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Removal of pharmaceutical residues using ozonation as intermediate process step at Linkoping WWTP, Sweden
Abstract
Pilot tests as basis for the design, implementation and operation of a future full-scale oxidation plant completing the existing sewage treatment in Linköping, Sweden, were performed. Using an ozonation step between bio-sedimentation and post-denitrification processes, the primary goal was the removal of the highest priority substances to effluent water levels that will not cause adverse effects in the recipient considering the natural dilution. The study included initial emission screenings, dose control trials, treatment performance studies and eco-toxicity studies. At an ozone dose of 5 mg O3/L, most substances could be removed. Ecotoxicological tests showed no negative effect for the tested ozone doses. High levels of oxygen into the denitrification could be rapidly reduced in the biology. The number of bacteria in the treated water could be significantly reduced even at relatively low ozone doses. Based on these results, the planning for the full-scale implementation of the treatment system was initiated in 2015.
... Especially in Germany and Switzerland, advanced treatment technologies have been tested on a large scale [10,11]. Also in Sweden, technologies have been tested [12][13][14][15][16][17]. In Germany, Austria and Sweden, first full-scale installations have already been accomplished. ...
... Generally, ozone treatment implies both a direct chemical reaction of the ozone molecule as well as indirect reactions with hydroxyl radicals, breaking specific chemical bonds within the targeted substances. There exist several studies investigating complementary treatment by ozone [11][12][13][14][15][17][18][19][20][21][22][23][24][25][26][27][28]. Results indicate that while ozone oxidation generally provides a removal effect on many targeted substances, a sufficient removal of some substances may not be achieved even at very high ozone doses. ...
... Some of these metabolites might be more or less toxic and require thus an extra treatment step after ozonation [19][20][21][22][25][26][27][28]. These problems can be handled using a more integrated treatment setup as proposed by [14] using an ozonation step between bio-sedimentation and post-denitrification processes. This configuration is realized as Sweden's first full-scale installation of micropollutant removal at municipal WWTPs. ...
Pharmaceutical residues, and other organic micropollutants that pass naturally through the human body into sewage, are in many cases unaffected by treatment processes at conventional wastewater treatment plants (WWTPs). Accumulated in the environment, however, they can significantly affect aquatic ecosystems. The present study provides an evaluation of a treatment system for the removal of pharmaceutical residues and other micropollutants. The system is based on a Membrane Bioreactor (MBR), including ultrafiltration (UF), followed by a biofilter using granulated active carbon (GAC) as filter material. It was found that all investigated micropollutants, such as pharmaceutical residues, phenolic compounds, bacteria and microplastic particles, present in wastewater, could be removed by the treatment system to below detection limits or very low concentrations. This shows that the combination of filtration, adsorption and biodegradation provides a broad and efficient removal of micropollutants and effects. The tested treatment configuration appears to be one of the most sustainable solutions that meets today’s and future municipal sewage treatment requirements. The treatment system delivers higher resource utilization and security than other advanced treatment systems including solely GAC-filters without biology.
... At an ozone concentration of 0.5 to 0.8 O3/mg dissolved organic carbon, the pharmaceuticals were reduced to a safe concentration level. Based on this data, a conversion of the WWTP in Linköping, Sweden, has been planned since 2015 [105]. Mamo et al. expanded their WWTP by an optimized MBR in form of nanofiltration. ...
... Diagram of the pilot WWTP of Baresel et al.[105] ...
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The ubiquitous presence of pharmaceuticals in the aquatic environment is a worldwide problem of today. Current analytical methods reveal ever more pharmaceuticals in different water bodies. The concentrations in waters that are detectable reach nano-and picogram ranges, i.e., ppb and ppt levels. Observed concentrations amount to as high as few micrograms. Among the major entry paths are wastewater treatment plants, which are often unable to eliminate the pharmaceuticals sufficiently relying on their three conventional purification stages. Hence, pharmaceuticals enter the aquatic environment without desirable deconstruction. Thus, advanced wastewater treatment processes are under development to retain or eliminate these trace contaminants. According to Decision 2018/840, a watchlist of 15 contaminants of significant interest has been established for the monitoring of surface waters in the European Union. The contaminants include biocides and pharmaceuticals, among them three estrogens, estrone (E1), 17-β-estradiol (E2) and 17-α-ethinylestradiol, (EE2), the antibiotics azithromycin, clarithromycin and erythromycin of macrolide type, ciprofloxacin and amoxicillin of fluoroquinolone and betalactame type. This review will provide an overview of the currently explored and researched methods for the realization of a fourth purification stage in wastewater treatment plants. To this purpose, biological, chemical and physical purification processes are reviewed and their characteristics and potential discussed. The degradation efficacy of the pharmaceuticals on the EU-Watch list will be compared and evaluated with respect to the most promising processes, which might be realized on large scale. Last but not least, recent and novel pilot plants will be presented and discussed.
... A broad variety of treatment processes has been used as biological post-treatment. However, several of these solutions such as constructed wetlands (Kharel et al., 2021), fixed-bed or moving-bed bioreactors (Bourgin et al., 2018), or ozonation as an intermediate step in the activated sludge process (Baresel et al., 2016) were applied infrequently and often only at pilot-scale. The most common solution for biological post-treatment is biofiltration in deep-bed filters with different media such as sand, anthracite, or granular activated carbon (GAC) Sauter et al., 2021a;Zimmermann et al., 2011). ...
Ozonation is an established solution for organic micropollutant (OMP) abatement in tertiary wastewater treatment. Biofiltration is the most common process for the biological post-treatment step, which is generally required to remove undesired oxidation products from the reaction of ozone with water matrix compounds. This study comparatively investigates the effect of filter media on the removal of organic contaminants and on biofilm properties for biologically activated carbon (BAC) and anthracite biofilters. Biofilms were analysed in two pilot-scale filters that have been operated for >50,000 bed volumes as post-treatment for ozonated wastewater treatment plant effluent. In parallel, the removal performance of bulk organics and OMP, including differentiation of adsorption and biotransformation through sodium azide inhibition, were carried out in bench-scale filter columns filled with material from the pilot filters. The use of BAC instead of anthracite resulted in an improved removal of organic bulk parameters, dissolved oxygen, and OMP. The OMP removal observed in the BAC filter but not in the anthracite filter was based on adsorption for most of the investigated compounds. For valsartan, however, biotransformation was found to be the dominant pathway, indicating that conditions for biotransformation of certain OMP are better on BAC than on anthracite. Adenosine triphosphate analyses in the media-attached biofilms of the pilot filters showed that biomass concentrations in the BAC filter were significantly higher than in the anthracite filter. The microbial communities (16S rRNA gene sequencing) appeared to be similar with respect to the types of organisms occurring on both filter materials. Alpha diversity also exhibited little variation between filter media. Beta diversity analysis, however, revealed that filter media and bed depth substantially influenced the biofilm composition. In practice, the impact of filter media on biofilm properties and biotransformation processes should be considered for the design of biofilters.
... Os fármacos são princípios ativos de medicamentos utilizados na medicina humana e veterinária (Liu & Wong, 2013). Após a ingestão, parte dos medicamentos são absorvidos pelo organismo e parte é excretada, no entanto, as estações de tratamento de esgoto convencionais não apresentam tecnologias para a remoção desses produtos completamente (Baresel et al. 2016). Como resultado, os medicamentos chegam até o ambiente e podem representar um risco para a biota (Thiebault et al. 2017). ...
