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Analysis and removal of emergingcontaminants in wastewater anddrinking waterMira Petrovic , Susana Gonzalez, Damia` Barcelo
The occurrence of trace organic contaminants in wastewaters, their
behavior during wastewater treatment and production of drinking water
are key issues in the re-use of water resources. Elimination of different
classes of emerging contaminants, such as surfactant degradates, phar-
maceuticals and polar pesticides in wastewater-treatment plants (WWTPs)was found to be rather low, so sewage effluents are one of the main
sources of these compounds and their treatment-resistant metabolites.
This article reviews the state-of-the-art in the analysis of several groups of
emerging contaminants (acidic pharmaceuticals, antibacterial agents,
acidic pesticides and surfactant metabolites) in wastewaters. It also dis-
cusses the elimination of emerging contaminants in WWTPs applying
conventional activated sludge treatment (AST) and advanced treatment
processes, such as membrane bioreactors (MBRs) and advanced oxidation
processes (AOPs), as well as during production of drinking water.
# 2003 Published by Elsevier B.V.
Keywords:Acidic pesticides; Acidic pharmaceuticals; Advanced treatment; Emerging
contaminants; Surfactant degradates; Wastewater treatment
1. Introduction
Until the beginning of the 1990s, non-
polar hazardous compounds (i.e. persis-
tent organic pollutants (POPs) and heavy
metals) were a focus of interest and
awareness as priority pollutants, so were
part of intensive monitoring programs.
Today, these compounds are less relevant
for the industrialized countries, since adramatic reduction of emissions has been
achieved through the adoption of appro-
priate measures and the elimination of
the dominant sources of pollution.
However, the emission of so-called
emerging or new unregulated con-
taminants has become an environmental
problem, and there is widespread con-
sensus that this kind of contamination
may require legislative intervention. This
group mainly comprises products used in
large quantities in everyday life, such as
human and veterinary pharmaceuticals,
personal care products, surfactants and
surfactant residues, plasticizers and var-
ious industrial additives. The character-istic of these contaminants is that they do
not need to be persistent in the environ-
ment to cause negative eects, since their
high transformation and removal rates
can be oset by their continuous intro-
duction into the environment. One of the
main sources of emerging contaminants
are untreated urban wastewaters and
WWTP euents (Fig. 1). Most current
WWTPs are not designed to treat these
types of substance and a high portion of
emerging compounds and their metabo-
lites can escape elimination in WWTPs
and enter the aquatic environment via
sewage euents.
The partial or complete closure of water
cycles is an essential part of sustainable
water-resource management, and the
increasing scarcity of pristine waters for
drinking water supply and the growing
consumption of water by industry and
agriculture should be countered by the
ecient, rational utilization of water
resources. One of the options is to
increase the re-use of euents for variouspurposes, especially in industrial and
agro/food production. However, because
of the high cost of the end-of-pipe
approach (i.e. drinking water treatment),
indirect potable re-use requires ecient
treatment of wastewaters prior to their
discharge. Thus, the occurrence of trace
organic contaminants in wastewaters,
their behavior during wastewater treat-
ment and production of drinking water
are key issues that require further study.
Mira Petrovic *,
Susana Gonzalez,
Damia` Barcelo
Department of Environmental
Chemistry, IIQAB-CSIC,
c/Jordi Girona 18-26, E-08034
Barcelona, Spain
*Corresponding author.
Tel.: +34 93 400 6172;
Fax: +34 93 204 5904;
E-mail: [email protected]
Trends in Analytical Chemistry, Vol. 22, No. 10, 2003 Trends
0165-9936/$ - see front matter # 2003 Published by Elsevier B.V. doi:10.1016/S0165-9936(03)01105-1 685
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Many believe that, of all emerging contaminants,
antibiotics are of greatest concern, since their emission
in the environment can increase the occurrence of
resistant bacteria in the environment [1]. However,
other emerging compounds, especially polar ones, such
as acidic pharmaceuticals, acidic pesticides and acidic
metabolites of non-ionic surfactants, also deserve parti-
cular attention. Because of their physico-chemical
properties (high water solubility and often poor degrad-
ability), they are able to penetrate through all natural
ltration steps and man-made treatments, thus pre-
senting a potential risk in drinking water supply [2,3].
Dierent classes of emerging contaminants, mainly
surfactant degradates, pharmaceuticals and personal
care products (PPCPs) and polar pesticides were found
to have rather low elimination rates and have been
detected in WWTP euents and in the receiving surfacewaters. However, for most emerging contaminants,
occurrence, risk assessment and ecotoxicological data
are not available, and it is dicult to predict their fate in
the aquatic environment. Partly, the reason for this is a
lack of analytical methods for their determination at
trace concentrations. Analysis of emerging con-
taminants is a real analytical challenge, not only
because of the diversity of chemical properties of these
compounds, but also because of generally low con-
centrations (usually at part per billion (ppb) or part per
trillion (ppt) levels) and the complexity of matrices.
