Next Article in Journal
Integrated Water Resources Management After 2030: An Agenda for Educators
Next Article in Special Issue
Persistent and Emerging Organic Contaminants in Natural Environments
Previous Article in Journal
Evaluation of Micrometeorological Models for Estimating Crop Evapotranspiration Using a Smart Field Weighing Lysimeter
Previous Article in Special Issue
Beyond Bioremediation: The Untapped Potential of Microalgae in Wastewater Treatment
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Water
Volume 17
Issue 2
10.3390/w17020188
water-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Degradation of X-Ray Contrast Media in Anaerobic Membrane Bioreactors

by
Jakub Konopka
1,
Joanna Kalka
2,* and
Sebastian Żabczyński
2
1
J.V. Technology Sp. z o. o., Męczenników Oświęcimia 1A, 41-922 Radzionków, Poland
2
Environmental Biotechnology Department, The Silesian University of Technology, Akademicka 2, 44-100 Gliwice, Poland
*
Author to whom correspondence should be addressed.
Water 2025, 17(2), 188; https://doi.org/10.3390/w17020188
Submission received: 29 November 2024 / Revised: 8 January 2025 / Accepted: 8 January 2025 / Published: 11 January 2025
(This article belongs to the Special Issue Persistent and Emerging Organic Contaminants in Natural Environments)
Browse Figures
Versions Notes

Abstract

:
The presence of pharmaceutical compounds, including iodinated contrast media (ICM), in aquatic systems poses significant ecological and health risks due to their biological activity at low concentrations. This study investigated the removal efficiency of three selected ICM—diatrizoate, iohexol, and iodipamide—from synthetic hospital wastewater using anaerobic membrane bioreactors (MBRs) operated at varying sludge ages of 40, 70, and 100 days. The results indicated that the performance of the MBRs in removing organic compounds improved with increased sludge age. Diatrizoate exhibited the highest removal efficiency, achieving 72% at a sludge age of 40 days and nearly 90% at 70 and 100 days, with no substantial differences between the two higher sludge ages. In contrast, iohexol and iodipamide demonstrated relatively low and inconsistent removal efficiencies, reaching a maximum of 40%, with no observable dependency on sludge age. The findings underscore the importance of optimizing sludge age in biological treatment processes for effective ICM removal.

