Eat seldom is better than eat frequently: Pharmaceuticals degradation kinetics, enantiomeric profiling and microorganisms in moving bed biofilm reactors are affected by feast famine cycle times.

Feast-famine (FF) regimes improved the removal of recalcitrant pharmaceuticals in moving bed biofilm reactors (MBBRs), but the optimal FF cycle remained unresolved. The effects of FF cycle time on the removal of bulk substrates (organic carbon and nitrogen) and trace pharmaceuticals by MBBR are systematically evaluated in this study. The feast to famine ratio was fixed to 1:2 to keep the same loading rate, but the time for the FF cycles varied from 18 h to 288 h. The MBBR adapted to the longest FF cycle time (288 h equaling 48 × HRT) resulted in significantly higher degradation rates (up to +183%) for 12 out of 28 pharmaceuticals than a continuously fed (non-FF) reactor. However, other FF cycle times (18, 36, 72 and 144 h) only showed a significant up-regulation for 2-3 pharmaceuticals compared to the non-FF reactor. Enantioselective degradation of metoprolol and propranolol occurred in the second phase of a two phase degradation, which was different for the longer FF cycle time. N-oxidation and N-demethylation pathways of tramadol and venlafaxine differed across the FF cycle time suggestin the FF cycle time varied the predominant transformation pathways of pharmaceuticals. The abundance of bacteria in the biofilms varied considerably between different FF cycle times, which possibly caused the biofilm to remove more recalcitrant bulk organic C and pharmaceuticals under long cycle times.

Transformation mechanisms of the antidepressant citalopram in a moving bed biofilm reactor: Substrate-depended pathways, eco-toxicities and enantiomeric profiles.

Citalopram (CIT) is one of the most consumed antidepressants and frequently detected in aquatic environments worldwide. Conventional wastewater treatment cannot remove this neuronal active pharmaceutical efficiently. Past studies showed that moving bed biofilm reactors (MBBRs) can degrade CIT but the exact transformation pathways and toxicity reduction remained unclear. In this study, the effects of substrate stimulation on CIT transformation in an MBBR were systematically investigated. The results showed that a co-metabolic stimulation by acetate increased the transformation rate by 54 % and 24 % at high (300 µg/L) and environmental concentration (1.8 µg/L) of CIT, respectively. Conversely, the complex substrates in raw wastewater reduced the reaction rates by 44 %, suggesting a competitive inhibition on the enzymatic sites. The substrate stimulation changed the enantiomeric fraction (EF) of CIT from racemic (EF=0.5) to 0.60 at the high CIT concentrations, while those at lower concentrations resulted in an EF of 0.33, indicating that probably different enantioselective enzymes degraded CIT at high concentrations than at low concentrations, i.e., the presence of 300 µg/L CIT was possibly sufficient to induce the synthesis of different enantioselective enzymes, than those originally present. Through non-target and target analysis, in total 19 transformation products (TPs) including 7 TPs that were hitherto not mentioned in the literature were identified. Among these were quaternary amines, alkenes and conjugate TPs. The major transformation pathways were a) nitrile hydrolysis (up to 43 %), b) amide hydrolysis, and c) N-oxidation. Dosing acetate up-regulated significantly the amide hydrolysis, N-oxidation and conjugation pathways but inhibited the N-demethylation and α-carbon hydroxylation pathways. The in-silico toxicity assessment of CIT and its TPs suggested the overall eco-toxic potential of TPs was reduced by MBBR. Furthermore, the degradation under carbon-limited (famine) conditions favored the formation of the more toxic carboxamide, N-desmethyl and alkene TPs, while carbon-rich conditions, promoted the production of the less toxic carboxylic acid, N-oxide and ester TPs. Therefore, this study demonstrated that a) the co-metabolic stimulation of CIT metabolization by dosing a simple carbon source or b) inhibition of CIT metabolization by complex substrates; c) substrate stimulation made a difference on CIT transformation rates, enantiomeric profiles, pathways and toxic potentials. Overall, a simple-carbon co-metabolic stimulated MBBR was an efficient up-regulation strategy to minimize hazardous CIT and CIT-TPs as much as possible.

Microbial biofilm metabolization of benzalkonium compounds (benzyl dimethyl dodecyl ammonium & benzyl dimethyl tetradecyl ammonium chloride).