This article reviews the state-of-the-art in the analy-
sis of several groups of emerging contaminants (acidic
pharmaceuticals, antibacterial agents, acidic pesticides
and surfactant metabolites) in wastewaters. It discusses
various aspects of current liquid chromatography (LC)
mass spectrometry (MS)-(MS) [LC-MS-(MS)] and gas
chromatography(GC)-MS [GC-MS] methodology, includ-
ing sample preparation. It also surveys the elimination
of emerging contaminants in WWTPs by AST and
applying advanced treatment processes, such as MBRs
and AOPs. In addition, it discusses the elimination in
treatmentprocessesatplantsfortreatingdrinkingwater.
2. Analysis of emerging contaminants in
wastewater
One of the major limitations in the analysis of emerging
contaminants remains the lack of methods for quanti-
cation of low concentrations. The prerequisite for
proper risk assessment and monitoring of the quality of
waste, surface and drinking waters is the availability of
multiresidual methods that permit measurement at the
low ng/l level (or even below that). However, these
compounds have received little attention because they
are not on regulatory lists as environmental pollutants.
However, today analytical methodology for dierent
groups of emerging contaminants is being developed
Figure 1. Components of a (partially) closed water cycle with indirect potable re-use.
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and an increasing number of methods is reported in the
literature. Still, analysis of this group of contaminants
requires further improvement in terms of sensitivity
and selectivity, especially for very complex matrices,
such as wastewater.
2.1. Acidic pharmaceuticals
Dierent methods, mainly based on LC-MS and GC-MS,
in combination with either polymer or C18-based solid-
phase extraction (SPE), are being developed for the ana-
lysis of pharmaceutical compounds. However, most
methods are tailored for neutral compounds (e.g. anti-
biotics) and less complex matrices (surface and ground-
water), while only a limited number of papers describe
procedures applicable to the analysis of polar drugs in
wastewater. A survey of analytical methods for the
quantication of regularly used polar pharmaceuticals
in wastewater matrices is given in Table 1.
A typical analytical method includes the use of octa-
decylsilica, polymeric, or hydrophilic-lipophilic balanced(HBL) supports for o-line SPE of water samples, with
either disks or, most frequently, cartridges at low pH
(typically pH=2).
Separation techniques include GC and LC, while, for
detection, MS is the technique most widely employed.
Because of the low volatility of polar pharmaceuticals,
GC-MS analysis requires an additional derivatization,
which makes sample preparation laborious and time
consuming, and also increases the possibility of con-
tamination and errors. Moreover, some compounds are
thermolabile and decompose during GC analysis (e.g.
carbamazepine forms iminostilben as degradation pro-
duct) [4].
As a result, use of LC-MS and LC-MS-MS is increasing.
When reviewing the principal methods for the analysis
of pharmaceuticals in aqueous environmental samples,
Ternes[4]indicated that LC-MS-MS is the technique of
choice for assaying polar pharmaceuticals and their
metabolites. However, he pointed out the diculty in
the enrichment step, as well as the low resolution and
signal suppression in the electrospray (ESI) interface
because of matrix impurities.
Farre et al. [5] compared LC-(ESI)-MS and GC-MS
(after derivatization with BF3-MeOH) for monitoring
some acidic and very polar analgesics (salicylic acid,ketoprofen, naproxen, diclofenac, ibuprofen and gem-
brozil) in surface water and wastewater. Results
showed a good correlation between methods, except for
gembrozil, for which derivatization was not com-
pletely achieved in some samples.
In general, the limits of detection (LODs) achieved
with LC-MS-(MS) methods were slightly higher than
those obtained with GC-MS methods (see Table 1); how-
ever, LC-MS methodology showed advantages in terms
of versatility and sample preparation being less compli-
cated (i.e., derivatization was not needed). Table1.
Metho
ds
fortheana
lysiso
faci
dicp
harmaceutica
lsinwastewaters
Compounds
Extraction
Derivatization
Chromatographic
method
Detection
LOD
(n
g/l)
Reference
Beza
fibrate,
diclofenac,
ibupro
fen,
gem
fibrozil,
carbamezapine
Sequentia
lSPE
(C18+po
lymericsorbent)
LC
MS
2
[48]
Sa
licy
licacid,
ibupro
fen,
ketopro
fen,
naproxen,
beza
fibrate,
diclofenac
SPE(po
lymericsorbent)
LC
MS
5
56
[5]
Beza
fibrate,
clofibricacid,
diclofenac,
fenopro
fen,
gem
fibrozil,
ibupro
fen,
inomethacin,ketopro
fen,
naproxen
SPE(C18)
LC
MS
MS
5
20
[49]
Beza
fibrate,
clofibricacid,
ibupro
fen
SPE(MCXorpo
lymericso
rbent)
LC
MS
MS
0.0
16
2.1
8
[50]
Ibupro
fen,
clofibricacid,
ketopro
fen,
naproxen,
diclofenac
SPE(HLB)
Diazomethane
GC
MS
0.3
4.5
[51]
Clofibricacid,
diclofenac,
ibupro
fen,p
henazone,
propyp
henazone
SPE(C18)
Pentafloro
benzy
lbromide
GC
MS
0.6
20
[52]
Clofibricacid,
naproxen,
ibupro
fen
SPE(po
larEmpore
disk)
BSTFA
(bis(trimethy
lsily
l)-tri
fluoroacetam
ide
)
GC
MS
0.4
2.6
[53]
Ibupro
fen,
naproxen,
ketopro
fen,
tolf
enamicacid,
diclofenac,
mec
lofenamicacid
SPE(HLB)
MTBSTFA
(N-methy
l-N-(
tert-butyldimethylsily
l)
trifluoroacetamide
)
GC
MS
20
[54]
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Table 2 summarizes the quantitation and qualier
ions used by the various authors for the determination
of polar drugs in wastewaters using selected ion mon-
itoring (SIM) or multiple reaction monitoring (MRM).