1. Introduction

The rapid development of modern medicine and pharmacology has resulted in the production of increasingly effective drugs; however, this progress also has significant environmental implications. Many pharmaceutical products (PPs) are introduced into the environment during their production, storage, and excretion, with municipal wastewater serving as the primary pathway (Figure 1). In wastewater treatment plants (WWTPs), pharmaceuticals are only partially removed, resulting in their presence in surface waters at concentrations in the µg/L range [1]. From surface waters, these substances can accumulate in aquatic organisms or infiltrate groundwater, eventually reaching drinking water sources [2,3,4,5,6,7,8,9].
The presence of pharmaceutical compounds in aquatic systems poses diverse risks to ecosystems, aquatic life, and human health. Many pharmaceuticals are biologically active even at low concentrations, affecting the reproduction, behavior, and survival of aquatic organisms. For instance, endocrine-disrupting compounds such as steroid hormones interfere with reproductive systems, while antibiotics contribute to the emergence of antibiotic-resistant bacteria, a significant public health threat [10,11]. Furthermore, pharmaceutical pollutants persist in various environmental compartments due to their low biodegradability, creating chronic exposure risks for ecosystems and humans reliant on these water sources [12,13].
Given the widespread distribution of pharmaceutical pollutants, protecting water resources is critical. This challenge aligns with the One Health concept, which recognizes the interconnectedness of human, animal, and environmental health. Pharmaceutical contamination not only threatens drinking water safety but also undermines ecosystem functions essential for food security and biodiversity. To mitigate these impacts, integrated strategies encompassing pharmaceutical lifecycle management, advanced wastewater treatment, and public education on proper drug disposal are necessary [14,15].
The most common pharmaceuticals detected in wastewater are antibiotics, anti-inflammatory and anti-rheumatics, beta blockers, lipid regulators, hormones, and iodinated contrast media [5].
Iodinated contrast media (ICM) are compounds used to enhance the visualization of internal organs in X-ray-based imaging techniques such as computed tomography, magnetic resonance imaging, and ultrasound. The ICM consist of a benzene ring carrying iodine atoms in positions 2, 4, and 6 (the iodine atoms are responsible for absorption of X-rays) with carboxyl and hydroxyl moieties in the side chains [16]. Contrast media are metabolically stable and administered in very high doses (up to 300 g per diagnostic session) and, after diagnosis, are excreted mainly in nonmetabolized forms via urine or feces within 24 h [17].
Around 20 years ago, the worldwide consumption of X-rays fluctuated between 3000 and 3500 tons per year [3,8]. However, their consumption has increased up to 12,000 tons in recent years [18]. One of the reasons was the outbreak of COVID-19, when the ICM were used to image lung conditions. Their high concentration in environmental waters (in surface water and wastewater up to µg/L and in hospital wastewater up to mg/L levels) is a consequence of their high consumption and the biochemical stability of ICM. The main emissions for ICM are hospitals and radiological practices. The levels of X-ray contrast media in wastewater are influenced by various factors, including the size and type of hospital, as well as the day of the week, since X-ray examinations are predominantly conducted in hospitals and radiology practices from Monday to Friday [19,20]. The concentration of ICM in hospital wastewater can be up to 3810 µg/L [18]. The main iodinated contrast media detected in hospital wastewater were as follows: diatrizoat (348.7 ± 241.0 µg/L), iomeprol (424.0 ± 2093 µg/L), iohexol (1910 ± 3810 µg/L), iopamidol (2599 ± 1512 µg/L), and iopromide (170.6 ± 156.3 µg/L) [8,18,21]. Similarly, the majority of contrast media detected in influents at wastewater treatment plants include diatrizoat, iopromide, iothalamic acid, ioxithalamic acid, iopamidol, iopromide, and iohexol [8,20,22]. The ICM concentrations in raw wastewaters ranges between 1.14 and 15 µg/L [8,20,23]. The majority of that X-ray contrast media were detected at the same levels in influents and effluents (at µg/L levels) of a municipal wastewater treatment plant (WWTP), which confirms that contrast media are not eliminated in conventional wastewater treatment processes [19,24]. Integrating advanced oxidation processes (AOPs) or other complementary methods with biological treatment is recommended for achieving higher removal efficiencies. However, due to their limited elimination in WWTPs, these substances persist and are detected in surface water and groundwater. For example, the concentrations in surface water are as follows: iohexol 0.06–1.5 µg/L and iopromide 0.051–1.1 µg/L [22]. Xu et al. [24] found diatrizoate in Tai Lake at a concentration of 0.00014 µg/L. The amount of ICM in drinking water was noticed at the following levels: diatrizoate 0.06–0.166 µg/L [25,26,27], iohexol 0.038–0.040 µg/L [27], and iomeprol 0.12 µg/L [28]. The total concentrations of the X-ray contrast media in tap water ranged from 0.004 to 0.1 µg/L [17]. The efficiency of ICM removal by the standard methods of the treatment of drinking waters like chlorination, ozonation, bio-activated carbon adsorption, and membrane methods (ultrafiltration) was only 38.3% [17].
Iodinated contrast media are considered one of the better-tolerated groups of pharmaceuticals products; however, they can still cause adverse effects. The use of nonionic ICM has led to a significant decrease in the frequency of side effects and reactions like headaches, nausea, urticaria omitting, and low blood pressure bronchospasm [29]. Studies have provided evidence that iodinated contrast media (ICM) can exert negative effects on higher biological cells through mechanisms such as apoptosis, growth inhibition, genotoxicity, DNA double-stranded breaks, and oxidative stress [17,30]. Arnnok et al. [30] observed the accumulation of ICM in fish brain and gonadal tissues. Considering the ecological risks associated with iodinated contrast media, attention must be given to the formation of transformation products during chlorine disinfection, including iodinated disinfection by-products (I-DBPs) such as iodoacetic acid (IAA) and iodinated trihalomethanes (I-THM) [17,31,32]. MacKeown et al. [32] and Liu et al. [33] proved that, generally, I-DPMs are more cytotoxic and genotoxic than brominated and chlorinated trihalomethanes.
One of the most widely recognized methods for the biological treatment of hospital wastewater is the conventional activated sludge (CAS) system. Following mechanical pre-treatment, biological treatment serves as the secondary stage of wastewater purification. This process typically takes place in bioreactors, where contaminants are biodegraded under aerobic, anoxic, or anaerobic conditions by means of the activated sludge. Then, the wastewater mixture is directed to secondary clarifiers, where the activated sludge is separated from the treated wastewater in the sedimentation process. The effluent is then discharged into the receiving body. A part of the activated sludge is recirculated back into the system to maintain microbial activity, while the excess sludge is removed for further processing or disposal. Shengliu et al. [34] investigated the removal efficiency of pharmaceutical products in hospital wastewater treated in a municipal wastewater treatment plant in China. They indicated that the elimination efficiency for various compounds ranged from 39% to 98%. Similarly, Al-Quarni et al. [35] studied the efficiency of pharmaceutical products removal from hospital wastewater in Saudi Arabia. The removal efficiencies exceed 80% for pharmaceuticals such as ibuprofen, ketoprofen, and naproxen [35]. Many researchers have demonstrated that one of the key parameters affecting pharmaceutical removal efficiency is sludge age. Generally, a longer SRT facilitates the development of slow-growing organisms (e.g., nitrifying bacteria), which consequently fosters a more diverse microbial community with a broader range of physiological capabilities [36,37]. A reasonable biological method for treating hospital wastewater is the application of membrane bioreactors (MBRs). This technology integrates membrane filtration, which retains all biomass within the bioreactor, thereby eliminating the necessity for secondary clarifiers and significantly extending the sludge age. In this system, the activated sludge operates as a low-loaded biomass, and the retention of activated sludge in MBRs enables microorganisms to adapt to toxic pollutants [38]. Some studies have shown that the removal of pharmaceuticals using MBRs is comparable to that achieved with conventional activated sludge systems (e.g., ibuprofen, caffeine, and galaxolide) [39]. However, MBR systems can achieve relatively higher removal efficiencies (40–65%) for following pharmaceutical products found in hospital wastewater, including indomethacin, diclofenac, mefenamic acid, and gemfibrozil [37,40].
The main aim of this study was to investigate the removal efficiency of selected iodinated contrast media (ICM) from synthetic hospital wastewater using anaerobic membrane bioreactors operated at different sludge ages. The sludge ages, selected on the basis of preliminary unpublished studies, were maintained at 40, 70, and 100 days in MBR A, MBR B, and MBR C, respectively, and the selected ICM were diatrizoate, iohexol, and iodipamide.

