics to biosolids is an important mechanism that affects whether an

antibioticwouldlikelybeintheaqueousphasevs.sorbedtobiosolids.Furthermore,
antibioticsthatstronglysorbtobiosolidsmaytendtoexistinthesettledsolids,while
weaklysorbedantibioticsmaytendtoexistpredominantlyintheslurry.Ifalagoonis
notmixedpriortolandapplication,onlytheantibioticsintheslurrymaybepredomi
-
na
ntly introduced to the environment. If the lagoon is mixed prior to land application,
allantibioticsinthelagoonmay,inthatcase,bereleasedtotheenvironment.
Thelinearsorptioncoefcient(K
D
) (L/kg) between an antibiotic and biosolids
inatreatmentprocessrepresentstheconcentrationofanantibioticsorbed(µg/kg)
relative to its concentration in the liquid phase (µg/L). The linear K
D
model is very
often used to model sorption of pharmaceuticals in sediment, solids, and soils due
to the linearity of isotherms at low adsorbate concentrations. Because there are a
variety of mechanisms for sorption of pharmaceuticals on the organic and inorganic
solids in treatment processes, prediction of K
D
is complex. Sorption onto solids can
involve a variety of mechanisms, including absorption into organic carbon, adsorp-
ti
on to mineral surfaces, ion exchange, and chemical reactions (Schwarzenbachet
a
l.,2003).Similarly,equilibriumsolubilityoftheantibioticintheaqueousp hase can
b
eaffectedbymanyfactors,includingtemperature,dissolvedsolids,andpH.
Kurwadkar et al. (2007) investigated the effects of sorbate speciation on the
sorption of selected sulfonamides in three loamy soils. Sulfonamides predominantly

existasanionsatpHlevelsabovetheirrespectivepK
2
values (5.3–7.5) (Qiang and
Adams, 2004), as neutral species at pH between their respective pK
2
and pK
1
values
(1.9–2.1)(QiangandAdams,2004),andascationsbelowtheirrespectivepK
1
values.
An effective K
D
canbeestimatedusingaweightedK
D
value approach (Schwarzen-
bachetal.,2 003; Kurwadkar et al., 2007), that is:
K
D,effective
= B
cationic
·K
D,cationic
+ B
neutral
·K
D,neutral
+ B
anionic
·K

D,anionic
where K
D,cationic
,K
D,neutral
,andK
D,anionic
are the linear partition coefcients for the
cationic, neutral, and anionic species, respectively, and B
cationic
, B
neutral
,andB
anionic
are the fractions of each species present at a specic pH. While this study addressed
sorption to soils rather than biosolids, the same general principles are likely to apply
inbiosolids.Extrapolatingtobiosolids,sulfonamidesmaybeexpectedtosorbmuch
lessatahigherpH(abovetheirpK
2
)duetothepredominanceoftheanionicform
andmuchmoreatalowerpH(betweentheirpK
1
and pK
2
) where the neutral form
predominatesandsorptiontoorganiccarboninbiosolidsmaybemoresignicant.
TypicalvaluesforlogK
D
are4tetracyclines,3fortylosin,and1forsulfon-
amides(Loftinetal.,2004).Thereforetetracyclinesandtylosinwouldtendtosorb

strongly to settled biosolids in a lagoon, whereas sulfonamides may appear in the
aqueousphasetoamuchlargerdegree.
© 2008 by Taylor & Francis Group, LLC
Treatment of Antibiotics in Swine Wastewater 337
RelatedworkbyVienoetal.(2007)examinedremovalofantibiotics,aswellas
other pharmaceuticals, in a municipal wastewater treatment plant in Finland. The
study concluded that the ciprooxacin is readily “eliminated” from wastewater by
sorption to biosolids due to high K
D
or K
OW
values (e.g., >4).
14.4 HYDROLYSIS OF ANTIBIOTICS IN LAGOONS
Antibiotics have opportunities to hydrolyze in storage basins, anaerobic lagoons, and
othertreatmentsystems.HydrolysisstudiesbyLoftinetal.(2007)wereconducted
indeionizedlabwaterandlteredlagoonslurryasafunctionofpH(2−11),tem-
perature (7 to 35°C), and ionic strength. This study showed that lincomycin (LNC),
trimethoprim (TRM), sulfadimethoxine (SDM), sulfathiazole (STZ), sulfachlorpyr-
id
azine(SCP),andtylosinA(TYL)wererecalcitranttohydrolysisinlagoonslurry
forpH5,7,and9.AtahigherpHof11,limitedhydrolysisofTYLwasobserved.
On the other hand, the tetracyclines—oxytetracycline (OTC), chlorotetracycline
(CTC), and tetracycline (TET)—were all readily hydrolyzed under anaerobic lagoon
conditions at pH levels of 5, 7, 9, and 11 (Figure 14.3). Researchers, including Loftin
et al. (2007), have noted that a wide range of hydrolysis byproducts of the tetra-
cy
clines occur under different conditions, including epi-, iso-, epi-iso-, anhydro-,
and epi-anhydro-analogues. More study is warranted of the partitioning behavior
of these compounds to estimate their mobility relative to the corresponding parent
tetracyclines. For a temperature of 22°C or greater, half-lives of OTC, CTC, and

