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Environmental Science & Technology

Elimination of micropollutants during post-treatment of
hospital wastewater with powdered activated carbon,
ozone and UVLubomira Kovalova1, Hansruedi Siegrist1, Urs von Gunten1,2, Jakob Eugster1, Martina Hagenbuch1,
Anita Wittmer1, Ruedi Moser3, Christa S. McArdell1*
1

Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Duebendorf,

Switzerland.
2

School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale

de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
3

Hunziker Betatech AG, CH-8411 Winterthur, Switzerland.

RECEIVED DATE:*Corresponding author Christa S. McArdell: phone +41 58 765 5483; fax +41 58 765 5028; e-mailchrista.mcardell@eawag.ch

The published version is available at:
Kovalova, L., Siegrist, H., Von Gunten, U., Eugster, J., Hagenbuch, M., Wittmer, A., … McArdell, C. S. (2013).
Elimination of micropollutants during post-treatment of hospital wastewater with powdered activated carbon,
ozone, and UV. Environmental Science and Technology, 47(14), 7899-7908. http://doi.org/10.1021/es400708

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ABSTRACT:
A pilot-scale hospital wastewater treatment plant consisting of a primary clarifier, membrane bioreactor
and five post-treatment technologies including ozone (O3), O3/H2O2, powdered activate carbon (PAC),
and low pressure UV light with and without TiO2 was operated to test the elimination efficiencies for 56
micropollutants. The extent of the elimination of the selected micropollutants (pharmaceuticals,
metabolites and industrial chemicals) was successfully correlated to physical-chemical properties ormolecular structure. By mass loading, 95% of all measured micropollutants in the biologically treatedhospital wastewater feeding the post-treatments consisted of iodinated contrast media (ICM). The
elimination of ICM by the tested post-treatment technologies was 50- 65% when using 1.08 g
O3/gDOC, 23 mg/L PAC, or a UV dose of 2400 J/m2 (254 nm). For the total load of analyzed
pharmaceuticals and metabolites excluding ICM the elimination by ozonation, PAC, and UV at thesame conditions was 90%, 86%, and 33%, respectively. Thus, the majority of analyzed substances canbe efficiently eliminated by ozonation (which also provides disinfection) or PAC (which provides
micropollutants removal, not only transformation). Some micropollutants recalcitrant to those two posttreatments, such as the ICM diatrizoate, can be substantially removed only by high doses of UV (96% at
7200 J/m2). The tested combined treatments (O3/H2O2 and UV/TiO2) did not improve the eliminationcompared to the single treatments (O3 and UV).

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Environmental Science & Technology

INTRODUCTION
Hospital wastewater contains pharmaceuticals and disinfectants1-4, as well as pathogens and antibiotic
resistant bacteria5-7 in high concentrations. Some of the environmentally relevant groups ofpharmaceuticals used in relatively high amounts in hospitals are antibiotics which contribute to the
spread of antibiotic resistance2, cytostatics which are potentially ecotoxic8-10 and X-ray contrast media
which are used in high quantities11, 12, but many more pharmaceuticals are present for which not
sufficient information is available for a risk assessment.
Treatment of the hospital wastewater at the source has advantages of avoiding dilution due to mixing
with the municipal sewage, avoiding losses into environment due to leaks and combined sewer
overflows, and preventing pathogens and antibiotic multi-resistant bacteria to enter the environment.11,
13, 14

Biological treatment of hospital wastewater on site showed to be feasible and efficient to remove

dissolved organic carbon (DOC) and chemical oxygen demand (COD) significantly to >90%, as well as
nitrogen (>99% N-elimination by denitrification).11, 15 Nevertheless, any biological treatment(conventional activated sludge or membrane bioreactor, MBR) is typically insufficient to eliminate themajority of micropollutants.11, 16, 17 Therefore, additional oxidative or other physical-chemical posttreatments are necessary. Good results in municipal wastewater treatment were obtained with ozone18-22,
activated carbon23-26, UV/H2O227, 28, and nanofiltration or reverse osmosis29-33.
Three post-treatment technologies, namely, ozonation (and O3/H2O2), UV in absence and presence ofTiO2 and powdered activated carbon (PAC) were selected in this study to estimate the efficiency for
hospital wastewater treatment. 56 target analytes including pharmaceuticals, human metabolites, andindustrial chemicals were chosen as elucidated in our earlier publication on their behavior during
treatment with MBR. 11 The main objectives of our study were to (1) determine elimination efficiencies
for 56 organic micropollutants by the selected post-treatment technologies, treating an effluent of an
MBR fed with raw hospital wastewater, and compare them to municipal wastewater treatment; to (2)ACS Paragon Plus Environment

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compare and predict the elimination efficiency of the selected micropollutants by the selected posttreatment technologies; and to (3) evaluate feasibility, energy consumption and costs.

MATERIALS AND METHODS
Wastewater Treatment Setup. A pilot plant was installed at the cantonal hospital in Baden,
Switzerland (346 beds, water consumption 673 L per bed and day). First, the wastewater was treated bya MBR (Picatech Huber AG, Kriens, Switzerland), as described elsewhere.11 MBR effluent water
quality was as follows: 6-8 mg/L DOC, 30 mg/L dissolved COD, 3.7 mg NO3-N/L, pH 8.1-8.5,
temperature 27-28 °C, 30-40 µg/L bromide. The MBR permeate was collected in a 1 m3 tank anddisconnected from the MBR for individual post-treatment experiments with activated carbon, ozone or
UV (SI, Figure S3). Experiments were performed in two replicates with different MBR permeate
composition. The removal efficiency was calculated as the average of the two replicate experiments.
Activated carbon treatment. Post-treatment of the MBR-permeate with PAC (Norit SAE Super,surface area 1300 m2/g, particle size d5015µm, pHPZC 9.8, Norit, Amersfoort, The Netherlands) took
place in a 180-L reactor. The constant MBR-permeate flow of 180 L/day resulted in a hydraulicresidence time of 1 day. The effluent of the PAC reactor was filtered through a flat sheet ultrafiltration
membrane (Martin System, siClaro FM 611, pore size 0.04 micrometer, and membrane surface 6.2 m2).
90 L/day of filtered PAC effluent was removed, while also 90 L/day of loaded PAC in solution waswithdrawn (5 L every 80 min) to keep the PAC retention time at 2 days (exception: experiments in June2009 were setup for 5 days of PAC retention time). For the required PAC doses of 10, 20, and 40 mg/L,
the start-up concentration in the PAC reactor was 20, 40, and 80 mg/L for PAC retention time of 2 days.
The dosing frequency of 150 mg PAC from a stock solution of 2 g/L was adjusted to 120, 60 or 30 min,to achieve the three different carbon doses. The reactor was emptied and cleaned before switching to thenext carbon concentration. The actual PAC concentration in the PAC-reactor, as well as temperature,
pH and DOC were regularly measured and recorded (Table S7). The influent of the first replicate
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Environmental Science & Technology(Monday-Friday) was sampled before the start of the experiment and after 2 and 4 days (concentrations
stayed constant over the time, the average taken as influent). The corresponding effluent was sampled
after 2 and 4 days (average taken as effluent). For the second replicate (Friday-Monday) the influent
was sampled before the start of the experiment and after 3 days (average taken as influent). The
corresponding effluent was sampled after 3 days. Equilibrium was found to be reached after 2 days.
Campaigns were run with 8±4 mg/L PAC, 23±7 mg/L PAC, and 43±14 mg/L PAC.
Ozone Treatment. A counter current bubble column of 2 m height and 4.5 L volume was used for the
post-treatment of the MBR-permeate with ozone. The ozone was produced from oxygen in the air with
the Chemodata 1.0 g/Hmax ozone generator (Chemonorm AG, Altendorf, Switzerland), with an ozone
production of 0.1 - 0.15 g O3/h. The ozone concentration was regulated by adjustment of the wastewater
flow. The MBR-permeate flows of 12-23 L/h resulted in the required ozone doses in the column(hydraulic residence time of 12-23 min). An ozone analyzer BMT 964 (BMT Messtechnik Gmbh,
Stahnsdorf, Germany) provided online measurement. The transferred ozone dose was calculated fromthe difference of the applied dose and the ozone in the off-gas (ozone transfer efficiency 66-78%). The
three tested transferred ozone doses of 4.2, 5.8, and 7 mg/L resulted in specific ozone concentrations of
0.64, 0.89, and 1.08 g O3/g DOC (Table S8). Additional experiments were conducted with the advanced
oxidation process O3/H2O2. For these experiments, the MBR permeate was pre-treated with 1.2 g O3/g
DOC, followed by addition of 2.5 mg/L H2O2 and 0.8 g O3/g DOC (H2O2:O3 molar ratio approx. 1:2). In
a parallel run, the same pre-treated wastewater was treated with 0.8 g O3/g DOC without an addition of
H2O2.
UV treatment. A commercially available setup from UBE Industries (Model 3 m3/h, UBE
corporation Europe, S.A., Castellon, Spain) with a volume of 3.3 L and a water flow of 0.6 m3/h wasused for the post-treatment of the MBR-permeate by UV (Table S9). The reaction column was
positioned around a low pressure UV lamp (254 nm, 220 V, 100-400 W overall energy consumption
including the 40 W lamp power consumption). A nominal fluence rate of 10 mW/cm2 and a hydraulicresidence time of 20 s resulted in a nominal fluence of 2 000 J/m2. The effective fluence rate of UVACS Paragon Plus Environment