Benzalkonium chlorides (BACs) are quaternary ammonium compounds (QUATs) that are used as biocides. The degradation of these compounds in wastewater treatment plants is essential to reduce their spread into the environment and thus prevent the development of QUAT-resistant genes. The biodegradation of two BACs (BAC-12 and BAC-14) was investigated in moving bed biofilm reactors (MBBRs). Degradation half-lives of 12 and 20 h for BAC-12 and - 14, respectively, were detected as well as the formation of 42 metabolites. Two new degradation pathways for the BACs were identified in this study: 1) one involving an ω-oxidation, followed by ß-oxidation and 2) one via an ω-oxidation followed by an α-oxidation that was succeeded by ß-oxidation. Similar metabolites were detected for both BAC-12 and BAC-14. Additional metabolites were detected in the study, that could not be assigned to the above-mentioned pathways, revealing even more metabolic pathways in the MBBR which is probably due to the complexity of the microbial community in the biofilm. Interestingly, both TP194 (Benzyl-(carboxymethyl)-dimethylazanium) and TP208B (Benzyl-(2-carboxyethyl)-dimethylazanium) were identified as end products of the ω/ß-pathway and the α/ß-pathway. TP208B, TP152 and TP250 that were identified in this study, as well as the known BDMA were discovered in the effluent of a wastewater treatment plant.

Mechanistic studies on the effect of easy degradable carbon on pharmaceuticals removal in intermittently fed moving bed biofilm reactors.

This study was conducted to provide for the first time systematic data on how intermittent feeding with carbon (ethanol) affects the kinetics of pharmaceuticals degradation in a moving bed biofilm reactor (MBBR). The relationship between the degradation rate constants (K) of 36 pharmaceuticals and the length of famine was tested with 12 different feast-famine ratios: For 17 pharmaceuticals, intermittent feeding increased K with a factor of 3-17, while for six other pharmaceuticals, it decreased K. Concerning intermittent loading, three dependencies were detected: 1) for some compounds (e.g., valsartan, ibuprofen, iohexol), the K decreased linearly with carbon loading, 2) for three compounds (2 sulfonamides and benzotriazole) K increased linearly with carbon loading 3) for most compounds (e.g., beta blockers, macrocyclic antibiotics, candesartan, citalopram, clindamycin, gabapentin) K had a maximum around 6 d famine (with 2 d feast). Optimizing processes on MBBRs need therefore be conducted based on a prioritization of compounds.

Sartan blood pressure regulators in classical and biofilm wastewater treatment - Concentrations and metabolism.

Sartans are a group of pharmaceuticals widely used to regulate blood pressure. Their concentration levels were monitored in 80 wastewater treatment plants (WWTP) in the Baltic Sea Region, reached from limit of detection up to 6 µg/L. The concentrations were significantly different in different countries, but consistent within the respective country. The degradation of sartans (losartan, valsartan, irbesartan) in moving bed biofilm reactors (MBBRs) that utilize biofilms grown on mobile carriers to treat wastewater was investigated for the first time, and compared with the degradation in a conventional activated sludge (CAS) treatment plant. The results showed the formation of six microbial transformation products (TPs) of losartan, four of valsartan, and four of irbesartan in biological wastewater treatment. Four of these metabolites have not been described in the literature before. Chemical structures were suggested and selected TPs were verified and quantified depending on availability of true standards. Valsartan acid was a common TP of losartan, valsartan, and irbesartan. Losartan and irbesartan also shared one TP: losartan/irbesartan TP335. Based on the mass balance analysis, losartan carboxylic acid is the main TP of losartan, and valsartan acid is the main TP of valsartan during the biotransformation process. For irbesartan, TP447 is likely to be the main TP, as its peak areas were two orders of magnitude higher than those of all the other detected TPs of this compound. The effects of adapting biofilms to different biological oxygen demand (BOD) loading on the degradation of sartans as well as the formation of their TPs were investigated. Compared to feeding a poor substrate (pure effluent wastewater from a CAS), feeding with richer substrate (1/3 raw and 2/3 effluent wastewater) promoted the metabolism of most compounds (co-metabolization). However, the addition of raw wastewater inhibited some metabolic pathways of other compounds, such as from losartan/irbesartan to TP335 (competitive inhibition). The formation of irbesartan TP447 did not change with or without raw wastewater. Finally, the sartans and their TPs were investigated in a full-scale CAS wastewater treatment plant (WWTP). The removal of losartan, valsartan, and irbesartan ranged from 3.0 % to 72% and some of the transformation products (TPs) from human metabolism were also removed in the WWTP. However, some of the sartan TPs, i.e., valsartan acid, losartan carboxylic acid, irbesartan TP443 and losartan TP453, were formed in the WWTP. Relative high amounts of especially losartan carboxylic acid, which was detected with concentrations up to 2.27 µg/L were found in the effluent.