2. Materials and Methods

2.1. Chemical Standards

Analytical standards of diatrizoate, iodipamide, and iohexol were supplied by Sigma-Aldrich (Poznań, Poland). The diatrizoate and iodipamide are considered as ionic ICM, and iohexol is considered as a nonionic ICM (Table 1).

2.2. Membrane Bioreactors Setup

For the purpose of this study, three anaerobic membrane bioreactors (MBRs) were started up (Figure 2). The working volume of all MBRs was equal to 45 L. The MBRs were equipped with the membranes manufactured by Kubota (Kubota Membrane Europe, London, UK) with a pore size equal to 0.4 µm and a total surface area of 0.1 m2. Three periods of MBRs were marked out during the study, which were differed sludge ages and loading rates:
  • The first period was from 1 to 17 days, which corresponded to the last 17 days of the adaptation period with regulation of the sludge age;
  • The second period was from 30 to 54 days, and the synthetic wastewater included ICM and regulation of the sludge age;
  • The third period was from 58 to 116 days maintaining a constant sludge age.
The parameters and operation conditions are shown in Table 2 and Table 3. The MBRs were fed with synthetic hospital wastewater, with the following composition: CH3COONa, KH2PO4, NH4Cl, MgSO4·7H2O, FeCl3·6H2O, and CaCl2·2H2O (all chemical compounds supplied by POCH, Gliwice, Poland); peptone (Witko Sp. z o. o., Łódź, Poland), and the studied ICM: diatrizoate, iohexol, and iodipamide.

2.3. Conventional Measurements

During the research period, the samples were collected from influents and effluents twice a week. All samples were filtered using a 0.45 µm glass filter. Dissolved oxygen and temperature were measured by a portable WTW 340i Do-meter (WTW GmbH, Weilheim, Germany). The mixed liquor suspended solids concentration was measured by the standard method. Chemical oxygen demand (COD), ammonia, nitrite, and nitrate nitrogen were measured by the Merck test (test numbers 14,541, 14,559, 100,609, and 14,764, respectively) with a Spectroquant® Nova 60 (Merck KGaA, Darmstadt, Germany).

2.4. Detection of ICM by HPLC

The X-ray contrast media were analyzed using reversed-phase high-performance liquid chromatography (RP HPLC) on an UltiMate 3000, (Dionex, Sunnyvale, CA, USA). The HPLC columns used were Hypersil Gold and LiChroCARTO 154-4 (Dionex, Sunnyvale, CA, USA).
For column C18, the mobile phase consisted of water, acetonitrile, and acetate buffer (prepared by mixing 1.2 mL acetic acid with 998.8 mL distilled water, adjusted to pH 5.7, and adding 110 mL acetonitrile) in a 55:42:3 (v/v/v) ratio. The mobile phase flow rate was set at 1 mL/min. For gradient elution, methanol (1 L methanol containing 5 mmol tetrabutylammonium bromide) and phosphate buffer (10 mmol K2HPO4, adjusted to pH 5.5 with NH3·H2O) were used. The flow rate was set to 1.3 mL/min, with the following gradient program:
  • 1–3.5 min: 7% methanol, 93% phosphate buffer;
  • 3.5–10 min: 20% methanol, 80% phosphate buffer;
  • 10.5–14 min: 7% methanol, 93% phosphate buffer.
The total run time was 14 min, with an injection volume of 20 µL. Detection was performed at wavelengths of 238 nm, 246 nm, 255 nm, and 265 nm.

3. Results

3.1. COD Elimination

A key operational parameter for controlling the bioreactor performance is the organic loading rate (OLR). If this parameter, expressed, for example, as BOD5, is between 0.05 and 0.2 gO2/gMLSS·d, the activated sludge is considered to operate under low-loaded conditions. When the organic load rate ranges from 0.2 to 0.4 gO2/gMLSS·d, the sludge is classified as medium-loaded. During the initial phase of the study, the COD load on activated sludge for all bioreactors was low and at a similar level, ranging from 0.04 to 0.08 gO2/gMLSS·d (with an average of 0.06 gO2/gMLSS·d), which was attributed to the high concentration of activated sludge in the bioreactors and low flow rates. Variations in the OLR were observed over time. In the second phase of the experiment, no significant differences in OLR were noticed between MBR B (average 0.1 gO2/gMLSS·d) and MBR C (average 0.08 gO2/gMLSS·d). However, MBR A showed a higher OLR compared to the other two bioreactors, averaging 0.15 gO2/gMLSS·d. This was attributed to its lower MLSS concentration relative to MBR B and MBR C. In the third phase of the study, a significant difference in OLR among the bioreactors was observed. The highest organic loading rate was recorded in MBR A, with an average value of 0.17 gO2/gMLSS·d, which was due to its relatively low sludge concentration. The lowest OLR was observed in MBR C, with an average of 0.09 gO2/gMLSS·d, while MBR B had an intermediate load of 0.11 gO2/gMLSS·d. All bioreactors operated as low-loaded systems. For comparison, Sengar and Vijayanandan [42] reported organic pollutant loads ranging from 0.014 to 0.023 gO2/gMLSS·d in their study, which were significantly lower than the values observed in this research.
Figure 3 shows the COD removal efficiency. During the first period, COD removal efficiency was high in all bioreactors, exceeding 90% in MBR B. However, by the end of the first period, the removal efficiency decreased and was lower in MBR A and MBR B compared to MBR C. This was attributed to different sludge ages, with MBR C having the highest concentration of MLSS. In the second period, a higher COD removal efficiency was observed in all MBRs compared to the first period, with the third period showing a trend of more stable efficiency compared to the previous periods. As shown in Figure 3, MBR A exhibited the highest instability in organic compound removal efficiency. There was no significant difference in COD removal efficiency between MBR B and MBR C. The average COD removal efficiency was 54%, 86%, and 82% for MBR A, B, and C, respectively.