Interdisciplinarity is still considered a challenge in teaching. From this perspective, Ecotoxicology presents itself as a science capable of permeating several areas, especially in Chemistry. The objective of this study was to demonstrate through a narrative literature review, the integration of Chemistry with Ecotoxicology in school education. This study was based on scientific articles and academic papers conducted in Brazil and published in Portuguese. We identified expository, practical and investigative methodologies that are related to chemistry and other subjects and environmental problems that are part of the student’s daily life. Teachers who use interdisciplinary proposals report success in developing critical thoughts and observations by students on the topics discussed. For this reason, the implementation of projects with interdisciplinary teaching and the application of active methodologies should be encouraged. The approximation between universities and schools can be very useful to achieve this objective so that the best infrastructure of laboratories and the knowledge acquired at the university can help in the formation of critical citizens and arouse interest and curiosity for science.
... The presence of β-agonists in our water does not come without possible human health and environmental consequences as they pass through our water treatment systems making it hard to be easily detected and completely removed. In our water treatment systems, organic pollutants are removed through evaporation to air, sorption to particles and subsequent sedimentation, and biological transformation (46). But removal by evaporation and sedimentations are generally not possible since β-agonists are neither volatile compounds nor solids particles (47). ...
β-agonists are a class of synthetic phenylethanolamine compounds that were originally designed to reduce asthma and chronic obstructive pulmonary disease. They remain widely used but unfortunately, misuse in animal farming and sports activities due to their huge medical and economic benefits. As a result, they have been found in a variety of matrices and subsequently end up in multiple water bodies in the environment. However, their environmental occurrence and fates are only evaluated on an occasional basis as they happen at a very trace level. The development of appropriate analytical procedures is critical in providing reliable data related to their occurrence and concentrations in various water bodies. Coupling high-performance liquid chromatography and mass spectrometry have been the most extensively used approach for great sensitivity and high selectivity for their determination in the environment. Sample preparation is important for obtaining lower detection limits, and the online solid-phase extraction has been comprehensively used considering the physicochemical properties of β-agonists. This review presented the systematic development of the preceding research on β-agonist detection approaches published between 1985-2020, emphasizing their analysis, resolution in environmental waters, and highlighting the significant scientific approach from the existing analytical techniques suitable for their ultra-trace determination.
... Increasing demand for removing parts of microplastics that pass through conventional water and wastewater treatment plants is comprehensible. As reported in the literature [104][105][106], several advanced methods and technologies for removing micropollutants have been evaluated on a large scale in several countries such as Germany, Sweden, and Switzerland. Here we represent and discuss some of the advanced methods, including magnetic-based techniques such as magnetic seed filtration and magnetic micro-submarines [107], photocatalytic micro-motors [108], membrane bioreactors coupled with activated carbon filters, rapid sand filtration, or CAS [109] and degradation-based techniques such as electrocatalysis [110], photocatalysis [111,112], biodegradation [113], and thermal degradation [114,115]. ...
Separation and removal of microplastic pollution from aquatic environments as a global environmental issue is classified as one of the major concerns in both water and wastewater treatment plants. Microplastics as polymeric particles less than 5 mm in at least one dimension are found with different shapes, chemical compositions, and sizes in soil, water, and sediments. Conventional treatment methods for organic separation have shown high removal efficiency for microplastics, while the separation of small microplastic particles, mainly less than 100 µm, in wastewater treatment plants is particularly challenging. This review aims to review the principle and application of different physical and chemical methods for the separation and removal of microplastic particles from aquatic environments, especially in water treatments process, with emphasis on some alternative and emerging separation methods. Advantages and disadvantages of conventional separation techniques such as clarification, sedimentation, floatation, activated sludge, sieving, filtration, and density separation are discussed. The advanced separation methods can be integrated with conventional techniques or utilize as a separate step for separating small microplastic particles. These advanced microplastic separation methods include membrane bioreactor, magnetic separation, micromachines, and degradation-based methods such as electrocatalysis, photocatalysis, biodegradation, and thermal degradation.
... To mitigate this release, particular attention has been directed towards advanced treatments, such as ozonation. The application of ozone is considered a suitable technology to further remove organic micropollutants from urban wastewater and is already implemented on full scale in several countries (Switzerland, Germany, and Sweden) (Baresel et al., 2016;Bourgin et al., 2018;Itzel et al., 2017). The removal efficiencies of various organic micropollutants are influenced by their reactivity with ozone and spontaneously formed hydroxyl radicals (Zimmermann et al., 2011), the ozone dose (Lee et al., 2013) and the composition of the wastewater (Schindler Wildhaber et al., 2015). ...
The present work aimed to study the effect of ozonation on the organic sum parameters linked to enhanced biodegradability. Laboratory experiments were conducted with the effluent of four Austrian urban wastewater treatment plants with low food to microorganism ratios and different matrix characteristics. Biochemical oxygen demand over 5 days (BOD5) was measured before ozonation and after application of different specific ozone doses (Dspec) (0.4, 0.6 and 0.8 g O3/g DOC). Other investigated organic parameters comprised chemical oxygen demand (COD), dissolved organic carbon (DOC), UV absorption at 254 nm (UV254), which are parameters that are applied in routine wastewater analysis. Carbamazepine and benzotriazole were measured as reference micropollutants. The results showed a dose-dependent increase in biological activity after ozonation; this increase was linked to the enhanced biodegradability of substances that are recalcitrant to biodegradation in conventional activated sludge treatment. The highest relative change was determined for BOD5, which already occurred between 0 and 0.4 g O3/g DOC for all samples. Increasing the Dspec to 0.6 and 0.8 g O3/g DOC resulted in a less pronounced increase. DOC was not substantially decreased after ozonation, which was consistent with a low reported degree of mineralization, while partial oxidation led to a quantifiable decrease in COD (7 to 17%). Delta UV254 and the decline in specific UV absorption after ozonation clearly correlated with Dspec. In contrast, for COD and biodegradable DOC (BDOC), a clear dose-response pattern was identified only after exposure to BOD5 measurement. Indications for improved biodegradability were further supported by the rise in the BOD5/COD ratio. The results indicated that subsequent biological processes have a higher degradation potential after ozonation. The further reduction in biodegradable organic carbon emission by the combination of ozonation and biological post treatment represents another step towards sustainable water resource management in addition to micropollutant abatement.
... Ozonation can be used to reduce the discharge of organic micropollutants and is generally applied in full-scale plants downstream the biological treatment with a subsequent biological post-treatment step to remove biodegradable by-products (Baresel et al., 2016;Bourgin et al., 2018;Itzel et al., 2020). Mechanistical predictions of the removal of organic micropollutants by ozone oxidation have primarily been based on kinetic constants (Lee et al., 2014;Liu et al., 2020). ...
Ozonation is an established technique used to reduce the discharge of organic micropollutants into the aquatic environment, but the possibility of predicting the ozone demand for different wastewater matrices is still limited, especially in the presence of suspended solids (SS). A new tool for the prediction of the removal of organic micropollutants with ozone, based on dissolved and particulate matter in activated sludge effluents, was therefore developed. The removal of 25 organic micropollutants was determined on laboratory scale in the presence and absence of suspended solids. The linear trajectories of the dose–response curves enabled the determination of a new set of removal constants, based on dissolved chemical oxygen demand (COD) and SS. The presence of SS had a more negative effect on the removal of slow-reacting micropollutants (removal constant <3.5 mg CODCr,diss·mg O3⁻¹) with ozone than on the fast-reacting micropollutants (removal constant >3.5 mg CODCr,diss·mg O3⁻¹). However, the decreased removal of the organic micropollutants was generally small, <10%, at typical SS concentrations, <25 mg SS·L⁻¹. Integration of the new removal constants based on COD and SS enabled the removal in an ozone pilot plant to be modelled with an average deviation of <10% for several organic micropollutants. The use of the frequently measured parameters, COD and SS, as input parameters could facilitate the future use of the tool to predict the removal of micropollutants during ozonation.