Effects of substrate loading on co-metabolic transformation pathways and removal rates of pharmaceuticals in biofilm reactors.

This study focused on the effects of substrate (raw wastewater) on the biological removal of 20 pharmaceuticals in moving bed biofilm reactors. This is the first study discriminating experimentally between effects of adaptation (45 d) and stimulation (100 h) on the removal of micropollutants. The results presented in this paper show: i) Tramadol and venlafaxine are subject to microbial N-oxidation (besides the known demethylation). ii) Changes in substrate loading, changed the preferential degradation pathways, e.g., from N-oxidation (under starvation) to N-demethylation of both model compounds: tramadol and venlafaxine, during adaptation and stimulation to high substrate supply. iii) In starving biofilms, the effects of stimulation on removal rates are minor (-100 to +150 %) in comparison to those caused by adaptation (-100 to +700 %). iv) Adaptation to high loadings resulted in increased removal rates (up to 700 % in selected cases) v) Adaptation to high loadings followed by high loading of stimulation, resulted in the highest increase of removal rates (+49 % to +1800 %) for hard-to-degrade compounds (e.g., diclofenac). All in all, this study shows that the efficiency of biofilm reactors is heavily dependent on their adaptation to substrate.

Further transformation of the primary ozonation products of tramadol- and venlafaxine N-oxide: Mechanistic and structural considerations.

Ozonation has been used to effectively remove micropollutants from the secondary effluent in several wastewater treatment plants. It is known that ozonation transforms tertiary amine compounds into their respective N-oxides, however in an earlier study a mass balance could not be closed at elevated ozone concentrations, leading to the assumption that more ozonation products are possible. This study was conducted to elucidate which (hitherto unknown) ozonation products can be formed from venlafaxine and tramadol when ozonating wastewater. Ozonation experiments were performed with tramadol and venlafaxine N-oxide in two different set-ups. Both tramadol- and venlafaxine N-oxide degraded during ozonation in pure (deionized) water in both semi-continuous and batch mode ozonation set-ups. 13 and 17 new transformation products were detected from tramadol- and venlafaxine N-oxide respectively, using high resolution mass spectrometry with ESI(+) ionization. Empirical chemical formulas were proposed based on the determination of the exact masses and interpretation of the product ion spectra. These transformation products result from the addition of one to three oxygen atoms and removal of C, -CH2, C2H2, C3H6, etc., from the parent molecule, respectively. Quenching experiments suggested that most of the transformation products originated from the direct reaction with ozone (eight for tramadol N-oxide and ten for venlafaxine N-oxide), whereas fewer products originated from the reaction with OH radicals (three for tramadol N-oxide and three for venlafaxine N-oxide). Reaction mechanisms and chemical structures of products are proposed, based on the available active sites and past literature on ozone reaction mechanisms. The experimental results are compared to theory and literature on ozone reactive sites and ozone reaction mechanisms. All in all this shows that there can be multiple ozonation products, and ozonation pathways can be complex, even if initially only one ozonation product is formed.

Integrating dissolved and particulate matter into a prediction tool for ozonation of organic micropollutants in wastewater.

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.

Fungi and biochar applications in bioremediation of organic micropollutants from aquatic media.

The conventional wastewater treatment system such as bacteria, is not able to remove recalcitrant micropollutants effectively. While, fungi have shown high capacity in degradation of recalcitrant compounds. Biochar, on the other hand, has gained attention in water and wastewater treatment as a low cost and sustainable adsorbent. This paper aims to review the recent applications of three major fungal divisions including Basidiomycota, Ascomycota, and Mucoromycotina, in organic micropollutants removal from wastewater. Moreover, it presents an insight into fungal bioreactors, fungal biofilm and immobilization system. Biochar adsorption capacities for organic micropollutants removal under different operating conditions are summarized. Finally, few recommendations for further research are established in the context of the combination of fungal biofilm with the technologies relying on the adsorption by porous carbonaceous materials.

Promoting the degradation of organic micropollutants in tertiary moving bed biofilm reactors by controlling growth and redox conditions.