3.2. ICM Elimination

The average concentration of the iodipamide in influent ranged between from 1.30 and 2.14 mg/L. In the second period, iodipamide removal was observed at 49% in MBR A, 54% in MBR B, and 51% in MBR C. After 54 days (third period), a lower removal rate was noted, likely due to a decrease in biomass concentration in the bioreactors, resulting from maintaining the appropriate sludge age. The elimination of these substances in the three periods decreased to 45% in all MBRs (Figure 4).
The average concentration of iohexol in the influent varied from 0.91 to 1.14 mg/L. In the second period, the iohexol elimination reached 17%, 19%, and 12% in MBR A, MBR B, and MBR C, respectively. In the third period, iohexol removal ranged from 1% to 35% in MBR A, 3% to 30% in MBR B, and 5% to 43% in MBR C, with average elimination rates of 16%, 15%, and 16%, respectively (Figure 5). This suggests that the removal efficiency in anaerobic MBRs is not dependent on sludge age.
The average concentration of diatrizoate in the influent ranged from 1.01 to 1.13 mg/L. In the second period, the average removal of this substance was 87%, 86%, and 90% in MBR A, MBR B, and MBR C, respectively. In the third period, the elimination of diatrizoate varied from 43% to 89% in MBR A, from 81 to 95% in MBR B, and from 83 to 93% in MBR C. The obtained results showed that the removal was slightly dependent on sludge age. At sludge age 40 d, the elimination of diatrizoate was lower than at the higher sludge ages. However, at a sludge age of 70 days, the average diatrizoate removal was 88%, and increasing the sludge age to 100 days did not further significantly improve the elimination, which remained at 89% (Figure 6).

4. Discussion

The average elimination of iodipamide in all the studied anaerobic membrane bioreactors was approximately 50%. Żabczyński et al. [43] achieved similar results of 54% removal for iodipamide in an aeration membrane bioreactor with 40 days sludge age and only 30% for 24 days sludge age. These results indicated that the efficiency of iodipamide elimination in aerobic membrane bioreactors depends on sludge age; however, the anaerobic membrane bioreactors did not show any significant differences in removal efficiency at different sludge ages.
The elimination of iohexol was inconsistent across all operating periods of the anaerobic membrane bioreactors, ranging from 1% to 35% in MBR A, 3% to 30% in MBR B, and 5% to 43% in MBR C. James et al. [44] studied the biodegradability ICM in a simultaneous nitrification and denitrification system in SBR (sludge age 20 days). The removal efficiency of iohexol was 47.8% with an aeration time of 300 min and a dissolved oxygen concentration of 1 mgO2/L. However, when the anoxic time was longer (300 min—phase three in this study), the observed concentration of iohexol in the effluent was higher than the influents, which could be explained by the accumulation of the iohexol from earlier cycles. Sengar and Vijayanandan [42] studied the removal of iodinated X-ray contrast media in an aerobic membrane bioreactor at a concentration of the dissolved oxygen around 4 mg/L and sludge aged 70 days. The average removal of iohexol was found to be 34.9%, but when the sludge age was reduced to 20 days, the removal efficiency decreased to less than 25%. Żabczyński et al. [43] achieved the results of 24% and 37% iohexol removal in an aeration membrane bioreactor at 24 and 40 days sludge age, respectively. This strongly suggests that the efficiency of iohexol elimination depends on both sludge age and aeration conditions. According to the literature, higher removal efficiencies may be achieved using ozonation, which results in a removal rate of 33–55% or by using combined UV/TiO2 pretreatment prior to MBR, potentially achieving 100% removal efficiency [44,45].
The elimination of diatrizoate was the highest among the studied ICMs, reaching nearly 90% in MBR A and exceeding this value in MBR B and MBR C, achieving 95% and 93%, respectively. Żabczyński et al. [43] achieved the result of 57% removal for diatrizoat in an aerobic membrane bioreactor at 40 days sludge age. Hapeshi et al. [46] achieved 73% efficiency of diatrizoate removal after 5 days of treatment in a moving bed biofilm reactor (MBBR) operating under denitrification and nitrification conditions. Haiβ and Kümmerer [47] obtained their results using the Zahn-Wellens test (OECD 302B) removal at a level of 83–88%. Ternes et al. [48] observed only 13% and 14% removal of diatrizoate using ozonation with ozone doses of 10 and 15 mg/L, respectively; however, when employing advanced oxidation processes (ozonation combined with UV radiation), they achieved a 36% removal. Borowska et al. [49] achieved over 90% removal of diatrizoate by means combining UV and aerobic MBR with 40 days sludge age and more than 80% efficiency of removal by means of UV/TiO2 and 40 days sludge age. During chromatographic analysis of the samples from the bioreactor’s effluent, a significant reduction in diatrizoate concentration was noticed. However, the chromatograms revealed the presence of an additional peak with a retention time closely approximating that of diatrizoate and an intensity comparable to the initial diatrizoate peak. This finding suggests that complete mineralization of the compound did not occur. Despite the apparent reduction in this contrast agent due to the biological processes within the bioreactors, a metabolite was generated, exhibiting structural and physical properties (e.g., similar affinity for the stationary phase) analogous to those of the parent compound. It is hypothesized that the structural modification of diatrizoate involved the removal of one or two iodine atoms (deiodination). Haiβ and Kümmerer [48], using the Zahn-Wellens test (OECD 302B), observed that, after 23 days, the diatrizoate was almost completely biotransformed but not fully mineralized. Based on previous studies, it is suggested that the biotransformation of diatrizoate involves several processes, including hydroxylation, deacetylation, deiodination, loss of amine groups, and loss of alcohol groups [46,47,48].