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treatment was calculated from the observed elimination rates of two compounds (diclofenac andiopromide) for which fluence-based rate constants are available from literature34 (SI, Pages S21-S22).
An effective fluence rate of 4 mW/cm2 was calculated for the reactor with hospital wastewater (39.8
W/m2 for diclofenac, 40.5 W/m2 for iopromide). The effective fluence rate is lower by a factor of 2.5
than the nominal fluence rate value (10 mW/cm2), probably due to the absorption of light by thewastewater in which the optical density is not negligible. The calculated effective fluence rate
corresponds to a fluence of 800 J/m2 for a single treatment. Typically 3 treatment cycles were appliedwith a cumulative dose of 2400 J/m2.
The UV/TiO2 experiments were performed with the same setup from UBE Industries after inserting
four conical cartridges around the UV lamp consisting of a photo-catalytic fiber (titanium-dispersed
silica-based fiber with a sintered anatase-TiO2 layer on the surface35). The column volume of this setup
was 3.0 L with a hydraulic residence time of 18 s. The calculated fluence rate with the photocatalytic
fiber was only 1.7 mW/cm2 (fluence of 306 J/m2 after a single treatment), less than half of the values
obtained for the reactor without the photocatalytic fibers.
The MBR-permeate was pre-filtered by a polypropylene filter (30 µm, Positech, Switzerland) prior to
UV treatment to retain particles. Further, two pre-filters with pore sizes of 25 µm and 5 µm, located justbefore the UV reactor, were part of the commercial setup. Because of the short hydraulic residence timeof the wastewater in the UV system, the experiments were conducted as follows. 200 L MBR permeate
was treated with UV and collected into another tank (called “first run”). Then the collected water wasrecirculated through the UV reactor for 180 minutes, which is equivalent to 9 cycles , as one cycle of
200 L at a flow rate of 600 L/h takes 20 minutes. The samples were taken at the start of each experimentand after 1, 2, 3, 6, and 9 cycles. The removal efficiencies were calculated for the first run and after 3
and 9 cycles.
Sample Preparation and Analysis of Micropollutants. A detailed description of the sample
preparation and analysis can be found elsewhere.11 Shortly, samples were filtered with a 0.7 µm GF/F
glass–fiber filter (Whatman, Dassel, Germany) and further through a 0.2 µm regenerated cellulose filter
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Environmental Science & Technology(Sartorius AG, Göttingen, Germany), spiked with isotope labeled internal standards and analyzed by online SPE-HPLC-MS/MS with a Triple Quadrupol mass spectrometer (TSQ Quantum Ultra, Thermo
Fisher Scientific). Limits of quantification are listed in the Supporting Informations (SI, Table S4).
Other measurements. The adsorbable organic halogen compounds (AOX) of three grab samples(effluents of: MBR, 43 mg/L PAC, and 1.08 g O3/g DOC) were determined coulometrically afterincineration according to DIN EN 1485-H14 and DIN EN ISO 9562 (by Bachema AG, Schlieren,
Switzerland).
Chemical oxygen demand (COD) was measured by a Dr. Lange test kit (Hach Lange GmbH,
Düsseldorf, Germany). Dissolved organic carbon (DOC) was determined using a Shimadzu TOC
analyzer. Bromate in the samples of high ozone dosages was measured by ion chromatography.36 For
gadolinium and platinum measurements, samples were acidified with 60% nitric acid (1%, v/v), andanalyzed by ICP-MS (Thermo Scientific, Element 2).

3. RESULTS AND DISCUSSION
3.1. Occurrence and Post-treatment Elimination Efficiencies. From the 67 target analytes (SI,
Table S1, S2), 9 were not detected in the raw hospital wastewater prior to the MBR treatment (SI, Table
S5), while cilastatin and paracetamol were removed during MBR treatment to non-detectable residues.11
The concentrations of the remaining 56 micropollutants after MBR treatment are listed in Table 1,
together with elimination efficiencies for the three post-treatments. Even after biological treatment,
concentrations are very high, e.g. at 3.4 mg/L for the iodinated contrast media (ICM) iopamidol, and forseveral other compounds higher than 10 µg/L (other ICM, 4/5 Methylbenzotriazole, benzotriazole, themetabolites of aminopyrine 4-AAA and 4-AA, ciprofloxacin, gabapentin). In total, ICM occur with aconcentration of 4.6 mg/L, from which a C-concentration of 1.2 mg/L was calculated (15-20% fractionof DOC). Elimination efficiencies were evaluated for the three different post treatments with PAC,
ozone and UV, each with three different dosages. Most compounds are eliminated well with PAC andozone, while elimination is much lower with UV. Due to low concentration or low frequency of
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detection, only partial information on elimination efficiencies was obtained for bezafibrate, ifosfamide,morphine, oseltamivir, oseltamivir carboxylate, ritonavir, sulfadiazine, thiopental, trimethoprim, andverapamil. Based on the results, we selected the doses 23 mg/L, 1.08 gO3/gDOC and 2400 J/m2 for
PAC, ozone and UV, respectively, for the further discussions in the following chapters, because they
showed relatively good abatement of micropollutants and are reasonable in the context of cost
constrains (see chapter 3.5.2). Elimination efficiencies with PAC and ozone normalized to DOC
compare very well with efficiencies in municipal wastewater treatment, as shown in Table S10 and S11
in a literature overview.

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Table 1. Post-treatment (O3, PAC, UV) elimination efficiencies (%) for 56 micropollutants
Influent(1)(µg/L)
1. 4-AAAc
2. 4-AAd
3. 4-FAAc
4. 4-MAAd
5. 4/5-TTrid
6. Atenolola
7. Atenolol acida
8. Azithromycinb
9. Benzotriazoleb
10. Bezafibratea
11. Carbamazepineb
12. Ciprofloxacinc
13. Clarithromycina
14. Clindamycinc
15. Cyclophosph.a
16. D617b
17. Diatrizoatec
18. Diclofenacb
19. Erythromycinc
20. Fluconazolea
21. Furosemideb
22. Gabapentinb
23. Hydrochloroth.a
24. Ifosfamideb
25. Indometacina
26. Iomeprold
27. Iopamidold
28. Iopromidec
29. Ioxitalamic a.c
30. Levetiracetama
31. Lidocainea
32. Mefenamic a.a
33. Metoprolola
34. Metronidazolec
35. Morphineb
36. N4-Ac-SMXa
37. Norfloxacinc
38. Oseltamivirc
39. Oseltamivir car.b
40. Oxazepama
41. Phenazonec
42. Primidoneb
43. Propranololb
44. Ranitidineb
45. Ritalinic acidb
46. Ritonavirb
47. Sotalola
48. Sulfadiazinea
49. SMXa
SMX+Ac-SMX
50. Sulfapyridinec
51. Thiopentalc
52. Tramadola
53. Trimethoprimc
54. Valsartanb
55. Venlafaxinea
56. Verapamila

11.3 ± 5.0
17.2 ± 8.0
4.79 ± 1.33
2.18 ± 3.01
40.2 ± 29.7
0.023 ± 0.024
1.87 ± 0.46
0.11 ± 0.18
10.1 ± 4.2<LOQ – 0.150
0.235 ± 0.128
15.7 ± 8.0
1.28 ± 0.84
1.16 ± 1.18
0.185 ± 0.064
0.143 ± 0.115
366 ± 259
0.858 ± 0.186<LOQ – 0.140
3.72 ± 1.71
2.46 ± 0.75
14.9 ± 18.7
1.84 ± 0.52
<LOQ – 0.600
0.064 ± 0.080
430 ± 466
3353 ± 5993
118 ± 108342 ± 204
0.551 ± 0.345
4.02 ± 3.74
0.491 ± 0.142
0.596 ± 0.227
1.86 ± 2.03
<LOQ – 0.280
0.455 ± 0.44
3.14 ± 1.82
0.036 ± 0.045
0.124 ± 0.115
1.06 ± 0.34
0.418 ± 0.259
0.601 ± 0.697
0.139 ± 0.067
0.454 ± 0.247
0.212 ± 0.103
0.024 ± 0.021
0.574 ± 0.467
2.33 ± 6.64
3.23 ± 4.70
3.76 ± 3.66
0.251
0.069 ± 0.079
0.891 ± 0.295
0.037 ± 0.037
0.455 ± 0.202
0.681 ± 0.275
0.005 ± 0.004