A novel process configuration was designed to increase biofilm growth in tertiary moving bed biofilm reactors (MBBRs) by providing additional substrate from primary treated wastewater in a sidestream reactor under different redox conditions in order to improve micropollutant removal in MBBRs with low substrate availability. This novel recirculating MBBR was operated on pilot scale for 13 months, and a systematic increase was seen in the biomass concentration and the micropollutant degradation rates, compared to a tertiary MBBR without additional substrate. The degradation rates per unit carrier surface area increased in the order of ten times, and for certain micropollutants, such as atenolol, metoprolol, trimethoprim and roxithromycin, the degradation rates increased 20-60 times. Aerobic conditions were critical for maintaining high micropollutant degradation rates. With innovative MBBR configurations it may be possible to improve the biological degradation of organic micropollutants in wastewater. It is suggested that degradation rates be normalized to the carrier surface area, in favor of the biomass concentration, as this reflects the diffusion limitations of oxygen, and will facilitate the comparison of different biofilm systems.

Laboratory and pilot evaluation of aquaporin-based forward osmosis membranes for rejection of micropollutants.

Aquaporin-based forward osmosis (AQP FO) membranes were applied both in laboratory- and pilot-scale for removing micropollutants from water. The effect of operating parameters (feed flow, draw flow, and transmembrane pressure) on the i) rejection of micropollutants, ii) water flux, iii) reverse salt flux, and iv) water recovery of the AQP FO membrane modules was studied. Among the 21 micropollutants spiked, only four compounds, atenolol, propranolol, metoprolol, and citalopram, permeated through the AQP FO membranes to an extent that they could be quantified in the draw solutions of both the laboratory and pilot systems. The rejection rates, based on the full mass balance calculations, were between 96.1% and 99.7%, and all the other 17 compounds showed rejection exceeding 90% on both systems. The pilot AQP FO system was further employed for six days to treat effluent from a membrane bioreactor (MBR) treating municipal wastewater. 35 micropollutants were investigated. 27 of these were identified and quantified in the MBR effluent. Minute fractions of gabapentin, benzotriazole, and metoprolol were detected passing through the AQP FO membranes into the draw side with a constant rejection of around 99.2%, 95.4%, and 99.9%. Almost all other micropollutants' minimum rejection rates exceeded 80%.

MBBRs as post-treatment to ozonation: Degradation of transformation products and ozone-resistant micropollutants.

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.

Removal of pharmaceutical metabolites in wastewater ozonation including their fate in different post-treatments.

Advanced treatment technologies for the removal of pharmaceuticals and other organic micropollutants in WWTPs primarily target the removal of parent compounds. Nevertheless, the removal of metabolites originating from human- or microbial metabolism during biological treatment needs comparable consideration, as some of them might be present in high concentrations and contribute to toxicity. This study was conducted to elucidate the removal of human and microbial metabolites of pharmaceuticals as a function of the specific ozone dose. Ozonation was performed on four sites with two pilot- and two full-scale plants operated downstream of conventional activated sludge plants. The ozone reactivity of all metabolites (expressed as the ozone dose to remove 90% of the compound/decadic ozone dose) was lower than those of their parent compounds. The decadic ozone dose was 1.0, 1.3 and 1.1 mg O3/mg DOC for Epoxy-carbamazepine, Di-OH-carbamazepine and N-Desmethyl tramadol, respectively. 20-40% of the remaining metabolites were removed in a polishing sand/BAC-filter (biological activated carbon). Similar removal was observed for Epoxy-carbamazepine, Di-OH-carbamazepine and Hydroxy-diclofenac in a constructed wetland. However, the sand/anthracite filter had no effect. All four metabolites were removed in a GAC (granulated activated carbon) filter.

Abiotic fate of tolylfluanid and dichlofluanid in natural waters.

To prevent the growth of unwanted organisms on ship hulls, antifouling paints, containing biocides such as tolylfluanid (N-[dichlor(fluor)methyl]sulfanyl-N-(dimethylsulfamoyl)-4-methylaniline) and dichlofluanid (N-(dichlorfluormethylthio)-N',N'-dimethyl-N-phenylsulfamid), are applied. There are concerns over their occurrence and fate in the marine environment due to long-term immersion in water. In the present study, the hydrolysis and photolysis of these compounds were investigated. Results showed that tolylfluanid and dichlofluanid hydrolyzed completely to their respective hydrolysis products DMST (N,N-dimethyl-N'-p-tolylsulfamide) and DMSA (N,N-dimethyl-N'-phenylsulfamide) in coastal water within 24 h. Furthermore, the transformation of tolylfluanid and dichlofluanid under natural sunlight was determined in selected marine waters (coastal water and sea water) in comparison to deionized water. The experiments revealed that photodegradation rates of DMST and DMSA in coastal water were higher than in sea water or deionized water. The indirect phototransformation of the hydrolysis products with selected reactive species (triplet state organic matter, singlet oxygen, and hydroxyl radicals) showed that DMST and DMSA mainly display triplet reactivity. The measured half-lives of the hydrolysis products in natural waters were 2.7 and 23 days, with DMST being considerably faster transformed than DMSA. However, several direct and indirect photoproducts have been newly identified and measured. DMS (N,N-dimethylsulfamide), was identified as the major phototransformation product in natural waters. It is generated by indirect photodegradation processes and exhibits potential persistence in the environment.

