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Article

Approaching Breakthrough: Resource-Efficient Micropollutant Removal with MBR-GAC Configuration

by
Christian Baresel
1,*,
Marion Salem
2,
Ross Roberts
2,
Andriy Malovanyy
1,
Heidi Lemström
2 and
Bahare Esfahani
1
1
IVL Swedish Environmental Research Institute, Box 210 60, 100 31 Stockholm, Sweden
2
SYVAB AB, 147 92 Grödinge, Sweden
*
Author to whom correspondence should be addressed.
Appl. Sci. 2024, 14(17), 7759; https://doi.org/10.3390/app14177759
Submission received: 3 July 2024 / Revised: 15 August 2024 / Accepted: 16 August 2024 / Published: 2 September 2024
(This article belongs to the Section Environmental Sciences)
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Abstract

:

Featured Application

The presented results are relevant for any existing or planned MBR installations facing the challenge of removing micropollutants. These findings offer significant opportunities for lowering operational costs and reducing the environmental footprint of quaternary treatment at wastewater treatment plants (WWTPs).

Abstract

The removal of micropollutants from municipal wastewater is crucial to mitigate negative environmental impacts on aquatic ecosystems. However, existing advanced treatment techniques often require extensive fossil resources to achieve the targeted removal of a broad range of micropollutants. This study presents the combination of Membrane Bioreactors (MBRs) and subsequent Granular Activated Carbon (GAC) filters as a resource-efficient solution. Based on long-term pilot studies at a municipal WWTP in Stockholm, Sweden, this investigation explores the MBR-GAC configuration as a sustainable alternative for quaternary treatment at WWTPs. Results from over three years demonstrate a high removal efficiency of over 80% for targeted pharmaceuticals and other organic micropollutants, such as per- and polyfluoroalkyl substances (PFASs), from the WWTP inlet to the outlet. The synergy between MBR and GAC technologies provides this high removal efficiency with considerably lower resource consumption and cost compared to traditional GAC installations. No breakthrough of micropollutants has been observed to date indicating even better resource efficiency than presented in this paper.

1. Introduction

Organic micropollutants (OMPs), such as pharmaceutical residues and per- and polyfluoroalkyl substances (PFASs), frequently pass through modern wastewater treatment plants (WWTPs) and end up in aquatic environments [1,2,3]. Previous studies have shown that these substances can reach concentrations in water bodies that affect aquatic organisms [4,5,6,7,8] and OMPs discharged from WWTPs may enter the aquatic food web, impacting higher organisms such as fish-eating birds, mammals, and humans [9]. Environmental antibiotics are also linked to increased antibiotic resistance in bacteria, posing a global health threat [10,11].
The negative impact of OMPs and the need for their mitigation has been recognized by various authorities such as the Swedish EPA [12] and the Swedish Research Council for Environment [13]. At the European level, the newly presented Urban Wastewater Treatment Directive (91/271/EEC [14]) will require quaternary treatment for certain OMPs at many WWTPs in member states, potentially extending further based on needs identified by the proposed amendment of the Environmental Quality Standards Directive (2000/60/EC [15]). As current WWTPs usually cannot remove OMPs, various treatment technologies have been proposed and evaluated in recent years (e.g., [16,17,18,19]). Today, ozone oxidation and activated carbon filtration (in the shape of granules, GAC, or powder, PAC) are the most well-established quaternary treatment techniques, as indicated by installations at WWTPs in Switzerland, which have been the foundation for the Urban Wastewater Treatment Directive [20]. However, ozonation, despite being cost-efficient for removing pharmaceutical residues even at high doses and long contact times, cannot remove PFASs from wastewater on its own [21,22,23], necessitating the use of activated carbon or other technologies.
The new requirements for OMP removal according to the sewage directive are based on the entire treatment process at WWTPs. Therefore, the total efficiency at a WWTP for OMP removal can benefit from complementary and synergistic treatment processes, especially secondary, tertiary, and quaternary treatment steps. Membrane bioreactors (MBRs) are gaining increasing popularity in municipal wastewater treatment, with an exponential increase in the number and scale of MBR facilities [24,25,26,27]. This popularity is due to MBRs’ low footprint, robust operation, and ability to meet high-quality demands on treated water. Recent research indicates that the sustainability of the MBR process can be further optimized [28], and the costs and environmental impact of the MBR process are already considered competitive with conventional activated sludge (CAS) processes (e.g., [29]). While standard MBR processes have no significant impact on OMP removal alone compared to CAS [30], the combination of the MBR process and activated carbon has been investigated by [31]. Recent studies have further explored the potential benefits of MBR-GAC systems for efficient removal of pharmaceuticals and as facilitator for water reuse schemes [32,33,34].
This study aims to provide results from a unique, long-term, and ongoing evaluation of the MBR-GAC configuration at a Swedish WWTP for the removal of OMPs. The presented results provide insights into the potential to reduce resource consumption and costs for OMP removal at WWTPs by this technology combination. The pilot trials are conducted in preparation for a potential and pre-designed full-scale implementation of the process in one of Stockholm’s WWTPs and thus are directly relevant for full-scale implementation. Reduced resource consumption while maintaining highly effective removal of not only pharmaceutical residues but also PFASs from wastewater would reduce the negative environmental impacts of the additional treatment required for OMP removal.