The use of triple-quadrupole MS in LC analysis has sub-
stantially increased the selectivity and the sensitivity of
the determination, resulting in LODs better than those
in single-quadrupole LC-MS. Acidic drugs were usually
detected using an ESI interface under negative ioni-
zation conditions and deprotonated molecules were
chosen as precursor ions. Typical fragmentation pat-
terns obtained with LC-MS-(MS) showed a loss of CO2(or loss of the acidic moiety), with a limited number of
other fragments. For example, for diclofenac, ibuprofen
and ketoprofen, the product ions generated by loss of
CO2 were the only fragment ions formed.
2.2. Acidic pesticides
Chlorinated phenoxy acid herbicides account for the
majority of pesticides used worldwide, and their pre-
sence in environmental waters is well documented.
However, their behavior during wastewater treatment
has rarely been studied. This group includes, for exam-
ple, mecoprop (MCPP), MCPA, 2,4-D, 2,4-DP 2,4,5-T,
2,4-DB. These compounds are characterized by high
polarity and thermal lability. For these reasons, LC is
generally more suitable for their analysis. However, the
methods used to determine chlorinated phenoxy acid
Table 2. Quantitation and diagnostic ions (m/z) used for the LC-MS and GC-MS, and base peaks of precursor and product ions used for LC-MS-MS analysisof acidic pharmaceuticals in wastewaters. Data compiled from references listed inTable 1
Compound Analytical method Ionization mode MS MS-MS
SIM ions Precursor (m/z) Product 1 (m/z) Product 2 (m/z)
Ibuprofen LC-MS NI 205, 161LC-MS-MS NI 205M-H 161M-H-CO2
GC-MS Positive EI 177, 220a
161, 343, 386b
263, 278, 234c
Diclofenac LC-MS NI 294, 250, 232LC-MS-MS NI 294M-H 205M-H-CO2
GC-MS Positive EI 214, 309a
214, 216, 475b
352/354/356d
Clofibric acid LC-MS NI 213, 127LC-MS-MS NI 213M-H 127M-H-CO2
85C4H5O2
GC-MS Positive EI 128, 228a
128, 130, 394b
128, 143, 286c
Benzafibrate LC-MS NI 360, 274LC-MS-MS NI 360M-H 274M-H-C4H6O2
154M-H-C12H14O3
GC-MS Positive EI 128, 228a
128, 130, 394b
Gemfibrozil LC-MS NI 249, 121LC-MS-MS NI 249M-H 121M-H-C7H12O2
Ketoprofen LC-MS NI 253, 209, 197
LC-MS-MS NI 253M-H 209M-H-CO2GC-MS Positive EI 209,268a
311d
Naproxen LC-MS NI 229, 185, 173, 170LC-MS-MS NI 229M-H 185M-H-CO2
170M-H-C2H3O2
GC-MS Positive EI 185, 244a
243,302, 185c
287d
aDiazomethane derivative.bPentafluorobenzyl derivative.cTrimethylsilyl derivative.dTert-butyldimethylsilyl derivative.
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herbicides are still dominated by GC with either elec-
tron capture detection (ECD) or MS detection. The main
disadvantage of GC analysis is that it requires prior deri-
vatization step, usually using highly toxic and carcino-
genic diazomethane or, less frequently used, acid
anhydrides, benzyl halides and alkylchloroformates.
The injection-port derivatization with an ion-pair
reagent has been successfully applied[6], as well as in
situderivatization prior to solid-phase microextraction
(SPME) [7].
Alternative methods based on LC-ESI-MS have been
proposed. When using LC-MS-(MS), phenoxy acid her-
bicides are detected under negative ionization condi-
tions, typically yielding [M-H]- ion and one abundant
fragment formed by the loss of the acidic moiety[8,9],
as shown in Fig. 2 for MCPP, 2,4DP and2,4,5T.
Recently, in-tube SPME followed by LC-MS was
applied for the determination of six chlorinated phen-
oxy acid herbicides[10]. With river water, LODs were
5^30 ng/l, but wastewater was not tested.
Figure 2. MS-MS spectra and the proposed fragmentation pattern of: (a) MCPP (precursor ion m/z 213); (b) Dichlorprop (2,4-DP) (precursor ion m/z 233);
and, (c) 2,4,5-T (precursor ion m/z 253).
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2.3. Antiseptics
Several methods have been proposed for the determina-
tion of triclosan (5-chloro-2-[2,4-dichlorophenoxy]
phenol), which is used as an antiseptic agent in a vast
array of personal care (e.g. toothpaste, acne cream,
deodorant, shampoo, toilet soap) and consumer pro-
ducts (childrens toys, footwear, kitchen cutting
boards).
A method based on diazomethane derivatization and
GC-ECD was applied for quantication of triclosan in
the wastewater of a slaughterhouse [11].