... Multiple studies have demonstrated that ozonation as an extra treatment step in WWTPs can reduce APIs in the effluent [7][8][9][10][11]. Ozone reacts non-selectively with pharma-ceuticals in a two-step process: Direct oxidation of molecules and indirect by produced hydroxyl (OH − ) radicals. ...
Hospital sewage constitutes an important point source for antibiotics and antibiotic-resistant bacteria due to the high antibiotic use. Antibiotic resistance can develop and cause problems in sewage systems within hospitals and municipal wastewater treatment plants, thus, interventions to treat hospital sewage on-site are important. Ozonation has proven effective in treating relatively clean wastewater, but the effect on untreated wastewater is unclear. Therefore, we piloted implementation of ozonation to treat wastewater in a tertiary hospital in Uppsala, Sweden. We measured active pharmaceutical ingredients (APIs) using liquid chromatography-mass spectrometry and antibiotic-resistant Enterobacteriaceae using selective culturing pre- and post-ozonation. Comparing low (1 m3/h) and high (2 m3/h) flow, we obtained a ‘dose-dependent’ effect of API reduction (significant reduction of 12/29 APIs using low and 2/29 APIs using high flow, and a mean reduction of antibiotics of 41% using low vs. 6% using high flow, 25% vs. 6% for all APIs). There was no significant difference in the amount of antibiotic-resistant Enterobacteiaceae pre- and post-ozonation. Our results demonstrate that ozonation of untreated wastewater can reduce API content. However, due to the moderate API decrease and numerous practical challenges in the on-site setting, this specific ozonation system is not suitable to implement at full scale in our hospital.
... Advanced sewage treatment technologies, such as ozonation, have been assessed and implemented in e.g. Sweden to improve the removal of APIs (Antoniou et al., 2013;Baresel et al., 2016). While ozonation can reduce the concentrations of several API parent compounds, a multitude of intermediary transformation products are created in the treated effluent, some with toxic properties (Lee and Gunten, 2016). ...
Sewage effluent ozonation can reduce concentrations of chemical pollutants including pharmaceutical residues. However, the formation of potentially toxic ozonation byproducts (OBPs) is a matter of concern. This study sought to elucidate toxicity mechanisms of ozonated carbamazepine (CBZ), an anti-epileptic drug frequently detected in sewage effluents and surface water, in zebrafish embryos (Danio rerio). Embryos were exposed to ozonated and non-ozonated CBZ from 3 hours post-fertilization (hpf) until 144 hpf. Embryotoxicity endpoints (proportion of dead and malformed embryos) were assessed at 24, 48, and 144 hpf. Heart rate was recorded at 48 hpf. Exposure to ozonated CBZ gave rise to cardiovascular-related malformations and reduced heart rate. Moreover, embryo-larvae exposed to ozonated CBZ displayed a lack of swim bladder inflation. Hence, the expression patterns of CBZ target genes involved in cardiovascular and embryonal development were investigated through a stepwise gene co-expression analysis approach. Two co-expression networks and their upstream transcription regulators were identified, offering mechanistic explanations for the observed toxicity phenotypes. The study presents a novel application of gene co-expression analysis elucidating potential toxicity mechanisms of an ozonated pharmaceutical with environmental relevance. The resulting data was used to establish a putative adverse outcome pathway (AOP).
... Wastewater treatment plants (WWTPs) have been identified as point sources of organic micropollutants such as pharmaceuticals, contrast media and antibiotics (Guillossou et al., 2019;Joss et al., 2008;Ruff et al., 2015;Stangroom et al., 1998). The first national policy on the introduction of advanced treatment for the removal of organic micropollutants was adopted in Switzerland in 2016 (Eggen et al., 2014), and full-scale plants have already been, or are currently being, realized in Switzerland , Germany (Itzel et al., 2017(Itzel et al., , 2020, Sweden (Baresel et al., 2016), and other countries. Several treatment options have been evaluated, and two of the most promising techniques are activated carbon and ozonation, applied separately or in combination (Abegglen and Siegrist, 2012;Altmann et al., 2014). ...
The objective of this study was to evaluate the influence of operational conditions and wastewater properties on the removal of pharmaceuticals, contrast media and antibiotics through ozonation, in order to facilitate the optimization of treatment and its implementation on a full scale. Pilot-scale ozone oxidation trials were performed on treated wastewater, before and after post-precipitation, over a seven-month period, including summer and winter months. Hydraulic retention times as short as 7 min were found to be sufficient for organic micropollutant removal. A short hydraulic retention time reduces both investment costs and land use. Neither the choice of ozone dispersion method, a static mixer or a Venturi injector, nor the wastewater temperature had any significant effect on the removal efficiency of organic micropollutants, however, higher removal was achieved after on-site post-precipitation with aluminum chloride.
... Ozonation is a treatment option for the removal of organic micropollutants from municipal wastewater and is being implemented on a full-scale in several countries (Itzel et al., 2020;Bourgin et al., 2018;Baresel et al., 2016). During ozonation, oxidation occurs via direct reactions with ozone and formed hydroxyl radicals at various reaction rates (Nöthe et al., 2009;Liu et al., 2020). ...
The degradation potential of micropollutants and transformation products in biological post-treatment after ozonation is partly unknown. A pilot plant with ozonation and subsequent biological treatment in a moving bed biofilm reactor (MBBR) was thus operated over 16 months to investigate the removal of micropollutants and the formation and removal of N-oxide transformation products. Lab-scale kinetic experiments were performed in parallel. At a moderate ozone dose of 0.5 g O3 g-1 DOC, further degradation of gabapentin and 3 iodinated contrast media (iomeprol, iopamidol, and iohexol) could be induced by the biofilm at prolonged exposure times. To facilitate comparison of feeding regimens in biofilm systems a new surface-related degradation rate constant was introduced. The availability of substrates in the pilot MBBR influenced the micropollutant degradation kinetics with increasing and decreasing degradation rates. N-oxides from erythromycin, clarithromycin, tramadol, and venlafaxine were formed during ozonation and could not be degraded by the biofilm.
... During ozonation of secondary treated municipal wastewater effluents, the mass-based ozone normalized to the dissolved organic carbon (DOC) content (i.e., mg O 3 /mg DOC) has often been used as an operating parameter to compare samples with varying DOC concentrations (Wert et al. 2009;Lee et al. 2014). For the elimination of MPs from effluents of MWWTPs, typical ozone doses lie between 0.25 and 1.5 mg O 3 /mg DOC (Baresel et al. 2016;Lee and von Gunten 2016). At low ozone doses (< 0.5 mg O 3 / mg DOC), more than 80% removal could be achieved for easily degradable MPs such as the pharmaceuticals diclofenac, sulfamethoxazole, and carbamazepine (von Sonntag and von Gunten 2012; Bourgin et al. 2018). ...
The objective of this study was the experimental evaluation of ozonation as an additional treatment step for the removal emerging contaminants from secondary effluents of two wastewater treatment plants (WWTPs), one receiving a primarily domestic wastewater (WWTP-A), and the other one domestic sewage together with pretreated tannery wastewater streams (WWTP-B). The experimental runs were conducted at two different pH values (i.e., original pH and adjusted pH of 10) and at six different ozone doses ranging between 0.2 and 1.5 mg O3/mg DOC. A total of 20 compounds, including 12 micropollutants (MPs) and 8 metabolites, were selected as the target analytes for the evaluation of ozonation performance. When the tested MPs and metabolites were considered individually, the maximum elimination level for each compound was reached at different doses; therefore, optimum ozone doses were determined based on the reduction of the total MP content. Ozonation at the original pH with an ozone dose in the range of 0.4–0.6 and 0.8–1.0 mg O3/mg DOC was selected as the optimum operating condition for WWTP-A and WWTP-B, respectively, both resulting in an average overall removal efficiency of 55%. Ozone treatment yielded only poor elimination for o-desmethyl naproxen (15%), which was found to be by far the main contributor accounting alone for approximately 30% of the total MP concentration in the secondary effluents. The systematic approach used in this study could well be adopted as a guide to other domestic and municipal WWTPs, which are thought to have a highly variable composition in terms of the MPs and metabolites.