5. Conclusions

The performance of anaerobic membrane bioreactors (MBRs) in organic compounds elimination demonstrated a dependence on sludge age, achieving 54% removal at a sludge age of 40 days and over 80% at 70 and 100 days, with no significant differences observed between the higher sludge ages. Among the iodinated contrast agents studied, diatrizoate was the most effectively removed, following a similar sludge age dependency: 72% removal at 40 days and nearly 90% at 70 and 100 days, again showing no significant differences at the higher sludge ages. The elimination of iodipamide and iohexol was relatively low and showed no dependence on sludge age, with the maximum removal rates in the third period reaching approximately 40%. Generally, in order to obtain the efficiency of iodinated contrast media removal, biological wastewater treatment should be combined with advanced oxidation processes (AOPs) or other complementary methods.

Author Contributions

Conceptualization, J.K. (Jakub Konopka) and S.Ż.; methodology, J.K. (Jakub Konopka) and S.Ż.; investigation, J.K. (Jakub Konopka); resources, S.Ż.; data curation, J.K. (Jakub Konopka); writing—original draft preparation, J.K. (Jakub Konopka) and S.Ż.; writing—review and editing, J.K. (Joanna Kalka) and S.Ż.; visualization, J.K. (Jakub Konopka); supervision, S.Ż. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Ministry of Education and Science Poland.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Conflicts of Interest