2. Materials and Methods

This study was performed at one of Sweden’s largest WWTPs, Himmerfjärdsverket, which is currently undergoing an upgrade. At the WWTP, an MBR pilot was utilized for the long-term evaluation of quaternary treatment of municipal wastewater.

2.1. Syvab’s Wastewater Treatment Plant (WWTP) Himmerfjärdsverket

Syvab’s WWTP Himmerfjärdsverket, located south of Stockholm, Sweden, has been in operation since 1974 and treats the wastewater of approximately 250,000 PE (110,000 m3/d). In 2020, a fundamental reconstruction of the plant was started, aiming to increase the treatment capacity to approximately 350,000 PE and to meet new effluent requirements (5 mg/L of biological oxygen demand, 7 days (BOD7), 6 mg/L of total nitrogen (TN) and 0.2 mg/L of total phosphorus (TP)). The chosen MBR process configuration was selected not only to reach these stricter treatment requirements but also to produce an effluent quality that is highly suitable for resource-efficient quaternary treatment for the removal of OMPs, focusing on pharmaceutical residues and PFASs. Since 2013, Syvab (Grödinge, Sweden) has been involved in several research projects regarding quaternary treatment. Following a pre-design study in 2019, a complementary GAC filtration was designed to be combined with the future MBR configuration [35]. Mapping of OMPs and related risk assessment of the receiving coastal water identified risks, especially for pharmaceuticals such as diclofenac and PFASs like perfluorooctanesulfonic acid (PFOS).

2.2. Large-Scale Membrane BioReactor and Activated Carbon Filtration Pilot (MBR-GAC)

A large-scale pilot plant (Qdim of 12 m3/h) with the MBR-GAC configuration (Figure 1) was established in 2020, with the MBR process representing a copy of the designated full-scale process [36]. The dynamic load to the pilot is linked to the actual inflow to the main WWTP. The biological process consists of three cascades with both anoxic and oxic zones fed with approximately the same load to utilize the carbon in the incoming wastewater for nitrogen removal and to avoid nitrate circulation flows. However, an external carbon source is added in the last cascade when necessary. For phosphorus removal, precipitation chemicals are added in the RAS/deox. The membranes used in the pilot are Zeeweed 500D (Veolia) ultrafiltration (UF) hollow fiber membranes (nominal pore size of 0.04 μm) installed in two parallel membrane tanks (Figure 1). This corresponds to the same membrane units as designed for the full-scale WWTP.
The design of the GAC filters was based on previous research collaborations between Syvab and IVL Swedish Environmental Research Institute [37,38,39]. The two GAC filter pilot lines, GAC L1 and GAC L2, operate as 2-stage filters in a lead/lag configuration to maximize the overall utilization of the carbon. The operation of the GAC filters, each with a filter bed depth of 1.9 m, commenced in the fall of 2020 (calendar week 40) and has continued, with a brief maintenance break for the MBR pilot, up to the present. Both GAC lines utilize Filtrasorb 400 (Chemviron) and are dynamically operated with equal share of the flow in accordance with the inflow to the MBR pilot.
Each filter achieves an Empty Bed Contact Time (EBCT) of 10 min, corresponding to an average surface loading rate of 10 m/h. While GAC L1 operates with conventional backwash intervals, GAC L2 employs a need-based backwash strategy determined by the clogging level in each filter. For more detailed information about the pilot configuration, see [36].

