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Water Research 39 (2005) 4790–4796

www.elsevier.com/locate/watres

Removal of cosmetic ingredients and pharmaceuticals insewage primary treatment

Marta Carballa, Francisco Omil�, Juan M. Lema

School of Engineering, Department of Chemical Engineering, University of Santiago de Compostela,

E-15782 Santiago de Compostela, Spain

Received 5 November 2004; received in revised form 12 September 2005; accepted 12 September 2005

Available online 24 October 2005

Abstract

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 Diazepam

and the antiepileptic Carbamazepine) and acidic compounds (the anti-inflammatories Ibuprofen, Naproxen and

Diclofenac). During the coagulation–flocculation assays, the main parameters considered were the selection of the

additives, their doses and the temperature of operation (12 or 25 1C). Musks—which are highly lipophilic and

Diclofenac—with significant sorption affinity—were removed around 50–70% at both temperatures independently of

the dose and type of coagulant used. However, the rest of the compounds, which are more hydrophilic, were affected to

a lesser degree (with maximum reductions below 25%). The exceptions to this behavior were Carbamazepine and

Ibuprofen, which were not removed under any condition tested. During the flotation assays, the parameters studied

were 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 in

some cases the operation at 12 1C gave similar results. The removal of musks and neutral compounds was higher in

wastewaters with a high fat content (around 150mg l�1).

r 2005 Elsevier Ltd. All rights reserved.

Keywords: Pharmaceuticals; Musks; Sewage; Coagulation–flocculation; Flotation; Adsorption; Fat; Temperature

1. Introduction

Pharmaceuticals and personal care products (PPCPs)

constitute a diverse group of chemicals that have

recently been recognized as particular contaminants of

the aquatic environment, especially in urbanized areas

e front matter r 2005 Elsevier Ltd. All rights reserve

atres.2005.09.018

ing author. Tel.: +34 981 59 44 88x16778;

80 50.

ess: eqomil@usc.es (F. Omil).

(Daughton and Ternes, 1999). PPCPs comprise all

prescription and over-the-counter drugs, diagnostic

agents, and other consumer chemicals, such as poly-

cyclic musk compounds frequently used as fragrances in

perfumes and other household products.

Due to the large amount of PPCPs consumed in

developed societies, significant concentrations of these

compounds can be found in wastewaters (Ternes, 1998;

Kanda et al., 2003; Kolpin et al., 2004; Cargouet et al.,

2004). However, conventional sewage treatment plants

d.

ARTICLE IN PRESSM. Carballa et al. / Water Research 39 (2005) 4790–4796 4791

(STPs) have been reported not to be an effective barrier

to these substances because of their low concentrations

and specific metabolic properties (Paxeus, 2004). There-

fore, those compounds which resist the treatment

processes commonly used in STPs or other transforma-

tions which can naturally occur in the environment, can

end up in surface and groundwaters, as well as in

sediments and soils.

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-

guished, recent works (POSEIDON Project (EVK1-CT-

2000-00047), 2005) have concluded that only two of

them, microbial degradation and sorption to suspended

solids, are really relevant. The effectiveness of these

removal mechanisms greatly depends on the physico-

chemical properties and the chemical structure of each

substance.