Identification of more than 100 new compounds in the wastewater: Fate of polyethylene/polypropylene oxide copolymers and their metabolites in the aquatic environment.

100 ethylene oxide (EO)/propylene oxide (PO) copolymer precursor and metabolites were detected in wastewater effluents. The homopolymers of EO and PO as well as the EO/PO copolymers are widely used as surfactants, e.g., for the production of cosmetics, pharmaceuticals and lubricants. Concomitantly, these compounds are discharged into the wastewater and the environmental fate of the PO homopolymers, also called polypropylene glycols (PPGs), and EO/PO copolymers is mostly unknown. In the present study, we identified hitherto unknown copolymer EO/PO homologous series and their metabolites in wastewater effluent. The identified compounds occur in homologous series and consist of PPGs and EO/PO copolymers, and their carbonylated, carboxylated and dicarboxylated metabolites. MBBR lab incubations of PPGs and EO/PO copolymers showed the successive degradation by cleavage of individual PO and EO groups, with high removal (>90%) in the initial 8 h for most of the copolymers. Carbonylated and carboxylated metabolites were degraded within 40 h. EO/PO copolymers with a higher number of EO and PO units showed a higher removal in MBBR and conventional activated sludge wastewater treatment plants. Polymers with lower molecular weight were initially formed by degradation of the EO/PO polymers. The mono-carboxylated metabolites were also detected in surface waters. Overall, our results provide new knowledge about degradation pathways of PO containing compounds and show the hitherto unnoticed occurrence of EO/PO copolymers and metabolites in the water cycle.

Concentration dependent degradation of pharmaceuticals in WWTP effluent by biofilm reactors.

Conventional wastewater treatment lacks the ability to remove many pharmaceuticals. This is leading to emissions to the natural aquatic environment, where these compounds pose a risk to the aquatic organisms. An advanced wastewater treatment technique that has shown promising results is Moving Bed Biofilm Reactors (MBBR). Initial degradation velocity and degradation rate constants of the pharmaceuticals are important parameters for designing an optimal MBBR system; however, the degradation efficiency varies across studies and one of the most plausible causes might be initial concentration. Thus, to verify the effect of initial concentration, the degradation of a mixture of 18 pharmaceuticals at different initial concentrations was studied. For this study MBBR's with very low BOD loading were used as they were conditioned with effluent water. The experiment was set up as a MBBR batch incubation, using effluent wastewater as medium, spiked with the 18 pharmaceuticals in seven different concentration levels (approximately 0-300 µg L-1). The degradation of 14 out of 18 pharmaceuticals was concentration-dependent. The initial degradation velocity of the pharmaceuticals was either proportional to the initial concentration or was following a typical Michaelis-Menten kinetic. The degradation velocity of one compound, i.e., sulfamethizole might have been inhibited at high concentrations. The degradation rate constants from single first-order fittings (KSFO) for some compounds deviated from the expected behavior at low concentrations (below 10 µg L-1). This is suggested to be caused by simplicity of the Michaelis-Menten model, not taking possible occurrence of co-metabolism and mass-transfer limitations into account at low concentrations. This study underlines the fact that K values cannot be interpreted without paying attention to the tested concentration level. Furthermore, it shows that the used MBBRs was able to handle high concentrations of pharmaceuticals, and that the most efficient removal occurs at concentrations above 100 µg L-1.

Leaching of herbicidal residues from gravel surfaces - A lysimeter-based study comparing gravels with agricultural topsoil.