... STP effluent ozonation is being implemented in Sweden in order to alleviate pharmaceutical pollution (Baresel et al., 2016). Ozone has the capacity to reduce the pharmaceutical load of STP effluents (Prasse et al., 2015). ...
Pharmaceutical residues are polluting the surface water environments worldwide. Sewage and waste-water treatment, therefore, needs to be improved in order to remove pharmaceutical residues from the effluent. One such treatment improvement is effluent ozonation. Even though ozonation has proven to be very efficient in reducing pharmaceutical parent compound concentrations in wastewater effluents, much remains unclear regarding potentially toxic ozonation by-product (OBP) formation. In this study, we sought to elucidate the aquatic toxicity of ozonated pharmaceuticals in zebrafish (Danio rerio) embryos in a static 144 h post fertilization (hpf) fish embryotoxicity (ZFET) assay. Three pharmaceuticals commonly detected in wastewater effluents, i.e. carbamazepine, diclofenac, and oxazepam, were selected for testing. Toxicity was assessed before and after 1 min ozonation (0.053 mg L À1 peak O 3 concentration) and 10 min ozonation (0.147 mg L À1 peak O 3 concentration). Chemical analysis showed that carbamaz-epine and diclofenac were largely removed by ozone (90 ± 11% and 97 ± 3.8%), whereas oxazepam was removed to a lesser extent (19 ± 5.7%). The ZFET assay revealed diverging toxicities. Diclofenac embry-otoxicity decreased with increasing ozonation. Oxazepam did not cause embryotoxicity in the ZFET assay either pre-or post ozonation, but larvae swimming activity was affected at 144 hpf. Carbamazepine embryotoxicity, on the other hand, increased with increasing ozonation. Chemical analysis showed the formation of two OBPs (carbamazepine-10,11-epoxide and 10,11-dihydrocarbamazepine), possibly explaining the increased embryotoxicity. The results of this study highlight the importance of new chemical and toxicological knowledge regarding the formation of OBPs in post-ozonated effluents.
... After years of pilot-and full-scale trials, ozone based treatments for the removal of organic micropollutants are currently being implemented in full-scale in Switzerland (Bourgin et al., 2018), Germany (Itzel et al., 2017), and Sweden (Baresel et al., 2016). The removal efficiencies of various organic micropollutants are influenced by the reactivity of the specific micropollutant with ozone and the spontaneously formed hydroxyl radicals (Zimmermann et al., 2011), the ozone dose (Antoniou et al., 2013), and the composition of the wastewater (Schindler Wildhaber et al., 2015;Zucker et al., 2015). ...
Ozone oxidation of organic micropollutants in biologically treated wastewater was investigated in pilot-scale after a high- and a low loaded activated sludge process. Higher ozone doses were required to remove organic micropollutants in the effluent wastewater from the high loaded activated sludge process. Further comparison of the micropollutant removal was based on normalized ozone doses, expressed as g O3/g DOC and g O3/g soluble COD (sCOD). A clear difference was noted for the two effluents when the micropollutant removal was normalized by DOC. This difference disappeared almost completely when the removal was linked to ozone doses normalized by sCOD. The dose-response curves for the organic micropollutants were practically linear in the removal range up to 95%. A linear prediction model was developed and compared with literature values to test the transferability of the obtained results. Results from this comparison indicated that the slope of the dose-response functions could be used to predict the removal efficiency of organic micropollutants at a third plant with an average uncertainty of 10%. The modeled ozone requirements were then set in relation to the COD concentrations in the discharged water from approximately 90 Swedish activated sludge treatment plants with and without nitrogen removal. This comparison highlighted the need for a well-functioning biological treatment for an effective ozone oxidation of organic micropollutants. The results in this study suggest that soluble COD should be further explored for design and modeling of ozone oxidation of organic micropollutants in biologically treated wastewater.
... Ozonation has been successfully used to reduce micropollutant levels in STPs in Switzerland and Germany for over a decade (Hollender et al. 2009, Margot et al. 2013, Eggen et al. 2014, and more countries are adopting this approach . In Sweden, there have been several pilot-scale projects investigating the effects of ozonation (Baresel et al. 2016, Beijer et al. 2017, El-taliawy et al. 2017. To investigate the effects of full-scale ozonation, Knivsta STP, north of Stockholm, was upgraded with an ozonation facility. ...
The World Health Organization (WHO) has identified antibiotic resistance as a major threat to human health. The environment has been suggested to play an important role in the emergence of antibiotic resistant bacteria. The external environment can act as a source of resistance genes that could potentially be transferred into human pathogens. It is also an important route for the dissemination of antibiotic resistance genes and bacteria. Sewage treatment plants (STPs) are among the most important routes by which antibiotics and antibiotic resistance genes enter the environment. It has been suggested that STPs are hotspots for the development of antibiotic resistance because they contain relatively high concentrations of antibiotics as well as both human and environmental bacteria. Further complicating matters, there is evidence that other substances with antimicrobial properties, such as biocides and metals, can cause antibiotic resistance due to co- and cross-resistance.
This thesis contributes new knowledge on the concentrations, mass flows, and removal efficiencies of antimicrobials in STPs and their connections to the emergence of antibiotic resistance. Paper I presents data on the levels of 40 different antimicrobials in the incoming wastewater, treated effluent, and digested sludge of eleven different STPs. Although not previously detected in STPs, chlorhexidine is shown to be ubiquitous in such plants. In Paper II, mass flows and removal efficiencies are calculated for eleven antimicrobials over various treatment steps in three STPs, showing that polar antimicrobials were inefficiently removed from the wastewater. In Paper III, the minimum selective concentration (MSC) for the antibiotic tetracycline was determined in a complex bacterial aquatic biofilm using both phenotypic and genotypic endpoints. It was found that 10 µg/L selected for phenotypic resistance, and 1 µg/L selected for certain resistance genes. Paper IV used metagenomics to determine whether there is selection for antibiotic-resistant bacteria in STPs and whether the extent of this selection can be correlated to the concentrations of antimicrobial compounds. No clear evidence for selection was identified. Paper V evaluates advanced wastewater treatment techniques for removing antimicrobial compounds using ozonation and granular activated carbon (GAC). The identity of the GAC material was found to strongly affect removal efficiency, and GAC was more efficient than ozonation for most compounds at the tested concentrations.
... Ozonation methods. Baresel et al. (2016) used ozonation as an intermediate treatment to remove pharmaceutical residuals in a pilot wastewater treatment plant. At an ozone dose of 5 mg O3/L, most substances were removed with no negative impact on wastewater toxicity. ...
This article reviews the scientific literature published in 2016 on physical, chemical, and biological treatment of hazardous contaminants and environmental bioremediation.