1.1. Physical properties of PPCPs

The sorption of micropollutants onto solids and,

accordingly, their behavior during the physico-chemical

treatment, depends basically on their physico-chemical

properties, such as lipophilicity or acidity. Two types of

coefficients have been mostly used to determine the

sorption effectiveness and the affinity of a given

substance to organic matter: the octanol-water partition

coefficient (Kow) and the organic carbon partition

coefficient (Koc). Kow is defined as the ratio between

the equilibrium concentrations of a certain compound in

octanol and water at a specific temperature and Koc

relates the concentrations sorbed to organic carbon and

Table 1

Physico-chemical properties of the PPCPs considered in this work (w

Galaxolide Tonalide Diclofenac Diazep

Structure

Solubility 1.8� 10�3a 1.2� 10�3a 2.4� 10�3a,b 5.0� 1

pKa — — 4.0–4.2a,b 3.3–3.4

logKow 5.9–6.3a 4.6–6.4a 4.5–4.8a,b 2.5–3.0

logKdc: 3.3–3.7 3.4–3.7 1.2–2.7 1.3–1.6

aLiebig (2004).bSyracuse Research Corporation (2004).cTernes et al. (2004).dKummerer (2000).eJones et al. (2002).fThe Kd value for Naproxen has been assumed based on its similar p

sludge (data not shown).

dissolved in water. However, some limitations have been

found in literature (Holbrook et al., 2004; Lai et al.,

2000) for the applicability of these coefficients to explain

the sorption behavior of some PPCPs. Therefore, the

solid–water distribution coefficient (Kd), defined as the

ratio between the concentrations of a substance in the

solid and in the aqueous phase at equilibrium conditions

(Eq. (1)), has been proposed as the most suitable

parameter (Schwarzenbach et al., 2003; Ternes et al.,

2004):

Kd ¼X

S(1)

where Kd is the solid–water distribution coefficient

(l kg�1); X the concentration in the solid phase

(mgPPCPkg solid�1); and S the concentration in the

aqueous phase (mg PPCP l�1).

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 substance

tendency to be ionized or dissociated in aqueous phase,

which is characterized by the dissociation constant,

pKa).

According to their physico-chemical properties,

PPCPs can be divided into three main groups: lipophilic

(with high Kow values), neutral (non-ionic) and acidic

(hydrophilic and ionic) compounds. Substances from

different therapeutical classes and representative of each

group have been considered in this work (Table 1): two

fragrances (Galaxolide and Tonalide), one tranquillizer

(Diazepam), one antiepileptic (Carbamazepine) and

three anti-inflammatories (Ibuprofen, Naproxen and

Diclofenac).

ater solubility in g l�1; Kd in l kg�1)

am Ibuprofen Naproxen Carbamazepine

0�2a,b 2.1� 10�2a,b 1.6� 10�2b 1.8� 10�2a,b

a,b,d 4.9–5.7a,b,d,e 4.2b,e 13.9e

a,b,d 3.5–4.5a,b,d,e 3.2b,e 2.3–2.5a,b,d,e

0.9 0.9f 0.1

roperties with Ibuprofen and other Kd measurements in digested

ARTICLE IN PRESS

Table 2

Measured concentrations of PPCPs in the spiked samples of

urban wastewater used in the coagulation–flocculation and

flotation assays (mg l�1)

Name Coagulation–

flocculation

Flotation

LF HF

Galaxolide 2–4 3–4 1–2

Tonalide 1–3 2–3 1–2

Diazepam 10–13 10–16 7–12

Carbamazepine 10–12 11–13 8–11

Ibuprofen 13–15 10–13 12–13

Naproxen 16–18 9–13 10–18

Diclofenac 14–18 10–18 12–23

M. Carballa et al. / Water Research 39 (2005) 4790–47964792

Galaxolide and Tonalide are very lipophilic com-

pounds with logKow values around 5.5–6.0. However,

while Carbamazepine and Diazepam are neutral sub-

stances, as derived from their chemical structure, the

anti-inflammatories are very acidic compounds (low pKa

values).

1.2. Physico-chemical processes

Coagulation–flocculation processes enhance the re-

moval of suspended solids and colloids, because the

addition of metal salts or organic compounds causes the

agglomeration of these particles, thus allowing their

elimination by decantation or filtration (Li and Gregory,

1991).

Lipophilic trace pollutants in water and wastewater

treatment systems are likely to be found associated with

colloids because in natural systems most colloids have

an organic coating (Stumm and Morgan, 1996). In

addition, positive charged molecules can be associated

to these colloids by means of low strength Van der

Waals bonds.