PAC(dose in mg/L) (2)823*4330 ± 673 ± 490 ± 292 ± 095 ± 299 ± 040 ± 181 ± 593 ± 268 ± 675 ± 467 ± 185 ± 493 ± 297 ± 0a
28 ± 0>88>88
98 ± 076 ± 194 ± 220 ± 0 e
100 ± 0 e
100 ± 0 e
69 ± 484 ± 294 ± 168 ± 12>86>86
98 ± 099 ± 1100 ± 0100 ± 0
>99 e
>99 e
e
100 ± 0100 ± 0 e
100 ± 0 e
96 ± 2 e>99 e
100 ± 0 e
>73
41 ± 673 ± 7100 ± 0>99>99
1±1
14 ± 218 ± 996 ± 198 ± 099 ± 0
>95 e
>88 e
>88 e
95 ± 299 ± 087 ± 398 ± 1>97>97
23 ± 142 ± 447 ± 197 ± 298 ± 088 ± 224 ± 0
>60
>60
>90
>91
>91
20 ± 465 ± 1090 ± 318 ± 269 ± 1180 ± 247 ± 585 ± 891 ± 02±2
9 ± 12
1 ± 1664 ± 773 ± 270 ± 299 ± 0100 ± 0100 ± 0
>99
>99
>99
>98
>99
>99
3 ± 22 e
67 ± 9 e
78 ± 5 e
n.a.
>63
>63
72 ± 392 ± 297 ± 199 ± 1 e
>99 e
>99 e
n.a.
>63
>63
12 ± 036 ± 4>36
98 ± 099 ± 0100 ± 088 ± 1197 ± 125 ± 82±0
79 ± 1088 ± 0
>91
>94
>94
>97
>96
>96
8±6
40 ± 457 ± 8n.a.
>87>87
91 ± 196 ± 199 ± 00 ± 0e40 ± 15 e>40 e
2 ± 8e33 ± 9 e
62 ± 11 e
7±7
39 ± 867 ± 985 ± 0 e
95 ± 2 e
>95 e
n.a.
>66
>66
98 ± 0100 ± 0100 ± 0n.a. e>83 e>83 e
89 ± 299 ± 199 ± 099 ± 0100 ± 0100 ± 0
>85
>88
>88

O3
(dose in g O3/g DOC) (3)
0.64
0.89
1.08
99 ± 199 ± 099 ± 0>83>83>83
96 ± 298 ± 198 ± 196 ± 097 ± 097 ± 190 ± 498 ± 0100 ± 0>23
>23
>23
97 ± 299 ± 1
>99
>91
>91
>91
66 ± 582 ± 090 ± 0n.a.
87 ± 4(s)
n.a.
>99
>99
>99
100 ± 0100 ± 0100 ± 0100 ± 0100 ± 0100 ± 0>98
>98
>98
33 ± 347 ± 057 ± 099 ± 0>99>99
7±2
10 ± 216 ± 2100 ± 0100 ± 0100 ± 0>93>93>93
27 ± 637 ± 247 ± 2>98>98>98
47 ± 1061 ± 474 ± 1
>98
>98
>98
20
41
62
>97
>97
>97
29 ± 640 ± 152 ± 331 ± 243 ± 255 ± 137 ± 349 ± 260 ± 22±2
13 ± 125 ± 743 ± 944 ± 954 ± 3
>98
>98
>98
>99
>99
>99
98 ± 1>97>97
4±0
25 ± 349 ± 4
n.a.
n.a.
n.a.
71 ± 080 ± 057 ± 3
>99
>99
>99
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
83 ± 161 ± 573 ± 1
71
>9
>9
49
68
78
>92
>92
>92
>98
>98
>98
84 ± 695 ± 199 ± 0
n.a.
n.a.
n.a.
>94
>94
>94
>47
>47
>47
99 ± 096 ± 198 ± 094 ± 296 ± 198 ± 1
>96
>96
>96
n.a.
n.a.
n.a.
>99
>99
>99
n.a.
n.a.
n.a.
61 ± 369 ± 178 ± 2100 ± 0100 ± 0100 ± 0
>76
>76
>76

UV
(fluence in J/m2)(4)
800
2 400
7 200
99 ± 042 ± 087 ± 153 ± 441 ± 655 ± 598 ± 143 ± 485 ± 025 ± 09 ± 1625 ± 10
1±5
6±4
5±5
5±2
-3 ± 1-9 ± 7-4 ± 27±4
12 ± 35±1
14 ± 423 ± 5
2±1
4±2
8±2
n.a.
n.a.
n.a.
1±2
1±0
1±2
15 ± 029 ± 457 ± 36±35±1
14 ± 11±98±415 ± 63±2
0±3-2 ± 17±1
6±2
12 ± 230 ± 172 ± 296 ± 088 ± 1>9847 ± 1
10 ± 03±0
10 ± 11±0
3±0
1±0
10 ± 013 ± 335 ± 65±61±6-3 ± 41±7
14 ± 350 ± 2
n.a.
n.a.
n.a.
6±5
9 ± 1324 ± 520 ± 565 ± 090 ± 228 ± 466 ± 092 ± 128 ± 1059 ± 392 ± 034 ± 352 ± 594 ± 210 ± 57 ± 100 ± 13
6±0
5±3
5±3
5±1
8±1
21 ± 52±00±1
4±0-9 ± 15-2 ± 36
22 ± 8>66>66
26 ± 07±1
14 ± 433 ± 114 ± 140 ± 163 ± 23±4
19 ± 140 ± 0
3
6
-2
1±0
5±2
12 ± 264 ± 545 ± 349 ± 68±2-5 ± 40±1
10 ± 312 ± 122 ± 315 ± 541 ± 171 ± 1
0±1
8±4
6±3
n.a.
n.a.
n.a.
79 ± 1>94
24 ± 210 ± 2>25>25
17 ± 155 ± 285 ± 316 ± 050 ± 378 ± 525 ± 769 ± 3-1 ± 3835473±1
14 ± 126 ± 15 ± 8 -12 ± 10
-8 ± 210±2
4±2
5±3-1 ± 72±2-1 ± 712 ± 719 ± 440 ± 5(1)

Post-treatment influent (MBR effluent) (2)Doses of PAC Norit SAE Super: 8 ± 4 mg/L; 23 ± 7 mg/L; and 43 ± 14 mg/L. (3)Doses of ozone: 0.64 ± 0.01 g
O3/g DOC; 0.89 ± 0.03 g O3/g DOC; and 1.08 ± 0.05 g O3/g DOC. (4)Applied fluence of 800 J/m2 in 1 run, 2400 J/m2 in 3 cycles, 7200 J/m2 in 9 cycles. * n=4(otherwise n=2). (s) spiked. a-d Analytical quality control label (see Table S4). e As reviewed in 37 Bold font: post-treatment effluent concentration is above 100
ng/L. Bold font, grey background: effluent concentration is above 10 µg/L. 4-AAA: 4-Acetamidoantipyrine, 4-AA: 4-Aminoantipyrine, 4-FAA: 4Formylaminoantipyrine, 4-MAA: 4-Methylaminoantipyrine, 4/5-Ttri: 4/5-Methylbenzotriazole, Cyclophosph.: Cyclophosphamide, Hydrochloroth.:Hydrochlorothiazide, a.: acid, N4-Ac-SMX: N4-acetylsulfamethoxazole, Oseltamivir car.: Oseltamivir carboxylate, SMX: sulfamethoxazole, SMX+AcSMX: sum of sulfamethoxazole and N4-acetylsulfamethoxazole. More on nomenclature and classification in Tables S1-S2.