Ozonation of wastewater can reduce the release of organic micropollutants, but may result in the formation of undesirable by-products, such as bromate from bromide. Bromide is one of the most abundant ions in seawater, the primary precursor of bromate during ozonation, and the end product in microbial bromate reduction. Investigations were carried out to compare the concentration of bromide in wastewater in coastal and non-coastal catchment areas, to monitor bromate formation during ozonation, and to assess the potential for subsequent bromate reduction with denitrifying carriers. Higher bromide concentrations were systematically observed in wastewater from coastal catchment areas (0.2–2 mg Br⁻/L) than in wastewater from non-coastal areas (0.06–0.2 mg Br⁻/L), resulting in elevated formation of bromate during ozonation. Subsequent investigations of bromate reduction in contact with denitrifying carriers from two full-scale moving bed biofilm reactors (MBBRs) showed that 80 % of the bromate formed during ozonation could be reduced to bromide in 60 min with first-order rate constants of 0.3–0.8 L/(gbiomass·h). Flow-through experiments with denitrifying carriers also showed that combined reduction of bromate and nitrate could be achieved below a concentration of 2 mg NOx⁻-N/L. These findings indicate that bromide-rich wastewater is more likely to be of concern when using ozonation in coastal than in non-coastal areas, and that bromate and nitrate reduction can be combined in a single biofilm reactor.
Managing environmental contamination with hydrolyzed polyacryamide (HPAM) is essential due to its persist long with slow biodegradability influence on the environment. In this study, the simultaneous combination of acoustic cavitation and microbubbles ozonation (US/O3) was applied to generate additional highly reactive hydroxyl radicals (·OH) and thus to enhance the degradation of HPAM. Compared with the two separated degradation process methods, the coupled method exerts a synergistic effect on the decomposition of HPAM, with an enhancement factor of 1.50. Effects of aeration pattern, ultrasound irradiation, operating temperature, initial HPAM concentration, and valance state of cations on the removal of HPAM were investigated intensively. An increase in valance state of cations contributes to HPAM removal. The maximum HPAM degradation, chemical oxygen demand (CODcr) removal and viscosity reduction of the HPAM wastewater were 97.35%, 89.01% and 93.25%, respectively. The degradation of HPAM conformed to the first-order reaction kinetic model. Removal of HPAM followed hydroxyl radical mechanism. The degradation mechanism of HPAM was also discussed with the change of FTIR and UV-Visible spectra of HPAM in investigated processes. The main reaction intermediates, such as heptanoic anhydride, oleamide, myristamide, acetic acid, acetamide, and propanamide, are identified and a possible degradation pathway is proposed during the US/O3 process. The process was proved to be a suitable technique for dealing with HPAM-containing wastewater.
The number of studies dealing with tertiary ozonation to remove trace organic contaminants (TrOCs) in effluents originating from wastewater treatment plants (WWTPs) is increasing due to the need for upgrading the WWTPs overall performance. To follow-up TrOCs removal in real-time during ozone-based treatment, online surrogate measurements are necessary, of which mainly spectroscopic surrogates (i.e. UV–VIS absorbance and fluorescence) are the emerging techniques in literature. This paper summarizes and reflects on the state-of-the-art as retrieved from more than 100 peer-reviewed studies published between January 2007 and December 2020 and dealing with (1) surrogate correlation models for the prediction of TrOCs removal in secondary effluent and (2) control strategies to adjust the ozone dose during (full-scale) operation. Next to the flow and load proportional ozone dosing strategies, controlling the ozone dose solely based on the characteristics of the effluent entering the ozonation unit, also a differential control strategy based on the change in characteristics due to ozonation of the WWTP effluent is highlighted. The latter seems the best option as flow and load proportional ozone dosing do not consider the amount and/or reactivity of the matrix constituents. The presence of organic and inorganic scavengers of ozone and radicals in the effluent matrix has a significant impact on the TrOCs removal efficiency. This effluent quality can differ in time and between WWTPs, hence the surrogate correlation models should be widely applicable. At the end of the review, recommendations are made for future research and implementation of an effective control strategy for (full-scale) applications.
Ozonation followed by biological post-treatment is an established technology for abatement of organic micropollutants (OMP) from municipal wastewater. Although the necessity of biological post-treatment for oxidation by-product (OBP) removal is widely accepted, there is still discussion about the appropriate design and operation. The presented pilot-study investigates the impact of filter material and contact time on the removal efficiency of bulk organics, OMP, and OBP in three different deep-bed filters operated in parallel as post-treatment after ozonation (biological activated carbon (BAC) filter, dual-media filter sand/BAC and dual-media filter sand/anthracite). The use of BAC instead of non-adsorptive filter material resulted in higher removal of DOC and dissolved oxygen which indicates increased biological activity. Moreover, both BAC containing filters showed additional removal for a number of OMP even at high treated bed volumes of >50 000 whereas no removal was observed in the sand/anthracite filter. Analysis of N-nitrosodimethylamine (NDMA) and several carbonyl compounds revealed a clear formation of these biodegradable OBP during ozonation. A strong correlation was found between carbonyl formation and the specific ozone dose. Removal of OBP in the sand/BAC and the sand/anthracite filter was tested at different empty bed contact times (EBCT). While NDMA was efficiently removed independent of EBCT changes, there was a slightly negative impact of shorter EBCT on the reduction of carbonyl compounds. Furthermore, it was demonstrated that the integration of enhanced phosphorus removal into post-treatment is feasible with relatively low efforts by inline coagulant dosing (FeCl3) in the filter influent.
The present chapter gives an overview of analytical methodologies employed for the identification and quantitation of metabolites formed in plants or plant cell cultures from drugs and personal care products after uptake from water or soil. Important aspects like experimental approaches for plant growing, extraction of the investigated analytes from plants, preconcentration strategies, and final analytical techniques allowing the proposal of (at least tentative) structures for drug-related metabolites are discussed. Special emphasis is also set on the elucidation of translocation processes by analyzing different plant parts. In one table, a comprehensive overview of the current state of knowledge available from the literature is given, with respect to the topics listed above.
The removal of micropollutants from municipal wastewater is challenged by the number of compounds with diverse physico-chemical properties. Ozonation is increasingly used to remove micropollutants from wastewater. However, ozonation does not necessarily result in complete mineralization of the organic micropollutants but rather transforms them into new compounds which could be persistent or have adverse environmental effects. To explore ozone dose dependency of the formation and successive removal of ozonation products, two pilot-scale and one full-scale ozonation plants were operated subsequent to a conventional activated sludge treatment. The results from these trials indicated that the concentrations of several N-oxides, such as Erythromycin N-oxide, Venlafaxine N-oxide and Tramadol N-oxide, increased up to an ozone dose of 0.56–0.61 mg O3/mg DOC while they decreased at elevated doses of 0.7–1.0 mg O3/mg DOC. Similar results were also obtained for two transformation products of Diclofenac (Diclofenac 2,5-quinone imine and 1-(2,6-dichlorophenyl)indolin-2,3-dione) and one transformation product of Carbamazepine (1-(2-benzoic acid)-(1H,3H)-quinazoline-2,4-dione), where the highest concentrations appeared around 0.27–0.31 mg O3/mg DOC. The formation maximum of a given compound occurred at a specific ozone dose that is characteristic for each compound, but seemed to be independent of the wastewater used for the experiments at the two pilots and the full-scale plant.
The advanced oxidation of paracetamol (PCT), frequently used analgesic, promoted by electro-oxidation (EOX), goethite catalyzed electro-Fenton (GEF) with goethite, ozonation and electro-peroxone (E-peroxone) was investigated. The degradation efficiency of the processes was evaluated considering the decay of PCT versus time. All the processes showed pseudo-first order character for PCT degradation. kobs values, at optimum conditions for an individual process, were defined as 0.0022, 0.0029, 0.0870 and 0.1662 min-1 for EOX, GEF, ozonation and E-peroxone processes, respectively. Where EOX and GEF processes showed poor degradation efficiencies, novel E-peroxone process provided complete removal of PCT. The degradation of the PCT would mostly occur by OH• and molecular O3 due to the higher rate constants achieved at E-peroxone and ozonation. Conversely, with lower kobs values gained at EOX, hydroxyl radicals would not contribute noticeably to the PCT degradation. In GEF process, due to relatively lower OH• production rate, lower kobs values were obtained for the degradation of PCT. The formation of reaction intermediates, aromatics and carboxylic acids, was also determined in this study.