TETwere16hoursorless(Loftinetal.,2007).Atcoldertemperatures(e.g.,7°C),
nearly an order-of-magnitude slower hydrolysis was observed. Due to the signicant
seasonal temperature uctuations observed in many swine lagoons, a wide range of
hydrolysis rates for tetracyclines would be expected, depending on both tempera
-
tu
reandpH.However,duetolongholdingtimes,ontheorderofmonths,complete
hydrolysistobelowdetectionwouldoftenbeexpected.
TylosinunderwentnohydrolysisinthepHrange5to9,butwasreadilydegraded
orlabileatalkalinepH(>11)attemperaturesof22°Corgreater.Thus,tylosinwould
notbeexpectedtoundergoappreciablehydrolysisinswinelagoonpHlevels.These
results suggest that tylosin, lincomycin, and the sulfonamides would be expected
to be recalcitrant to abiotic degradation (hydrolysis) in swine lagoons. In warmer
seasons or locations, oxytetratracycline and related compounds might be expected to
hydrolyzetosomegreaterorlesserdegree.
14.5 BIOLOGICAL TREATMENT OF ANTIBIOTICS
IN CONVENTIONAL SWINE TREATMENT SYSTEMS
Whenantibioticsenteratreatmentlagoon,therearemanypotentialtransforma-
tion and partitioning reactions that can potentially occur. Transformation reactions
include anaerobic or aerobic biodegradation depending on redox conditions, hydro-
ly
sis,andphotolysis.Partitioningreactionsforantibioticsinacommontreatment
lagoon are primarily to suspended and settled solids. In the subsequent sections,
these potential removal mechanisms are discussed in more detail.
© 2008 by Taylor & Francis Group, LLC
338 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems
14.5.1 ANAEROBIC BIODEGRADATION
Very few studies have investigated the biodegradation of antibiotics in anaerobic
swinelagoons.AnaerobicbiodegradationinswinelagoonslurrywasstudiedbyLof-
ti

netal.(2004)inlaboratorymicrocosmexperiments.Inthiswork,solubleCOD
was readily removed. In these microcosms, sulfathiazole exhibited little degradation
over a 2-month period (half-life = 222 days), suggesting that sulfathiazole would
likely be biorecalcitrant under anaerobic conditions. This persistence also suggests
overall concerns with sulfonamides in swine lagoons, that is, their presence in slurry
applied to the environment. Similarly, lincomycin also was persistent with a half-life
of78daysinoneslurryandnodegradationinanother.
Oxytetracycline, on the other hand, appears much more readily biodegradable
under anaerobic conditions with half-lives of approximately 1 month in two different
slurries. For example, with a 3-month treatment time, the concentrations of oxytetra
-
cyclinedecreasedtoonly12%ofitsinitialvalue.Tylosinewasobservedtodegrade
even more readily under anaerobic conditions with a half-life of approximately 1 day
OH
OH
OH
HO
Cl
HCl
OH
OH
NH
2
OH
OO
O
N
HO
HO
HO

H
HCl
HO
OH
NH
2
HO
OO
O
N
H
HO
HCl
OH
NH
2
OH
OO
O
N
H
FIGURE 14.3 Structures of chlorotetracycline (top), oxytetracycline (middle), and tetracy-
cline (bottom). (Courtesy of ChemFinder 2004, Cambridgesoft Corp.)
© 2008 by Taylor & Francis Group, LLC
Treatment of Antibiotics in Swine Wastewater 339
in both swine lagoon slurries studies. Abiotic degradation rates were much slower
(i.e.,approximately2weeks)inthesameautoclavedslurries.
Thus, the amount of anaerobic biodegradation treatment of antibiotics that would
be expected is highly dependent on the nature of the antibiotics. While the sulfonamide
and lincosamide were relatively recalcitrant, the tetracycline and macrolide were rela