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3.2. Prediction of the micropollutants’ elimination from physical-chemical properties
3.2.1. Ozone. The reactivity of micropollutants with ozone at a certain pH (apparent second order rate
constant, k”O3,app) can be estimated based on their molecular structures and pKa values, and roughly
divided into three classes38: (i) low or no reactivity with ozone (k”O3,app < ~10 M-1s-1): nitro group,
amides, N-phenyl amides; (ii) intermediate reactivity with ozone (~10> k”O3,app > ~1×105 M-1s-1):
primary amines, protonated secondary amines, thioethers, anisols, quinones, naphtalenes, nondissociated phenols; and (iii) high reactivity with ozone (k”O3,app > ~1×105 M-1s-1): olefins, dissociatedphenols (phenolates), anilines, thiophenols, deprotonated thiols, and tertiary amines. The reactivity ofozone-reactive moieties (ORMs) increases or decreases by neighbouring electron donating or electron
withdrawing groups, respectively. Molecules without ORMs are typically oxidized by hydroxyl radicals(•OH) which are formed as secondary oxidants during ozonation. 38, 39 In a recent study we showed that
it is possible to predict the abatement of ozone-resistant micropollutants by measuring •OH exposures 40.
This theoretical approach is well applicable to predict elimination. O3 reactivity estimations aredescribed in Table S6 and presented in comparison with the achieved eliminations in Table S11. All thecompounds that showed ≥ 97% or higher elimination from the hospital wastewater at an ozone dose of
1.08 gO3/gDOC contained moieties with high or intermediate reactivity with ozone (Tables S11-A, S11B). Although the range for intermediate reactivity is relatively large with its five orders of magnitude,
only < 20% of the target micropollutants belong to this group. For compounds without ORMs reactivity
with •OH is typically high (second-order rate constant typically in the range of 109 – 1010 M-1s-1),although the •OH concentration is very low compared to the ozone concentration and most of the •OH
are scavenged by the matrix prior to reacting with micropollutants. 38, 39
Further to the correlation of the elimination to the molecular structure, a comparison to known
ozonation rate constants from literature was performed (Figure 1, Table S11). For compounds for whichozone rate constants were not available (e.g. ritonavir), the reactivity range with ozone (none/low,intermediate and high reactivity) was estimated based on the structure (Table S6) and indicated in
Figure 1 with open symbols at an arbitrary log k”O3 within the appropriate reactivity range. The
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compounds with apparent ozonation rate constants at pH 8-8.5 >105 M-1s-1 (carbamazepine,
ciprofloxacin, clarithromycin, diclofenac, furosemide, lidocaine, mefenamic acid, ranitidine,sulfamethoxazole, and tramadol), show removal above 97%. As the ozone rate constants decrease adecrease in transformation is observed.

Reactivity with ozone
intermediate

none / low

high
1
16
13
55 12 11 49 18 37

5

100

25
45

33

% Elimination by ozone

9
40

80
24
15

52 21 31

44

36

54
42

60

7

46

3 32
14
23
4

22

28
27
30
26

34
20

40
29

20

17

known kO value
3
estimated reactivity

0
-1

0

1

2

3
log kO

4

5

6

7

3

Figure 1 Elimination of micropollutants during ozonation of hospital wastewater (1.08 gO3/gDOC, 7
mg/L O3, pH 8.5) versus ozonation rate constants from literature (M-1s-1, Table S11) or estimatedreactivity at pH 8-8.5 (Table S6) if kO3 is not available. Arrows represent log kO3<1 or 10, respectively.
See Table 1 for micropollutant numbering. Micropollutants for which quantification of elimination was
limited by LOQ (2, 6, 8, 10, 19, 35, 38, 39, 41, 43, 47, 48, 50, 51, 53, and 56) are not included.

3.2.2. PAC
Adsorption is depicted relative to the Dow of the adsorbates (micropollutants) in Figure 2. As theadsorption to activated carbon depends on multiple properties of micropollutants and carbon, prediction
for adsorption is not as accurate as for ozonation (Table S10). Interactions between the adsorbent (PAC)and adsorbate are controlled by non-specific dispersive interactions. In case of charged adsorbates also
electrostatic interactions with a charged adsorbent surface can be important. Properties of an adsorbate
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that mainly influence the adsorption process are its octanol-water distribution coefficient (Kow, or Dow
when accounting for acid-base speciation), pKa, molecular size, aromaticity versus aliphaticity, andpresence of specific functional groups. Properties of an adsorbent that mainly influence the adsorption
process are its surface area, pore size and texture, surface chemistry (functional groups, point of zerocharge pHPZC), and mineral matter content.41, 42 Despite of complex interactions, all compounds in ourdata set with logDow > 2 were removed completely (Figure 2) or to below their LOQs (Table S10-C).
Furthermore, for uncharged compounds with logDow ~ 2 and smaller, a decreasing trend in adsorption
efficiency with decreasing logDow values was observed. A good estimation for uncharged compounds
was possible, as no electrostatic interactions with the functional groups on the surface of the activatedcarbon occur and only dispersive forces are present. As also shown in Figure 2, a simple estimationfrom logDow values for charged polar compounds does not work and leads to an underestimation ofelimination efficiencies for many compounds (e.g. ciprofloxacin, furosemide, atenolol acid). At theworking pH 8.8, the surface of the utilized activated carbon with pHPZC 10 is predominantly positively
charged. This may explain the strong sorption of some compounds with anionic functional groups (e.g.
furosemide), others, however, show much lower elimination (e.g. sulfamethoxazole). The sameobservation is made for polar zwitterionic compounds. For polar cationic compounds, a generalstatement is difficult since only compounds with logDow ~ 0 and higher were analyzed for which a
certain adsorption is expected. Although the pHPZC of the carbon is known, the actual functional groups
responsible for electrostatic interaction are not known and this can be a possible explanation for thevarying behavior of individual charged compounds.

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Micropollutant polarity
moderately polar

polar

100

12

37
7

23

54
50

36

21

47

2 20

31

44

16 8 32
5
41

9

28

% Removal by PAC

14
18 33

3

80
30 15
27

1

52

55

apolar
40

11

13

42
4

34

26

60
22

40

45

39

48
49
neutral20

cation17

zwitterion

29

anion

0
-3

-2

-1

0
log Dow

1

2

3

Figure 2 Removal of micropollutants from hospital wastewater (23±7 mg/L PAC, pH 8.8) as afunction of logDow at pH 9 (Table S3). See Table 1 for micropollutant numbering. Micropollutants forwhich quantification of the elimination was limited by LOQ (6, 10, 19, 24, 25, 35, 38, 43, 46, 51, 53,
and 56) are not included.

3.2.3. UV No quantitative structure activity relationship (QSAR) to the fluence-based photolysis rate
constants of homologous compounds is known. Therefore, a prediction of the elimination efficiency by
UV from molecular structures or physical chemical properties is currently not possible. Elimination of acontaminant by photolysis was shown to be predictable only when experimentally determined fluencebased rate constants are available.34

3.3. Elimination efficiencies of different classes of analytes
3.3.1. Iodinated X-ray Contrast Media (ICM). Within the group of ICM, different elimination behaviorof uncharged ICM (iomeprol, iopamidol, and iopromide) compared to the charged diatrizoate andioxitalamic acid were observed. Adsorption of ICM to PAC is expected to be low (low logKow values,
SI, Table S6). Charged ICM are even more polar (logDow values in Table S3) and are eliminated
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significantly less than uncharged ICM. For ICM, elimination by ozonation is comparable, or lessefficient than by adsorption (Figure 3 shows a comparison of the removal efficiencies of ozonation and
PAC). ICM have second-order rate constants <1 M-1s-1 and elimination is dominated by oxidation by•

OH. 39 Concentrations in the µg/L to low mg/L range could still be found in the effluent. Removal by

UV for uncharged ICM is relativly high, comparable to removal by high PAC doses. For the twocharged ICM, only UV proved to be efficient, at the investigated doses for each treatment. The
maximum tested UV dose (9 cycles, fluence 7200 J/m2), though energetically very demanding, canremove around 95% of diatrizoate and ioxitalamic acid, although the remaining concentrations in theUV effluent of up to 20 µg/L are still considerable.

11.12.13.14.16.
18.21.23.31.32.
33.
37.44.
52.55.
7.
5.

54. 40.

100
20.

36.

28.

9.

% Removal by PAC

80

42.

30.
15.

34.

3.
4.

1.

27.

60

26.

22.

40

45.
49.

20

17.

29.