The aquatic environment is the main destination for many organic pollutants originating from human activity. Pharmaceuticals are significant contributors to this pollutant cocktail. One major route of pharmaceuticals into the aquatic environment is through discharges from sewage treatment plants (STPs) with inadequate pharmaceutical removal capacity. Adverse effects in aquatic organisms exposed to pharmaceuticals have been illustrated in a multitude of studies. Advanced sewage treatment technologies are therefore being evaluated as potential methods for improving pharmaceutical removal, for example whole-effluent ozonation. However, it remains important to assess how the ozonation treatment modulates the biological effect in aquatic organisms exposed to the STP effluent due to the formation of ozonation by-products (OBPs).
This thesis aimed to investigate outcomes of ozonation treatment of STP effluents with a special focus on pharmaceuticals, by combining chemical analysis and in vivo testing using zebrafish (Danio rerio). Firstly the effects of an ozonated STP effluent on reproduction and behavior of adult zebrafish were evaluated at a Swedish STP (Knivsta municipal STP) with a full-scale ozonation step. Fish exposed over 21 days to the ozonated STP effluent spawned significantly more eggs than fish exposed to the nonozonated effluent and tap water. Vitellogenin induction (a biomarker for estrogenic pollutants) and a possible anxiety-related behavior were also observed in fish exposed to the ozonated STP effluent. Chemical analysis of the pre- and post ozonated STP effluent was used to screen for the presence of 105 pharmaceuticals, of which 24 could be detected. The average ozone removal efficiency of these pharmaceuticals was 77%.
The thesis work then focused on how ozonation would affect zebrafish embryotoxicity of three pharmaceuticals detected in the Knivsta STP effluent (i.e. carbamazepine, diclofenac, and oxazepam). While embryotoxicity of diclofenac was eliminated, exposure to oxazepam and carbamazepine induced embryotoxic responses following ozonation, suggesting formation of OBPs. The thesis therefore proceeded to investigate the toxicities of isolated carbamazepine OBPs. It was revealed that two carbamazepine OBPs, BQM and BQD, were the drivers of ozonated carbamazepine embryotoxicity. The thesis concludes that the formation of specific pharmaceutical OBPs explains adverse biological outcomes of effluent ozonation. The results add valuable information for the continuing efforts to improve STP effluent treatment.
Thesis deposited at https://pub.epsilon.slu.se/16749/
The toxicity and fate of pharmaceuticals and other emerging micro-organic contaminants in the natural and built environments have been the focus of much research over the last twenty years. Recently, particular focus has been centred on the fate of antimicrobial chemicals, including antibiotics and antifungals. The occurrence of such chemicals in the environment is thought to contribute to the selection of resistance in exposed microorganisms.
This special issue (SI) brings together a broad range of recent advances in the field of emerging micro-organic contaminants, ranging from medicinal contaminants to industrial chemicals in the environment. Notable these range from chemical extraction and large-scale analysis to adverse effects on non-target aquatic organisms and potential risk to humans via contaminated foodstuffs. Additionally, this special issue also presents novel contaminant treatment/ degradation methods of both physical and biological nature.
Trace organic contaminants (TrOCs) such as pharmaceuticals, pesticides, personal care products, etc. are entering our aquatic environment through the discharge of treated wastewater from municipal water resource recovery facilities (WRRFs). These installations are currently not designed to cope with those contaminants and upgrades with advanced treatment technologies to reduce the TrOC discharge are needed. One of the most promising technologies is the use of ozonation as a tertiary treatment prior to discharge. The wide application of ozonation on WRRFs is however challenged by the unavailability of an online ozone dosing control framework that ensures efficient TrOC abatement and minimizes the by-product formation potential at the lowest possible costs. In this PhD, a generic framework is developed which can be applied for numerous TrOCs that are currently known or that might be detected in future and at different treatment sites. The main goal was to develop, calibrate and validate a surrogate-based correlation model in view of variable effluent conditions, ensuring an easily applicable and reliable control framework. New correlations are presented based on UVA254 and fluorescence surrogate parameters, considering kinetic information, and reflecting the ongoing reaction mechanisms. The developed models were further validated on different WRRFs and during pilot-scale experimentation. Practical and economical aspects were given special attention during pilot-scale experimentation. Finally, the main potential for surrogate parameters, i.e. effectively controlling the ozone dose in terms of TrOC abatement and costs, was shown.
Residues and metabolites of pharmaceuticals can pollute environmental compartments, food commodities and workplaces, thus posing a serious threat to human health and environmental integrity. Needless to say, this challenge is increasingly attracting the attention of the international scientific community, the decision makers and the layman. Much concern has been expressed over the past few years over the deleterious consequences of the discharge of medicinal products, often as unused or expired products, into the various environmental compartments, to say nothing of their occurrence in foodstuff and feedstuff and of their undue presence in the workplace. This widespread presence inescapably raises a number of questions among which of prime importance is the reliable quantification of such residues and metabolites in the various media in order to assess whether and to what extent they can endanger biota and humans.
This work summarizes the key findings of an overview of the scientific literature in this field approximately over the past three years (2014–2016) with particular regard to the most fit-for-purpose analytical approaches currently resorted to for the detection, identification and quantification of residues of medicinal products in the most diverse matrices along with the assessment of their noxious potential. A total of almost 1000 papers, reports and other publicly available documents published in the said period were scanned.
During the last decade, several screening programs for pharmaceuticals at Swedish wastewater treatment plants (WWTPs) have been conducted by research institutes, county councils, and wastewater treatment companies. In this study, influent and effluent concentrations compiled from these screening programs were used to assess the occurrence and reduction of non-antibiotic pharmaceuticals for human usage. The study is limited to full-scale WWTPs with biological treatment. Based on the data compiled, a total of 70 non-antibiotic pharmaceuticals have been detected, at concentrations ranging from a few ng/L to several μg/L, in the influent water. The influent concentrations were compared with the sale volumes and for many pharmaceuticals it was shown that only a small fraction of the amount sold reaches WWTPs as dissolved parent compounds. Pharmaceuticals with low reduction degrees at traditional WWTPs were identified. Further comparison based on the biological treatment showed lower reduction degrees for several pharmaceuticals in trickling filter plants compared with activated sludge plants with nitrogen removal.
Wastewater treatment plants do not eliminate micropollutants completely and are thus important point sources for these substances. Ozonation and activated carbon treatment might be beneficial for ecosystem health as these techniques provide effective barriers to organic contaminants. However, a toxicity evaluation is required to investigate toxicity reduction and to assess the potential formation of toxic oxidation byproducts during ozonation. Therefore a comparative toxicity evaluation of different treated wastewater effluents was performed on site at a half scale treatment plant equipped with an ozonation step and an activated carbon treatment step in parallel subsequent to conventional activated sludge treatment. For this purpose four invertebrate and one higher plant toxicity test were selected to assess potential biological effects on whole organisms. The reproduction test with the mudsnail Potamopyrgus antipodarum exhibited a decreased reproductive output after advanced treatment compared to conventional treatment. This indicates an effective estrogenicity removal by ozonation and activated carbon treatment and is confirmed by results of the yeast estrogen screen with a reduction of in vitro estrogenic activity by >75%. The Lumbriculus variegatus test revealed a significantly enhanced toxicity after ozonation compared to conventional treatment whereas this effect was reduced following subsequent sand filtration. When ozonation was applied, a significantly increased genotoxicity was observed, detected with the comet assay using haemolymph of the zebra mussel. Again, this effect was removed by subsequent sand filtration to the level of conventional treatment. Activated carbon treatment even resulted in a significant reduction of genotoxicity. Adverse effects after the ozone reactor are possibly a result of the formation of toxic oxidation byproducts. Biologically active sand filtration obviously is an effective barrier to such compounds.