-
tively easily degraded. More studies are needed in order to be able to realistically
estimate and model the anaerobic biodegradation of antibiotics in swine lagoons.
14.5.2 AEROBIC BIODEGRADATION
Relatively little information is available on aerobic biodegradation of antibiotics in acti-
vated sludge, aerated lagoons, or other processes.
Wo
rk by Ingersleveta
l.(2001)suggests
thatantibioticsmaygenerallydegrademuchmorerapidl yundera
erobic conditions than
under anaerobic conditions. They examined tylosin, oxytetracycline, metronidazole,
and olaquindox in laboratory microcosms and demonstrated that for these antibiotics,
aerobic biodegradation was signicantly more rapid than anaerobic biodegradation.
The use of aerated lagoons, and aerated “caps” (an aerobic zone as the surface
layer)onanaerobiclagoons,isapotentiallyviableoptionformoreeffectivelytreat
-
in
gantibioticsinswinewastewatertreatmentsystems.Anaerated“cap”iscreatedby
oxygenating the surface layer sufciently to maintain dissolved oxygen at the surface
on an otherwise anaerobic lagoon. More research in needed to better develop, opti
-
mi
ze, and implement this technology.
14.5.3 INHIBITION OF ANAEROBIC BIODEGRADATION
BY
ANTIBIOTICS IN SWINE LAGOONS
Swinemanureconsistsofacomplexmixtureoffats,carbohydrates,andproteins.
Anaerobicbiodegradationofswinemanureoccursbyaseriesofmetabolicsteps,
specically:(1)conversionofcomplexorganicstovolatilefattyacidsbyfermenta-

t
i
veorganisms;(2)conversionofvolatilefattyacidstoacetateandhydrogenbyfatty-
acid oxidizing organisms; and (3) conversion of acetate and hydrogen to methane by
methanogens (archea). Because antibiotics may often be present in swine manure
and, hence, in
t
heswinelagoonslurry,thereispotentialfortheantibioticstonega
-
ti
vely impact the anaerobic biodegradation of other waste constituents in a lagoon.
WorkbyLoftinetal.(2005)investigatedtheinhibitionofanaerobicbiological
activityinswinelagoonslurryinlab-scalemicrocosmexperiments.Thisworkmon
-
it
ored the impacts of varying concentrations of sulfonamides, tetracycline, linco-
my
cin, and tylosin on the production of methane, hydrogen, and volatile fatty acids,
including acetate.
Thesestudiesshowedasignicant(20to50%)inhibitionofmethaneproduction
foralloftheantibioticsstudied.Furthermore,antibioticdosagesof1,5,and25mg/L
ofaspecicantibioticallcausedsimilarinhibitions,whichingeneralplateauedat
approximately20to45%.Sanzetal.(1996)alsosawaplateauingeffectforampi
-
c
i
llin, novobiocin, penicillin, kanamycin, gentamicin, spectinomycin, streptomycin,
tylosin,andtetracyclinesoverawiderangeofinhibition(from0to100%).Thisrapid
plateauing in the inhibition of methane productions suggested that there exist certain
© 2008 by Taylor & Francis Group, LLC

340 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems
bacterial subpopulations within the slurry that are greatly inhibited by antibiotics
(evenatlowantibioticconcentrations[e.g.,1mg/L]),whileothersareresistanttothe
effects of the antibiotics.
IntheworkbyLoftinetal.(2004),nobuildupofacetateorhydrogenwas
observed, suggesting that the methanogens were the microbial population most sig
-
ni
cantlyinhibitedasmightmostcommonlybeanticipated.S
imi l
arly, volatile fatty
acids were not observed to build up in concentration, suggesting that the fatty-acid
oxidizing organisms were not the most inhibited population. Thus this work sug
-
gested, but did not prove, that the fermentative organisms were the most signicantly
inhibited microbial population.
Akeyconsequenceofthisobservedinhibitionofanaerobicmetabolismin
lagoons is that the presence of antibiotics may reduce the amount of manure degra
-
dation achieved in a swine waste treatment system. Furthermore, these ndings sug-
g
e
st that if the amount of antibiotics entering a lagoon could be reduced then more
effective treatment might be achieved. Finally this reduction in antibiotics could
potentially be attained by pretreating the wastewater between a barn and the bio
-
l
o
gicaltreatmentsystemtoremoveantibiotics,orbyreducingtheapplicationrateof
antibioticsgiventotheswine.Forexample,byeliminatingtheuseofantibioticsfor