Lindstro m et al. [12] detected triclosan and methyl
triclosan in lakes and in a river in Switzerland applying
either SPE (macroporous polymeric adsorbent), dia-
zoethane derivatization, silica clean-up and GC-MS
analysis or passive sampling with semi-permeable
membrane devices (SPMDs). LODs varied with the
sample matrix and were
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2.4. Alkylphenolic compounds
The trace analysis of alkylphenol ethoxylates (APEOs)
and their acidic metabolites by LC-MS or LC-MS-MS
using atmospheric pressure chemical ionization (APCI)
and ESI was recently reviewed by Petrovic et al. [15,16]
and the analytical performances for oligomeric mix-
tures of APEOs discussed. Generally, an ESI interface is
used for the analysis of alkylphenolic compounds
because of its higher sensitivity, especially for alkyl-
phenols and carboxylated compounds.
Alkylphenoxy carboxylates (APECs) were detected in
both NI and PI modes. In the NI mode, using ESI, APECs
give two types of ions:
one corresponds to the deprotonated molecule
[MH] (m/z 277, 321, 263 and 307, corre-
sponding to nonylphenol carboxylate (NPE1C),
nonylphenol ethoxycarboxylate (NPE2C), octyl-
phenol carboxylate (OPE1C), and octylphenol
ethoxycarboxylate (OPE2C), respectively); and, the other corresponds to deprotonated alkyl-
phenols[17].
The relative abundance of these two ions depends on
the extraction voltage. In the presence of ammonium
acetate and when using an APCI under PI conditions,
NPE1C gave [M+NH4]+ ions at m/z 296, while NPE2C
gave [M+NH4]+ ion atm/z 340 [18].
LC-ESI-MS was also applied for the analysis of the
dicarboxylated breakdown products [carboxylated
alkylphenoxy carboxylates (CAPECs)] in wastewaters
[19,20]. However, the identication of these com-
pounds using LC-MS, under conditions giving only
molecular ions, is dicult, since CAnPEmCs have the
same molecular mass as APECs but have one ethoxy
unit less and a shorter alkyl chain (An1PEm1C).
Moreover, since some compounds partly co-elute, the
unequivocal assignment of the individual fragments
can be accomplished only by using LC-MS-MS. Typical
fragmentation patterns obtained with LC-ESI-MS-MS
showed the formation of the carboxy-alkylphenoxy
fragment, with the additionally loss of CO2or an acetic
acid group, in the case of CA5PE12C leading tom/z149
and 133 fragments [19].
MS-MS spectra of APECs [19,21,22] show intensesignals at m/z 219 (for NPECs) andm/z 205 (for OPECs),
which are produced after the loss of the carboxylated
(ethoxy) moiety, while sequential fragmentation of the
alkyl chain resulted in ions with m/z 133 and 147.
To overcome the problem of low volatility of acidic
alkylphenolic compounds, various o-line and on-line
derivatization protocols have been developed. O-line
derivatization to corresponding triemethylsilyl ethers,
methyl ethers, acetyl esters, pentauorobenzoyl or hep-
tauorobutyl esters, respectively, was applied as a
common approach in GC-MS.
On-line direct GC injection-port derivatization using
ion-pair reagents (tetraalkylammonium salts), has
been also reported [23]. The most signicant ions in
GC-(EI)-MS of methylated NPECs were fragments pro-
duced by rupture of the benzylic bond in the branched
nonyl side-chain [23^25]. GC-CI-MS spectra of the
NPECs with isobutane as reagent gas showed char-
acteristic hydride ion-abstracted fragment ions shifted
by 1 Da from those in the corresponding EI mass spectra
[22]. When using ammonia as reagent gas, intense
ammonia-molecular ion adducts of the methyl esters,
with little or no secondary fragmentation, were repor-
ted for NPECs[26]. The ions selected were as follows:
m/z 246, 310, 354 and 398 for NPE1C, NPE2C,
NPE3C and NPE4C, respectively.
3. Elimination by AST
The present state-of-the-art of wastewater treatmentinvolves the AST process preceded by conventional
physico-chemical pre-treatment steps. Table 3 sum-
marizes data on the elimination of emerging con-
taminants in WWTPs.
3.1. PPCPs
Daughton and Ternes [1] reviewed the occurrence of
over 50 individual PPCPs (metabolites from more than
10 broad classes of therapeutic agents or personal care
products in environmental samples) mainly in WWTP
euents, surface and ground water and much less fre-
quently in drinking water. Acidic drugs comprised the
major group of PPCPs detected in municipal WWTPs
and, among them, bezabrate, naproxen, and ibupro-
fen were most abundant (concentrations up to 4.6 mg/l
in German municipal WWTPs).
Tixier et al.[27]found that carbamezapine presented
the highest daily load from the WWTP into Lake Grei-
fensee (Switzerland), followed by diclofenac and
naproxen. Their elimination during passage through a
municipal sewage treatment in most cases was found to
be quite low (see Table 3), in the range 35^90%, and
some compounds, such as carbamazepine, exhibited an
extremely low removal (only 7%) [28]. Consequently,
through sewage euents, PPCPs can enter receivingsurface waters and thus present a risk in the production
of drinking water. For example, clobric acid, a metabo-
lite of three lipid regulating agents (clobrate, etobrate
and fenobrate), has been identied in river and ground
water and even in drinking water at concentrations up
to 165 ng/l [29,30].