Author Jakub Konopka was employed by the company J.V. Technology Sp. z o. o. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. Sengar, A.; Vijayanandan, A. Comprehensive review on iodinated X-ray contrast media: Complete fate, occurrence, and formation of disinfection byproducts. Sci. Total Environ. 2021, 769, 144846. [Google Scholar] [CrossRef] [PubMed]
  2. Anderson, P.D.; D’Aco, V.J.; Shanahan, P.; Chapra, S.C.; Buzby, M.E.; Cunningham, V.L.; Duplessie, B.M.; Hayes, E.P.; Mastrocco, F.J.; Parke, N.J.; et al. Screening analysis of human pharmaceutical compounds in U.S. surface waters. Environ. Sci. Technol. 2004, 38, 838–849. [Google Scholar] [CrossRef] [PubMed]
  3. Daughton, C.; Ternes, T.A. Pharmaceuticals and personal care products in the environment: Agents of subtle change? Environ. Health Perspect. 1999, 107 (Suppl. S6), 907–938. [Google Scholar] [CrossRef]
  4. Giger, W.; Alder, A.C.; Golet, E.M.; Kohler, H.P.E.; McArdell, C.S.; Molnar, E.; Siegrist, H.; Suter, M.J.F. Occurrence and fate of antibiotics as trace contaminants in wastewaters, sewage sludges, and surface waters. Chimia 2003, 57, 485–491. [Google Scholar] [CrossRef]
  5. Joss, A.; Żabczyński, S.; Göbel, A.; Hoffmann, B.; Löffler, D.; McArdell, C.S.; Ternes, T.A.; Thomsen, A.; Siegrist, H. Biological degradation of pharmaceuticals in municipal wastewater treatment: Proposing a classification scheme. Water Res. 2006, 40, 1686–1696. [Google Scholar] [CrossRef]
  6. McArdell, C.S.; Molnar, E.; Suter, M.J.F.; Giger, W. Occurrence and fate of macrolide antibiotics in wastewater treatment plants and in the Glatt Valley Watershed, Switzerland. Environ. Sci. Technol. 2003, 37, 5479–5486. [Google Scholar] [CrossRef] [PubMed]
  7. Metcalfe, C.D.; Miao, X.-S.; Koenig, B.G.; Struger, J. Distribution of acidic and neutral drugs in surface waters near sewage treatment plants in the lower Great Lakes, Canada. Environ. Toxicol. Chem. 2003, 22, 2881–2889. [Google Scholar] [CrossRef] [PubMed]
  8. Pérez, S.; Barceló, D. Fate and occurrence of X-ray contrast media in the environment. Anal. Bioanal. Chem. 2007, 387, 1235–1246. [Google Scholar] [CrossRef]
  9. Tixier, C.; Singer, H.P.; Oellers, S.; Müller, S.R. Occurrence and fate of carbamazepine, clofibric acid, diclofenac, ibuprofen, ketoprofen, and naproxen in surface waters. Environ. Sci. Technol. 2003, 37, 1061–1608. [Google Scholar] [CrossRef] [PubMed]
  10. Hirsch, R.; Ternes, T.A.; Lindart, A.; Haberer, K.; Wilken, R.-D. A sensitive method for the determination of iodine-containing diagnostic agents in aqueous matrices using LC electrospray tandem-MS detection. Fresenius J. Anal. Chem. 2000, 366, 835–841. [Google Scholar] [CrossRef] [PubMed]
  11. Watkinson, A.J.; Murby, E.J.; Kolpin, D.W.; Costanzo, S.D. The occurrence of antibiotics in an urban watershed: From wastewater to drinking water. Sci. Total Environ. 2009, 407, 2711–2723. [Google Scholar] [CrossRef] [PubMed]
  12. Sui, Q.; Cao, X.; Lu, S.; Zhao, W.; Qiu, Z.; Yu, G. Occurrence, sources, and fate of pharmaceuticals and personal care products in groundwater: A review. Emerg. Contam. 2015, 1, 14–24. [Google Scholar] [CrossRef]
  13. Kumar, M.; Sarma, D.K.; Shubham, S.; Kumawat, M.; Verma, V.; Prakash, A.; Tiwari, R. Environmental endocrine-disrupting chemical exposure: Role in non-communicable diseases. Front. Public Health 2020, 8, 553850. [Google Scholar] [CrossRef] [PubMed]
  14. Fekadu, S.; Alemayehu, E.; Dewil, R.; Van der Bruggen, B. Pharmaceuticals in freshwater aquatic environments: A comparison of the African and European challenge. Sci. Total Environ. 2019, 654, 324–337. [Google Scholar] [CrossRef]
  15. Khan, A.H.A.; Barros, R. Pharmaceuticals in water: Risks to aquatic life and remediation strategies. Hydrobiology 2023, 2, 395–409. [Google Scholar] [CrossRef]
  16. Węgrzyn, A.; Żabczyński, S. Monitoring of bacteria biodiverisity in anaerobic membrane bioreactors (AnMBRs) dealing with wastewater containing X-ray contrast media compounds. Environ. Prot. Eng. 2014, 1, 151–164. [Google Scholar]
  17. Yan, H.; Zhang, T.; Yang, Y.; Li, J.; Liu, Y.; Qu, D.; Feng, L.; Zhang, L. Occurrence of iodinated contrast media (ICM) in water environments and their control strategies with a particular focus on iodinated by-products formation: A comprehensive review. J. Environ. Manag. 2024, 351, 119931. [Google Scholar] [CrossRef] [PubMed]
  18. Ternes, T.A.; Hirsch, R. Occurrence and behavior of X-ray contrast media in sewage facilities and the aquatic environment. Environ. Sci. Technol. 2000, 34, 2741–2748. [Google Scholar] [CrossRef]
  19. Heberer, T. Occurrence, fate, and removal of pharmaceutical residues in the aquatic environment: A review of recent research data. Toxicol. Lett. 2002, 131, 5–17. [Google Scholar] [CrossRef]
  20. Kovalova, L.; Siegrist, H.; Singer, H.; Wittmer, A.; McArdell, C.S. Hospital wastewater treatment by membrane bioreactor: Performance and efficiency for organic micropollutant elimination. Environ. Sci. Technol. 2012, 46, 1536–1545. [Google Scholar] [CrossRef] [PubMed]
  21. Watanabe, Y.; Bach, L.T.; Van Dinh, P.; Prudente, M.; Aguja, S.; Phay, N.; Nakata, H. Ubiquitous detection of artificial sweeteners and iodinated X-ray contrast media in aquatic environmental and wastewater treatment plant samples from Vietnam, the Philippines, and Myanmar. Arch. Environ. Contam. Toxicol. 2016, 70, 671–681. [Google Scholar] [CrossRef] [PubMed]