Ozonation as advanced wastewater treatment method is an effective technique for micropollutant removal. However, the application of this method carries the inherent danger to produce toxic oxidation byproducts. For an ecotoxicological assessment conventionally treated wastewater, wastewater after ozonation and ozonated wastewater after sand filtration were evaluated in parallel at an operating treatment plant via the fish early life stage toxicity test (FELST) using rainbow trout (Oncorhynchus mykiss). The FELST revealed a considerable developmental retardation of test organisms exposed to ozonated WW. This was accompanied by a significant decrease in body weight and length compared to reference water, to the conventionally treated WW and to the ozonated water after sand filtration. Hence sand filtration obviously prevents from adverse ecotoxicological effects of ozonation. An additional test with yolk-sac larvae resulted in a significant reduction of vitellogenin levels in fish exposed to ozonated wastewater compared to fish reared in conventionally treated wastewater. This demonstrates the effective removal of estrogenic activity by ozonation. Adverse ozonation effects may have been a result of the conversion of chemicals into more toxic metabolites. However, sand filtration reduced toxication effects indicating that these oxidation byproducts are readily degradable or adsorbable. The results indicate that in any case ozonation should not be applied without subsequent post treatment appropriate for oxidation byproducts removal (e.g. sand filtration).
Wastewater reclamation is an upcoming approach that will significantly affect wastewater treatment systems. Despite the fact that technology for treating wastewater to an effluent water quality that meets various quality standards for reuse is already available and applied, the reuse of water is not just a simple and straightforward road. Significant additional energy and civil infrastructure is required to treat the water to a standard that allows it to be safely reused. The total impact of treating and reusing water may be higher than the environmental benefits. Thus, it is crucial the life-cycle impacts from upstream and downstream processes of various reuse technologies, i.e. production of chemicals, energy use, eutrophication, sludge handling, etc. The present paper provides a comprehensive evaluation considering different reuse purposes, treatment technologies and plant size. The results of this study suggest that all these factors are highly significant for the environmental impact of wastewater treatment systems for non-potable applications.
Pharmaceutical residues, which pass naturally through the human body into sewage, are in many cases virtually unaffected by conventional wastewater treatment. Accumulated in the environment, however, they can significantly impact aquatic life. The present study indicates that many pharmaceutical residues found in wastewater can be removed with activated carbon in a cost-efficient system that delivers higher resource utilisation and security than other carbon systems. The experiment revealed a substantial separation of the analysed compounds, notwithstanding their relatively high solubility in water and dissimilar chemical structures. This implies that beds of activated carbon may be a competitive alternative to treatment with ozone. The effluent water used for the tests, performed over 20 months, originated from Stockholm's largest sewage treatment plant. Passing through a number of different filters with activated carbon removed 90-98% of the pharmaceutical residues from the water. This paper describes pilot-scale tests performed by IVL and the implications for an actual treatment plant that has to treat up to several thousand litres of wastewater per second. In addition, the advantages, disadvantages and costs of the method are discussed. This includes, for example, the clogging of carbon filters and the associated hydraulic capacity limits of the activated carbon.
At a pilot scale wastewater treatment plant ozonation and powdered activated carbon filtration were assessed for their efficacy to remove trace organic contaminants from secondary treated effluents. A chemical analysis of 16 organic compounds was accompanied by a comprehensive suite of in vitro and in vivo bioassays with the focus on genotoxicity to account for the potential formation of reactive oxidation products. In vitro experiments were performed with solid phase extracted water samples, in vivo experiments with native wastewater in a flow through test system on site at the treatment plant. The chemical evaluation revealed an efficient oxidation of about half of the selected compounds by more than 90% at an ozone dose of 0.7 g/g DOC. A lower oxidizing efficiency was observed for the iodinated X-ray contrast media (49–55%). Activated carbon treatment (20 mg/L) was less effective for the removal of most pharmaceuticals monitored. The umuC assay on genotoxicity delivered results with about 90% decrease of the effects by ozonation and slightly lower efficiency for PAC treatment. However, the Ames test on mutagenicity with the strain YG7108 revealed a consistent and ozone-dose dependent increase of mutagenicity after wastewater ozonation compared to secondary treatment. Sand filtration as post treatment step reduced the ozone induced mutagenicity only partly. Also the fish early life stage toxicity test revealed an increase in mortality after ozonation and a reduced effect after sand filtration. Only activated carbon treatment reduced the fish mortality compared to conventional treatment on control level. Likewise the in vivo genotoxicity detected with the comet assay using fish erythrocytes confirmed an increased (geno-)toxicity after ozonation, an effect decrease after sand-filtration and no toxic effects after activated carbon treatment.
In the year 2010, effluents from 90 European wastewater treatment plants (WWTPs) were analyzed for 156 polar organic chemical contaminants. The analyses were complemented by effect-based monitoring approaches aiming at estrogenicity and dioxin-like toxicity analyzed by in vitro reporter gene bioassays, and yeast and diatom culture acute toxicity optical bioassays. Analyses of organic substances were performed by solid-phase extraction (SPE) or liquid-liquid extraction (LLE) followed by liquid chromatography tandem mass spectrometry (LC-MS-MS) or gas chromatography high-resolution mass spectrometry (GC-HRMS). Target microcontaminants were pharmaceuticals and personal care products (PPCPs), veterinary (antibiotic) drugs, perfluoroalkyl substances (PFASs), organophosphate ester flame retardants, pesticides (and some metabolites), industrial chemicals such as benzotriazoles (corrosion inhibitors), iodinated x-ray contrast agents, and gadolinium magnetic resonance imaging agents; in addition biological endpoints were measured. The obtained results show the presence of 125 substances (80% of the target compounds) in European wastewater effluents, in concentrations ranging from low nanograms to milligrams per liter. These results allow for an estimation to be made of a European median level for the chemicals investigated in WWTP effluents. The most relevant compounds in the effluent waters with the highest median concentration levels were the artificial sweeteners acesulfame and sucralose, benzotriazoles (corrosion inhibitors), several organophosphate ester flame retardants and plasticizers (e.g. tris(2-chloroisopropyl)phosphate; TCPP), pharmaceutical compounds such as carbamazepine, tramadol, telmisartan, venlafaxine, irbesartan, fluconazole, oxazepam, fexofenadine, diclofenac, citalopram, codeine, bisoprolol, eprosartan, the antibiotics trimethoprim, ciprofloxacine, sulfamethoxazole, and clindamycine, the insect repellent N,N'-diethyltoluamide (DEET), the pesticides MCPA and mecoprop, perfluoroalkyl substances (such as PFOS and PFOA), caffeine, and gadolinium.
Increased public awareness, potential human health effects, and demonstrated impacts on aquatic ecosystems have stimulated recent interest in pharmaceuticals, personal care products (PPCPs), and endocrine-disrupting compounds (EDCs) in water and wastewater. Due to the potential public and environmental health implications, some agencies are taking a proactive approach to controlling trace organic contaminant (TOrC) concentrations in water supplies. This review describes some of the research related to the toxicity and estrogenicity of wastewater-derived TOrCs in addition to regulatory guidance from several international agencies. This review also evaluates pilot- and full-scale studies to characterize the efficacy of ozonation for TOrC mitigation in wastewater applications.