0
0

20

40

60

80

100

% Elimination by ozone

Figure 3. Comparison of micropollutants’ elimination by ozone and PAC. Ozone dose: 7 mg/L (1.08
gO3/gDOC, pH 8.5); PAC dose: 23±7 mg/L, pH 8.8. See Table 1 for micropollutant numbering.
3.3.2. Corrosion inhibitors. Methylbenzotriazole and benzotriazole are relatively well eliminated byadsorption to PAC as well as by ozonation. Nevertheless, concentrations of 200-1000 ng/L still remain
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even after application of the highest tested doses due to high inflow concentrations of these compounds.
Both compounds are moderately polar with methylbenzotriazole slightly more hydrophobic thanbenzotriazole (SI, Tables S3, S6), which resulted in 97 and 94% elimination at the highest tested PAC
dose for the two compounds, respectively. Ozone rate constants of the two structurally similar
compounds are in the intermediate range, with higher value for methylbenzotriazole (104 M-1s-1 foranion38, pKa 8.9) due to the presence of an electron donating methyl group that increases the reactivity
compared to benzotriazole (2650 M-1s-1 for anion38, pKa 8.6). No significant elimination by UV wasobserved up to an applied dose of 7200 J/m2.
3.3.3. Metamizole metabolites. Four human metabolites of the analgesic metamizole (aminopyrine)
were abundant in the MBR-treated hospital wastewater: 4-methylaminoantipyrine (4-MAA, hydrolysis
product of metamizole), 4-aminoantipyrine (4-AA, second generation TP), 4-acetamidoantipyrine (4AAA, third generation TP), and 4-formylaminoantipyrine (4-FAA, third generation TP). These
moderately hydrophilic pyrazolone derivates are well removed by ozonation due to an olefin group,
which has a high ozone reactivity. Only partial elimination could be achieved by adsorption to PAC andUV treatment. This resulted in effluent concentrations between ∼500 and 3000 ng/L after treatment with
PAC, and up to above 20 µg/L for 4-AA after the treatment with the highest tested UV dose (7200
J/m2).
3.3.4. Cyclophosphamide. Cyclophosphamide is a polar uncharged cytostatic with a similar
persistence to PAC and ozone treatment as uncharged ICM. The concentration of cyclophosphamide isabout 3 orders of magnitude lower than the concentrations of ICM, however, its toxicity is considerably
higher. With a logKow value ~0, no active sites for ozone attack, and no photochemical removal, theresulting final concentration of cyclophosphamide is often >100 ng/L, despite its relatively low influent
concentrations. The structurally related cytostatic ifosfamide shows similar removal trends, although it
was rarely detected in the wastewater.
3.3.5. Gabapentin and levetiracetam. The two structurally unrelated compounds are both antiepileptic
preparations occurring in raw hospital wastewaters in µg/L levels.11 Gabapentin is a very polar
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carboxylic acid (logDow -1.6 at pH 9) that shows only poor adsorption. At pH 8-8.5 it contains a
protonated primary amine, which shows intermediate reactivity with ozone. Levetiracetam is a polar anduncharged compound with a higher log Dow than gabapentin, which results in a slightly higher PAC
adsorption compared to gabapentin (Figure 3). Levetiracetam has no ozone-reactive moieties (twoamides), which leads to only a partial removal due to reaction with •OH. Therefore, the twoantiepileptics are not removed satisfactorily by any of the tested post-treatment technologies. The
remaining concentrations are >100 ng/L and in case of gabapentin, µg/L levels (Table 1).
3.3.6. Fluconazole, metronidazole, and sulfonamides. Anti-infectives discussed here in detail don’t
include antivirals or antibiotics which are either not frequently detected in the post-treatment influent(e.g. ritonavir, roxithromycin) or are well removed by both PAC and ozonation (e.g. ciprofloxacin,clarithromycin). The moderately hydrophilic antimycotic fluconazole, a triazole derivative, has noactive sites for ozone attack and therefore exhibits similar elimination efficiency by ozonation as ICM
due to only •OH oxidation. Elimination by adsorption to PAC is better, 95% at a PAC dose of 23 mg/L
(Figure 3). Metronidazole is polar and uncharged, similar to levetiracetam, which resulted in acomparable elimination efficiency (~75%) with the highest PAC dose of 43 mg/L. It contains a nitro
group, which deactivates the molecule for ozone attack, resulting in elimination efficiencies comparable
to compounds which were eliminated only by •OH. No significant elimination by UV was observed for
fluconazole and metronidazole. The sulfonamides sulfadiazine and sulfapyridine were found in theinfluent of the post-treatments only in low concentrations. Sulfamethoxazole was always detected in therange of 1-10 µg/L in the influent, and mostly above 100 ng/L in the effluent of the three posttreatments. The three sulfonamides differ in their pKa values and slightly in polarity (SI, Table S3),
which influences their adsorption behavior. At the working pH 8.8, the least charged and at the sametime the most hydrophobic of the three – sulfapyridine - shows the highest elimination efficiency by
PAC (Table 1). Due to the aniline functional group, the three sulfonamides react very fast with ozone.20
As most of the attack occurs at the aniline ring, N4-acetylated metabolites of sulfonamides, e.g. N4acetylsulfamethoxazole, exhibit lower reactivity with ozone due to deactivation due to the presence of
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the N-acetyl instead of a NH2 functional group. The three sulfonamides are also to a lower extent
sensitive to UV treatment.
3.3.7 Gadolinium and platinum. Additionally to organic micropollutants, the two metals were
measured. They occur in raw wastewater of the studied hospital mainly due to gadolinium complexes
used as magnetic resonance imaging (MRI) contrast media and platinum containing cytostatics (see SI,
Figures S1-S2), in average concentrations of 13.4 µg/L and 220 ng/L, respectively. After the MBR
treatment, average concentrations of 12.9 µg/L for Gd and 130 ng/L and for Pt were found. Platinumcontaining cytostatics were previously reported to sorb to 60% to activated sludge of a hospitalwastewater.43 Metals are principally not removed by ozonation or photolysis. The results for the PAC
dose of 10 mg/L and the ozone dose of 0.64 g O3/ g DOC show 47% elimination of platinum by PAC,
but no significant elimination neither of platinum by ozonation nor of gadolinium by any of thosetreatments. Gadolinium-containing contrast media are therefore very stable against oxidation and are notadsorbing to PAC.

3.4. Options to enhance the post-treatment steps 3.4.1. Ozone. Further experiments were performedby adding hydrogen peroxide. This accelerates ozone decomposition and partially increases the •OH
exposure in the system.38 Thus, the elimination of micropollutants with low reactivity with ozone may
be enhanced.44 To minimize the consumption of ozone by the background organic matter, the MBR
permeate was pre-treated with ozone prior to the O3/H2O2 experiment. Results from this first treatment
with 1.2 g O3/gDOC agreed well with the previously shown data. Micropollutant elimination after the
post-ozonation with hydrogen peroxide was not significantly improved (±10%) compared to ozone
alone (SI, Figure S4). This is in agreement with previous studies, where only little improvement was
found for O3/H2O2 compared to O3 alone, especially in waters with high DOC.44
3.4.2. PAC. Elimination efficiencies of the PAC process could potentially be improved if it iscombined with nanofiltration (instead of ultrafiltration), which would additionally retain micropollutantsby the membrane.45 However, due to its high micropollutant concentration, the nanofiltration
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concentrate has to be treated or otherwise taken care of.46 Alternatively, loaded activated carbon from
PAC post-treatment can be pumped to the MBR for recycling and thereby significantly increase theelimination in the bioreactor.23 No additional experiments on any of those processes were performed inthis study.
3.4.3. UV. The photocatalytic treatment of hospital wastewater MBR permeate by UV with a TiO2
photocatalyst showed lower elimination than UV treatment alone (SI, Table S12). With thephotocatalytic TiO2 fibers, there might be an additional indirect phototransformation, however thescreening and absorption of the light by the fibers proved to be higher than the possible indirect
phototransformation. The calculated fluence rate with the photocatalytic fiber was only 1.7 mW/cm2,
less than half of the value for the reactor without the photocatalytic fibers (4.0 mW/cm2) (SI, Page S21S22). Heterogeneous advanced oxidation by UV/TiO2 involves direct and indirect photolysis. A
micropollutant is adsorbed and attacked by •OH formed on the TiO2 surface. Unfortunately, the quantum
yield for the reaction of •OHTiO2 formation is very low and the whole process could suffer from adisadvantage of this inefficient step.47 Another process that is known to significantly improve UV
treatment of micropollutants is addition of hydrogen peroxide. It was shown before that the eliminationof atenolol, carbamazepine, primidone, and trimethoprim can be significantly improved by the additionof hydrogen peroxide. Using a low pressure UV lamp at 700 J/m2, the elimination of trimethoprim withaddition of 20 mg/L H2O2 was enhanced from <10% to 92%.27 Good elimination was also shown forsulfamethoxazole, clarithromycin, and lidocaine using a low pressure UV lamp with addition of H2O2.28

3.5. Overall comparison of the three post-treatment technologies. 3.5.1. DOC Removal. The
difference between the tested technologies in removal of dissolved organic carbon (DOC) is verysignificant. A decrease of 60% in DOC levels was observed after the treatment of MBR permeate by 23
mg PAC/L (SI, Table S7). The highest tested dose of 43 mg PAC/L removes around 70% of DOC andimproves the wastewater quality of the MBR permeate from 6.3 mg C/L to 2.0 mg C/L. The decrease in
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S9). While PAC removes DOC efficiently by adsorption, mineralization of dissolved organic matter
during ozonation and UV treatment is small.
3.5.2. Organic micropollutants. For this comparison, a realistic dose was selected for each treatment: 7
mg/L ozone (1.08 gO3/gDOC ozone; higher doses could produce an excess of bromate); 23 mg/L PAC(upper margin of range commonly used at full-scale without recycling to the biological reactor 23); and 3
cycles for UV treatment (2400 J/m2; a higher fluence is unrealistic due to high energy consumption, seesection 3.5.4). An evaluation of the three tested technologies with regard to micropollutant removal issummarized in Table 2. For comparison, the overall elimination efficiencies of the combined treatmentswith MBR are also shown. Removal efficiencies for the sum of the load of all target analytes (52-63%)
are close to ICM removal efficiencies (50-65%) for the three single post-treatments, because the MBR
effluent before the post-treatment consists of over 95% of ICM by load. Thus, it is more meaningful toevaluate elimination efficiencies in sub-groups: 1) iodinated X-ray contrast media (ICM); 2)
pharmaceuticals and metabolites excluding ICM; and 3) industrial chemicals.