3.2. Acidic pesticides
Chlorinated phenoxy acids are widely used in agri-
culture, but also as herbicides on lawns, algicides in
paints and coatings and roof-protection agents in
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at-roof sealants. As a result, residues of these sub-
stances are introduced into the aquatic system through
dierent pathways.For example, inthe catchmentareaof
Lake Greifensee, 65% of MCPP originated from WWTPs
andtheremaining35%fromdiusesources[31].
Degradation of acidic pesticides under laboratory
conditions is well studied, but there are few publica-
tions dealing with their behavior in real WWTPs. Gen-
erally, AST was found to be ineective in removing
chlorinated phenoxy acid herbicides from settled sew-
age. However, under laboratory conditions MCPP
proved to be biodegradable (nearly 100%); however,
this requires a long adaptation time (lag-phase) of acti-
vated sludge[32]. In real WWTPs, this presents a majordiculty since, like the majority of herbicides, MCPP is
applied only during a short growth period of plants,
which means that WWTPs that contain a non-adapted
activated sludge, receive shock-loads of herbicides,
which will not be eliminated.
A long acclimatization period (about 4 months) was
also observed in a bench-scale study using sequencing
batch reactors before 2,4-D biodegradation was estab-
lished [33]. Subsequently, at steady-state operation,
all reactors achieved practically complete removal
(>99%) of 2,4-D.
3.3. Alkylphenolic surfactants
Although their environmental acceptability is strongly
disputed, APEOs are still among the most widely used
non-ionic surfactants. Currently, under optimized con-
ditions, more than 90^95% of these surfactants are
eliminated by conventional biological wastewater
treatment (normally AST). Even if such high elimina-
tion rates are achieved, the principal problem is the for-
mation of treatment-resistant metabolites out of the
parent surfactants. The widespread incidence of APEO-
derived compounds in treated wastewaters and the sub-
sequent disposal of euents into aquatic system raise
concerns about the impact of these compounds on the
environment. Studies have shown that their neutral(alkylphenols and short ethoxy chain ethoxylates) and
acidic treatment-resistant metabolites (APECs) possess
the ability to mimic natural hormones by interacting
with the estrogen receptor.
It was estimated that 60^65% of all nonylphenolic
compounds introduced into WWTPs are discharged
into the environment 19% as carboxylated deriva-
tives, 11% as lipophilic nonylphenol ethoxylate
(NP1EO) and nonylphenol diethoxylate (NP2EO), 25%
as nonylphenol (NP) and 8% as non-transformed
nonylphenol ethoxylates (NPEOs) [34].
Table 3. Elimination at WWTPs (AST). Data complied from references [12,28,36,51,5457]
Compound Averageelimination (%)a
Effluentconcentrations(g/l)
Main degradationproducts
Observation
Non-ionic surfactantsAlkylphenol ethoxylates 9099
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However, contrary to the general belief that NPECs
are the refractory metabolites, Di Corcia et al. [35]
found that CAPECs are the dominant products of NPEO
biotransformation. By averaging data relative to the
treated euents of ve major activated sludge WWTPs
of Rome (Italy) over 4 months, relative abundances of
NPEOs (nEO =1 and 2), NPECs and CAPECs were found
to be respectively 102%, 245%and667%.
The concentrations of the acidic metabolites, NPECs
and CAPECs typically are in the low mg/l range. How-
ever, high values (up to several hundred mg/l) are detec-
ted in euents of WWTPs receiving industrial
wastewaters, especially from tannery, textile, pulp and
paper industries [36].
4. Elimination by modern WWTPs
Although adopted as the best available technology; bio-
logical treatment eects only partial removal of a widerange of emerging contaminants, especially polar ones,
which are discharged into the nal euent. Thus, it has
become evident that the application of more enhanced
technologies may be crucial to fulll the requirements
to recycle municipal and industrial wastewaters as
drinking water. In recent years, there have been studies
of new technologies for not only wastewater treatment
but also production of drinking water. Among them
membrane treatment, using both biological (MBRs) and
non-biological processes (reversed osmosis, ultraltra-
tion, nanoltration), and AOPs are most frequently
considered as they may be appropriate for removing
trace concentrations of emerging polar contaminants.
4.1. Membrane processes
MBR technology is considered the most promising
development in microbiological wastewater treatment.
Now, when economic reasons no longer limit the appli-
cation of MBRsin industrialand municipal WWTPs [37],
andnew requirements arebeingset forwastewatertreat-
ment, MBRs may be key in direct or indirect recycling of
wastewaters, because of two of their characteristics:
(a) the low sludge load in terms of BOD, so that the
bacteria are forced to mineralize poorly degrad-able organic compounds; and
(b) the long life of the sludge gives the bacteria time
to adapt to the treatment-resistant substances
[38,39].
However, although many articles have reported on
the application of MBRs to the treatment of urban and
industrial wastewaters, there are few papers reporting
on the behavior of emerging contaminants during MBR
treatment, and all of those deal with nonylphenolic
compounds.
Using an MBR unit that comprises three bioreactors
and an external ultraltration unit followed by gran-
ular activated carbon (GAC) adsorption, Witgens et al.