2.3. Sampling and Analysis

The long-term evaluation has included 14 weekly samples collected over more than three years of operation. Automatic samplers continuously gathered flow-proportional composite samples from the untreated wastewater, the MBR effluent, and the final effluent after each GAC filter line. Weekly samples were also collected in the effluent from the full-scale WWTP for comparison. The OMPs investigated include a wide range of pharmaceuticals commonly identified in Swedish wastewater, along with the eleven different PFASs (PFAS11), as listed in Table A1. Due to economic considerations, PFAS analyses were not conducted for every sampling event.
In addition, pharmaceuticals and industrial chemicals listed in the proposed sewage directive for quaternary treatment, but not previously analyzed, were included in the last two sampling campaigns (see Table A2). Standard analytical methods, as described below, were applied at IVL’s laboratory.
Pharmaceuticals were extracted from water samples (200–300 mL) with solid phase extraction (SPE) using 200 mg 6 cc Oasis Hydrophilic-Lipophilic-Balanced (HLB) column from Waters. Then, 50 mg ethylenediaminetetraacetic acid (EDTA) was added to the sample together with 100 ng isotopically labeled internal standards prior to extraction. Filter-aid (4 g) was added to the column and the cartridge was washed with 6 mL methanol (MeOH) and conditioned with 6 mL milli-Q water (MQ). The sample was applied slowly (2 drops/sec). The column was washed with 2 mL MQ after sample application and analytes were eluted with 5 mL MeOH, followed by 5 mL acetone. The extract was evaporated to dryness under nitrogen stream and heat (40 °C) and re-dissolved in 1 mL MeOH: MQ (1:1) with 0.1% EDTA followed by sonication for 5 min and centrifugation at 14,000 rpm for 5 min. The supernatant was transferred to a vial. Analysis was performed with high performance liquid chromatography (HPLC) coupled to a triple quadrupole mass spectrometer (MS/MS) equipped with an electrospray ionization source (ESI) from Shimadzu (Oregon, USA). The analysis was performed in multiple ion monitoring mode (MRM) using both positive and negative ionization. The chromatographic separation was performed on a biphenyl Core-shell column (3.0 × 100 mm, 2.6 µm, 100 Å) from Phenomenex (California, USA) with a gradient elution program and 0.4 mL/min flow rate. The mobile phases consisted of MQ with 2 mM acetic acid and MeOH. Analyte concentrations were quantified using a linear 7-point calibration with R2 > 0.990. Limit of detection and quantification (LOD and LOQ) were estimated from the noise quantified in the procedural blank samples (3x S/N and 10x S/N, respectively). Recoveries of each pharmaceutical compound were estimated from a spiked procedural blank containing 100 ng/mL of each analyte which was extracted and analyzed together with the samples.