growthpromotion(whereitisstillpracticed),theproblemcouldpossiblybemini
-
m
i
zedorreduced.
14.6 CHLORINE TREATMENT FOR ANTIBIOTICS
IN SWINE WASTEWATER
14.6.1 A
NTIBIOTIC REMOVAL
Chlorinetreatmentofwastewaterfromabarn,priortodischargeintoatreatment
process,isapotentialmeansofremovingantibioticsthatcouldpromoteantibiotic-
resistant bacterial growth within the lagoon, or may inhibit anaerobic activity within
the lagoon. Chlorine treatment of treated wastewater (e.g., lagoon slurry) prior to
eld application is, similarly, a potential method for removing antibiotics, thereby
preventing their introduction into the environment. Chlorine treatment prior to
eld application may also have potential for removing antibiotic-resistant bacteria,
therebypreventingtheirreleaseintotheenvironment.
ThepHhasbeenshowntohaveahighlysignicanteffectontheoxidationrates
of selected antibiotics due to the speciation of the stronger hypochlorous acid (HOCl)
to the weaker hypochlorite ion (OCl
-
) (Chamberlain and Adams, 2006). Because the
acid dissociation constant for HOCl/OCl
-
is approximately 7.6, at pH levels greater
than 7.6, hypochlorite will be the most prevalent oxidant species of the two.
Oxidation of antibiotics and disinfection of antibiotic resistant bacteria by indi
-
vidual addition of free chlorine or monochloramine were studied by Qiang et al.
(2006). The study looked at the oxidation of sulfonamides (sulfamethizole [SML],

STZ, sulfamethazine [SMN], sulfamethoxazole [SMX], and SDM) in inuents and
efuentsfromtwolagoonsystems.Bothlagoonsystemshadtwocellsinseries,
with one of the lagoons utilizing aeration in its rst cell. In laboratory experiments,
© 2008 by Taylor & Francis Group, LLC
Treatment of Antibiotics in Swine Wastewater 341
antibioticswerespikedandthentreatedwithchlorine(ormonochloramine)forthree
samplematrices:(1)theinuenttotherstcellfromthebarn(INF);(2)theefu-
en
tfromtherstcellandinuenttothesecondcell(EFF);and(3)bulkslurryfrom
thesecondcellofaswinelagoonsystem(OV),whichisgenerallyeldapplied.The
characteristics of each stream for both systems are shown in Table 14.1.
Ox
idation using free chlorine, or preformed monochloramine for comparison,
was studied in detail to determine its effectiveness in removing of the sulfonamides.
Addition of free chlorine (HOCl/OCl
-
)toswinewastewaterresultsinrapidconver-
sionofthefreechlorinetomonochloramine,amuchweakeroxidantanddisinfec-
ta
ntthanHOCl,eventhoughitissimilartoOCl
–
. Thus, the ammonia concentration
inswinewasteplaysacriticalroleintheoxidationofanyantibioticspresentdue
toitscompetitionforoxidant,anditsroleinconvertingfreechlorinetoaweaker
oxidant (monochloramine).
This work showed that the free chlorine concentration decreases very quickly
after application due to reactions with ammonia and other wastewater constituents.
The monochloramine formed thereafter decreases only slowly with time. These
effects could be seen for the inuent and efuent in the rst lagoon of the nonaerated
system,withthetotalchlorineconcentrationrapidlydroppingfrom500mg/Lto

approximately200mg/L(asfreechlorine),followedbyaslowdecline(asthemono
-
ch
loramine continued to react with wastewaterconstituents)(
Figure14.4B). Asa
result,rapidoxidationofthevesulfonamideswasalsoobservedduringtheinitial
500
Total Chlorine (mg/L) Total Chlorine (mg/L)
400
300
200
100
0
500
400
300
200
100
0
A-INF
SML
SMX
STZ SMN
SDM
C/C
0
(percent)
C/C
0
(percent)