Evidence from the past shows that pesticide use in populated areas may impact groundwater quality. The approval of herbicides such as diflufenican and glyphosate for use on paved and unpaved gravel surfaces in the European Union is based on their behaviour and fate in agricultural soils. However, this might be very different from their fate in gravel surfaces. We therefore conducted an outdoor study with 21 small lysimeters containing different gravel types and a sandy arable topsoil as control. The lysimeters were sprayed with a commercial product for gardening, containing diflufenican and glyphosate. The concentrations of the herbicides and their relevant degradation products in the outlet was followed for 19 months. Diflufenican, glyphosate and AMPA did not leach from any of the lysimeters. However, one diflufenican degradation product (AE-0) leached from two of the gravel types for more than a year and a second degradation product (AE-B) leached from all gravels for up to one year. Concentrations in the leachate peaked at 0.5-3 µg/L, with highest concentrations over the longest periods observed with rock chippings on top of the gravel. We conclude, that the different properties of gravel compared to those of agricultural soils may lead to very different herbicide leaching patterns but also that the leaching depends highly on the type of gravel and type of herbicide.

Hydrothermal liquefaction of sewage sludge; energy considerations and fate of micropollutants during pilot scale processing.

The beneficial use of sewage sludge for valorization of carbon and nutrients is of increasing interest while micropollutants in sludge are of concern to the environment and human health. This study investigates the hydrothermal liquefaction (HTL) of sewage sludge in a continuous flow pilot scale reactor at conditions expected to reflect future industrial installations. The processing is evaluated in terms of energy efficiency, bio-crude yields and quality. The raw sludge and post-HTL process water and solid residues were analyzed extensively for micropollutants via HPLC-MS/MS for target pharmaceuticals including antibiotics, blood pressure medicine, antidepressants, analgesics, x-ray contrast media, angiotensin II receptor blockers, immunosuppressant drugs and biocides including triazines, triazoles, carbamates, a carboxamide, an organophosphate and a cationic surfactant. The results show that a positive energy return on investment was achieved for all three HTL processing temperatures of 300, 325 and 350 °C with the most beneficial temperature identified as 325 °C. The analysis of the HTL by-products, process water and solids, indicates that HTL is indeed a suitable technology for the destruction of micropollutants. However, due to the large matrix effect of the HTL process water it can only be stated with certainty that 9 out of 30 pharmaceuticals and 5 out of 7 biocides products were destroyed successfully (over 98% removal). One compound, the antidepressant citalopram, was shown to be moderately recalcitrant at 300 °C with 87% removal and was only destroyed at temperatures ≥325 °C (>99% removal). Overall, the results suggest that HTL is a suitable technology for energy efficient and value added sewage sludge treatment enabling destruction of micropollutants.

The occurrence of modern organic antifouling biocides in Danish marinas.

Antifouling biocides are known to leach out of paints and into the aquatic environment. There is currently a data gap on the occurrence of the current antifouling biocides, as legislative changes caused a change in the antifouling market. Therefore, a comprehensive monitoring study was performed across 13 Danish marinas, both waters and sediments were analyzed, including a transect and a study with seasonal resolution. Three biocides, i.e., Medetomidine, Tralopyril, and DCOIT were not detected in any of the samples. More commonly found, in 11 of the 13 marinas, were the hydrolysis products of Dichlofluanid (DMSA) and Tolylfluanid (DMST). These biocides rapidly dropped in concentration and reached background levels around 200 m from the source. The antifouling biocide Irgarol 1051 was found in all sediment samples and half of all water samples. The concentrations of Irgarol were lower than previously monitored. The decrease can likely be attributed to legislative changes and its disapproval for use since 2016.

Municipal wastewater treatment targeting pharmaceuticals by a pilot-scale hybrid attached biofilm and activated sludge system (Hybas™).

A hybrid wastewater treatment process with combined attached biofilm (moving bed biofilm reactor) and activated sludge, named as Hybas™, was implemented for the treatment of municipal wastewater. The system consisted of six staged reactors in series including pre-denitrification and nitrification in the Hybas™ line and post-denitrification in a pure MBBR. In addition to the significant removal of nutrients and organic matter from municipal wastewater, Hybas™ also showed removal capacity for pharmaceuticals. Of particular interest was the enhanced removal for pharmaceuticals (i.e. X-ray contrast media) compared to other biological systems. Spiking experiments showed that the maximum removal rate constants (k, h-1) for 10 out of the 21 investigated pharmaceuticals (including diclofenac) were observed to occur within the two aerobic Hybas ™ reactors, operated in a flow-shifting mode that allows even biofilm growth of nitrifying bacteria. In total, 14 out of the 21 pharmaceuticals were removed by more than 50% during continuous flow operation in the all Hybas™ line and post-denitrification MBBR. The calculated and estimated removal contributions of pharmaceuticals by each individual reactor were also assessed.