[40]reported the removal of more than 90% of NP in
wastewater from a waste-dump leachate plant. The use
of a set of laboratory nanoltration membranes resul-
ted in the retention of more than 70% of NP and this
process was regarded as an alternative for the nal
treatment of MBR euents.
Li et al.[41]used GC-MS and LC-MS-MS to assess the
elimination eciency in a membrane-assisted biologi-
cal WWTP. The results showed that, compared to con-
ventional WWTPs, membrane-assisted biological
treatment with biomass concentrations of about 20 g/l
could improve the eciency of eliminating NPEOs (and
other ionic and non-ionic surfactants), but could not
entirely stop the dischargewith the permeates.
4.2. Treatment by AOPs
There have been studies of AOPs, which use a combi-nation of ozone with other oxidation agents (UV radia-
tion, hydrogen peroxide, TiO2) to enhance the
degradation of polar pharmaceuticals [42^44] and
NPEO metabolites [45].
Ternes et al.[44]used a pilot plant for ozonation and
UV disinfection of euents from a German municipal
WWTP containing antibiotics, beta blockers, anti-
phlogistics, lipid-regulator metabolites, musk frag-
rances and iodinated X-ray contrast media. When
10^15 mg/l ozone was used (contact time, 18 min), no
pharmaceuticals were detected. However, the ionic
iodinated X-ray contrast compounds exhibited removal
eciencies no higher than 14%.
In another study [43], ozonation was demon-
strated to be a suitable tool for carbamazepine abate-
ment, even under the process conditions usually
adopted in drinking water facilities. However, despite
good primary elimination, a low degree of mineraliza-
tion was observed and there was no proper total carbon
balance, even after prolonged ozonation, which
indicated the presence of unidentied degradation
products.
However, the degradation eciency of an AOP is lim-
ited by the radical scavenging capacity of the matrix of
the treated water. Thus, for sucient degradation of thepharmaceuticals (>90%) from wastewater, the ozone
concentration has to be equal to the dissolved organic
carbon (DOC) value[42],which means that economic
considerations have to underpin the feasibility of the
process for wastewater treatment.
Recently, using a laboratory-scale reactor, Ike et al.
[45] determined that the eectiveness of ozone treat-
ment in the degradation of NPEO metabolites follows
the order: NPE1C>>NP>NP1EO. Acidic metabolites
were completely degraded within 4^6 min (initial con-
centration, 0.4^1.0 mg/l), the NP concentrations were
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reduced by 75^80% in 6 min, while only 25^50% of
NP1EOwas eliminatedin thesame time.
5. Elimination in drinking water-treatment
plants
The occurrence of organic micro-contaminants in raw
water and their removal in the course of production of
drinking water and possible formation of disinfection
by-products are key issues in relation to the quality of
drinking water. Although, compounds discussed in this
review are currently not regulated in drinking water
directives, precautionary principles should be
employed, and the removal of all organic micro-con-
taminants should be as high as possible. However, sev-
eral studies have shown that the removal of emerging
polar contaminants during drinking water treatment is
incomplete.
The elimination of selected pharmaceuticals (clobric
acid, diclofenac, carbamezapine, bezabrate) during
drinking water treatment was investigated in the
laboratory, at the pilot-plant scale and in real water-
works in Germany[46].Sand ltration under aerobic
and anoxic conditions, as well as occulation using
iron(III) chloride, did not signicantly eliminate the
target pharmaceuticals, while ozonation was quite
eective in eliminating these polar compounds. Diclofe-
nac and carbamezapine were reduced by more than
90%, bezabrate was eliminated by 50%, while clobric
acid was stable even at high ozone doze. Filtration with
granular activated carbon (GAC) under waterworks con-
ditions was very eective in removing pharmaceuticals,
apart from clobric acid,less of which was adsorbed.
Figure 4. Fate of nonylphenolic compounds during production of drinking water. (a) Total concentration of nonylphenolic compounds and their elimination
during different treatment steps at waterworks Sant Joan Despi` (Barcelona, Spain); (b) Average composition (calculated on a molar basis) of nonylphenolic
compounds in raw water; and, (c) Average composition (calculated on a molar basis) of nonylphenolic compounds in pre-chlorinated water.
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The behavior of polar alkylphenolic compounds dur-
ing processing of contaminated water in waterworks
and their possible occurrence in treated water was
rarely considered to be of interest and there are hardly
any data available for drinking water.
The elimination of neutral and acidic nonylphenolic
compounds and their brominated and chlorinated deri-
vatives during drinking water-treatment processes at
the waterworks that supply drinking water to Barce-
lona (Spain) was investigated utilizing a very sensitive
LC-MS-MS method [47]. The concentration of total
nonylphenolic compounds NPECs (nEO=0^1), NPEOs
(nEO=0^1) and NP in raw water from the Llobregat
river entering the waterworks was in the range
8.3^21.6 mg/l, with NPE2C being the most abundant
compound. Pre-chlorination reduced the concen-
tration of short-ethoxy chain NPECs and NPEOs by
25^35%, and of NP by almost 90%. However, this
reduction was partly because of their transformation
to halogenated derivatives. After pre-chlorination,halogenated nonylphenolic compounds represented
approximately 13% of the total metabolite pool, of
which 97% were in the form of brominated acidic
metabolites. The eciency of further treatment steps to
eliminate nonylphenolic compounds (calculated for the
sum of all short-ethoxy chain metabolites, including
halogenated derivatives) was as follows:
settling and occulation followed by rapid sand
ltration (7%);
ozonation (87%);
GAC ltration (73%); and,
nal disinfection with chlorine (43%), resulting
in overall elimination in the range 96^99%
(mean 98% for four sampling dates), as shown in
Fig. 4.