100
80
60
40
20
0
A-EFF
A-INF
A-EFF100
80
60
40
20
0
0 1 2
Time (hr)
(A) (B)
3 4 5 6 0 1 2
Time (hr)
3 4 5 6
FIGURE 14.4 Oxidationofsulfonamideswithfreechlorine(FC)asafunctionofreac-
tion time in the inuent (A-INF) and efuent (A-EFF) of a swine lagoon system (“System
A”): (A) decomposition of sulfonamides; (B) decay of total chlorine. Data are from duplicate
runs(mean±standarddeviation).Experimentalconditions:pH=6.6;FCdose=500mg/L.
(Reprinted with permission from Qiang et al., 2006. Copyright 2006 American Chemical
Society.)
© 2008 by Taylor & Francis Group, LLC
342 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems
periodinwhichfreechlorinewasdominant(Figure14.4A).Thiswasfollowedby
slowfurtheroxidationoftheantibioticsbymonochloramineofotheroxidantspecies

(Figure14 .4A).
The
workbyQiangetal.(2006)suggestedthatapplicationofchlorinedosages
near the breakpoint (where all ammonia is converted to molecular nitrogen) is rec-
om
mended for complete removal of both antibiotics and bacteria (including most
antibiotic-resistant bacteria). The breakpoint generally occurs at a chlorine dosage
near7.6mg/Loffreechlorinepermg/Lofammoniapresent.Thisresultsingener-
al
ly high chlorine dosages being required for oxidation of sulfonamides in swine
wastewater. For example, chlorine dosages between 200 and 1000 mg/L of free chlo-
ri
ne were required to remove the ve study sulfonamides (Figure 14.5). We hypothe-
size that signicant concentrations of chlorinated oxidation byproducts would result
from these oxidation reactions.
These results suggest that relatively high chlorine dosages could be used to
removeantibioticsbetweenabarnandthetreatmentlagoonandtherebyreducethe
antibioticsenteringthelagoon.Thiscouldbeaccomplishedinthepipeorconduit
leadingfromthebarntothelagoon(ortreatmentsystem)withsufcientmixing
andcontacttime.Theseresultsalsosuggestthatlagoonslurrycouldbetreatedwith
chlorineinthepipeusedtopumptheslurrytoadjacenteldsforeldapplication(in
aplugowmode)orinatankusedforlagoonslurrytransport(inbatchmode).
Free chlorine is rapidly consumed by ammonia and, therefore, limits the
removalofantibiotics.Thesecondtwo-cellswinelagoon(LagoonB)studiedby
Qiangetal.(2006)hadaerationinitsrstcell.Theammoniaconcentrationinthe
efuentfromthesecondcellwasonly14mg/LasNH
3
-N (Table 14.1), while the
ammoniaconcentrationswere120and200mg/LasNH
3

-N in the inuent and efu-
entfromtherstcell,respectively.Therefore,muchlesschlorinewasrequiredto
fullyoxidizetheammoniaintheslurryfrombothcells.Abreakpointdosageof
approximately100mg/Loffreechlorinewasrequiredtoremovethe14mg/Lof
ammonia (Figure 14.6A), a
lthough m
onochloraminewasnotfullyremoveduntila
largerdosagewasadministered.Furthermore,completeremovalofallvesulfon-
am
idesstudiedwasachievedwithadosageof100mg/Lofchlorine,orless,inthe
secondcell.Signicantlylargerchlorinedosageswererequiredfortheinuentand
efuentwastewaterfromtherstlagoonduetothehighammoniaconcentrations
(Figure
14.6B). For comparison, typical chlorine dosages for disinfecting septic tank
efuent, and for municipally-treated activated sludge efuent, range from 20 to 60
mg/Land2to30mg/LasCl
2
,respectively(MetcalfandEddy,2003).
14.6.2 SIMULTANEOUS DISINFECTION
If achievable, it would be benecial to reduce the introduction of antibiotic-resistant
bacteria formed in swine, or in swine lagoons, prior to introduction into the environ-
me
nt.InonestudybyQiangetal.(2006),freechlorinewasobservedtodecreasethe
bacterial count (based on most probable number [MPN] methods) by approximately
four orders of magnitude, with relatively low chlorine dosages (e.g., less than 50
mg/L)inbothinuentandefuentstreamsfromanonaeratedlagoon(Figure 14.7).
© 2008 by Taylor & Francis Group, LLC
Treatment of Antibiotics in Swine Wastewater 343
However, much higher dosages of chlorine (up to 2000 mg/L) were not able to com-
pletelyinactivateallbacteriapresent,eveninlteredslurry.