Tertiary wastewater treatment plant effluent before and after ozonation (0.6-1.1g O₃/g DOC) was tested for aquatic ecotoxicity in a battery of standardised microbioassays with green algae, daphnids, and zebrafish eggs. In addition, unconjugated estrogen and 17β-hydroxyandrogen immunoreactive substances were quantified by means of enzyme immunoassays, and endocrine effects were analysed in a 21-day fish screening assay with adult male and female medaka (Oryzias latipes). Ozonation decreased estrogen-immunoreactivity by 97.7±1.2% and, to a lesser extent, androgen-immunoreactivity by 56.3±16.5%. None of the short-term exposure ecotoxicity tests revealed any adverse effects of the tertiary effluent, neither before nor after the ozonation step. Similarly in the fish screening assay, reproductive fitness parameters showed no effects attributed to micropollutants, and no detrimental effects of the effluents were observed. Based on the presented screening, ozonation effectively reduced steroid hormone levels in the wastewater treatment plant effluent without increasing the effluent's ecotoxicity.
This study investigates biofiltration for the removal of dissolved organic carbon (DOC), pharmaceuticals and personal care products (PPCPs), and for the reduction of non-specific toxicity expressed as baseline toxicity equivalent concentration (baseline-TEQ). Two filtering media, sand and granular activated carbon, were tested. The influence of pre-ozonation and empty-bed contact time (EBCT, from 30 to 120 min) was determined. The experiments were performed at a pilot-scale with real WWTP effluent. A previous study showed that biological activity had developed on the filtering media and dissolved organic removal had reached a steady state before sampling commenced. The results show that biological activated carbon (BAC) has a good potential for the removal of DOC (35-60%), PPCPs (>90%) and baseline-TEQ (28-68%) even without pre-ozonation. On the contrary, the sand shows limited improvement of effluent quality. Varying the EBCT does not influence the performance of the BAC filters; however, dissolved oxygen concentration could be a limiting factor. The performances of the BAC filters were stable for over two years suggesting that the main mechanism of organic matter and PPCPs removal is biodegradation. It is concluded that BAC filtration without pre-ozonation could be implemented as a low cost advanced treatment option to improve WWTP effluent chemical quality.
Concerns about endocrine disrupting compounds in sewage treatment plant (STP) effluents give rise to the implementation of advanced treatment steps for the elimination of trace organic contaminants. The present study investigated the effects of ozonation (O(3)) and activated carbon treatment (AC) on endocrine activities [estrogenicity, anti-estrogenicity, androgenicity, anti-androgenicity, aryl-hydrocarbon receptor (AhR) agonistic activity] with yeast-based bioassays. To evaluate the removal of non-specific toxicity, a cytotoxicity assay using a rat cell line was applied. Wastewater (WW) was sampled at two STPs after conventional activated sludge treatment following the secondary clarifier (SC) and after subsequent advanced treatments: O(3), O(3) + sand filtration (O(3-SF)), and AC. Conventional treatment reduced estrogenicity, androgenicity, and AhR agonistic activity by 78-99% compared to the untreated influent WW. Anti-androgenicity and anti-estrogenicity were not detectable in the influent but appeared in SC, possibly due to the more effective removal of respective agonists during conventional treatment. Endocrine activities after SC ranged from 2.0 to 2.8 ng/L estradiol equivalents (estrogenicity), from 4 to 22 μg/L 4-hydroxytamoxifen equivalents (anti-estrogenicity), from 1.9 to 2.0 ng/L testosterone equivalents (androgenicity), from 302 to 614 μg/L flutamide equivalents (anti-androgenicity), and from 387 to 741 ng/L β-naphthoflavone equivalents (AhR agonistic activity). In particular, estrogenicity and anti-androgenicity occurred in environmentally relevant concentrations. O(3) and AC further reduced endocrine activities effectively (estrogenicity: 77-99%, anti-androgenicity: 63-96%, AhR agonistic activity: 79-82%). The cytotoxicity assay exhibited a 32% removal of non-specific toxicity after O(3) compared to SC. O(3) and sand filtration reduced cytotoxic effects by 49%, indicating that sand filtration contributes to the removal of toxicants. AC was the most effective technology for cytotoxicity removal (61%). Sample evaporation reduced cytotoxic effects by 52 (AC) to 73% (O(3)), demonstrating that volatile substances contribute considerably to toxic effects, particularly after O(3). These results confirm an effective removal or transformation of toxicants with receptor-mediated mode of action and non-specific toxicants during O(3) and AC. However, due to the limited extractability, polar ozonation by-products were neglected for toxicity analysis, and hence non-specific toxicity after O(3) is underestimated.
The removal efficiency for 220 micropollutants was studied at the scale of a municipal wastewater treatment plant (WWTP) upgraded with post-ozonation followed by sand filtration. During post-ozonation, compounds with activated aromatic moieties, amine functions, or double bonds such as sulfamethoxazole, diclofenac, or carbamazepine with second-order rate constants for the reaction with ozone >10(4) M(-1) s(-1) at pH 7 (fast-reacting) were eliminated to concentrations below the detection limit for an ozone dose of 0.47 g O3 g(-1) dissolved organic carbon (DOC). Compounds more resistant to oxidation by ozone such as atenolol and benzotriazole were increasingly eliminated with increasing ozone doses, resulting in >85% removal for a medium ozone dose (approximately 0.6 g O3 g(-1) DOC). Only a few micropollutants such as some X-ray contrast media and triazine herbicides with second-order rate constants <10(2) M(-1) s(-1) (slowly reacting) persisted to a large extent. With a medium ozone dose, only 11 micropollutants of 55 detected in the secondary effluent were found at >100 ng L(-1). The combination of reaction kinetics and reactor hydraulics, based on laboratory-and full-scale data, enabled a quantification of the results by model calculations. This conceptual approach allows a direct upscaling from laboratory- to full-scale systems and can be applied to other similar systems. The carcinogenic by-products N-nitrosodimethylamine (NDMA) (< or =14 ng L(-1)) and bromate (<10 microg L(-1)) were produced during ozonation, however their concentrations were below or in the range of the drinking water standards. Furthermore, it could be demonstrated that biological sand filtration is an efficient additional barrier for the elimination of biodegradable compounds formed during ozonation such as NDMA. The energy requirement for the additional post-ozonation step is about 0.035 kWh m(-3), which corresponds to 12% of a typical medium-sized nutrient removal plant (5 g DOC m(-3)).
Disinfection byproduct (DBP) formation in tertiary wastewater was examined after ozonation (O(3)) and advanced oxidation with O(3) and hydrogen peroxide (O(3)/H(2)O(2)). O(3) and O(3)/H(2)O(2) were applied at multiple dosages to investigate DBP formation during coliform disinfection and trace contaminant oxidation. Results showed O(3) provided superior disinfection of fecal and total coliforms compared to O(3)/H(2)O(2). Color, UV absorbance, and SUVA were reduced by O(3) and O(3)/H(2)O(2), offering wastewater utilities a few potential surrogates to monitor disinfection or trace contaminant oxidation. At equivalent O(3) dosages, O(3)/H(2)O(2) produced greater concentrations of assimilable organic carbon (5-52%), aldehydes (31-47%), and carboxylic acids (12-43%) compared to O(3) alone, indicating that organic DBP formation is largely dependent upon hydroxyl radical exposure. Bromate formation occurred when O(3) dosages exceeded the O(3) demand of the wastewater. Bench-scale tests with free chlorine showed O(3) is capable of reducing total organic halide (TOX) formation potential by at least 20%. In summary, O(3) provided superior disinfection compared to O(3)/H(2)O(2) while minimizing DBP concentrations. These are important considerations for water reuse, aquifer storage and recovery, and advanced wastewater treatment applications.
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