Cultivation of the macrophyte Lemna minor and the microalgae Chlorella sorokiniana in thermal mineral waters: Biomass characteristics, radioisotopes and heavy metals content

Microalgae and macrophytes are commonly used as human and animal food supplements. We examined the cultivation of the microalgae Chlorella sorokiniana and the duckweed Lemna minor in thermal waters under batch and sequencing batch conditions and we characterized the produced biomass for the presence of essential nutrients as well as for heavy metals and radioisotope content. The highest specific growth rate for the microalgae was observed when 5 or 15 mg/L N were supplemented while the optimal conditions for Lemna minor were observed in the co-presence of 5 mg/L N and 1.7 mg/L P. Lemna minor presented higher concentrations of proteins and lipids comparing to the studied microalgae. Both organisms contained high amounts of lutein (up to 1378 mg/kg for Lemna minor) and chlorophyll (up to 1518 mg/kg for Lemna minor) while β-carotene and tocopherols were found at lower concentrations, not exceeding a few tens of mg/kg. The heavy metal content varied between the two species. Lemna minor accumulated more Cd, Cu, K, Mn, Na, Ni, and Zn whereas Al, Ca and Mg were higher in Chlorella sorokiniana. Both organisms could be a significant source of essential metals but the occasional exceedance of the statutory levels of toxic metals in food products raises concern for potential risk to either humans or animals. Application of gamma-spectroscopy to quantify the effective dose to humans from 228Ra, 226Ra and 40K showed that Chlorella sorokiniana was well under the radiological limits while the collected mass of Lemna minor was too small for radiological measurements with confidence.

Use of ornamental plants in floating treatment wetlands for greywater treatment in urban areas

Floating treatment wetlands are considered a promising and low-cost technology for the treatment of polluted water and wastewater. However, their functionality and efficiency in different types of wastewater are not fully understood. In this study, several ornamental plant species (monocultures: Canna sp., Iris sp., polyculture: Iris orientalis, Cyperus sp., Acorus gramineus) were tested in two different types of floating mats, including a media supported floating mat (MSFM) or a simple plastic grid, and evaluated for optimal removal of the studied pollutants. The results regarding pollutant removal revealed that planted systems grown in MSFM achieved significantly higher removal rates (up to 90 %) compared to the plastic grid (up to 80 %). Statistically significant higher removal rates were obtained for the planted systems compared to the unplanted systems either grown in MSFM (for turbidity (planted: 82-90 %; unplanted: 44 %), COD (planted: 74-84 %; unplanted: 32 %) and BOD5 (planted: 76-85 %; unplanted: 51 %), respectively) or grown in the plastic grid (for turbidity (planted: 64-78 %; unplanted: 44 %) and COD (planted: 43-75 %; unplanted: 32 %), respectively). During the experimental period (7 months), all plants managed to survive and withstand the weather variations. The plants in polyculture followed by Iris sp. plants in plastic grid floating mats were better adapted, as indicated by maximum quantum efficiency of PSII values and chlorophyll content index, while all the plants were considered well adapted in the MSFM. Overall, the implementation of floating treatment wetlands with ornamental vegetation for greywater treatment in urban areas seems to be a sustainable and efficient approach.

Vertical flow constructed wetlands as green facades and gardens for on-site greywater treatment in buildings: Two-year mesocosm study on removal performance

This study focuses on the performance and clogging of vertical flow constructed wetlands (VFCWs) planted with climbing ornamentals and ornamental plants for greywater treatment, after two years of operation at mesocosm level. Different substrate (sand, vermiculite) and vegetation (Trachelospermum jasminoides, Lonicera japonica, Callistemon laevis) types were evaluated to determine the optimal removal of pollutants. Results revealed that, during the second year of operation, removal efficiencies of turbidity and COD were significantly higher (1st year: 54-94 %; 71-89 %, 2nd year: 82-98 %; 86-95 %, respectively) for both studied planted substrates, compared to the first year. Moreover, it was found that sand systems from each studied plant as well as from the unplanted systems, were more effective compared to vermiculite for most of the studied parameters (turbidity, TSS, COD, anionic surfactants, pathogens). Sand systems were also quite effective in removing total coliforms (5 log reduction) and Escherichia coli (4 log reduction). At the end of the two-year experiment, all planted systems with sand had significantly higher hydraulic conductivity than the unplanted ones. With reference to evapotranspiration, even though planted systems had significantly higher losses, C. laevis systems demonstrated less water losses than the other vegetated systems. According to the findings, the studied plants managed to continue growing without facing added stress. Therefore, the application of climbing and ornamental plants in VFCWs for greywater treatment in buildings seems a promising option for developing green infrastructures in urban areas and enhancing the removal efficiency of such systems.

Leachate management in medium- and small-sized sanitary landfills: a Greek case study

The sustainable management of landfill leachates remains a matter of important concern in many countries. We used as case study a medium-sized Greek landfill, and we initially investigated the performance of the existing secondary leachate treatment system. The activated sludge process removed chemical oxygen demand (COD), biochemical oxygen demand (BOD), NH4-N, and PO4-P by 55%, 84%, 94%, and 14%, respectively, but the effluents did not meet the legislation requirements for discharge or reuse. Afterwards, different management options of these effluents (co-treatment with sewage in the centralized treatment plant, onsite tertiary treatment with reverse osmosis, granular activated carbon (GAC), ozonation, photo-Fenton, or constructed wetlands) were evaluated regarding their operational costs and environmental footprint. The use of constructed wetlands presented the lower operational cost, energy requirements, and greenhouse gas (GHG) emissions, not exceeding 21.5 kg CO2eq/day. On the other hand, the power consumption and the GHG emissions of the other on-site technologies ranged from 0.37 kWh/m3 and 5.56 kg CO2eq/day (use of GAC) to 39.19 kWh/m3 and 588.6 kg CO2eq/day (use of ozonation), respectively. The co-treatment of the leachates with municipal wastewater required 0.6 kWh/m3 and emitted 30.18 kg CO2eq/day. For achieving zero-discharge of the treated leachates, a system consisting of constructed wetlands and evaporation ponds in series was designed.