This was suggestive that either (1) bacteria were shielded from chlorine disinfec-
tion by particles or (2) chlorine-resistant bacteria might be present in both the swine
manure and swine lagoon slurry. While the shielding mechanism is well understood,
further study by Macauley et al. (2006a) did nd that chlorine-resistant bacteria
were indeed present and appeared closely related to Bacillus subtilis and Bacillus
licheniformis.
A-INF
A-EFF
A-OV
C/C
0
(percent)C/C
0
(percent)
100
80
60
40
20
0
C/C
0
(percent)
100
80
60
40
20
0
100

80
60
40
20
0
FC (mg/L)
0 500 1000 1500 2000 2500
SML
SMX
STZ SMN
SDM
FIGURE 14.5 Decompositionofsulfonamidesasafunctionofafreechlorine(FC)dose
in the inuent (A-INF) and efuent (A-EFF) from the rst cell, and efuent (A-OV) from
the second cell of a swine lagoon system (“System A”). Data are from duplicate runs (mean
± standard deviation). Experimental conditions: reaction time = 2.5 h, pH = 6.6. (Reprinted
with permission from Qiang et al., 2006. Copyright 2006 American Chemical Society.)
© 2008 by Taylor & Francis Group, LLC
344 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems
(A) (B)
0
20
40
60
80
100
0 200 400 600 800 1000 1200
FC (mg/L)
B-EFF
0
20

40
60
80
100
C/C
o
(%)
SML STZ SMN
SMX SDM
B-INF
0
20
40
60
80
100
C/C
o
(mg/L)
SML STZ SMN
SMX SDM
B-OV
0
20
40
60
80
0 50 100 150 200 250 300
FC (mg/L)
C (mg/L)

Total Cl2 MCA NH3- N
Total Cl
2
NH
3
-
N
Antibiotic
C/C
0
(percent)
Constituent
Concentration
(mg/L)
Antibiotic
C/C
0
(percent)
Antibiotic
C/C
0
(percent)
FIGURE 14.6 Decompositionofsulfonamidesasafunctionofafreechlorine(FC)doseintheinuent(B-INF)andefuent(B-EFF)fromtherst
(aerated)cell,andefuent(B-OV)fromthesecondcell.(Qiangetal.,2006.Withpermission)
© 2008 by Taylor & Francis Group, LLC
Treatment of Antibiotics in Swine Wastewater 345
14.6.3 COMPARISON OF SELECTED CLASSES OF ANTIBIOTICS
In general, sulfonamides and lincomycin are expected to be persistent in lagoon
slurry—thatis,resistanttobiologicalandabioticdegradation.Furthermore,sul-
fonamidesareexpectedtosorbonlyweaklytolagoonsolids.Thus,sulfonamides

mayposeanespeciallysignicantrisk(withrespecttoexposure)duetotheir
presence in lagoon slurry that is frequently discharged into the environment by
eldapplication.Ontheotherhand,tetracyclinesandtylosinappeartosorbmore
stronglytolagoonsolidsandtodegrademorerapidlythanthesulfonamides.Thus,
tetracyclinesandtylosinmaynotposeassignicantathreattotheenvironment
astheseothercompoundsduetoreducedconcentrationsinlagoonslurry(atleast
withrespecttoexposure).
Whilethistreatmentstudyfocusedontheoxidationofsulfonamides,clean
water studies of the oxidation of other antibiotics with chlorine and chloramine pro-
videsomeinsightastotherelativeefciencyforoxidationofotherantibiotics.In
work by Chamberlain and Adams (2006), carbodox and the macrolides (roxithro-
mycin, erythromycin, and tylosin) were much more rapidly and fully oxidized by
chlorine than were the sulfonamides. This rapid oxidation was observed over a wide
pH range. Thus, while not tested, removal of these other classes of antibiotics in this
mannermay,infact,bemoreefcientthanwhenusedforthesulfonamides.
14.7 OTHER TREATMENT APPROACHES
Physicochemical treatments other than chlorine oxidation may be potentially effec-
tive for treating antibiotics in swine waste, though few have been studied in detail.
Chemicaltreatmentsthatmeritmorestudymightincludeozone,chlorinedioxide,
and ultraviolet (UV) oxidation.
Doddetal.(2006)studiedozonationofantibioticcompoundsinsecondaryefu-
entfromamunicipalwastewatertreatmentplant.Theyfoundthatadosageof3mg/
FIGURE 14.7 Inactivation of bacteria in the inuent and efuent of a swine lagoon system
(A)withfreechlorine(FC).(Qiangetal.,2006.Withpermission.)
1.0E+00
1.0E+02
1.0E+04
1.0E+06
1.0E+08
1.0E+10