Table 2 Comparison of MBR and the three post-treatment technologies (O3, PAC, UV) for groups of
micropollutants: elimination of micropollutant loads.
Combined treatments(same doses as for the single treatments)

Single treatments

MBR*

1.08
gO3/gDOC
O3

23 mg/L
PAC

2400 J/m2
UV

MBR+O3

MBR+PAC

MBR+UV

Iodinated X-ray
contrast media,
ICM

Load before (mg/d)
Load after (mg/d)
Elimination (%)

943'060
922'8882

922'888462'47950

922'888361'360
61

922'888324'69665

943'060
462'47951

943'060
361'360
62943'060
324'696
66

Pharmaceuticals(without ICM)
+ metabolites

Load before (mg/d)
Load after (mg/d)
Elimination (%)

211'205
21'60390

21'6032'103
90

21'603
2'991
86

21'60314'511
33

211'205
2'103
99

211'2052'991
99

211'205
14'511
93

Industrial
chemicals

Load before (mg/d)
Load after (mg/d)
Elimination (%)

81'602
16'19080

16'190320
98

16'190
1'418
91

16'190
15'226
681'602
320100

81'602
1'418
98

81'602
15'22681

Sum of all
analyzed
micropollutants

Load before (mg/d)
Load after (mg/d)
Elimination (%)

1'235'867
960'68122

960'681464'90152

960'681365'76862

960'681354'43363

1'235'867
464'90162

1'235'867
365'76870

1'235'867
324'69671*as in 11

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As discussed in 3.3.1, ICM are very difficult to remove by any of the three tested technologies,
although adsorption to PAC (61%) and UV treatment with very high doses (65%) show a slightly better
performance than ozonation (50%). An alternative and more efficient solution to remove ICM is
probably by collecting and incinerating the patients’ urine in hospitals and from out-patients.
For the sub-group of pharmaceuticals and metabolites excluding ICM, performance of ozonation(90%) is slightly better compared to PAC (86%), while UV (33%) is not satisfactory. A similar trend
and an even stronger difference between ozonation (98%), PAC (91%) and UV (6%) is observed for the
sub-group of industrial chemicals. Micropollutants of those two sub-groups, containing the majority ofanalyzed substances, can thus be treated most efficiently by ozonation or PAC. Most of the target
micropollutants have similar elimination efficiencies by ozonation and PAC (Figure 3). Few exceptions
are gabapentin, oseltamivir carboxylate, ritalinic acid, sulfadiazine, and sulfamethoxazole – for whichozonation is more efficient, or fluconazole, iopromide, levetiracetam, metronidazole, 4-MAA, and 4AAA – for which PAC is more efficient. The anionic ICM diatrizoate and ioxitalamic acid show
unsatisfactory removal by either ozone or PAC, and were the only compounds for which direct
phototransformation by UV at high doses of 2400 J/m2 turned out to be most efficient.
3.5.3 Energy consumption. For the analysis of energy consumption of the different post-treatments,
calculations for municipal wastewater treatment can be used. For ozonation, an energy consumption of
0.02 kWh/g ozone is needed for the generation of ozone from oxygen, including the production andtransport of oxygen.19, 48 When using 5-10 mg/L ozone, the total energy consumption is 0.1 - 0.2
kWh/m3. Energy consumption at the municipal wastewater treatment plant would rise by about 20-40%
when using ozonation. For PAC treatment, the energy consumption at the plant is only around 0.05
kWh/m3, so lower than for ozonation.48, 49 However, the production of PAC is energy intensive, what isreflected in the high costs of PAC (2 €/kg PAC). The UV reactor has a total energy consumption of 100400 W, depending on the selection of the pump, including a lamp power consumption of 40 W. In asingle treatment with a flow rate of 1000 L/h the energy consumption of the photocatalytic reactor is0.1-0.4 kWh/m3 and with nine cycles 0.9-3.6 kWh/m3. Therefore, the energy consumption in a single
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UV treatment is in a similar range as with 7 mg/L ozone (0.12 kWh/m3), however, with much lower
elimination efficiencies. Even with nine cycles the elimination by UV is lower than with ozone for mostcompounds except for ICM. UV/H2O2 was found to efficiently oxidize micropollutants but energy
requirements were substantially higher compared to ozonation. 28, 50
3.5.4 Cost. The treatment of hospital wastewater with ozone or PAC following an MBR would cost
2.90 or 3.20 CHF (2.40 or 2.70 €) per m3, respectively (details of the calculation are given in Tables
S14-S16). In Switzerland, municipal wastewater treatment costs about 2 CHF (1.70 €) per m3
wastewater (median), and with an additional treatment with ozone or PAC costs are estimated to bearound 2.20 CHF (1.80 €) per m3. The costs per m3 wastewater for the treatment of hospital wastewater(i.e. requiring biological treatment followed by either ozonation or PAC) is slightly higher than for thetreatment of the whole wastewater stream at the central municipal wastewater plant with the same
technology. If the hospital has a separate treatment and discharges the treated wastewater directly to thereceiving water, the investment cost for the municipal wastewater treatment will hardly change; only theoperation cost is reduced, which is in the range of 1-1.50 CHF (0.80-1.20 €) per m3 (for BOD, nutrientand micropollutant removal, depending on the size of the plant). The hospital has the advantage ofreusing the treated wastewater for gardening, which would then additionally reduce the drinking water
cost. Additionally there is no loss of raw hospital wastewater by combined sewer overflows andexfiltration from sewer systems.
3.5.5. Other important aspects. The main advantage of PAC over ozonation and UV is the “trueremoval” of chemicals from the wastewater by adsorption to carbon (that can be incinerated after use),rather than transformation to oxidation or photodegradation products. Those transformation products areoften unknown and have a potential to also have ecotoxicological effects.51, 52 It is recommended thatafter oxidative treatments a sand filter (biofilter) is installed to eliminate well degradable transformation
products. It was shown that sand filtration is an effective barrier to toxic oxidation byproducts
originating mainly from the matrix. 53, 54 Furthermore, ozonation can produce bromate, which is formedin bromide-containing waters and is the ozonation by-product of major concern.55 In our study, the
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bromide level in the MBR effluent was 30-40 µg/L, representative for municipal wastewater treatment
plants in Switzerland. Bromate was never found in quantifiable concentrations above 1 µg/L even for ahigh ozone dose of 1.08 g ozone/g DOC (7 mg/L ozone), thus it is well below the drinking water
standard of 10 µg/L.56
A value to consider to fulfill requirements of municipal wastewater treatment plant effluents is
AOX (adsorbable organic halogen compounds). AOX typically consists of compounds formed duringchlorination, which are potentially toxic. Hospital wastewater, however, is special due to the highconcentrations of non-toxic X-ray contrast media, which contain iodine. Organic iodine compounds may
account for about 50% of AOX input into municipal wastewater.57 The AOX value, measured in thisstudy only once (SI, Table S13), was decreased from 0.56 mg/L in the MBR permeate better by PAC(around 70%) than by ozonation (40%). The AOX in the final effluent after post-treatments, however,can be above requirements for wastewater treatment plant effluent (requirement for Switzerland: 0.08mg/L).58
Another important issue, specific for hospital wastewaters, is preventing input of pathogenic or(multi-)resistant bacteria and other potentially dangerous microorganisms and parasite eggs further into
the environment. Even though the MBR is a good barrier, a further disinfection step is advisable. For
inactivation of pathogens and possibly removal of antibiotic resistance, UV or ozonation are more
efficient compared to PAC.