Literature information about the removal of PPCPs

by coagulation–flocculation processes is scarce. When

some data is available, it is related to either a post-

treatment (Romero et al., 2003) or drinking water

treatment, and normally they are combined with other

technologies, such as activated carbon or filtration

(Ternes et al., 2002; Boyd et al., 2003; Stackelberg

et al., 2004).

Flotation techniques, in which finely suspended parti-

cles are separated by adhering to the surface of rising

bubbles, have proved to be efficient, practical and

reliable methods for the removal of fat, as well as other

contaminants, such as oils, biomolecules or suspended

solids from water (Zouboulis and Avranas, 2000).

Besides, micropollutants like lipophilic PPCPs can be

removed from the wastewaters by flotation due to their

solubilization in the lipid fractions or sorption onto

small aggregates. For instance, Paxeus (2004) associated

the removal of Carbamazepine in a STP with the

presence of an unusual high content of silicone oil in the

wastewaters.

1.3. Objectives

The aim of this work is to improve the removal

efficiencies of three groups of PPCPs (musks, neutral

and acidic pharmaceuticals), which have different

sorption 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

as the type and dose of coagulant, the fat content of the

wastewaters and the temperature has been studied.

2. Material and methods

2.1. Wastewaters

The wastewaters used in this work were collected from

an urban STP located in Santiago de Compostela (NW

of Spain). The STP, which was surveyed in a previous

work (Carballa et al., 2004), corresponds to 100,000

inhabitants approximately and comprises three main

sections: pre-treatment (coarse/fine screening and grit/fat

removal), primary treatment (sedimentation) and biolo-

gical treatment (conventional activated sludge). The inlet

flow to the primary clarifier was used for coagulation–

flocculation experiments, whereas the inlet to the fat

separator was used for flotation assays. The main

characteristics of the wastewater are: total solids (TS),

500–900mg l�1; volatile solids (VS), 200–500mg l�1; total

suspended solids (TSS), 100–400mg l�1; volatile sus-

pended solids (VSS); 100–300mg l�1; total chemical

oxygen demand (CODt), 200–800mg l�1; soluble chemi-

cal oxygen demand (CODs), 100–500mg l�1; and fat

content, 60–70mg l�1.

2.2. PPCPs

The PPCPs used in this work were Galaxolide,

Tonalide, Carbamazepine, Diazepam, Ibuprofen, Na-

proxen and Diclofenac. Two solutions, one containing

musks plus the neutral pharmaceuticals and the other

one with the acidic substances, were spiked to 10L of

urban wastewater in order to attain higher levels than

those found in raw wastewaters (Carballa et al., 2004).

Once prepared, the resulting PPCPs concentrations were

measured (Table 2). These values include both the

background content (already present in sewage) and the

spike.

ARTICLE IN PRESSM. Carballa et al. / Water Research 39 (2005) 4790–4796 4793

2.3. Coagulation–flocculation assays

Coagulation–flocculation assays were carried out in a

Jar-Test device, in vessels of 1 l of liquid volume. The

influence of three additives was studied: ferric chloride

(FeCl3, 50 g l�1), aluminum sulfate (Al2(SO4)3, 50 g l

�1)

and aluminum polychloride (PAX, 17.5% w/w). The

assays were conducted at two temperatures, 12 and

25 1C, simulating winter and summer conditions, respec-

tively. The test included an initial 3min period of rapid

stirring (150 rpm), after the addition of the coagulant

and lime for neutralization, followed by 5min of slow

mixing (50 rpm) for emulsion breaking and floc forma-

tion, and finally 1 h period without mixing, for floc

separation. The influence of the type and dose of

coagulant and the temperature was studied. Since the

objective of the work was to enhance PPCPs removal

during sewage primary treatment, all the experiments

were carried out at the neutral pH necessary for the

further biological treatment.