Combined use of strictly anaerobic MBBR and aerobic MBR for municipal wastewater treatment and removal of pharmaceuticals

An integrated lab-scale wastewater treatment system consisting of an anaerobic Moving Bed Biofilm Reactor (AnMBBR) and an aerobic Membrane Bioreactor (AeMBR) in series was used to study the removal and fate of pharmaceuticals during wastewater treatment. Continuous-flow experiments were conducted applying different temperatures to the AnMBBR (Phase A: 35 °C; Phase B: 20 °C), while batch experiments were performed for calculating sorption and biotransformation kinetics. The total removal of major pollutants and target pharmaceuticals was not affected by the temperature of the AnMBBR. In Phase A, the average removal of dissolved chemical oxygen demand (COD), biological oxygen demand (BOD), and ammonium nitrogen (NH₄-N) was 86%, 91% and 96% while in Phase B, 91%, 96% and 96%, respectively. Removal efficiencies ranging between 65% and 100% were observed for metronidazole (MTZ), trimethoprim (TMP), sulfamethoxazole (SMX), and valsartan (VAL), while slight (<30%) or no removal was observed for carbamazepine (CBZ) and diclofenac (DCF), respectively. Application of a mass balance model showed that the predominant mechanism for the removal of pharmaceuticals was biotransformation, while the role of sorption was of minor importance. The AeMBR was critical for VAL, SMX and TMP biodegradation; the elimination of MTZ was strongly enhanced by the AnMBBR. In both bioreactors, Bacteroidetes was the dominant phylum in both bioreactors over time. In the AnMBBR, Cloacibacterium and Bacteroides had a higher abundance in the biocarriers compared to the suspended biomass.

Granular activated carbon stimulates biogas production in pilot-scale anaerobic digester treating agro-industrial wastewater

This work examines the continuous addition (5 g/L) of conductive granular activated carbon (GAC) in an integrated pilot-scale unit containing an anaerobic digester (180 L) and an aerobic submerged membrane bioreactor (1600 L) connected in series for the treatment of agro-industrial wastewater. Biogas production increased by 32 % after the addition of GAC. Methanosaeta was the dominant methanogen in the digester, and its relative abundance increased after the addition of GAC. The final effluent after post-treatment with the aerobic membrane bioreactor had a total solids content <0.01 g/L and a chemical oxygen demand between 120 and 150 mg/L. A simple cost analysis showed that GAC addition is potentially profitable, but alternatives ways of retaining the GAC in the system need to be found. Overall, this study provides useful scientific data for the possible application of GAC in full-scale biogas projects.

Removal of microfiber in vertical flow constructed wetlands treating greywater

Nature-based solutions such as constructed wetlands (CW) are considered as a sustainable, green technology for greywater treatment. However, their efficiency to remove microplastics is not well-known even though greywater is considered as a significant source of microfiber pollution. In this study, the removal of fiber microplastics from greywater using a vertical flow constructed wetland (VFCW) was investigated. For the purposes of this study, an experimental wetland was constructed, planted with the flowering plant Zantedeschia aethiopica and filled with a substrate made of sand/gravel of several sizes. The system's performance was monitored for five months during which it received real laundry wastewater. Promising results were obtained showing the significant removal of microfibers from the influent (> 95 %). Moreover, the ability of the system to remove microfibers from laundry wastewater was not significantly affected from the hydraulic loading rate (HLR) applied. The average microfibers concentration decreased from 71 ± 25 microparticles/L in the influent to 1 ± 1 microparticles/L in the effluent of VFCW when an HLR of 63.7 mm/d was applied. High removal efficiencies were also observed for COD and turbidity (93 % and 94 %, respectively). Thus, the results indicate a significant improvement in the overall quality of laundry wastewater due to the use of the VFCW.

Occurrence of pharmaceuticals in the wastewater of a Greek hospital: Combining consumption data collection and LC-QTOF-MS analysis

In this article we applied drug consumption approach and chemical analysis in parallel to investigate the concentrations of a large number of pharmaceuticals in different streams of a General Hospital. Drugs consumption data was collected during two periods (Period 1, 2) and the predicted environmental concentrations (PECs) were estimated for the wastewater of a building housing specific medical services (Point A) and for the entire hospital (Point B). Hospital wastewater samples (HWW) samples were also collected from these points and periods and the measured environmental concentrations (MEC) were determined using UHPLC-ESI-QTOF-MS/MS. According to consumption data, the highest number of drugs was consumed in the departments of Hematology, Intensive Care Unit, Cardiology, Internal Medicine, and Oncology, while the number of active substances used in the hospital was 413 (Period 1) and 362 (Period 2). For most substances, much higher PEC and MEC values were found at the HWW of Point A indicating that on-site treatment of this stream could be examined in the future. The application of wide-scope target analysis allowed the quantification of 122 compounds, while 21 additional substances were identified using suspect screening. The highest mean concentrations in Period 1 were found for acetaminophen (1100 μg/L) and rifaximin (723 μg/L), while in Period 2 for iopromide (458 μg/L) and acyclovir (408 μg/L). Among the detected compounds, 19 metabolites were determined. Atenolol acid, 1-hydroxy-midazolam and clopidogrel carboxylic acid were quantified at concentrations much higher than parent compounds indicating the importance of metabolites' monitoring in HWW. Calculation of PEC/MEC ratio for 36 pharmaceuticals showed sufficient correlation of these values for 19 % to 33 % of the substances depending on the examined period and sampling point. The parallel collection of drugs consumption data and chemical analysis give a thorough picture of the substances present in HWW and their main sources, facilitating decision-making for their better management.