ACKNOWLEDGMENT: We thank the collaborators of the project from Eawag S. Canonica, Y. Lee,R. Fankhauser, E. Salhi, and D. Kistler. We acknowledge the great support of the Cantonal hospital of
Baden, especially A. Eggmann and H. Wernli. Hoffmann-La Roche Ltd. (Basel, Switzerland) is
acknowledged for supplying oseltamivir reference standard and Chemonorm AG (Altendorf,
Switzerland) for supplying the ozone generator. We thank Prof. A. Reller (University of Augsburg,

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Germany) for funding the studies on the UV/TiO2 reactor from a project with the Schwyzer-foundation.
The work was further funded by the Swiss State Secretariat for Education and Research (SER)/COST
within COST Action 636, the EU project Neptune (contract no 036845, SUSTDEV-2005-3.II.3.2)
within the Energy, Global Change and Ecosystems Programme of the Sixth Framework (FP6-2005Global-4), the Swiss Federal Office for the Environment (FOEN), the Swiss Cantons AG, BE, BL, GE,
SG, SH, SO, SZ, TG, VD, ZH, and the Federal Office for Spatial Development (ARE), co-financed by
the budget 2 of NRP in the framework of the InterReg IVB North West Europe project PILLS.

SUPPORTING INFORMATION: Analyzed micropollutants, analytical method, gadolinium andplatinum measurements, parameters of the post-treatment plants, more information on elimination of
micropollutants and comparison with literature, AOX, cost evaluation (Tables S1−S16, Figures S1−S4).
This material is available free of charge via the Internet at http://pubs.acs.org.

REFERENCES
(1)

(2)

(3)

(4)

(5)

(6)

Hartmann, A.; Alder, A.C.; Koller, T.; Widmer, R.M., Identification of fluoroquinolone
antibiotics as the main source of umuC genotoxicity in native hospital wastewater.
Environmental Toxicology and Chemistry 1998, 17, (3), 377-382.
Kummerer, K., Drugs in the environment: emission of drugs, diagnostic aids and disinfectants
into wastewater by hospitals in relation to other sources - a review. Chemosphere 2001, 45, (67), 957-969.
Ort, C.; Lawrence, M.G.; Reungoat, J.; Eaglesham, G.; Carter, S.; Keller, J., Determining thefraction of pharmaceutical residues in wastewater originating from a hospital. Water Research
2010, 44, (2), 605-615.
Weissbrodt, D.; Kovalova, L.; Ort, C.; Pazhepurackel, V.; Moser, R.; Hollender, J.; Siegrist, H.;
McArdell, C.S., Mass flows of x-ray contrast media and cytostatics in hospital wastewater.
Environmental Science and Technology 2009, 43, (13), 4810-4817.
Blanch, A.R.; Caplin, J.L.; Iversen, A.; Kuehn, I.; Manero, A.; Taylor, H.D.; Vilanova, X.,
Comparison of enterococcal populations related to urban and hospital wastewater in various
climatic and geographic European regions. J Appl Microbiol 2003, 94, (6), 994-1002.
Guardabassi, L.; Petersen, A.; Olsen, J.E.; Dalsgaard, A., Antibiotic resistance in Acinetobacter
spp. isolated from sewers receiving waste effluent from a hospital and a pharmaceutical plant.
Appl Environ Microbiol 1998, 64, (9), 3499-502.

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(7)

(8)

(9)
(10)
(11)

(12)
(13)
(14)

(15)

(16)

(17)

(18)

(19)

(20)

(21)

(22)

(23)

Page 24 of 27

Reinthaler, F.F.; Posch, J.; Feierl, G.; Wuest, G.; Haas, D.; Ruckenbauer, G.; Mascher, F.;
Marth, E., Antibiotic resistance of E. coli in sewage and sludge. Water Research 2003, 37, (8),1685-1690.
Gebel, T.; Lantzsch, H.; Pleszow, K.; Dunkelberg, H., Genotoxicity of platinum and palladium
compounds in human and bacterial cells. Mutation Research/Genetic Toxicology andEnvironmental Mutagenesis 1997, 389, (2), 183-190.
Jolibois, B.; Guerbet, M., Hospital Wastewater Genotoxicity. Annals of occupational hygiene
2006, 50, (2), 189-196.
Zounkova, R.; Kovalova, L.; Blaha, L.; Dott, W., Ecotoxicity and genotoxicity assessment ofcytotoxic antineoplastic drugs and their metabolites. Chemosphere 2010, 81, (2), 253-260.
Kovalova, L.; Siegrist, H.; Singer, H.; Wittmer, A.; McArdell, C.S., Hospital Wastewater
Treatment by Membrane Bioreactor: Performance and Efficiency for Organic Micropollutant
Elimination. Environmental Science & Technology 2012, 46, (3), 1536-1545.
Pineau, C.; Heinzmann, B., Getrennte Erfassung von jodorganischen Röntgenkontrastmitteln in
Krankenhäusern. Wasser Abwasser GWF 2005, 146, (9), 646-653.
Joss, A.; Siegrist, H.; Ternes, T.A., Are we about to upgrade wastewater treatment for removing
organic micropollutants? Water Science and Technology 2008, 57, (2), 251-255.
Verlicchi, P.; Galletti, A.; Petrovic, M.; Barcelo, D., Hospital effluents as a source of emerging
pollutants: An overview of micropollutants and sustainable treatment options. Journal of
Hydrology 2010, 389, (3-4), 416-428.
Beier, S.; Cramer, C.; Koster, S.; Mauer, C.; Palmowski, L.; Schroder, H.F.; Pinnekamp, J., Fullscale membrane bioreactor treatment of hospital wastewater as forerunner for hot-spot
wastewater treatment solutions in high density urban areas. Water Science and Technology 2011,
63, (1), 66-71.
Gobel, A.; Thomsen, A.; McArdell, C.S.; Joss, A.; Giger, W., Occurrence and sorption behaviorof sulfonamides, macrolides, and trimethoprim in activated sludge treatment. Environmental
Science & Technology 2005, 39, (11), 3981-3989.
Joss, A.; Keller, E.; Alder, A.C.; Gobel, A.; McArdell, C.S.; Ternes, T.; Siegrist, H., Removal ofpharmaceuticals and fragrances in biological wastewater treatment. Water Research 2005, 39,(14), 3139-3152.
Flyborg, L.; Bjorlenius, B.; Persson, K.M., Can treated municipal wastewater be reused after
ozonation and nanofiltration? Results from a pilot study of pharmaceutical removal inHenriksdal WWTP, Sweden. Water Science and Technology 2010, 61, (5), 1113-1120.
Hollender, J.; Zimmermann, S.G.; Koepke, S.; Krauss, M.; McArdell, C.S.; Ort, C.; Singer, H.;
von Gunten, U.; Siegrist, H., Elimination of organic micropollutants in a municipal wastewater
treatment plant upgraded with a full-scale post-ozonation followed by sand filtration.
Environmental Science and Technology 2009, 43, (20), 7862-7869.
Huber, M.M.; Gobel, A.; Joss, A.; Hermann, N.; Loffler, D.; McArdell, C.S.; Ried, A.; Siegrist,
H.; Ternes, T.A.; von Gunten, U., Oxidation of pharmaceuticals during ozonation of municipal
wastewater effluents: A pilot study. Environmental Science & Technology 2005, 39, (11), 42904299.
Ternes, T.A.; Stueber, J.; Herrmann, N.; McDowell, D.; Ried, A.; Kampmann, M.; Teiser, B.,
Ozonation: A tool for removal of pharmaceuticals, contrast media and musk fragrances fromwastewater? Water Research 2003, 37, (8), 1976-1982.
Zimmermann, S.G.; Wittenwiler, M.; Hollender, J.; Krauss, M.; Ort, C.; Siegrist, H.; vonGunten, U., Kinetic assessment and modeling of an ozonation step for full-scale municipal
wastewater treatment: Micropollutant oxidation, by-product formation and disinfection. Water
Research 2011, 45, (2), 605-617.
Boehler, M.; Zwickenpflug, B.; Hollender, J.; Ternes, T.; Joss, A.; Siegrist, H., Removal of
micropollutants in municipal wastewater treatment plants by powder-activated carbon. Water
Science & Technology 2012, 66, (10), 2115-2121.
ACS Paragon Plus Environment

24

Page 25 of 27

(24)

(25)

(26)

(27)
(28)

(29)
(30)

(31)

(32)
(33)

(34)
(35)

(36)

(37)

(38)
(39)
(40)

Environmental Science & Technology

Kazner, C.; Fink, G.; Ternes, T.A.; Wintgens, T.; Melin, T. Removal of organic micropollutants
by nanofiltration in combination with adsorption on powdered activated carbon for artificial
groundwater recharge with reclaimed wastewater. in Micropol & Ecohazard Conference,Frankfurt, June 17 – 20. 2007.
Metzger, S.; Kapp, H.; Seitz, W.; Weber, W.H.; Hiller, G.; Suessmuth, W., Entfernung voniodierten Röntgenkontrastmitteln bei der kommunalen Abwasserbehandlung durch den Einsatz
von Pulveraktivkohle. Wasser Abwasser GWF 2005, 9, 638-645.
Snyder, S.A.; Wert, E.C.; Lei, H.; Westerhoff, P.; Yoon, Y., Removal of EDCs andpharmaceuticals in drinking and reuse treatment processes. Report of a study sponsored by
Awwa Research foundation. 2007, 331 pages.
Rosario-Ortiz, F.L.; Wert, E.C.; Snyder, S.A., Evaluation of UV/H2O2 treatment for theoxidation of pharmaceuticals in wastewater. Water Research 2009, 44, (5), 1440-1448.
Koehler, C.; Venditti, S.; Igos, E.; Klepiszewski, K.; Benetto, E.; Cornelissen, A., Elimination ofpharmaceutical residues in biologically pre-treated hospital wastewater using advanced UV
irradiation technology: A comparative assessment. Journal of Hazardous Materials 2012, 239240, 70-77.
Bellona, C.; Drewes, J.E.; Xu, P.; Amy, G., Factors affecting the rejection of organic solutes
during NF/RO treatment - a literature review. Water Research 2004, 38, (12), 2795-2809.
Kazner, C.; Lehnberg, K.; Kovalova, L.; Wintgens, T.; Melin, T.; Hollender, J.; Dott, W.,
Removal of endocrine disruptors and cytostatics from effluent by nanofiltration in combination
with adsorption on powdered activated carbon. Water Science and Technology 2008, 58, (8),1699-1706.
Radjenovic, J.; Petrovic, M.; Ventura, F.; Barcelo, D., Rejection of pharmaceuticals in
nanofiltration and reverse osmosis membrane drinking water treatment. Water Research 2008,
42, (14), 3601-3610.
Siegrist, H.; Joss, A., Review on the fate of organic micropollutants in wastewater treatment andwater reuse with membranes. Water Science and Technology 2012, 66, (6), 1369-1376.
Busetti, F.; Linge, K.L.; Heitz, A., Analysis of pharmaceuticals in indirect potable reuse systems
using solid-phase extraction and liquid chromatography-tandem mass spectrometry. Journal of
Chromatography A 2009, 1216, (31), 5807-5818.
Canonica, S.; Meunier, L.; von Gunten, U., Phototransformation of selected pharmaceuticals
during UV treatment of drinking water. Water Research 2008, 42, (1-2), 121-128.
Ishikawa, T., Photocatalytic fiber with gradient surface structure produced from a
polycarbosilane and its applications. International Journal of Applied Ceramic Technology
2004, 1, (1), 49-55.
Salhi, E.; von Gunten, U., Simultaneous determination of bromide, bromate and nitrite in lowµg/L levels by ion chromatography without sample pretreatment. Water Research 1999, 33,(15), 3239-3244.
Michael, I.; Rizzo, L.; McArdell, C.S.; Manaia, C.M.; Merlin, C.; Schwartz, T.; Dagot, C.; FattaKassinos, D., Urban wastewater treatment plants as hotspots for the release of antibiotics in theenvironment: A review. Water Research 2013, 47, (3), 957-995.
von Sonntag, C.; von Gunten, U., Chemistry of Ozone in Water and Wastewater Treatment:
From Basic Principles to Applications. 2012: IWA Publishing. 320.
von Gunten, U., Ozonation of drinking water: Part I. Oxidation kinetics and product formation.
Water Research 2003, 37, (7), 1443-1467.
Lee, Y.; Gerrity, D.; Lee, M.; Bogeat, A.E.; Salhi, E.; Gamage, S.; Trenholm, R.A.; Wert, E.C.;
Snyder, S.A.; von Gunten, U., Prediction of Micropollutant Elimination during Ozonation of
Municipal Wastewater Effluents: Use of Kinetic and Water Specific Information. Environmental
Science & Technology 2013, ASAP, DOI: 10.1021/es400781r.

ACS Paragon Plus Environment

25

Environmental Science & Technology

(41)

(42)
(43)

(44)
(45)

(46)
(47)
(48)
(49)

(50)

(51)
(52)

(53)

(54)

(55)
(56)
(57)
(58)

Page 26 of 27

de Ridder, D.J.; Villacorte, L.; Verliefde, A.R.D.; Verberk, J.Q.J.C.; Heijman, S.G.J.; Amy,
G.L.; van Dijk, J.C., Modeling equilibrium adsorption of organic micropollutants onto activatedcarbon. Water Research 2010, 44, (10), 3077-3086.
Moreno-Castilla, C., Adsorption of organic molecules from aqueous solutions on carbon
materials. Carbon 2004, 42, (1), 83-94.
Fuerhacker, M.; Lenz, K.; Mahnik, S.; Weissenbacher, N.; Mader, R.; Knasmüller, S.; Ferk, F.;
Uhl, M.; Bursch, W.; Koellensperger, G.; Hann, S., Chemische Analyse, Risikobewertung und
Entfernung von ausgewählten Zytostatika aus Abwasserströmen aus Krankenhäusern - Teil II"Risikoabschätung und Risikomanagement". BMLFUW 2006, 168.
Acero, J.L.; von Gunten, U., Characterization of oxidation processes: ozonation and the AOP
O3/H2O2. Journal American Water Works Association 2001, 93, (10), 90-100.
Kazner, C.; Meier, J.; Wintgens, T.; Melin, T., Capillary nanofiltration coupled with powdered
activated carbon adsorption for high quality water reuse. Water Science and Technology 2009,
60, (1), 251-259.
Benner, J.; Salhi, E.; Ternes, T.; von Gunten, U., Ozonation of reverse osmosis concentrate:
Kinetics and efficiency of beta blocker oxidation. Water Research 2008, 42, (12), 3003-3012.
Bolton, J.R., Ultraviolet Application Handbook (second edition). 2001: Bolton Photosciences
Inc.
Abegglen, C.; Joss, A.; Siegrist, H., Eliminating micropollutants: wastewater treatment methods.
Eawag News 2009, 67e, 25-27.
Abegglen, C.; Beier, S.; Pinnekamp, J.; Mauer, C.; Siegrist, H., Mikroverunreinigungen:
Energieverbrauch und Kosten weitergehender Verfahren auf kommunalen ARA. GWA Gas,
Wasser, Abwasser 2011, 7, 479-486.
Katsoyiannis, I.A.; Canonica, S.; von Gunten, U., Efficiency and energy requirements for thetransformation of organic micropollutants by ozone, O3/H2O2 and UV/H2O2. Water Research
2011, 45, (13), 3811-3822.
Escher, B.I.; Fenner, K., Recent Advances in Environmental Risk Assessment of Transformation
Products. Environmental Science & Technology 2011, 45, (9), 3835-3847.
Rosal, R.; Gonzalo, M.S.; Boltes, K.; Leton, P.; Vaquero, J.J.; Garcia-Calvo, E., Identification ofintermediates and assessment of ecotoxicity in the oxidation products generated during theozonation of clofibric acid. Journal of Hazardous Materials 2009, 172, (2-3), 1061-1068.
Stalter, D.; Magdeburg, A.; Oehlmann, J., Comparative toxicity assessment of ozone andactivated carbon treated sewage effluents using an in vivo test battery. Water Research 2010, 44,(8), 2610-2620.
Stalter, D.; Magdeburg, A.; Weil, M.; Knacker, T.; Oehlmann, J., Toxication or detoxication? In
vivo toxicity assessment of ozonation as advanced wastewater treatment with the rainbow trout.
Water Research 2010, 44, (2), 439-448.
von Gunten, U., Ozonation of drinking water: Part II. Disinfection and by-product formation inpresence of bromide, iodide or chlorine. Water Research 2003, 37, (7), 1469-1487.
von Gunten, U.; Salhi, E., Bromate in drinking water: A problem in Switzerland? Ozone:
Science and Engineering 2003, 25, (3), 159-166.
Kummerer, K., Pharmaceuticals in the Environment: Sources, fate, effects, and risks, ed.
Kummerer, K. Vol. 2. 2004, Berlin Heidelberg: Springer.
Swiss Water Protection Regulation, 814.201, Gewässerschutzverordnung vom 28. Oktober 1998
(GSchV), www.admin.ch/ch/d/sr/c814_201.html.

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