2.4. Flotation assays

Flotation assays were carried out in a unit consisting

of a pressurized vessel of 2 l (where air was dissolved into

the wastewater) and a flotation cell of 1 l (Metcalf and

Eddy, 1991). The pressurized cell has two inlets (for air

and water), and one outlet for the pressurized liquid.

Also, a manometer was set up in the air line to check the

pressure. The dissolved air was then introduced into the

flotation cell where the fine air bubbles produced by

depressurization helped flocs flotation. The influence of

the content of fat in wastewaters and the temperature

was studied. The assays were carried out in duplicate.

Two types of wastewater with different concentrations

of fat were used: a low fat (LF) and high fat (HF)

wastewater, with approximately 60 and 150mg l�1,

respectively. While the LF wastewater was directly

taken from the STP considered, the HF wastewater

was synthetically prepared by adding fat (as liquid

butter) to the LF wastewater, in order to evaluate

exclusively the influence of the wastewater fat content.

2.5. Analytical techniques

TS, VS, TSS, VSS, COD and fat were analyzed

according to Standard Methods (APHA, 1999). pH was

determined using a selective electrode and temperature

with a digital thermometer. The soluble content of the

fragrances, anti-inflammatories, Carbamazepine and

Diazepam was determined after a solid-phase extraction

(SPE) of 500ml samples using 60mg OASIS HLB

cartridges (Waters, Milford, MA, USA). Meclofenamic

acid and dihydrocarbamazepine were added to the

samples as surrogate standards. All compounds were

quantitatively eluted from the cartridge using 3ml of

ethyl acetate. This extract was then divided into two

fractions: one of them being used for the direct

determination of the soluble content of Carbamazepine,

Diazepam and fragrances; the other for the determina-

tion of the soluble content of the anti-inflammatories. In

the latter case, compounds were silylated previously to

their gas chromatographic separation (Rodriguez et al.,

2003). In both cases, GC/MS was used to determine the

concentration of the investigated compounds in the

SPE extract. Values given for the different samples

correspond to the average value of two aliquots of

each sample.

3. Results and discussion

3.1. Coagulation–flocculation assays

Preliminary assays with FeCl3, Al2(SO4)3 and PAX

were performed at 12 and 25 1C without PPCPs addition

in order to adjust the dose range for each coagulant.

Several concentrations of FeCl3, (100–500mg l�1),

Al2(SO4)3 (100–500mg l�1) and PAX (250–1250mg l�1)

were tested and the parameters monitored were the TSS

and CODt concentrations in the supernatant. Although

the differences were not significant in the range

considered, it was observed (data not shown) that the

higher removal efficiencies for TSS and CODt were

achieved in the following dose range: 200–300mg l�1

(FeCl3), 250–350mg l�1 Al2(SO4)3 and 700–950mg l�1

(PAX).

Afterwards, the influence of coagulant dose (in those

ranges) and temperature on PPCPs removal was

analyzed. From the results obtained (data not shown),

it can be concluded that there is no significant influence

(less than 5%) either of the coagulant dose or of the

temperature (12 or 25 1C) on PPCPs removal in the

considered range. Because of that, the following assays

were carried out at 25 1C with the following coagulant

concentration: 250mg FeCl3 l�1, 300mg Al2(SO4)3 l

�1

and 850mg PAX l�1. Besides, a blank assay (an

experiment without any additive) was carried out to

monitor the removal of these compounds merely

associated with the sedimentation of solids in the

beakers. The results obtained are summarized in Fig. 1.