6. Conclusions
The application of advanced LC-MS and GC-MS tech-
nologies to environmental analysis has allowed the
determination of a broader range of compounds and
thus permitted more comprehensive assessment ofenvironmental contaminants. Among the various com-
pounds considered as emerging pollutants, acidic phar-
maceuticals, surfactant degradates and acidic
pesticides are of particular concern, because of both
their ubiquity in the aquatic environment and health
concerns.
Elimination of these emerging contaminants during
wastewater and drinking water treatment is not satis-
factory, so control of improved treatment has to be
strict to ensure that the proportion of these micro-con-
taminants removed is as high as possible. Thus, in view
of the possible re-use of WWTP euents, more research
is needed to evaluate the fate of emerging contaminants
and their eects in the aquatic environment. Moreover,
as disinfection processes (either chlorination or ozona-
tion) potentially shift the assessment of the risk of
human consumption of the parent compound to its
degradation products, generic analytical protocols will
have to be developed for the simultaneous determina-
tion of parent compounds and their metabolites.
Acknowledgements
The work described in this article was supported by the
EU Project P-THREE (EVK1-CT-2002-00116) and by
the Spanish Ministerio de Ciencia y Tecnologia
(PPQ2002-10945-E). M. Petrovic acknowledges the
Ramon y Cajal contract from the Spanish MCyT. S.
Gonzalez acknowledges the grant from the Spanish
MCyT (PPQ2001-1805-CO3-01).
References
[1] C.G. Daughton, A.T. Ternes, Environ. Health Perspect. 107
(1999) 907.
[2 ] T. P. K ne pp er , F . S ac he r, F. T. L an ge , H .J . B ra uc h,
F. Karrenbrock, O. Roeden, K. Linder, Waste Manage. 19
(1999) 77.
[3] I. Janssens, T. Tanghe, W. Verstraete, Water Sci. Technol. 35
(1997) 12.
[4] T.A. Ternes, Trends Anal. Chem. 20 (2001) 419.
[5] M. Farre, I. Ferrer, A. Ginebreda, M. Figueras, L. Olivella,
L. Tirapu, M. Vilanova, D. Barcelo, J. Chromatogr. A 938(2001) 187.
[6] W.H. Ding, C.H. Liu, S.P. Yeh, J. Chromatogr. A 896 (2000)
111.
[7] T. Henriksen, B. Svensmark, B. Lindhardt, R.K. Juhler,
Chemosphere 44 (2001) 1531.
[8] O. Pozo, E. Pitarch, J.V. Sancho, F. Hernandez, J. Chromatogr.
A 923 (2001) 75.
[9] R. Bossi, K.V. Vejrup, B.B. Morgensen, W.A.H. Asam,
J. Ch romat ogr. A 957 (2002 ) 27.
[10] M. Takino, S. Daishima, T. Nakahara, Analyst (Cambridge,
U.K.) 126 (2001) 602.
[11] M. Graovac, M. Todorovic, M.I. Trtanj, M.M. Kopecni,
J.J. C omor, J. Ch romato gr. A 705 (1995 ) 313 .
[12] A. Lindstrom, I.J. Buerge, T. Poiger, P.A. Bergqvist,
M.D. Mu ller, H.R. Buser, Environ. Sci. Technol. 36 (2002)
2322.
[13] D.C. McAvoy, B. Schatowitz, M. Jacob, A. Hauk, W.S. Eckho,
Environ. Toxicol. Chem. 21 (2002) 1323.
[14] A. Agu era, A.R. Fernandez-Alba, L. Piedra, M. Mezcua,
M.J. Gomez, Anal. Chim. Acta 480 (2003) 193.
[15] M. Petrovic, D. Barcelo, J. Mass. Spectrom. 36 (2001) 1173.
[16] M. Petrovic, E. Eljarrat, M. Lopez de Alda, D. Barcelo,
J. Ch romat ogr. A . 974 (2002 ) 23.
[17] M. Petrovic, A. Diaz, F. Ventura, D. Barcelo, Anal. Chem. 73
(2001) 5886.
[18] A. Di Corcia, J. Chromatogr. A 794 (1998) 165.
[19] N. Jonkers, T.P. Knepper, P. de Voogt, Environ. Sci. Technol.
35 (2001) 335.
Trends in Analytical Chemistry, Vol. 22, No. 10, 2003 Trends
http://www.elsevier.com/locate/trac 695
-
7/25/2019 anlisis y remosin de contaminantes en aguas
12/12
[20] A. Di Corcia, A. Constantino, C. Crescenzi, E. Marinoni,
R. Samperi, Environ. Sci. Technol. 32 (1998) 2401.
[21] M. Petrovic, A. Diaz, F. Ventura, D. Barcelo, J. Am. Soc. Mass
Spectrom. 14 (2003) 516.