PFASs were extracted from water samples (200–300 mL) with SPE using a 150 mg Evolute WAX column with depth filter from Biotage (Uppsala, Sweden). Then, 10 ng isotopically labeled internal standard was added to the sample prior to extraction. The cartridge was washed with 4 mL 0.1% ammonium: MeOH (v/v) solution and 4 mL MeOH and then conditioned with 5 mL MQ. The sample was applied slowly (2 drops/sec). The column was washed with 4 mL 25 mM ammonium acetate buffer (pH 4) after sample application and analytes were eluted with 4 mL MeOH, followed by 4 mL 0.1% ammonium:MeOH (v/v) solution. The extract was evaporated to 1 mL under nitrogen stream and heat (40 °C). The extract was transferred to a vial and 50 ng volumetric standard (3,5-bis(trifluoromethyl)phenyl acetic acid) was added. Analysis was performed with HPLC-MS/MS equipped with an ESI from Shimadzu (Oregon, USA). The analysis was performed in MRM using negative ionization. The chromatographic separation was performed on a C18 Shim-pack column (2.1 × 55 mm, 3 µm, HSS) from Shimadzu (Oregon, USA) with a gradient elution program and 0.4 mL/min flow rate. The mobile phases consisted of MQ with 2 mM ammonium acetate and methanol with 2 mM ammonium acetate. Analyte concentrations were quantified using a linear 11-point calibration curve with R2 > 0.990. LOD and LOQ were estimated from the noise quantified from multiple injections of the lower calibration standards (3x S/N and 10x S/N respectively). The volumetric standard was used for ensuring adequate recovery (100–80%) of the isotopically labeled internal standards in all the samples.
The differences in LOD and LOQ calculations, as well as the recovery estimations for pharmaceuticals and PFASs, are attributed to the different properties of the compounds in each group. PFASs are a more homogenous group of compounds with similar chemical and physical properties, whereas pharmaceuticals are a broad group of compounds. This enables a more specific extraction and analysis of PFASs, removing many interfering sub-stances from the sample matrix, thus lowering the detection limit below concentrations in procedural blanks. For this reason, the LOD and LOQ are estimated from repeated injections of the lowest calibration point for PFASs, but from procedural blanks for pharmaceuticals. As PFASs have similar chemical properties, a volumetric standard can be used to ensure adequate recovery of the isotopic internal standards, therefore compensating for any losses during the extraction. The heterogeneity of the pharmaceuticals makes such estimations difficult as it is costly and time consuming to include a volumetric standard for each compound. Therefore, all sample concentrations are corrected for recovery estimated from a spiked procedural blank.