  22. Kormos, J.L.; Schulz, M.; Kohler, H.-P.E.; Ternes, T.A. Biotransformation of selected iodinated X-ray contrast media and characterization of microbial transformation pathways. Environ. Sci. Technol. 2010, 44, 4498–4507. [Google Scholar] [CrossRef] [PubMed]
  23. Carballa, M.; Omil, F.; Lema, J.M.; Llompart, M.; Garcia-Jares, C.; Rodriguez, I.; Gomez, M.; Ternes, T.A. Behavior of pharmaceuticals, cosmetics, and hormones in sewage treatment plant. Water Res. 2004, 38, 2918–2926. [Google Scholar] [CrossRef] [PubMed]
  24. Xu, Z.; Li, X.; Hu, X.; Yin, D. Distribution and relevance of iodinated X-ray contrast media and iodinated trihalomethanes in an aquatic environment. Chemosphere 2017, 184, 253–260. [Google Scholar] [CrossRef]
  25. Putschew, A.; Schittko, S.; Jekel, M. Quantification of triiodinated benzene derivatives and X-ray contrast media in water samples by liquid chromatography–electrospray tandem mass spectrometry. J. Chromatogr. A 2001, 930, 127–134. [Google Scholar] [CrossRef]
  26. Seitz, W.; Weber, W.H.; Jiang, J.-Q.; Lloyd, B.J.; Maier, M.; Maier, D.; Schulz, W. Monitoring of iodinated X-ray contrast media in surface water. Chemosphere 2006, 64, 1318–1324. [Google Scholar] [CrossRef]
  27. Singh, R.R.; Rajnarayanan, R.; Aga, D.S. Binding of iodinated contrast media (ICM) and their transformation products with hormone receptors: Are ICM the new EDCs? Sci. Total Environ. 2019, 692, 32–36. [Google Scholar] [CrossRef]
  28. Kim, S.J.; Grossberg, J.A.; Nogueira, R.G.; Haussen, D.C. Hyperacute unilateral contrast-induced parotiditis during cerebral angiography. Radiol. Case Rep. 2018, 13, 225–227. [Google Scholar] [CrossRef] [PubMed]
  29. Yang, H.; Li, X.; Zheng, X.; Zhi, H.; Tang, G.; Ke, Y.; Liu, B.; Ma, H. Comparing the toxicity of iodinated X-ray contrast media on eukaryote- and prokaryote-based quantified microarray assays. Ecotoxicol. Environ. Saf. 2022, 240, 113678. [Google Scholar] [CrossRef] [PubMed]
  30. Arnnok, P.; Singh, R.R.; Burakham, R.; Pérez-Fuentetaja, A.; Aga, D.S. Selective uptake and bioaccumulation of antidepressants in fish from effluent-impacted Niagara River. Environ. Sci. Technol. 2017, 51, 10652–10662. [Google Scholar] [CrossRef] [PubMed]
  31. Zhou, N.; Liu, H.; Yang, X.; Watson, P.; Yang, F. Disinfection byproducts of iopamidol, iohexol, diatrizoate, and their distinct acute toxicity on Scenedesmus sp., Daphnia magna, and Danio rerio. Chemosphere 2023, 333, 138885. [Google Scholar] [CrossRef] [PubMed]
  32. MacKeown, H.; von Gunten, U.; Criquet, J. Iodide sources in the aquatic environment and its fate during oxidative water treatment—A critical review. Water Res. 2022, 217, 118417. [Google Scholar] [CrossRef] [PubMed]
  33. Liu, S.; Li, Z.; Dong, H.; Goodman, B.A.; Qiang, Z. Formation of iodotrihalomethanes, iodo-acetic acids, and iodo-acetamides during chloramination of iodide-containing waters: Factors influencing formation and reaction pathways. J. Hazard. Mater. 2017, 321, 28–36. [Google Scholar] [CrossRef]
  34. Yuan, S.; Jiang, X.; Xia, X.; Zhang, H.; Zheng, S. Detection, occurrence and fate of 22 psychiatric pharmaceuticals in psychiatric hospital and municipal wastewater treatment plants in Beijing, China. Chemosphere 2013, 90, 2520–2525. [Google Scholar] [CrossRef]
  35. Al Qarni, H.; Collier, P.; O’Keeffe, J.; Akunna, J. Investigating the removal of some pharmaceutical compounds in hospital wastewater treatment plants operating in Saudi Arabia. Environ. Sci. Pollut. Res. 2016, 23, 13003–13014. [Google Scholar] [CrossRef]
  36. Clara, M.; Kreuzinger, N.; Strenn, B.; Gans, O.; Martinez, E.; Kroiss, H. The solids retention time—A suitable design parameter to evaluate the capacity of wastewater treatment plants to remove micropollutants. Water Res. 2005, 39, 97–106. [Google Scholar] [CrossRef] [PubMed]
  37. Verlicchi, P.; Galletti, A.; Petrovic, M.; Barceló, D. Hospital effluents as a source of emerging pollutants: An overview of micropollutants and sustainable treatment options. J. Hydrol. 2010, 389, 416–428. [Google Scholar] [CrossRef]
  38. Bhandari, G.; Chaudhary, P.; Gangola, S.; Gupta, S.; Gupta, A.; Rafatullah, M.; Chen, S. A review on hospital wastewater treatment technologies: Current management practices and future prospects. J. Water Process Eng. 2023, 56, 104516. [Google Scholar] [CrossRef]
  39. Oppenheimer, J.; Stephenson, R.; Burbano, A.; Liu, L. Characterizing the passage of personal care products through wastewater treatment processes. Water Environ. Res. 2007, 79, 2564–2577. [Google Scholar] [CrossRef]
  40. Ajala, O.J.; Tijani, J.O.; Salau, R.B.; Abdulkareem, A.S.; Aremu, O.S. A review of emerging micro-pollutants in hospital wastewater: Environmental fate and remediation options. Results Eng. 2022, 16, 100671. [Google Scholar] [CrossRef]
  41. Drug Bank. Available online: https://go.drugbank.com/ (accessed on 8 August 2024).
  42. Sengar, A.; Vijayanandan, A. Fate and removal of iodinated X-ray contrast media in membrane bioreactors: Microbial dynamics and effects of different operational parameters. Sci. Total Environ. 2023, 869, 161827. [Google Scholar] [CrossRef]
  43. Żabczyński, S.; Buczyński, R.; Ziembińska, A. X-ray contrast media removal in membrane bioreactors. In Proceedings of the Low Carbon Earth Summit 2011: BIT’s 1st World Congress of Environmental Biotechnology, Dalian, China, 19–26 October 2011. [Google Scholar]