[22] C. Hao, T.R. Croley, R.E. March, B.G. Koenig, C.D. Metcalfe,
J. Mas s. Sp ectrom . 35 (2000 ) 818 .
[23] W.H. Ding, C.T. Chen, J. Chromatogr. A 862 (1999) 113.
[24] M. Ahel, T. Conrad, W. Giger, Environ. Sci. Technol. 21
(1987) 697.[25] E. Stephanou, M. Reinhard, H.A. Ball, Biomed. Environ. Mass
Spectrom. 15 (1988) 275.
[26] J.A. Field, R.L. Reed, Environ. Sci. Technol. 30 (1996) 3544.
[27] C. Tixier, H.P. Singer, S. O llers, S.R. Mu ller, Environ. Sci.
Technol. 37 (2003) 1061.
[28] T.A. Ternes, Water Res. 32 (1998) 3245.
[29] H.J. Stan, M. Linkerha nger, Vom Wasser 83 (1994) 57.
[30] T. Heberer, H.J. Stand, Vom Wasser 86 (1996) 19.
[31] A.C. Gerecke, M. Scharer, H.P. Singer, S.R. Mu ller,
R.P. Schwarzenbach, M. Sagesser, U. Ochsenbein, G. Popow,
Chemosphere 48 (2002) 307.
[32] L. Nitscheke, A. Wilk, W. Schu ssler, G. Metzner, G. Lind,
Chemosphere 39 (1999) 2313.
[33] S.S. Mangat, P. Elefsiniotis, Water Res. 33 (1999) 861.
[34] M. Ahel, W. Giger, M. Koch, Water Res. 28 (1994) 1131.[35] A. Di Corcia, R. Cavallo, C. Crescenzi, M. Nazzari, Environ. Sci.
Technol. 34 (2000) 3914.
[36] M. Petrovic, D. Barcelo, Concentrations of surfactants in
wastewater treatment plants, in: T. Knepper, P. de Vooght,
D. Barcelo (Editors), Analysis and Fate of Surfactants in the
Aquatic Environment, Elsevier, Amsterdam, The Netherlands,
2003, pp. 655^673.
[37] M. Gander, B. Jeerson, S. Judd, Sep. Purif. Technol. 18 (2000)
119.
[38] T.A. Peters, R. Gunther, K. Vossenkaul, Filtr. Sep. 2000
(2000) 18.
[39] P. Co te, H. Buisson, C. Pound, G. Arakaki, Desalination 113
(1997) 189.
[40] T. Wintgens, M. Gellenkemper, T. Melin, Desalination 146
(2002) 387.
[41] H.Q. Li, F. Jiku, H.F. Schroder, J. Chromatogr. A 889 (2000)
155.
[42] C. Zwiener, F.H. Frimmel, Water Res. 34 (2000) 1881.
[43] R. Andreozzi, R. Marotta, G. Pinto, A. Pollio, Water Res. 36
(2002) 2869.[44] T.A. Ternes, J. Stu ber, N. Herrmann, D. McDowell, A. Ried,
M. Kampmann, B. Teiser, Water Res. 37 (2003) 1976.
[45] M. Ike, M. Asano, F.D. Belkada, S. Tsunoi, M. Tanaka,
M. Fujita, Water Sci. Technol. 46 (2002) 127.
[46] T.A. Ternes, Environ. Sci. Technol. 36 (2002) 3855.
[47] M. Petrovic, A. Diaz, F. Ventura, D. Barcelo, Environ. Sci.
Technol. 37 (2002) 4442.
[48] R.Loos,G. Hanke,S.J.Eisenreich,J. Environ.Monit.5 (2003)384.
[49] X.-S. Miao, B.G. Koenig, C.D. Metcalfe, J. Chromatogr. A 952
(2002) 139.
[50] D. Calamari, E. Zuccato, S. Castiglioni, R. Bagnati, R. Fanelli,
Environ. Sci. Technol. 37 (2003) 1241.
[51] S. O llers, H.P. Singer , P. Fa ssler, S.R. Mu ller, J. Chr omatogr. A
911 (2001) 225.
[52] V. Koutsouba, Th. Heberer, B. Fuhrmann, K. Schmidt-Baum-ler, D. Tsipi, A. Hiskia, Chemosphere 51 (2003) 69.
[53] G.R. Boyd, H. Reemtsma, D.A. Grimm, S. Mitra, Sci. Total
Environ. 311 (2003) 135.
[54] I. Rodriguez, J.B. Quintana, J. Carpintero, A.M. Carro,
R.A. Lorenzo, R. Cela, J. Chromatogr. A 985 (2003) 265.
[55] B. Ferrari, N. Paxeus, R.L. Giudice, A. Pollio, J. Garric, Ecotox-
icol. Environ. Safety, 55 (2003) 359.
[56] M. Stumpf, T.A. Ternes, R.D. Wilken, S.V. Rodrigues,
W. Baumann, Sci. Total Environ. 225 (1999) 135.
[57] R.K. Juhler, S.R. Sorensen, L. Larsen, Water Res. 35 (2001)
1371.
Trends Trends in Analytical Chemistry, Vol. 22, No. 10, 2003
696 http://www.elsevier.com/locate/trac