1.0E+12
0 500 1000 1500 2000 2500
FC (mg/L)
MPN (cfu/mL)
A-INF A-EFF
© 2008 by Taylor & Francis Group, LLC
346 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems
Lorgreaterofozonewasabletoremoveatleast99%ofthe“fast-reactingantibiot-
ics” (i.e., with second-order rate constants of at least 5(10
4
)L·mole
-1
·sec
–1
). A strong
pH dependency was observed for the removal of many compounds due to specia-
ti
on of the antibiotic or the hydroxide-ion-catalyzed decomposition of ozone to the
less selective oxidant, hydroxyl radical. At pH 7.7 (typical for common anaerobic
lagoons),Doddetal.(2006)foundthatthe“fast-reacting”antibioticsincludedmac
-
rolides (i.e., roxithromycin, azithromycin, tylosin), sulfonamides (i.e., sulfamethoxa-
zo
le), uoroquinolones (i.e., ciprooxacin, enrooxacin), trimethoprim, lincomycin,
C-lactams (
i.e., cephalexim), tetracycline, and vancomycin. Other antibiotics, includ-
ingN(4)-acetylsulfamethoxazole,penicillinG,andamikacin,werenotasreadily
removed (Dodd et al., 2006).
Macauleyetal.(2006b)examinedthedisinfectionofswinewastewaterusing
ozone. Their results showed that bacterial disinfection based on MPN varied greatly

between different anaerobic lagoons at swine CAFOs. For example, an ozone dosage
of 20 mg/L resulted in almost no disinfection in one lagoon but nearly 2-log reduc
-
ti
on in another lagoon. In both lagoon slurries studied, a relatively high ozone dosage
of100mg/Lresultedin3.3-to3.9-logreductioninMPN.
Huber et al. (2005) studied the oxidation of various pharmaceuticals using chlo
-
rinedioxide.Theirworkshowedthat,forawiderangeofantibiotics(andotherphar-
ma
ceuticals), the kinetic rate constants with chlorine dioxide were approximately
twoordersofmagnitudelowerthanthoseforozoneandgenerallyhigherthanthose
forchlorine.ForthecompoundsexaminedintheHuberetal.(2005)study,the
reactivity with chlorine dioxide was similar to that with chlorine. These antibiotics
included both sulfamethoxazole and roxithromycin. More study is needed to estab
-
li
shitsviabilityofusingchlorinedioxideasadisinfectantinswinewastewater.
Macauleyetal.(2006b)showedthatUVwaseffectivefordisinfectingbacteria
fromswinelagoonwastewater.Macauleyetal.(2006b)didnot,however,reportthe
concurrent removal of antibiotics during UV disinfection. Earlier work by Adams et
al. (2002), however, demonstrated that UV dosages of 100 times greater than what
is typically used for disinfection resulted in only a 50 to 80% reduction in the con
-
ce
ntrations of seven common antibiotics (i.e., carbadox, sulfachlorpyridazine, sul-
fa
dimethoxine, sulfamerazine, sulfamethazine, sulfathiazole, and trimethoprim) in
both laboratory water and ltered surface water. A key factor in this limited removal
was the competitive absorbance of the UV radiation between the background con

-
stituents and the antibiotics themselves. In a swine lagoon, even less removal would
generallybeexpectedduetotherelativelyhighUVabsorbanceoflagoonslurryor
wastewater,ascomparedtodrinkingwaters.
Also,avarietyofmembranesystemscouldbedevelopedthatmightremove
antibiotics present in swine wastewater. However, due to the costs associated with
membrane systems, this approach can only be imagined to have limited application
in large-scale animal agriculture in the current economic and regulatory climate.
14.8 CONCLUDING REMARKS
The most promising approaches to limiting the discharge of antibiotics into the envi-
ronmentduringlandapplicationappeartoinclude:(1)reducingoftheuseofantibiotics
© 2008 by Taylor & Francis Group, LLC
Treatment of Antibiotics in Swine Wastewater 347
in animal agriculture, especially as it relates to growth promotion; (2) switching, where
possible,fromantibioticsthataremoredifculttotreat(e.g.,sulfonamides)tomore
easily treatable options; and (3) using chlorination (especially after aerobic biological
ammonia removal). Much more research is needed to fully address the feasibility of
each of these (and other) options.
REFERENCES
Adams,C.,Wang.Y.,Loftin,K.,andMeyer,M.(2002)Removalofantibioticsfromsurface
and distilled water in conventional water treatment processes. J. Environ. Engin.128:3,
253–260.
Ch
amberlain, E. and Adams, C. (2006) Oxidation of sulfonamides and macrolides with free
chlorine and monochloramine. Water Res.
40, 2463–2592.
Dodd, M., Bufe, M O., and von Gunten, U. (2006) Oxidation of antibacterial molecules
by aqueous ozone: moiety-specic reaction kinetics and applications to ozone-based
wastewater treatment. Environ. Sci. Technol. 4
0, 1969–1977.