3. Results

During the pilot trials, the MBR pilot was operated in design mode to meet the new effluent requirements (5 mg/L BOD7, 6 mg/L TN, and 0.2 mg/L TP) with a good operational margin. Membrane operation, including scouring aeration, maintenance, and recovery cleanings, was performed according to the supplier’s recommendations. The first GAC filter pilot (GAC L1) was commissioned a few weeks before the second line, resulting in fewer EBVs being treated in the second line (GAC L2). For more information about the general operation of the MBR-GAC pilot, see [36].

3.1. Removal Efficiency for Pharmaceuticals

Concentrations of pharmaceuticals (provided in Figure A1 in the Appendix A) indicate expected variations between the various sampling occasions and different levels for different substances. Variations in the incoming wastewater are explained by variations of wastewater flow and infiltration to the sewer system and consumption variations of various pharmaceuticals throughout seasons. Variations after the quaternary treatment may in addition be attributed to factors such as a varying EBCT in the GAC filters due to flow variations, which may imply varying adsorption, biological degradation, or desorption of certain substances. Substances such as paracetamol, naproxen, and ibuprofen show highest concentrations and variations in the incoming wastewater. These substances, however, are removed in the main treatment process, while the persistent pharmaceuticals remain unaffected. These pharmaceuticals are removed in the quaternary treatment with a general trend of increasing concentrations after both GAC filter lines over time.
Figure 2 shows the removal efficiencies for pharmaceuticals across the main treatment process and the entire process, including quaternary treatment by the two GAC pilot lines. Results for each sampling occasion are shown in relation to the calendar week when sampling was performed and, in addition, for how many EBVs that have been treated in the GAC-filter lines at each sampling. As the second line (GAC L2) was put into operation some weeks later than GAC L1 due to a pump failure, treated EBVs are somewhat lower for this line compared to GAC L1. Removal efficiencies were only calculated for substances that could be quantified in the incoming wastewater. Concentration after treatment below level of detection (LOD) were considered as the LOD value and concentration below level of quantification (LOQ) as LOQ/2. Both diclofenac, identified as a significant risk substance for receiving water, and the average reduction of the sixteen most persistent substances are presented (including diclofenac, see also Table A1). The average removal of persistent substances serves as an indicator similar to the required average removal of various indicator substances according to the new wastewater directive, as these persistent substances are generally not removed by the main treatment process.
Results indicate that the removal efficiency in the biological treatment stage of the process varied between sampling occasions but remained low, consistent with other studies. Negative removal rates in the MBR process for both diclofenac and other persistent pharmaceuticals were commonly observed. This is explained by the fact that substances are excreted as conjugates (e.g., glucuronide conjugates) that are deconjugated in the biological treatment, and the complex chemical matrix in incoming untreated wastewater suppresses signals during analysis. Both mechanisms result in a lower observed value in the raw wastewater than the actual concentration. Variations in removal efficiency over the MBR process cannot be explained by variations in incoming substance concentrations, although such variations were observed.
For occasions with substantial negative removal in the main process, a lower treatment efficiency over the entire treatment were also observed, as the quaternary treatment cannot completely compensate for this (Figure 2). Except for these few samples, the removal of diclofenac and the persistent pharmaceuticals generally exceeded a potential target of 80%. This is also true after treating more than 50,000 EBVs in each line (>100,000 EBVs in each filter), corresponding to a dose of <10 g GAC/m3, without any replacement of filter material yet.
Removal efficiencies for at least four and two substances from categories 1 (amisulprid, citalopram, metoprolol, and venlafaxine) and 2 (benzotriazole and 4- and 6-methylbenzotriazole), respectively, according to the proposed sewage directive, were investigated in the last two sample campaigns. Results indicated a moderate negative removal of −30 to −40% in the MBR process but a total removal over MBR-GAC L1 and MBR GAC L2 of 80–92%, even in the last occasion at 56,000 and 52,000 treated EBVs for L1 and L2, respectively.

3.2. Removal Efficiency for PFASs

Concentrations of PFAS11 (provided in Figure A2 in the Appendix A) show variations between the various sampling occasions and different levels for different PFASs. In difference to pharmaceuticals, only a few PFASs are affected by the main treatment process also the quaternary treatment does not imply a significant reduction of most analyzed PFASs. For PFOS, however, concentrations are significant lower already after the main treatment process (MBR permeate), with variations of concentrations in the MBR permeate and after the quaternary treatment related to incoming variations.
Figure 3 presents removal rates for PFOS and ∑PFAS11 over the MBR process and the entire treatment process, including quaternary treatment. Unlike pharmaceutical removal, PFOS removal is primarily achieved in the MBR process, with the GAC filters contributing with only minor removal. Removal efficiency for PFOS over both pilot lines (MBR-GAC L1 and L2) generally exceeded 80%, except for a few occasions. For ∑PFAS11, the results differ, with a negative removal already observed in the MBR process. Except for the last sampling campaign, where incoming PFAS concentrations were lower than in previous sampling occasions, removal of ∑PFAS11 varies between low to moderate rates. However, as there are currently no defined removal targets for PFASs at WWTPs, an assessment of the removal efficiency towards such target was not possible.

3.3. Full-Scale Implications

Removal rates for pharmaceuticals and PFASs in the MBR-GAC pilot can be compared to removal rates in the current full-scale WWTP, which consists of a conventional activated sludge process (Figure 4). Because the main focus initially was on the treatment performance of the MBR-GAC pilot only, analysis of pharmaceuticals and PFASs have not been performed in the full-scale WWTP in the beginning of the study and not at all samplings as indicated in Figure 4. As observed in the MBR process, removal rates in the full-scale WWTP vary across different sampling campaigns. On average, diclofenac was removed by 13%, the sixteen most persistent pharmaceuticals by 3%, PFOS by 13%, and ∑PFAS11 by 11%. It should be noted that when high negative removal efficiencies were observed in the MBR pilot (Figure 2 and Figure 3), similar observations were made in the full-scale process (Figure 4), indicating the composition of the incoming wastewater as the main influencing factor, rather than the treatment process itself.
An initial evaluation of the two different backwash strategies indicates that the need-based strategy reduces backwash events by more than 50% compared to standard design. This results in less downtime for the GAC filters and a substantial reduction in the backwash water that needs to be re-treated in the main treatment process.
The increased utilization of the GAC capacity further implies substantial cost reductions in future full-scale implementations. The pre-design of the quaternary treatment at the Himmerfjärdsverket WWTP estimated 430 MSEK as investment and approximately 42 MSEK/year as operational cost for the GAC filter installation with a standard design of 20,000 EBVs before GAC replacement [35]. While investment costs are not affected by reduced GAC consumption, the increased number of EBVs that can be treated according to the pilot trials implies a reduction of at least 50% in operational costs, with less need for human resources due to fewer replacements. This, as already at the current state more than 50,000 EBVs have been treated and the capacity of the GAC filters is yet to reached.
Additionally, the environmental impact caused by the production of virgin GAC and the reactivation of spent activated carbon can be reduced with every additional EBVs treated compared to conventional design.

4. Discussion

The efficient and long-lasting removal of persistent pharmaceuticals in the investigated GAC filters can be attributed to several factors. The MBR process, used as a pretreatment to the quaternary treatment, produces high-quality effluent with no particles and low levels of nutrients and easily degradable organic pollutants. This creates good conditions for any filter-adsorbent, as it prevents filter clogging in several ways. Clogging due to particles is avoided, and the formation of a thick biofilm is prevented due to the limited substrate available for bacterial growth. With fewer traditional pollutants in the water passing through the GAC filters, there is less competition for adsorption sites, thereby increasing the adsorption of OMPs.
High concentrations of OMPs on the filter material and the lack of other more readily available substrates may also facilitate biofilm formation, with OMPs serving as a substrate. This would allow for biological regeneration of the filter materials, as adsorbed OMPs and other organic molecules are biologically degraded, liberating adsorption sites and increasing further OMP adsorption. This phenomenon has been indicated by studies, such as those by [39] and [40]. Additionally, the high oxygen concentrations in the MBR effluent, caused by continuous air scouring of the membranes, may further aid in the biological degradation of OMPs.
The high removal rates of PFOS and other PFASs in the MBR process, compared to the CAS process in the full-scale WWTP, are more challenging to explain. A new research project has recently been initiated to investigate the underlying mechanisms. One potential explanation could be the removal of PFOS by foam, which commonly forms in MBR processes due to the enrichment of extracellular polymeric substances (EPSs). This foaming can be likened to foam fractionation for removing PFASs from aqueous matrices, as suggested by studies like [41]. Due to intensive foaming in the MBR pilot, the system was modified after the first year of operation to remove excess sludge by surface sludge extraction from the biological basins only. This may have favored PFAS removal by foam, as a foam destruction and mixing with process water, which would reintroduce PFASs into the water phase, is avoided.
In comparison with ozonation as the most relevant other quaternary treatment techniques, similar removal efficiency for investigated pharmaceuticals can be expected, depending on plied ozone doses. For such an evaluation, actual tests have to be performed. Considering PFAS removal, however, no removal can be expected by ozonation [21,22,23]. Aspects such as the risk of formation of toxic degradation and by-products by ozonation that may require a post treatment e.g., by GAC filtering [37], significant increased onsite energy demands at the WWTP for ozone production, and potential for future regulations on other OMPs, such as PFASs, made the utility focus on the investigate combination of MBR-GAC as the main quaternary treatment. However, at the time of process selection, a potential significant removal of PFOS in the MBR process, as observed in this study, was not considered.
The resource and cost reduction potential presented here provides only an indication based on the current state of the pilot trials. A replacement of the filter material has not yet been performed. If only the adsorbent in the first filter in series is replaced, while the adsorbent in the second filter is moved to the first position to receive a high load of OMPs for maximum capacity utilization, the expected lifetime of the filter material will be extended until a complete adsorbent exchange is necessary. Consequently, resource consumption and associated operation costs will be lower than currently presented. Given the general increase in activated carbon prices due to rising demand, cost savings from improved utilization of carbon capacity become even more important.

5. Conclusions

The presented study indicates that two-stage GAC filtration following an MBR process may provide an effective and resource-efficient combination for OMP removal. Considering that MBR processes are increasingly being accepted as a sustainable solution in municipal wastewater treatment due to their high treatment capacity and performance, the presented quaternary treatment solution may be relevant for an increasing number of facilities. This is particularly pertinent in light of the recently proposed sewage directive requiring the removal of various pharmaceutical and industrial substances, as well as the challenges posed by other OMPs such as PFASs.

Author Contributions

All listed authors have contributed substantially to this article. Conceptualization, methodology, supervision, project administration, and funding acquisition: C.B., A.M., R.R. and H.L.; data curation and investigation: M.S., R.R. and B.E.; writing—original draft preparation: C.B. and B.E.; writing—review and editing; C.B., M.S., R.R., A.M. and H.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Swedish EPA (NV-03803-19), Foundation IVL, and Syvab.

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors upon request. In particular, the vast amount of analysis data for each substance and sample occasion will be provided upon request.

Conflicts of Interest

The authors declare no conflicts of interest.

Appendix A

Table A1. Analyzed organic micropollutants.
Table A1. Analyzed organic micropollutants.
SubstanceAverage
Recovery		Average LOD
(ng/mL)		Average LOQ
(ng/mL)
Pharmaceuticals
Atenolol 1109%14
Carbamazepine 1106%13
Ciprofloxacin 1,2104%620
Citalopram 179%14
Clarithromycin 1,2106%14
Diclofenac 1107%310
Erythromycin 293%14
Fluconazole 1110%13
Furosemide 167%517
Ibuprofen87%1034
Ketoconazole43%619
Losartan 1104%38
Methotrexate106%621
Metoprolol 1107%13
Naproxen127%514
Oxazepam 1131%26
Paracetamol144%620
Propranolol 191%13
Sertraline51%25
Sulfamethoxazole 1,2108%25
Tramadol 150%39
Trimethoprim 1,2108%13
Venlafaxine 161%14
Zolpidem104%13
Per- and polyfluoroalkyl substances (PFAS)
Perfluorobutane sulfonic acid (PFBS)N/A0.050.15
Perfluoropentanoic acid (PFPeA)N/A0.060.17
Perfluorohexane sulfonic acid (PFHxS)N/A0.060.17
Perfluorohexanoic acid (PFHxA)N/A0.080.24
Perfluoroheptanoic acid (PFHpA)N/A0.080.26
Perfluorooctane sulfonic acid (PFOS)N/A0.060.17
Perfluorooctanoic acid (PFOA)N/A0.070.22
Perfluorononanoic acid (PFNA)N/A0.140.46
∑PFAS11
1—persistent pharmaceutical. 2—antibiotic.
Table A2. Organic micropollutants from categories 1 and 2 according to Urban Wastewater Treatment Directive (91/271/EEC).
Table A2. Organic micropollutants from categories 1 and 2 according to Urban Wastewater Treatment Directive (91/271/EEC).
CategorySubstance
Category 1—substances that can be very easily removed with advanced purificationAmisulpride
Carbamazepine
Citalopram
Clarithromycin
Diclofenac
Hydrochlorothiazide
Metoprolol
Venlafaxine
Category 2—substances that are easy to remove with advanced purificationBenzotriazole
Candesartan
Irbesartan
Mixture of 4- and 6-methylbenzotriazole
Applsci 14 07759 g0a1
Figure A1. Concentration of analyzed pharmaceuticals and sum of the sixteen most persistent pharmaceuticals in the four sampling locations over the pilot (MBR IN, MBR permeate, and the effluent of GAC L1 and GAC L2) for sample occasions (calendar week). Only quantifiable concentrations are presented.
Figure A1. Concentration of analyzed pharmaceuticals and sum of the sixteen most persistent pharmaceuticals in the four sampling locations over the pilot (MBR IN, MBR permeate, and the effluent of GAC L1 and GAC L2) for sample occasions (calendar week). Only quantifiable concentrations are presented.
Applsci 14 07759 g0a1
Applsci 14 07759 g0a2
Figure A2. Concentration of PFAS11 in the four sampling locations over the pilot (MBR IN, MBR permeate, and the effluent of GAC L1 and GAC L2) for sample occasions (calendar week). The total column height corresponds to ∑PFAS11. Only quantifiable concentrations are presented.
Figure A2. Concentration of PFAS11 in the four sampling locations over the pilot (MBR IN, MBR permeate, and the effluent of GAC L1 and GAC L2) for sample occasions (calendar week). The total column height corresponds to ∑PFAS11. Only quantifiable concentrations are presented.
Applsci 14 07759 g0a2

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Figure 1. Schematic description of the plot configuration including cascade MBR-process and the two 2-stage GAC filter lines.
Figure 1. Schematic description of the plot configuration including cascade MBR-process and the two 2-stage GAC filter lines.
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Figure 2. Removal efficiency in the MBR-GAC pilot for all analyzed pharmaceuticals and the sixteen most persistent pharmaceuticals for sample occasions (calendar week and treated EBVs).
Figure 2. Removal efficiency in the MBR-GAC pilot for all analyzed pharmaceuticals and the sixteen most persistent pharmaceuticals for sample occasions (calendar week and treated EBVs).
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Figure 3. Removal efficiency in the MBR-GAC pilot for all analyzed PFASs (∑PFAS11) and only PFOS for sample occasions (calendar week and treated EBVs).
Figure 3. Removal efficiency in the MBR-GAC pilot for all analyzed PFASs (∑PFAS11) and only PFOS for sample occasions (calendar week and treated EBVs).
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Figure 4. Removal efficiencies in the full-scale Himmerfjärdsverket WWTP for (a) all analyzed pharmaceuticals and the sixteen most persistent pharmaceuticals; and (b) all analyzed PFASs (∑PFAS11) and only PFOS for sample occasions (calendar week).
Figure 4. Removal efficiencies in the full-scale Himmerfjärdsverket WWTP for (a) all analyzed pharmaceuticals and the sixteen most persistent pharmaceuticals; and (b) all analyzed PFASs (∑PFAS11) and only PFOS for sample occasions (calendar week).
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MDPI and ACS Style

Baresel, C.; Salem, M.; Roberts, R.; Malovanyy, A.; Lemström, H.; Esfahani, B. Approaching Breakthrough: Resource-Efficient Micropollutant Removal with MBR-GAC Configuration. Appl. Sci. 2024, 14, 7759. https://doi.org/10.3390/app14177759

AMA Style

Baresel C, Salem M, Roberts R, Malovanyy A, Lemström H, Esfahani B. Approaching Breakthrough: Resource-Efficient Micropollutant Removal with MBR-GAC Configuration. Applied Sciences. 2024; 14(17):7759. https://doi.org/10.3390/app14177759

Chicago/Turabian Style

Baresel, Christian, Marion Salem, Ross Roberts, Andriy Malovanyy, Heidi Lemström, and Bahare Esfahani. 2024. "Approaching Breakthrough: Resource-Efficient Micropollutant Removal with MBR-GAC Configuration" Applied Sciences 14, no. 17: 7759. https://doi.org/10.3390/app14177759

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