Except for Carbamazepine and Ibuprofen, which were

not affected by the addition of any coagulant, Fig. 1

shows that the use of an additive increased the removal

efficiencies of all PPCPs tested. In the case of musks,

while ferric chloride and aluminum sulfate lead to

similar eliminations of both substances (around 50%),

the use of aluminum polychloride improved the removal

efficiencies of each: 63% for Galaxolide and 71% for

Tonalide. Conversely, the elimination of Diclofenac was

higher with ferric chloride and aluminum sulfate

(around 70%), although PAX also gave a significant

ARTICLE IN PRESS

Galaxolide

Tonalide

Diclofenac

Diazepam

Naproxen

2010 40 50 60 70 80 90 1000 30

2010 40 50 60 70 80 90 1000 30

Removal (%)

BlankFeCl3Al2(SO4)3PAX

BlankFeCl3Al2(SO4)3PAX

BlankFeCl3Al2(SO4)3PAX

BlankFeCl3Al2(SO4)3PAXBlankFeCl3Al2(SO4)3PAX

Fig. 1. Removal efficiencies from the aqueous phase obtained

during the coagulation–flocculation assays.

20100 30 40 100

Galaxolide

Tonalide

Diazepam

Carbamazepine

Diclofenac

Naproxen

Ibuprofen

12°C25°C

12°C25°C

12°C25°C

12°C25°C

50 60

12°C25°C

12°C25°C

12°C25°C

70 80 90

Removal (%)20100 30 40 10050 60 70 80 90

Fig. 2. Removal efficiencies from the aqueous phase obtained

during the flotation assays with low fat (60mg l�1) wastewaters.

M. Carballa et al. / Water Research 39 (2005) 4790–47964794

reduction (around 50%). The concentrations of Diaze-

pam and Naproxen were reduced by 20–25%. While for

Diazepam there were no significant differences between

ferric chloride and aluminum sulfate, Naproxen was

only removed with ferric chloride. In both cases, PAX

was the less effective additive (below 5%).

The different behavior obtained in coagulation–floc-

culation assays for each compound can be explained by

their different physico-chemical properties. In this way,

the good removal of musks is concordant with their high

ability to attach to solid particles (logKd values between

3.3 and 3.7), mainly due to hydrophobic interactions

with the lipid fractions of the sludge cells membrane

(absorption).

The maximum removal efficiency expected for a given

compound can be estimated from its distribution

between the solid (Eq. (2)) and the aqueous (Eq. (3))

phases, using the Kd value and the PPCP concentration

in 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%):

% solid phase ¼Kd SS

1þ Kd SS� 100, (2)

% liquid phase ¼1

1þ Kd SS� 100. (3)

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 (logKd ranged from 1.2 to 2.7), the

foreseen figures (15–40%) appear to be quite lower that

those obtained in the experiments (50–70%). This can be

due to the acidic nature of this compound (pKa�4),

which in aqueous phase remains partially ionized. The

coagulant enhances the binding of Diclofenac to the

suspended 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

lower Kd values.

Finally, Carbamazepine and Ibuprofen were not

eliminated at any tested conditions, which is in

accordance with their very low Kd values.

3.2. Flotation assays

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

200ml operating inside the pressurized cell at 6.4 atm.

These conditions implied the following air–solid ratios

(A/S): 0.07 (12 1C) and 0.01 (25 1C).

The effect of the initial content of fat in wastewaters

and temperature (12 and 25 1C) was studied. Two types

of wastewaters with different concentrations of fat were

used: a LF and HF wastewater, with approximately 60

and 150mg l�1. The assays were carried out in duplicate.

Fig. 2 shows the results obtained for the different

PPCPs considered when LF wastewaters were used. A

similar behavior between both musks can be observed:

their concentrations in the aqueous phase were

substantially reduced at both temperatures (35–45%),

with the highest removal by efficiencies being obtained

at 25 1C. The elimination of Diazepam was similar to

that obtained for musks (40–45%), although no

significant difference was observed between both tem-

peratures. However, according to its lower lipophilicity

(logKow around 2.4), Carbamazepine was removed

to a lesser extent (around 20%) independently of the

ARTICLE IN PRESSM. Carballa et al. / Water Research 39 (2005) 4790–4796 4795

temperature. The anti-inflammatories were also affected

by flotation, the highest removals being those obtained

for Diclofenac (20–40%). For these three compounds,

temperature influenced removal significantly and, as for

musks, the highest values were obtained at 25 1C.