Huber, M., Korhonen, S., Ternes, T., and von Gunten, U. (2005) Oxidation of pharmaceuticals
duringwatertreatmentwithchlorinedioxide.Water Research 3
9, 3607–3617.
Ingerslev, F., Toräng, L., Loke, M-L, Halling-Sørensoen, B., and Nyholm, N. (2001) Primary
biodegradation of veterinary antibiotics in aerobic and anaerobic surface water simula-
ti
on systems. Chemosphere 4
4, 865–872.
Kurwadkar,S.,Adams,C.,Meyer,M.,andKolpin,D.(2007)Effectsofsorbatespeciation
on sorption of selected sulfonamides in three loamy soils.
J. Agric. Food Chem. 55,
1370–1376.
Lo
ftin,K.,Adams,C.,andSurampalli,R.(2004)Thefateandeffectsofselectedveterinary
antibiotics on anaerobic swine lagoons. Water Environment Federation’s 77th Annual
Technical Exhibition and Conference (WEFTEC),
Washington, D.C., (October, 2004).
Loftin, K., Adams,C., Meyer,M.,andSurampalli, R. (2007) Effectsof ionic strength,temperature,
andpHondegradationofselectedantibiotics(inreviewinJ. Environmental Quality).
Lo
ftin, K., Henny, C., Adams, C., Surampali, R., and Mormile, M. (2005) Inhibition of
microbial metabolism in anaerobic lagoons by selected sulfonamides, tetracyclines,
lincomycin, and tylosin tartrate. Environ. Toxicol. Chem. 2
4:4, 782–788.
Macauley, J., Adams, C., and Mormile, M. (2006a) Presence and absence of known tet-resis-
ta
nt genes in tetracycline resistant isolates from an anaerobic swine lagoon (in review
at Canadian J. Microbiol.).
Ma
cauley, J., Qiang, Z., Adams, C., Surampalli, R., and Mormile, M. (2006b) Disinfec-

ti
on of swine wastes using chlorine, ultraviolet light, and ozone. Water Research 40
,
2017–2026.
Metcalf and Eddy (2003) Wastewater Engineering: Treatment and Reuse, 4t
h Edition, (Ed.
Tchobanoglous, Burton, and Stensel), McGraw-Hill, New York.
Miner, J.R., Humenik, F., and Overcash, M. (2000) Managing Livestock Wastes to Preserve
Environmental Quality,
IowaStateUniversityPress,Ames,IA.
Qiang, Z. and Adams, C. (2004) Potentiometric determination of acid dissociation constants
(pKa) for human and veterinary antibiotics. Water Res. 3
8, 2874–2890.
Qiang, Z., Adams, C., and Surampalli, R. (2004) Determination of ozonation rate constants
for lincomycin and spectinomycin. Ozone Sci. Eng. 2
6,1–13.
Qiang,Z.,MacCauley,J.,Mormile,M.,Sura mpalli, R., and Adams, C. (2006) Treatment of
antibiotics and antibiotic resistant bacteria in swine wastewater with free chlorine. J.
Agric. Food Chem.
54, 8144–8154.
Sanz, J., Rodriguez, N., and Amils, R. (1996) The action of antibiotics on the anaerobic diges-
tion process. App. Microbiol. Biotechnol. 46, 587–592.
© 2008 by Taylor & Francis Group, LLC
348 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems
Schwarzenbach, R., Gschwend, P., and Imboden, D. (2003) Environmental Organic Chemis-
try,
2nd Edition, Wiley-Interscience, Hoboken, NJ.
Vieno, N., Tuhkanen, T., and Kronberg, L. (2007) Elimination of pharmaceuticals in sewage
treatment plants in Finland.
Water Res. 41, 1001–1012.

© 2008 by Taylor & Francis Group, LLC