  44. James, S.N.; Sengar, A.; Vijayanandan, A. Investigating the biodegradability of iodinated X-ray contrast media in simultaneous nitrification and denitrification system. J. Hazard. Mater. 2023, 452, 131196. [Google Scholar] [CrossRef]
  45. Jeong, J.; Jung, J.; Cooper, W.J.; Song, W. Degradation mechanisms and kinetic studies for the treatment of X-ray contrast media compounds by advanced oxidation/reduction processes. Water Res. 2010, 44, 4391–4398. [Google Scholar] [CrossRef]
  46. Hapeshi, R.; Lambrianides, A.; Koutsoftas, P.; Kastanos, E.; Michael, C.; Fatta-Kassinos, D. Investigating the fate of iodinated X-ray contrast media iohexol and diatrizoate during microbial degradation in an MBBR system treating urban wastewater. Environ. Sci. Pollut. Res. 2013, 20, 3592–3606. [Google Scholar] [CrossRef]
  47. Haiß, A.; Kümmerer, K. Biodegradability of the X-ray contrast compound diatrizoic acid, identification of aerobic degradation products and effects against sewage sludge micro-organisms. Chemosphere 2006, 62, 294–302. [Google Scholar] [CrossRef] [PubMed]
  48. Ternes, T.A.; Stüber, J.; Herrmann, N.; McDowell, D.; Ried, A.; Kampmann, M.; Teiser, B. Ozonation: A tool for removal of pharmaceuticals, contrast media, and musk fragrances from wastewater? Water Res. 2003, 37, 1976–1982. [Google Scholar] [CrossRef]
  49. Borowska, E.; Felis, E.; Żabczyński, S. Degradation of iodinated contrast media in aquatic environment by means of UV, UV/TiO2 process, and by activated sludge. Water Air Soil Pollut. 2015, 226, 151. [Google Scholar] [CrossRef] [PubMed]
Water 17 00188 g001
Figure 1. Occurrence and fate of pharmaceuticals in the environment.
Figure 1. Occurrence and fate of pharmaceuticals in the environment.
Water 17 00188 g001
Water 17 00188 g002
Figure 2. Flow scheme of the laboratory-scale anaerobic membrane bioreactor. Reactors A, B and C differed in sludge age: A—40 d, B—70 d, C—100 d.
Figure 2. Flow scheme of the laboratory-scale anaerobic membrane bioreactor. Reactors A, B and C differed in sludge age: A—40 d, B—70 d, C—100 d.
Water 17 00188 g002
Water 17 00188 g003
Figure 3. Effect of the removal of COD in anaerobic membrane bioreactors.
Figure 3. Effect of the removal of COD in anaerobic membrane bioreactors.
Water 17 00188 g003
Water 17 00188 g004
Figure 4. Elimination of iodipamide in anaerobic membrane bioreactors. II and III refers to second and third period of research.
Figure 4. Elimination of iodipamide in anaerobic membrane bioreactors. II and III refers to second and third period of research.
Water 17 00188 g004
Water 17 00188 g005
Figure 5. Elimination of iohexol in anaerobic membrane bioreactors. II and III refers to second and third period of research.
Figure 5. Elimination of iohexol in anaerobic membrane bioreactors. II and III refers to second and third period of research.
Water 17 00188 g005
Water 17 00188 g006
Figure 6. Elimination of diatrizoate in anaerobic membrane bioreactors. II and III refers to second and third period of research.
Figure 6. Elimination of diatrizoate in anaerobic membrane bioreactors. II and III refers to second and third period of research.
Water 17 00188 g006
Table 1. Structure, molecular weight, and CAS number of ICM used in the studies [41].
Table 1. Structure, molecular weight, and CAS number of ICM used in the studies [41].
Compound and PropertiesChemical Structure
Iohexol (C19H26I3N3O9)
MW: 821.14
CAS:-No: 66108-95-0, non ionic
Osmolality: 322–844 mOsm/kg H2O		Water 17 00188 i001
Diatrizoate (C11H9I3N2O4)
MW: 613.9136
CAS:-No: 117-96-4, ionic
Osmolality: 1500–2000 mOsm/kg H2O		Water 17 00188 i002
Iodipamide (C20H14I6N2O6)
MW: 1139.7618
CAS:-No: 606-17-7, ionic
Osmolality: 664 mOsm/kg H2O		Water 17 00188 i003
Table 2. The operation conditions of the MBRs.
Table 2. The operation conditions of the MBRs.
ParameterUnitMBR AMBR BMBR C
Reactor volumeL454545
Hydraulic retention time (HRT)D2.82.82.8
Sludge ageD4070100
Temperature°C19.5–26.119.6–26.019.7–25.9
pH 8.0–9.08.0–9.08.0–9.0
Dissolved oxygenmgO2/L<1.00<1.00<0.76
Table 3. The parameters of the MBRs.
Table 3. The parameters of the MBRs.
ParameterUnitMBR AMBR BMBR CMBR AMBR BMBR CMBR AMBR BMBR C
First PeriodSecond PeriodThird Period
Sludge concentration g/L 3.2–5.24.2–5.44.6–5.62.3–3.33.5–4.34.1–5.31.9–2.73.1–4.34.2–5.0
Sludge organic loading rategCOD/gMLSS d0.04–0.080.04–0.070.04–0.070.12–0.160.08–0.100.06–0.090.14–0.210.08–0.150.08–0.10
Sludge NH4+-N loading rategNH4+-N/gMLSS d0.003–0.0040.003–0.0050.003–0.0050.006–0.009 0.004–0.0060.003–0.0050.007–0.0110.004–0.0080.004–0.006
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Konopka, J.; Kalka, J.; Żabczyński, S. Degradation of X-Ray Contrast Media in Anaerobic Membrane Bioreactors. Water 2025, 17, 188. https://doi.org/10.3390/w17020188

AMA Style

Konopka J, Kalka J, Żabczyński S. Degradation of X-Ray Contrast Media in Anaerobic Membrane Bioreactors. Water. 2025; 17(2):188. https://doi.org/10.3390/w17020188

Chicago/Turabian Style

Konopka, Jakub, Joanna Kalka, and Sebastian Żabczyński. 2025. "Degradation of X-Ray Contrast Media in Anaerobic Membrane Bioreactors" Water 17, no. 2: 188. https://doi.org/10.3390/w17020188

APA Style

Konopka, J., Kalka, J., & Żabczyński, S. (2025). Degradation of X-Ray Contrast Media in Anaerobic Membrane Bioreactors. Water, 17(2), 188. https://doi.org/10.3390/w17020188

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop