Removal of cosmetic ingredients and pharmaceuticals in
Marta Carballa, Francisco OmilÃ, Juan M. Lema
School of Engineering, Department of Chemical Engineering, University of Santiago de Compostela,
Received 5 November 2004; received in revised form 12 September 2005; accepted 12 September 2005
Two physico-chemical processes, coagulation–flocculation and flotation, have been assessed for enhancing the
removal of some selected pharmaceutical and personal care products (PPCPs) present in sewage. Eight compounds,representative of three main groups of PPCPs according to their physico-chemical properties, have been selected:lipophilic compounds (the synthetic musks Galaxolide and Tonalide), neutral compounds (the tranquillizer Diazepamand the antiepileptic Carbamazepine) and acidic compounds (the anti-inflammatories Ibuprofen, Naproxen andDiclofenac). During the coagulation–flocculation assays, the main parameters considered were the selection of theadditives, their doses and the temperature of operation (12 or 25 1C). Musks—which are highly lipophilic andDiclofenac—with significant sorption affinity—were removed around 50–70% at both temperatures independently ofthe dose and type of coagulant used. However, the rest of the compounds, which are more hydrophilic, were affected toa lesser degree (with maximum reductions below 25%). The exceptions to this behavior were Carbamazepine andIbuprofen, which were not removed under any condition tested. During the flotation assays, the parameters studiedwere the initial content of fat in wastewaters and temperature. Again, musks were removed to a greater degree(35–60%), followed by Diazepam (40–50%) and Diclofenac (20–45%) and, to a lesser extent, Carbamazepine(20–35%), Ibuprofen (10–25%) and Naproxen (10–30%). The best results were always obtained at 25 1C, although insome cases the operation at 12 1C gave similar results. The removal of musks and neutral compounds was higher inwastewaters with a high fat content (around 150 mg lÀ1). r 2005 Elsevier Ltd. All rights reserved.
Keywords: Pharmaceuticals; Musks; Sewage; Coagulation–flocculation; Flotation; Adsorption; Fat; Temperature
PPCPs comprise allprescription and over-the-counter drugs, diagnostic
Pharmaceuticals and personal care products (PPCPs)
agents, and other consumer chemicals, such as poly-
constitute a diverse group of chemicals that have
cyclic musk compounds frequently used as fragrances in
recently been recognized as particular contaminants of
perfumes and other household products.
the aquatic environment, especially in urbanized areas
Due to the large amount of PPCPs consumed in
developed societies, significant concentrations of these
Corresponding author. Tel.: +34 981 59 44 88x16778;
E-mail address: [email protected] (F. Omil).
However, conventional sewage treatment plants
0043-1354/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.watres.2005.09.018
M. Carballa et al. / Water Research 39 (2005) 4790–4796
(STPs) have been reported not to be an effective barrier
dissolved in water. However, some limitations have been
to these substances because of their low concentrations
and specific metabolic properties (There-
) for the applicability of these coefficients to explain
fore, those compounds which resist the treatment
the sorption behavior of some PPCPs. Therefore, the
processes commonly used in STPs or other transforma-
solid–water distribution coefficient (Kd), defined as the
tions which can naturally occur in the environment, can
ratio between the concentrations of a substance in the
end up in surface and groundwaters, as well as in
solid and in the aqueous phase at equilibrium conditions
(Eq. (1)), has been proposed as the most suitable
Different mechanisms, such as sorption, biodegrada-
tion, volatilization and fotooxidation, can be considered
for PPCPs removal in STPs. Although in many cases,the differences between them cannot be easily distin-
) have concluded that only two ofthem, microbial degradation and sorption to suspended
where Kd is the solid–water distribution coefficient
solids, are really relevant. The effectiveness of these
removal mechanisms greatly depends on the physico-
(mg PPCP kg solidÀ1); and S the concentration in the
chemical properties and the chemical structure of each
This coefficient takes into account the two main
sorption mechanisms: absorption (hydrophobic interac-tions characterized by the Kow value) and adsorption
(electrostatic interactions related to the substancetendency to be ionized or dissociated in aqueous phase,
The sorption of micropollutants onto solids and,
which is characterized by the dissociation constant,
accordingly, their behavior during the physico-chemical
treatment, depends basically on their physico-chemical
properties, such as lipophilicity or acidity. Two types of
PPCPs can be divided into three main groups: lipophilic
coefficients have been mostly used to determine the
(with high Kow values), neutral (non-ionic) and acidic
sorption effectiveness and the affinity of a given
(hydrophilic and ionic) compounds. Substances from
substance to organic matter: the octanol-water partition
different therapeutical classes and representative of each
coefficient (Kow) and the organic carbon partition
group have been considered in this work (): two
coefficient (Koc). Kow is defined as the ratio between
fragrances (Galaxolide and Tonalide), one tranquillizer
the equilibrium concentrations of a certain compound in
(Diazepam), one antiepileptic (Carbamazepine) and
octanol and water at a specific temperature and Koc
three anti-inflammatories (Ibuprofen, Naproxen and
relates the concentrations sorbed to organic carbon and
Table 1Physico-chemical properties of the PPCPs considered in this work (water solubility in g lÀ1; Kd in l kgÀ1)
a. bcd. efThe Kd value for Naproxen has been assumed based on its similar properties with Ibuprofen and other Kd measurements in digested
M. Carballa et al. / Water Research 39 (2005) 4790–4796
Galaxolide and Tonalide are very lipophilic com-
as the type and dose of coagulant, the fat content of the
pounds with log Kow values around 5.5–6.0. However,
wastewaters and the temperature has been studied.
while Carbamazepine and Diazepam are neutral sub-stances, as derived from their chemical structure, theanti-inflammatories are very acidic compounds (low pKa
The wastewaters used in this work were collected from
Coagulation–flocculation processes enhance the re-
an urban STP located in Santiago de Compostela (NW
moval of suspended solids and colloids, because the
of Spain). The STP, which was surveyed in a previous
addition of metal salts or organic compounds causes the
agglomeration of these particles, thus allowing their
inhabitants approximately and comprises three main
elimination by decantation or filtration
sections: pre-treatment (coarse/fine screening and grit/fat
removal), primary treatment (sedimentation) and biolo-
Lipophilic trace pollutants in water and wastewater
gical treatment (conventional activated sludge). The inlet
treatment systems are likely to be found associated with
flow to the primary clarifier was used for coagulation–
colloids because in natural systems most colloids have
flocculation experiments, whereas the inlet to the fat
separator was used for flotation assays. The main
addition, positive charged molecules can be associated
characteristics of the wastewater are: total solids (TS),
to these colloids by means of low strength Van der
500–900 mg lÀ1; volatile solids (VS), 200–500 mg lÀ1; total
suspended solids (TSS), 100–400 mg lÀ1; volatile sus-
Literature information about the removal of PPCPs
pended solids (VSS); 100–300 mg lÀ1; total chemical
by coagulation–flocculation processes is scarce. When
oxygen demand (CODt), 200–800 mg lÀ1; soluble chemi-
some data is available, it is related to either a post-
cal oxygen demand (CODs), 100–500 mg lÀ1; and fat
treatment, and normally they are combined with othertechnologies, such as activated carbon or filtration
The PPCPs used in this work were Galaxolide,
Flotation techniques, in which finely suspended parti-
Tonalide, Carbamazepine, Diazepam, Ibuprofen, Na-
cles are separated by adhering to the surface of rising
proxen and Diclofenac. Two solutions, one containing
bubbles, have proved to be efficient, practical and
musks plus the neutral pharmaceuticals and the other
reliable methods for the removal of fat, as well as other
one with the acidic substances, were spiked to 10 L of
contaminants, such as oils, biomolecules or suspended
urban wastewater in order to attain higher levels than
Besides, micropollutants like lipophilic PPCPs can be
Once prepared, the resulting PPCPs concentrations were
removed from the wastewaters by flotation due to their
solubilization in the lipid fractions or sorption onto
background content (already present in sewage) and the
small aggregates. For instance, associated
the removal of Carbamazepine in a STP with thepresence of an unusual high content of silicone oil in the
Measured concentrations of PPCPs in the spiked samples ofurban wastewater used in the coagulation–flocculation and
The aim of this work is to improve the removal
efficiencies of three groups of PPCPs (musks, neutral
and acidic pharmaceuticals), which have differentsorption properties, during sewage primary treatment
by coagulation–flocculation and flotation processes.
This objective is based on the hypothesis that the
distribution of PPCPs between the solids and the
aqueous phase can be modified by the addition of some
chemicals (coagulants, flocculants, tensoactives, etc.).
The influence of the main operational parameters, such
M. Carballa et al. / Water Research 39 (2005) 4790–4796
ethyl acetate. This extract was then divided into twofractions: one of them being used for the direct
Coagulation–flocculation assays were carried out in a
determination of the soluble content of Carbamazepine,
Jar-Test device, in vessels of 1 l of liquid volume. The
Diazepam and fragrances; the other for the determina-
influence of three additives was studied: ferric chloride
tion of the soluble content of the anti-inflammatories. In
(FeCl3, 50 g lÀ1), aluminum sulfate (Al2(SO4)3, 50 g lÀ1)
the latter case, compounds were silylated previously to
and aluminum polychloride (PAX, 17.5% w/w). The
assays were conducted at two temperatures, 12 and
). In both cases, GC/MS was used to determine the
25 1C, simulating winter and summer conditions, respec-
concentration of the investigated compounds in the
tively. The test included an initial 3 min period of rapid
SPE extract. Values given for the different samples
stirring (150 rpm), after the addition of the coagulant
correspond to the average value of two aliquots of
and lime for neutralization, followed by 5 min of slow
mixing (50 rpm) for emulsion breaking and floc forma-tion, and finally 1 h period without mixing, for flocseparation. The influence of the type and dose of
coagulant and the temperature was studied. Since theobjective of the work was to enhance PPCPs removal
during sewage primary treatment, all the experimentswere carried out at the neutral pH necessary for the
Preliminary assays with FeCl3, Al2(SO4)3 and PAX
were performed at 12 and 25 1C without PPCPs additionin order to adjust the dose range for each coagulant.
Al2(SO4)3 (100–500 mg lÀ1) and PAX (250–1250 mg lÀ1)
Flotation assays were carried out in a unit consisting
were tested and the parameters monitored were the TSS
of a pressurized vessel of 2 l (where air was dissolved into
and CODt concentrations in the supernatant. Although
the wastewater) and a flotation cell of 1 l (
the differences were not significant in the range
). The pressurized cell has two inlets (for air
considered, it was observed (data not shown) that the
and water), and one outlet for the pressurized liquid.
higher removal efficiencies for TSS and CODt were
Also, a manometer was set up in the air line to check the
achieved in the following dose range: 200–300 mg lÀ1
pressure. The dissolved air was then introduced into the
(FeCl3), 250–350 mg lÀ1 Al2(SO4)3 and 700–950 mg lÀ1
flotation cell where the fine air bubbles produced by
depressurization helped flocs flotation. The influence of
Afterwards, the influence of coagulant dose (in those
the content of fat in wastewaters and the temperature
ranges) and temperature on PPCPs removal was
was studied. The assays were carried out in duplicate.
analyzed. From the results obtained (data not shown),
Two types of wastewater with different concentrations
it can be concluded that there is no significant influence
of fat were used: a low fat (LF) and high fat (HF)
(less than 5%) either of the coagulant dose or of the
wastewater, with approximately 60 and 150 mg lÀ1,
temperature (12 or 25 1C) on PPCPs removal in the
respectively. While the LF wastewater was directly
considered range. Because of that, the following assays
taken from the STP considered, the HF wastewater
were carried out at 25 1C with the following coagulant
was synthetically prepared by adding fat (as liquid
concentration: 250 mg FeCl3 lÀ1, 300 mg Al2(SO4)3 lÀ1
butter) to the LF wastewater, in order to evaluate
and 850 mg PAX lÀ1. Besides, a blank assay (an
exclusively the influence of the wastewater fat content.
experiment without any additive) was carried out tomonitor the removal of these compounds merely
associated with the sedimentation of solids in thebeakers. The results obtained are summarized in
TS, VS, TSS, VSS, COD and fat were analyzed
Except for Carbamazepine and Ibuprofen, which were
not affected by the addition of any coagulant,
determined using a selective electrode and temperature
shows that the use of an additive increased the removal
with a digital thermometer. The soluble content of the
efficiencies of all PPCPs tested. In the case of musks,
fragrances, anti-inflammatories, Carbamazepine and
while ferric chloride and aluminum sulfate lead to
Diazepam was determined after a solid-phase extraction
similar eliminations of both substances (around 50%),
(SPE) of 500 ml samples using 60 mg OASIS HLB
the use of aluminum polychloride improved the removal
cartridges (Waters, Milford, MA, USA). Meclofenamic
efficiencies of each: 63% for Galaxolide and 71% for
acid and dihydrocarbamazepine were added to the
Tonalide. Conversely, the elimination of Diclofenac was
samples as surrogate standards. All compounds were
higher with ferric chloride and aluminum sulfate
quantitatively eluted from the cartridge using 3 ml of
(around 70%), although PAX also gave a significant
M. Carballa et al. / Water Research 39 (2005) 4790–4796
coagulant enhances the binding of Diclofenac to thesuspended solids throughout the trivalent cations, thus
allowing a further removal from the water phase.
Diazepam and Naproxen removal is also improved by
the action of coagulants (20–25%), although in a lower
extent than Diclofenac, which can be explained by their
Finally, Carbamazepine and Ibuprofen were not
eliminated at any tested conditions, which is in
accordance with their very low Kd values.
Preliminary assays were carried out to determine the
pressurized liquid flow necessary to produce fat separa-tion in the flotation cell. This value was adjusted to
200 ml operating inside the pressurized cell at 6.4 atm.
These conditions implied the following air–solid ratios
Fig. 1. Removal efficiencies from the aqueous phase obtained
(A/S): 0.07 (12 1C) and 0.01 (25 1C).
during the coagulation–flocculation assays.
The effect of the initial content of fat in wastewaters
and temperature (12 and 25 1C) was studied. Two types
reduction (around 50%). The concentrations of Diaze-
of wastewaters with different concentrations of fat were
pam and Naproxen were reduced by 20–25%. While for
used: a LF and HF wastewater, with approximately 60
Diazepam there were no significant differences between
and 150 mg lÀ1. The assays were carried out in duplicate.
ferric chloride and aluminum sulfate, Naproxen was
shows the results obtained for the different
only removed with ferric chloride. In both cases, PAX
PPCPs considered when LF wastewaters were used. A
was the less effective additive (below 5%).
similar behavior between both musks can be observed:
The different behavior obtained in coagulation–floc-
culation assays for each compound can be explained by
substantially reduced at both temperatures (35–45%),
their different physico-chemical properties. In this way,
with the highest removal by efficiencies being obtained
the good removal of musks is concordant with their high
at 25 1C. The elimination of Diazepam was similar to
ability to attach to solid particles (log Kd values between
that obtained for musks (40–45%), although no
3.3 and 3.7), mainly due to hydrophobic interactions
significant difference was observed between both tem-
with the lipid fractions of the sludge cells membrane
peratures. However, according to its lower lipophilicity
(log Kow around 2.4), Carbamazepine was removed
The maximum removal efficiency expected for a given
to a lesser extent (around 20%) independently of the
compound can be estimated from its distributionbetween the solid (Eq. (2)) and the aqueous (Eq. (3))
phases, using the Kd value and the PPCP concentrationin the aqueous (S) and solid (X) phase. For musks, these
maximum values ranged from 60% to 85%, very close
to those obtained in these experiments (50–70%):
When applying the same methodology for calculating
the elimination of Diclofenac, which could be obtained
after a coagulation–flocculation treatment, just con-
sidering its Kd value (log Kd ranged from 1.2 to 2.7), theforeseen figures (15–40%) appear to be quite lower that
those obtained in the experiments (50–70%). This can bedue to the acidic nature of this compound (pKa$4),
Fig. 2. Removal efficiencies from the aqueous phase obtained
which in aqueous phase remains partially ionized. The
during the flotation assays with low fat (60 mg lÀ1) wastewaters.