Fig. 3 shows the results obtained for the different

PPCPs studied when HF wastewaters were used. It can

be observed that the elimination of musks is higher

(around 60%) under these conditions and that tempera-

ture did not significantly influence removal. This

behavior was also observed for Carbamazepine and

Diazepam, with removals increasing to 35% and 50%,

respectively. Once again, these rates were uninfluenced

by temperature. Since the soluble content of the anti-

inflammatories was independent on the fat content in

the wastewaters, their removal patterns were similar to

those observed in the assays with LF wastewaters:

20–45% for Diclofenac, 10–30% for Naproxen and

10–20% for Ibuprofen. Temperature clearly influence

removal efficiencies, since the best results were obtained

once again at 25 1C.

The different affinities of PPCPs for organics can be

clearly seen when HF wastewaters were used. While the

removal of lipophilic substances, such as musks, is

enhanced, the elimination of more polar compounds

remains at the same level. Furthermore, there are no

significant differences in the removal of these substances

when LF or HF wastewaters are used. This shows that

not only the physico-chemical properties of the PPCPs

has to be considered, but also the presence of the other

substances in the medium, such as the fat globules, the

colloidal matter or the flocs formed during coagula-

tion–flocculation assays.

The influence of temperature in the various flotation

assays depends on the type of PPCP. For Carbamaze-

20100 30 40 100

Galaxolide

Tonalide

Diazepam

Carbamazepine

Diclofenac

Naproxen

Ibuprofen

12°C25°C

12°C25°C

12°C25°C

12°C25°C

50 60

12°C25°C

12°C25°C

12°C25°C

70 80 90

Removal (%)20100 30 40 10050 60 70 80 90

Fig. 3. Removal efficiencies from the aqueous phase obtained

during the flotation assays with high fat (150mg l�1) waste-

waters.

pine and Diazepam, and regardless of the initial fat

content, no effect was observed. However, for anti-

inflammatories, the best results were obtained at 25 1C

with both LF and HF wastewaters. In the case of musks,

while higher removal efficiencies were attained at 25 1C

when LF wastewaters were used, no significant

differences between both temperatures were observed

with HF wastewaters.

4. Conclusions

Compounds with high sorption properties (high

logKd values), such as musks (Galaxolide and Tonalide)

and Diclofenac, are significantly removed during coa-

gulation–flocculation with efficiencies of 70% in the

temperature range of 12–25 1C. Lipophilic compounds,

like musks, are mainly absorbed on the lipid fractions of

the sludge, while acidic compounds, like Diclofenac, are

mainly adsorbed due to electrostatic interactions.

Compounds with lower Kd values, such as Diazepam,

Carbamazepine, Ibuprofen and Naproxen, were reduced

to a lesser extent (Diazepam and Naproxen), up to 25%,

or not affected at any condition tested (Carbamazepine

and Ibuprofen). Although PAX gives the best results for

musks, the option of ferric chloride appears to be the

most suitable since the concentration of PAX required is

quite high.

All substances were removed during flotation assays

with higher efficiencies when HF wastewaters were used

(around 60% for musks, 35% for Carbamazepine, 50%

for Diazepam and 20–45% for the anti-inflammatories).

For musks, Carbamazepine and Diazepam, temperature

was not very important. However, in the case of

Diclofenac, Naproxen and Ibuprofen, the best results

were attained at 25 1C, independently of wastewater fat

content. Although the results obtained are quite

satisfactory 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

tertiary treatment of STPs.

Acknowledgments

This work was supported by the EU (POSEIDON

project, EVK1-CT-2000-00047) and the Spanish Minis-

ter of Education and Science (FARMEDAR project,

CTM2004-04475).

ARTICLE IN PRESSM. Carballa et al. / Water Research 39 (2005) 4790–47964796

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