M. Carballa et al. / Water Research 39 (2005) 4790–4796
temperature. The anti-inflammatories were also affected
pine and Diazepam, and regardless of the initial fat
by flotation, the highest removals being those obtained
content, no effect was observed. However, for anti-
for Diclofenac (20–40%). For these three compounds,
inflammatories, the best results were obtained at 25 1C
temperature influenced removal significantly and, as for
with both LF and HF wastewaters. In the case of musks,
musks, the highest values were obtained at 25 1C.
while higher removal efficiencies were attained at 25 1C
shows the results obtained for the different
PPCPs studied when HF wastewaters were used. It can
differences between both temperatures were observed
be observed that the elimination of musks is higher
(around 60%) under these conditions and that tempera-ture did not significantly influence removal. Thisbehavior was also observed for Carbamazepine andDiazepam, with removals increasing to 35% and 50%,
respectively. Once again, these rates were uninfluencedby temperature. Since the soluble content of the anti-
Compounds with high sorption properties (high
inflammatories was independent on the fat content in
log Kd values), such as musks (Galaxolide and Tonalide)
the wastewaters, their removal patterns were similar to
and Diclofenac, are significantly removed during coa-
those observed in the assays with LF wastewaters:
gulation–flocculation with efficiencies of 70% in the
20–45% for Diclofenac, 10–30% for Naproxen and
temperature range of 12–25 1C. Lipophilic compounds,
10–20% for Ibuprofen. Temperature clearly influence
like musks, are mainly absorbed on the lipid fractions of
removal efficiencies, since the best results were obtained
the sludge, while acidic compounds, like Diclofenac, are
mainly adsorbed due to electrostatic interactions.
The different affinities of PPCPs for organics can be
Compounds with lower Kd values, such as Diazepam,
clearly seen when HF wastewaters were used. While the
Carbamazepine, Ibuprofen and Naproxen, were reduced
removal of lipophilic substances, such as musks, is
to a lesser extent (Diazepam and Naproxen), up to 25%,
enhanced, the elimination of more polar compounds
or not affected at any condition tested (Carbamazepine
remains at the same level. Furthermore, there are no
and Ibuprofen). Although PAX gives the best results for
significant differences in the removal of these substances
musks, the option of ferric chloride appears to be the
when LF or HF wastewaters are used. This shows that
most suitable since the concentration of PAX required is
not only the physico-chemical properties of the PPCPs
has to be considered, but also the presence of the other
All substances were removed during flotation assays
substances in the medium, such as the fat globules, the
with higher efficiencies when HF wastewaters were used
colloidal matter or the flocs formed during coagula-
(around 60% for musks, 35% for Carbamazepine, 50%
for Diazepam and 20–45% for the anti-inflammatories).
The influence of temperature in the various flotation
For musks, Carbamazepine and Diazepam, temperature
assays depends on the type of PPCP. For Carbamaze-
was not very important. However, in the case ofDiclofenac, Naproxen and Ibuprofen, the best resultswere attained at 25 1C, independently of wastewater fat
content. Although the results obtained are quitesatisfactory for all PPCPs, it is possible that for some
of them removal could be improved by adding some
chemical which modifies surface properties.
Taking into account that some PPCPs, as well as
other micropollutants present in sewage, appear to be
not readily biodegradable, enhancing their removal in
the sewage primary treatment could be an interesting
strategy for minimizing costs in the biological and
This work was supported by the EU (POSEIDON
project, EVK1-CT-2000-00047) and the Spanish Minis-
Fig. 3. Removal efficiencies from the aqueous phase obtainedduring the flotation assays with high fat (150 mg lÀ1) waste-
ter of Education and Science (FARMEDAR project,
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