Thermally activated persulfate oxidation of ampicillin: Kinetics, transformation products and ecotoxicity

The heat-activated persulfate system showed encouraging results for the destruction of the widely used antibiotic Ampicillin (AMP). AMP removal follows exponential decay, and the observed kinetic constant was enhanced with persulfate (PS) dosage at the range 50-500 mg L^-1 and temperature (40-60 °C), while AMP thermolysis at 60 °C was almost negligible. The apparent activation energy was estimated to 124.7 kJ mol^-1_. Alkaline conditions, water matrix constituents like bicarbonates, humic acid, and real water matrices retarded AMP oxidation. Experiments performed with tert-butanol and methanol as scavengers demonstrated the contribution of sulfate radicals as the dominant reactive species. Seven transformation products (TPs) of AMP have been identified from AMP destruction. An EC₅₀ value equal to 187 mg L^-1 was calculated for 72 h of exposure of the microalgae Chlorella sorokiniana to AMP. According to the ecotoxicity experiments that conducted after treatment of AMP with PS for different reaction times, no important inhibition of microalgae was noticed for contact time of 72 h and 10 d. These results indicate the formation of no toxic AMP by-products for the applied experimental conditions.

Sorption of two common antihypertensive drugs onto polystyrene microplastics in water matrices

Recent studies have shown the widespread occurrence of microplastics in multiple environmental compartments. When discharged into the aquatic environment, microplastics interact with other chemicals acting as vectors of organic and inorganic micropollutants. In the present study, we examined the sorption of two commonly used antihypertensive drugs, valsartan (VAL) and losartan (LOS), onto polystyrene (PS) microplastics and we studied the effects of water matrix, solution's pH, salinity, and microplastics' aging on their sorption. According to the results, the sorption of VAL and LOS onto PS is a slow process that reaches equilibrium after 12 days. The sorption of both target micropollutants was pH-dependent and significantly decreased under alkaline conditions. The removal of VAL was enhanced in the presence of 100 mM of Ca²⁺ while no statistical significant effects were observed when Na⁺ was added. The increase of salinity either did not affect or decreased the removal of LOS. Lower sorption of both drugs was observed when aged PS was used despite that the specific surface area for aged PS was 39% higher than pristine. Calculation of the sorption distribution coefficient (K_d) for different water matrices showed that the increase of matrix complexity inhibited target compounds' removal and the sorption rate decreased from bottled water > river water ≈ treated wastewater for the two compounds. For VAL, the K_d values ranged between 795 ± 63 L/kg (bottled water) and 384 ± 88 L/kg (river water), while for LOS between 4453 ± 417 L/kg (bottled water) and 3078 ± 716 L/kg (treated wastewater). Both VAL and LOS sorption onto PS microplastics can be described by hydrophobic and electrostatic interactions. The current results indicate that PS particles could affect the transportation of antihypertensive drugs in the aquatic environment causing potential adverse effects on the environment and public health.

Dairy wastewater management in EU: Produced amounts, existing legislation, applied treatment processes and future challenges

Dairy industry consumes high water amounts and generates highly contaminated wastewater. EU-27 is the second largest milk producer and the main cheese exporter in the world. The main objectives of the current study was to estimate the amounts of dairy wastewater (DWW) that are produced annually in different EU countries and to present the relevant existing EU legislation. The main treatment practices currently applied as well as the future opportunities for sustainable DWW management were also discussed. According to the results a total amount of 192.5 × 10⁶ m³ of DWW are annually produced in EU-27 countries, 49% of them are due to the production of cheeses, while 19%, 18% and 13% are due to the production of drinking milk, acidified milk and butterfat products, respectively. Six countries (Germany, France, Italy, Poland, Spain and Netherlands) contribute to the generation of more than 73% of DWW, while the annual per capita DWW production ranges between 36 L (Luxembourg) and 1441 L (Ireland). Since 2019, EU has established best available techniques (BAT) for the dairy industry in order to achieve efficient monitoring of the produced wastewater, reduced water consumption and increased resource efficiency. The main on-site treatment processes that are currently applied include in series wastewater pretreatment for the removal of fat and pH adjustment, anaerobic or/and aerobic biological processes for the decrease of organic loading and nutrients and use of membranes for the cases that recovered water is going to be reused. Limited information is so far available for the operational treatment cost of the different processes. Data originated from a large dairy industry in Cyprus showed an operational cost equal to 1.21 €/m³ of treated wastewater. The main future challenge for the dairy industry and water treatment sector is the adoption of novel processes aiming to DWW valorization under the frame of circular economy.

Exploring the integrity of targeted PFASs in extracted wastewater samples during transport and storage stages

Little information exists on the effects of shipping and handling on per- and polyfluoroalkyl substances (PFASs) in environmental samples. Thus, we evaluated the integrity of dried wastewater extracts and the sensitivity of our high-resolution mass spectrometry (HRMS) instrument to perform such analyses by monitoring 13 representative PFASs in samples extracted, evaporated, and stored at room temperature up to one month. Relative to zero-day recoveries of six detected PFASs ranged between 94 and 124% (RSD <38%) for influents, between 88 and 126% (RSD <18%) for effluents after 28 days. Larger variabilities are tentatively associated with the lack of specific mass-labeled standards and the interactions between analytes and remaining matrix components over time. In a second stage, a mix of local and international dry-shipped wastewater samples were analyzed and the same PFASs were quantified. Up to six PFASs were identified, with median concentrations ranging from 1.3 (perfluoro butyl sulfonate (PFBS)) to 7.7 ng/L (perfluoro hexanoic acid (PFHxA)) and from 1.5 (PFBS) to 13.8 ng/L (PFHxA) in local influents and effluents respectively; and from 0.7 (perfluoro hexyl sulfonate (PFHxS)) to 52.8 ng/L (PFHxA) and from 0.5 (PFHxS) to 21.4 ng/L (PFHxA) in Greek influents and effluents, respectively. The importance of this study lies on the need to consider the wider recovery shifts and expanded variability ranges of PFASs derived from the transport and storage times of dried extracts, particularly when applied to HRMS and wide-scope screening approaches.

Ecotoxicity and biodegradation of the bacteriostatic 3,3',4',5-tetrachlorosalicylanilide (TSCA) compared to the structurally similar bactericide triclosan

This article studies the ecotoxicity of 3,3',4',5-tetrachlorosalicylanilide (TCSA) using different bioassays and examines its fate in activated sludge batch experiments. Despite of the common use of TCSA as chemical uncoupler in wastewater treatment systems and as preservative in several products, limited data has been published for its ecotoxicity, while no information is available for its biodegradation. Among different bioassays, the highest toxicity of TSCA was noticed for Daphna magna (48-h LC₅₀: 0.054 mg L^-1), followed by Vibrio fischeri (15-min EC₅₀: 0.392 mg L^-1), Lemna minor, (7-d EC₅₀: 5.74 mg L^-1) and activated sludge respiration rate (3-h EC₅₀: 31.1 mg L^-1). The half-life of TSCA was equal to 7.3 h in biodegradation experiments with activated sludge, while use of mass balances showed that 90% of this compound is expected to be removed in an aerobic activated sludge system, mainly due to biodegradation. A preliminary risk assessment of TSCA using the Risk Quotient methodology showed possible ecological threat in rivers where wastewater is diluted up to 100-fold. Comparison with the structurally similar 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan, TCS) showed that both compounds have similar biodegradation potential and seem to cause analogous toxicity to Vibrio fischeri and activated sludge. Specifically, TCS was biodegraded quite rapidly by activated sludge (half-life: 6.2 h), while EC₅₀ values equal to 0.134 mg L^-1 and 39.9 mg L^-1 were calculated for Vibrio fischeri, and activated sludge respiration rate. Future research should focus on monitoring of TSCA concentrations in the environment and study its effects in long-term toxicity and bioaccumulation tests.

Comparing the use of a two-stage MBBR system with a methanogenic MBBR coupled with a microalgae reactor for medium-strength dairy wastewater treatment

Two systems were compared for medium-strength dairy wastewater treatment. The first comprised a methanogenic Moving Bed Biofilm Reactor (AnMBBR) and an aerobic MBBR (AeMBBR), while the second an AnMBBR and a sequencing batch reactor (SBR) with Chlorella sorokiniana. The AnMBBR, under ambient conditions, achieves biogas production sufficient enough to attain energy autonomy. The produced energy was 0.538 kWh m^-3, whereas the energy consumption 0.025 kWh m^-3. Its coupling with the AeMBBR removed COD, NH₄-N TKN, and PO₄-P by 93 ± 4%, 97 ± 3%, 99 ± 1% and 49 ± 15%, respectively, while the use of the SBR as a second step eliminated totally COD but partially the other pollutants. The higher nitrogen removal in the first system was due to nitrification occurring in the AeMBBR. The acclimatization of microalgae to dairy wastewater enhanced their growth. Their protein content was 54.56%, while starch and lipids were 3.39% and 23.1%, respectively.

FoodOmicsGR_RI. A Consortium for Comprehensive Molecular Characterisation of Food Products

The national infrastructure FoodOmicsGR_RI coordinates research efforts from eight Greek Universities and Research Centers in a network aiming to support research and development (R&D) in the agri-food sector. The goals of FoodOmicsGR_RI are the comprehensive in-depth characterization of foods using cutting-edge omics technologies and the support of dietary/nutrition studies. The network combines strong omics expertise with expert field/application scientists (food/nutrition sciences, plant protection/plant growth, animal husbandry, apiculture and 10 other fields). Human resources involve more than 60 staff scientists and more than 30 recruits. State-of-the-art technologies and instrumentation is available for the comprehensive mapping of the food composition and available genetic resources, the assessment of the distinct value of foods, and the effect of nutritional intervention on the metabolic profile of biological samples of consumers and animal models. The consortium has the know-how and expertise that covers the breadth of the Greek agri-food sector. Metabolomics teams have developed and implemented a variety of methods for profiling and quantitative analysis. The implementation plan includes the following research axes: development of a detailed database of Greek food constituents; exploitation of "omics" technologies to assess domestic agricultural biodiversity aiding authenticity-traceability control/certification of geographical/genetic origin; highlighting unique characteristics of Greek products with an emphasis on quality, sustainability and food safety; assessment of diet's effect on health and well-being; creating added value from agri-food waste. FoodOmicsGR_RI develops new tools to evaluate the nutritional value of Greek foods, study the role of traditional foods and Greek functional foods in the prevention of chronic diseases and support health claims of Greek traditional products. FoodOmicsGR_RI provides access to state-of-the-art facilities, unique, well-characterised sample sets, obtained from precision/experimental farming/breeding (milk, honey, meat, olive oil and so forth) along with more than 20 complementary scientific disciplines. FoodOmicsGR_RI is open for collaboration with national and international stakeholders.

Converting treatment wetlands into "treatment gardens": Use of ornamental plants for greywater treatment

Nowadays, the use of constructed wetlands for on-site greywater treatment is a very promising option. The successful application of this nature-based solution at full scale requires public acceptance, economic feasibility and the production of high-quality treated greywater. This work focuses on the use of ornamental plants as vertical flow constructed wetland (VFCW) vegetation for greywater treatment, aiming to improve aesthetic and acceptability of the system. The performance and economic feasibility of the proposed green technology were examined during a 2-years study. Results show that Pittosporum tobira and Hedera helix can grow in VFCW operating with greywater without any visible symptoms. These species tolerated both drought and flooding conditions, making them ideal for use not only in residential buildings but also in seasonal hotels and holiday homes. In contrast, partial defoliation of Polygala myrtifolia plants was observed during the winter period. High average removal efficiencies were observed for BOD (99%), COD (96%) and TSS (94%) in all examined VFCWs including unplanted beds. Phosphorus removal gradually decreased from 100% during first months of operation to 15% during second year of operation. In addition, total coliforms concentration reduced by 2.2 log units in the effluent of all planted systems, while lower removal efficiency was observed in the absence of plants. The mean concentration of BOD and TSS in the treated greywater met the standards for indoor reuse (<10 mg/L). Cost payback periods for the installation of the proposed technology in a multi-family building, a single house and a hotel in Greece were found 4.7, 16.6 and 2.5 years, respectively. Overall, the "treatment gardens" proposed in this study provide a technically and economically feasible solution for greywater treatment, with the additional benefit of improving the aesthetic of urban, semi-urban and touristic areas.

Wide-scope target analysis of emerging contaminants in landfill leachates and risk assessment using Risk Quotient methodology

Raw and treated leachate samples were collected from different landfills in Greece and analyzed for several groups of emerging contaminants using high resolution mass spectrometric workflows to investigate the possible threat from their discharge to the aquatic environment. Fifty-eight compounds were detected; 2-OH-benzothiazole was found at 84 % of the samples and perfluorooctanoic acid at 68 %. Bisphenol A, valsartan and 2-OH-benzothiazole had the highest average concentrations in raw leachates, after biological treatment and after reverse osmosis, respectively. In untreated leachates, Risk Quotients > 1 were calculated for 35 and 18 compounds when maximum and average concentrations were used, indicating an ecological threat for the aquatic environment. Leachates' biological treatment partially removed COD and NH₄⁺-N, as well as 52.3 % of total emerging contaminants. The application of reverse osmosis resulted in a 98 % removal of major pollutants, 99 % removal of total emerging contaminants and a significant decrease of ecotoxicity to Lemna minor. Beside the decrease of the detected micropollutants during treatment, RQs > 1 were still calculated for 13 and 3 compounds after biological treatment and reverse osmosis, respectively. Among these, special attention should be given to 2-OH-benzothiazole and bisphenol A that had RQ values much higher than 1 for all tested organisms.

Risk assessment of PFASs in drinking water using a probabilistic risk quotient methodology

We evaluated health risks associated with perfluorinated and polyfluorinated alkyl substances (PFASs) found in drinking water applying human risk assessment (HRA) methodology. Using data on worldwide occurrence of PFASs in drinking water and recent guidelines for PFASs in drinking water, we applied four scenarios based on different toxicological threshold values to calculate age-dependent risk quotients (RQ) for different PFASs. The mean concentrations of the most frequently detected compounds (PFOS and PFOA) were highest in North America (99.2 and 30.7 ng L^-1, respectively), and lowest in Asia (PFOS: 3.0 ng L^-1) and Europe (PFOA: 4.87 ng L^-1). Using HRA methodology and maximum reported concentrations, only PFOS and PFOA, examined individually, showed any threat to human health. Specifically, calculations with the average and maximum concentrations of PFOS showed RQ values higher than 0.2 or 1, respectively, for some age groups under specific scenarios. Similarly, using maximum PFOA concentrations, a RQ equal to 0.2 for infants up to 3 months was calculated under scenario 4. Regional differences on RQ values were observed when PFOS concentrations from Europe, North America and Asia were used. Estimation of the human health risk due to mixtures of PFASs using average concentrations showed that the RQ_mix was higher than 0.2 for infants up to 3 months (scenario 3) and infants and children up to 6 years old (scenario 4). More importantly, evaluation of the guideline values set by the EU and the Health Advisory Levels issued by the USEPA resulted (under some scenarios) in RQ values higher than 0.2 for PFOS and PFOA for specific age groups, indicating that further discussion is needed for the monitoring and prioritization of these compounds.

Biodegradability assessment of food additives using OECD 301F respirometric test

The ready biodegradability of twenty food additives, belonging to the classes of artificial sweeteners, natural sweeteners, preservatives and colorings, was investigated using activated sludge as inoculum and OECD 301F respirometric test. According to the results, saccharin, aspartame, sodium cyclamate, xylitol, erythritol, maltitol, potassium sorbate, benzoic acid and sodium ascorbate are characterized as readily biodegradable compounds, partial biodegradation (<60% during the test) was noticed for steviol, inulin, alitame, curcumin, ponceau 4R and tartrazine, while no biodegradation was observed for the other five compounds. The duration of lag phase before the start of biodegradation varied between the target compounds, while their ultimate biodegradation half-life values ranged between 0.7 ± 0.1 days (benzoic acid) and 24.6 ± 1.0 days (curcumin). The expected removal of target compounds due to ultimate biodegradation mechanism was estimated for a biological wastewater treatment system operated at a retention time of one day and percentages higher than 40% were calculated for sodium cyclamate, potassium sorbate and benzoic acid. Higher removal percentages are expected in full-scale Sewage Treatment Plants (STPs) due to the contribution of other mechanisms such as sorption to suspended solids, (bio)transformation and co-metabolic phenomena. Further biodegradation experiments should be conducted under different experimental conditions for the food additives that did not fulfill the requirements of the applied protocol. Future studies should also focus on the occurrence and fate of food colorants and natural sweeteners in full-scale STPs.

Investigation of biomass production, crude protein and starch content in laboratory wastewater treatment systems planted with Lemna minor and Lemna gibba

The use of duckweed-based wastewater treatment systems for producing biomass with high crude protein and starch content was investigated in the current study. For this reason, three lab-scale systems were used; System 1 was planted with Lemna minor, System 2 with Lemna gibba and System 3 with the combination of the two duckweeds. The studied duckweeds were cultivated using secondary treated wastewater as substrate (Phase A), in the presence of excess NH₄-N (Phase B) and using water with no nutrients (Phase C). All systems achieved average NH₄-N removal higher that 90%. The specific duckweeds growth rates and the specific duckweeds growth rates normalized to the area ranged between 0.14 d^-1 and 8.9 g m^-2 d^-1 (System 1) to 0.19 d^-1 and 14.9 g m^-2 d^-1(System 3). The addition of NH₄-N resulted in a significant increase of biomass protein content, reaching 44.4% in System 3, 41.9% in System 2 and 39.4% in System 1. The transfer of biomass in water containing no nutrients resulted in the gradual increment of the starch content up to the end of the experiment. The highest starch content was achieved for the combination of the two duckweeds (46.1%), followed by L. gibba (44.9%) and L. minor (43.9%).

Growth inhibition and fate of benzotriazoles in Chlorella sorokiniana cultures

Benzotriazoles are among the most commonly found organic micropollutants in the aquatic environment. In this study, toxicity experiments were conducted in order to investigate the effects of different benzotriazoles on Chlorella sorokiniana growth. Four compounds were tested; 1H-benzotriazole (BTR), xylytriazole (XTR), 5-methyl-1H-benzotriazole (5TTR) and 5-chlorobenzotriazole (CBTR). The fate of these micropollutants was also studied under batch conditions and the effect of different mechanisms on their elimination was investigated. According to the results, the EC₅₀ values in single-substance toxicity experiments were calculated to 8.3 mg L^-1 for BTR, 22 mg L^-1 for 5TTR and 38.7 mg L^-1 for CBTR. A slight inhibition on microalgae growth was noted at the maximum tested concentration of XTR (77 mg L^-1), while no inhibition was observed when a mixture of target BTRs was tested at 200 μg L^-1. Calculation of the Risk Quotient (RQ) showed no possible ecological threat in the presence of 5TTR, XTR and CBTR, while RQ values close or higher than 1 were estimated for BTR. All target contaminants were significantly eliminated in microalgae experiments that lasted 16 days. Their removal efficiency ranged between 42.2 ± 3.1% (XTR) to 97.2 ± 0.9% (XTR), while their half-life values were estimated to 2.4 ± 0.5 days for 5TTR, 6.5 ± 0.6 days for BTR, 15.2 ± 1.4 days for CBTR and 20.7 ± 2.0 days for XTR. Photodegradation was the main mechanism affecting BTR, XTR and CBTR removal, while bioremoval processes enhanced 5TTR elimination. The addition of sodium acetate decreased the removal efficiency of BTRs possibly due to catabolite repression. This is the first study investigating the toxicity and fate of BTRs in microalgae cultures.

Review on the occurrence and fate of microplastics in Sewage Treatment Plants

Microplastics are plastic fragments lower than 5 mm that are detected in the environment causing various effects on organisms. Several research articles have recognized Sewage Treatment Plants as important sources of polyethylene and polypropylene beads, polyester, polyamide and other types of microplastics. For their determination, techniques such as visual identification using microscope, Fourier-transform infrared and RAMAN spectroscopy are used, while chemical oxidation, enzymatic maceration and density separation are applied as pretreatment methods for the removal of the inorganic and organic content. Microplastics' concentrations range up to 3160 particles L^-1, 125 particles L^-1 and 170.9 × 10³ particles Kg^-1 TS dw in raw, treated wastewater and sludge, respectively. Their removal during wastewater treatment ranges between 72% and 99.4%; the main processes that contribute to their removal are primary and secondary treatment, while the effect of tertiary treatment depends on the applied technology. Entrapment in suspended solids and accumulation to sludge are the major mechanisms governing their fate. A standardized protocol for samples' collection and pretreatment as well as microplastics' isolation and characterization is needed; future reseach should investigate the possible chemical and physical changes of microplastics during treatment, and their role as carriers for the transfer of emerging micropollutants.

Production of municipal solid waste and sewage in European refugees' camps: The case of Lesvos, Greece

Since 2015, Lesvos Island (Greece) is a key entry location for people seeking asylum in the EU. This article presents information for the production of municipal solid waste and sewage in the asylum seekers reception sites of Moria and Kara Tepe for the period between May 2016 and April 2017. According to the results, the annual produced municipal solid waste and sewage in the refugees' camps were 1464 tons and 95,550 m³, respectively. Taking into account the population served, the average daily per capita generation of municipal solid waste was 0.88 kg per asylum seeker and day, significantly lower than that calculated for the permanent population the same period (1.39 kg per inhabitant and day). The daily production of sewage was 54 L per asylum seeker and day, while the corresponding value for the permanent population was 211 L per inhabitant and day. The total methane emissions from solid waste and sewage production in studied refugees' camps were estimated to 178.6 tons per year or 35.5 kg CH₄ per asylum seeker and year. Further investigation is needed for the characterization of the produced solid waste and sewage in order to assure the sustainable design and operation of these sites.

Review on fresh and dried figs: Chemical analysis and occurrence of phytochemical compounds, antioxidant capacity and health effects

Fig fruit (Ficus carica L.) is one of the most important agricultural products of the tropic and subtropics areas. In the Middle East and the Mediterranean region, the fig is included in diet since the ancient years and it is considered as the symbol of longevity. This review presents the main phytochemical compounds found in fresh and dried figs of different varieties, describes the analytical methods used for their determination and discuss the antioxidant capacity and the potential effects of figs in human health. Phenolic acids and flavonoids are the major types of phytochemical compounds that have been found in fresh and dried figs. Their levels are strongly influenced by various factors such as the color, the part of fruit, the maturity and the drying process. Gallic acid, chlorogenic acid, rutin, quercetin-3-O-rutinoside and epicatechin are the most predominant phenolic acids and flavonoids in dried and fresh fig varieties. Extracts of dark-colored varieties contain higher amount of phenolic compounds than the light-colored varieties. Fruit skin contributes most to the amount of phenolic compounds compared to the fruit pulp. The ripening stage affects the concentrations of phenolic compounds in figs, the maximum have been found in ripe fruit. On the other hand, contradictory results have been reported in the literature regarding the effect of air- and sun- drying on the total content of phytochemical compounds, as well as on the concentrations of individual phenolic compounds and carotenoids in figs. The antioxidant capacity of figs is highly correlated with their amount of phenolic compounds. The leaves, roots, fruit and latex of the plant are known for their health properties including acetyl cholinesterase inhibition, antifungal, anti-helminthic and anticarcinogenic activities. Future efforts should be focused on the application of fig extracts as functional ingredients of food products, on clinical trials in order to confirm the beneficial effect of plant extracts in human health and, on the valorization of the waste material produced during figs' processing.

Biodegradation of bilge water: Batch test under anaerobic and aerobic conditions and performance of three pilot aerobic Moving Bed Biofilm Reactors (MBBRs) at different filling fractions

The bilge water that is stored at the bottom of the ships is saline and greasy wastewater with a high Chemical Oxygen Demand (COD) fluctuations (2-12 g COD L^-1). The aim of this study was to examine at a laboratory scale the biodegradation of bilge water using first anaerobic granular sludge followed by aerobic microbial consortium (consisted of 5 strains) and vice versa and then based on this to implement a pilot scale study. Batch results showed that granular sludge and aerobic consortium can remove up to 28% of COD in 13 days and 65% of COD removal in 4 days, respectively. The post treatment of anaerobic and aerobic effluent with aerobic consortium and granular sludge resulted in further 35% and 5% COD removal, respectively. The addition of glycine betaine or nitrates to the aerobic consortium did not enhance significantly its ability to remove COD from bilge water. The aerobic microbial consortium was inoculated in 3 pilot (200 L) Moving Bed Biofilm Reactors (MBBRs) under filling fractions of 10%, 20% and 40% and treated real bilge water for 165 days under 36 h HRT. The MBBR with a filling fraction of 40% resulted in the highest COD decrease (60%) compared to the operation of the MBBRs with a filling fraction of 10% and 20%. GC-MS analysis on 165 day pointed out the main organic compounds presence in the influent and in the MBBR (10% filling fraction) effluent.

Removal mechanisms of benzotriazoles in duckweed Lemna minor wastewater treatment systems

The fate of five benzotriazoles (1H-benzotriazole, BTR; 4-methyl-1H-benzotriazole, 4TTR; 5-methyl-1H-benzotriazole, 5TTR; xylytriazole, XTR and 5-chlorobenzotriazole, CBTR) was studied in batch and continuous-flow Lemna minor systems and the role of different mechanisms on their removal was evaluated. Single and joint toxicity experiments were initially conducted using the Organization for Economic Co-operation and Development (OECD) protocol 221 and no inhibition on specific growth rate of Lemna minor was observed for concentrations up to 200μgL^-1. All tested substances were significantly removed in batch experiments with Lemna minor. Excepting 4TTR, full elimination of CBTR, XTR, 5TTR and BTR was observed up to the end of these experiments (36d), while the half-life values ranged between 1.6±0.3d (CBTR) and 25±3.6d (4-TTR). Calculation of kinetic constants for hydrolysis, photodegradation, and plant uptake revealed that for all BTRs the kinetic constants of plant uptake were by far higher comparing to those of the other mechanisms, reaching 0.394±0.161d^-1 for CBTR. The operation of a continuous-flow Lemna minor system consisted of three mini ponds and a total hydraulic residence time of 8.3d showed sufficient removal for most target substances, ranging between 26% (4TTR) and 72% (CBTR). Application of a model for describing micropollutants removal in the examined system showed that plant uptake was the major mechanism governing BTRs removal in Lemna minor systems.

Fate of antimicrobials in duckweed Lemna minor wastewater treatment systems

The fate of four antimicrobials (cefadroxil, CFD; metronidazole, METRO; trimethoprim, TRI; sulfamethoxazole, SMX) was studied in Lemna minor systems and the role of different mechanisms on their removal was evaluated. All micropollutants were significantly removed in batch experiments with active Lemna minor; the highest removal was observed for CFD (100% in 14 d), followed by METRO (96%), SMX (73%) and TRI (59%) during 24 d of the experiment. Calculation of kinetic constants for hydrolysis, photodegradation, sorption to biomass and plant uptake revealed significant differences depending on the compound and the studied mechanism. For METRO, TRI and SMX the kinetic constants of plant uptake were by far higher comparing to those of the other mechanisms. The transformation products of antimicrobials were identified using UHPLC-QToF-MS. Two were the main degradation pathways for TRI; hydroxylation takes place during both phyto- and photodegradation, while demethylation occurs only in absence of Lemna minor. The operation of a continuous-flow duckweed system showed METRO and TRI removal equal to 71±11% and 61±8%, respectively. The application of mass balance and the use of published biodegradation constants showed that plant uptake and biodegradation were the major mechanisms governing METRO removal; the most important mechanism for TRI was plant uptake.

Chlorination of benzothiazoles and benzotriazoles and transformation products identification by LC-HR-MS/MS

The fate of four benzotriazoles [1-H-benzotriazole (1-H-BTRi), tolyltriazole (TTRi), xylyltriazole (XTRi) and 1-hydroxy-benzotriazole (1-OH-BTRi)] and three benzothiazoles [benzothiazole (BTH), 2-hydroxy-benzothiazole (2-OH-BTH) and 2-amino-benzothiazole (2-amino-BTH)], during chlorination batch experiments was investigated. In the first step, their degradation under different experimental conditions (applied molar ratio of NaOCl and the target contaminant (m.r.), reaction's contact time, pH value of the reaction's solution and the influence of total suspended solids (TSS) presence) was investigated and their removal kinetics parameters (k_obs and t_1/2) were determined. In the second step, LC-QTOFMS/MS was used for the detection and identification of transformation products (TPs) formed during chlorination, through the application of suspect and non-target screening approaches. Four and five TPs of XTRi and 2-amino-BTH, respectively, were detected and tentatively identified, while 1-H-BTRi was proven to be formed by the chlorination of 1-OH-BTRi. Moreover, since the identified TPs were also detected in spiked wastewater samples, after lab-scale chlorination experiments, toxicity assessment was carried out by ECOSAR calculations for the environmental relevance of their occurrence. The proposed chlorinated TPs were proven to be more toxic than their parent compounds.

Hybrid Moving Bed Biofilm Reactor for the biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater

A laboratory scale Hybrid Moving Bed Biofilm Reactor (HMBBR) was used to study the removal of five benzotriazoles and one benzothiazole from municipal wastewater. The HMBBR system consisted of two serially connected fully aerated bioreactors that contained activated sludge (AS) and K3-biocarriers and a settling tank. The average removal of target compounds ranged between 41% (4-methyl-1H-benzotriazole; 4TTR) and 88% (2-hydroxybenzothiazole; OHBTH). Except for 4TTR, degradation mainly occurred in the first bioreactor. Calculation of biodegradation constants in batch experiments and application of a model for describing micropollutants removal in the examined system showed that AS is mainly involved in biodegradation of OHBTH, 1H-benzotriazole (BTR) and xylytriazole (XTR), carriers contribute significantly on 4TTR biodegradation, while both types of biomass participate on elimination of 5-chlorobenzotriazole (CBTR) and 5-methyl-1H-benzotriazole (5TTR). Comparison of the HMBBR system with MBBR or AS systems from literature showed that the HMBBR system was more efficient for the biodegradation of the investigated chemicals. Biotransformation products of target compounds were identified using ultra high-performance liquid chromatography, coupled with a quadrupole-time-of-flight high-resolution mass spectrometer (UHPLC-QToF-MS). Twenty two biotransformation products were tentatively identified, while retention time denoted the formation of more polar transformation products than the parent compounds.

Using mechanisms of hydrolysis and sorption to reduce siloxanes occurrence in biogas of anaerobic sludge digesters

Hydrolysis of hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6) and dodecamethylcyclohexasilane (D6_silane) and their sorption to digested sludge was studied in batch experiments. Hydrolysis was affected by the type of the compound and the applied temperature, while the relevant half-life values ranged between 0.07±0.01d (D3, 55°C) and 48.4±17.1d (D6_silane, 4°C). D5 showed the greatest affinity for sorption to digested sludge (logK_d: 3.84±3.42), the lowest LogK_d value was found for D3 (1.46±0.95). Prediction of investigated compounds' fate in a single-stage anaerobic digestion system indicated that volatilization seems to be the major fate in both mesophilic and thermophilic conditions. The addition of a pre-digester with 3d retention time would significantly decrease the expected concentrations of all siloxanes in biogas, enhancing their removal through hydrolysis and sorption to sludge.

Drugs of abuse and alcohol consumption among different groups of population on the Greek Island of Lesvos through sewage-based epidemiology

The occurrence of 22 drugs of abuse, their metabolites, and the alcohol metabolite ethyl sulphate was investigated in raw sewage samples collected during the non-touristic season from three sewage treatment plants (STPs), which serve different sizes and types of population in the Greek island of Lesvos. Using the sewage-based epidemiology approach, the consumption of these substances was estimated. Five target analytes, cocaine (COC), benzoylecgonine (BE), 3,4-methylenedioxymethamphetamine (MDMA), 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-COOH) and ethyl sulphate (EtS) were detected at concentrations above their limit of quantification, whereas the rest eighteen target compounds were not detected. THC-COOH was detected in most of the samples with concentrations ranging between <20 and 90ngL(-1), followed by EtS (range <1700-12,243ngL(-1)). COC, BE, and MDMA were present only in the STP that serves Mytilene (the main city of the island), at mean concentrations of 3.9ngL(-1) for COC (95% CI: 1.7-6.1), 9.4ngL(-1) for BE (95% CI: -1.6-23) and 3.2ngL(-1) for MDMA (95% CI: 1.2-5.1). Back-calculations to an amount of used substance indicated more intense use of drugs among city population than rural and University population with average values of 9.5 and 1.2mgday(-1) per 1000 inhabitants for COC (95% CI: -1.43-20.4) and MDMA (95% CI: 0.52-1.85), respectively, and 2.8gday(-1) per 1000 inhabitants for tetrahydrocannabinol (THC) (95% CI: 2.4-3.1), the active ingredient of cannabis. Alcohol consumption was observed to be higher in the city population (5.4mL pure alcohol per day per inhabitant) than in the rural population (3.4mL pure alcohol per day per inhabitant), but the difference was not statistically significant. Consumption of THC differed significantly among the three STPs.

Evaluation of polar organic micropollutants as indicators for wastewater-related coastal water quality impairment

Results from coastal water pollution monitoring (Lesvos Island, Greece) are presented. In total, 53 samples were analyzed for 58 polar organic micropollutants such as selected herbicides, biocides, corrosion inhibitors, stimulants, artificial sweeteners, and pharmaceuticals. Main focus is the application of a proposed wastewater indicator quartet (acesulfame, caffeine, valsartan, and valsartan acid) to detect point sources and contamination hot-spots with untreated and treated wastewater. The derived conclusions are compared with the state of knowledge regarding local land use and infrastructure. The artificial sweetener acesulfame and the stimulant caffeine were used as indicators for treated and untreated wastewater, respectively. In case of a contamination with untreated wastewater the concentration ratio of the antihypertensive valsartan and its transformation product valsartan acid was used to further refine the estimation of the residence time of the contamination. The median/maximum concentrations of acesulfame and caffeine were 5.3/178 ng L(-1) and 6.1/522 ng L(-1), respectively. Their detection frequency was 100%. Highest concentrations were detected within the urban area of the capital of the island (Mytilene). The indicator quartet in the gulfs of Gera and Kalloni (two semi-enclosed embayments on the island) demonstrated different concentration patterns. A comparatively higher proportion of untreated wastewater was detected in the gulf of Gera, which is in agreement with data on the wastewater infrastructure. The indicator quality of the micropollutants to detect wastewater was compared with electrical conductivity (EC) data. Due to their anthropogenic nature and low detection limits, the micropollutants are superior to EC regarding both sensitivity and selectivity. The concentrations of atrazine, diuron, and isoproturon did not exceed the annual average of their environmental quality standards (EQS) defined by the European Commission. At two sampling locations irgarol 1051 exceeded its annual average EQS value but not the maximum allowable concentration of 16 ng L(-1).

Assessing the risk associated with the presence of emerging organic contaminants in sludge-amended soil: A country-level analysis

Greece was used as case study and the environmental risk associated with the existence of 99 emerging organic contaminants (EOCs) in sludge-amended soil was estimated using risk quotient (RQ) approach. Data on the concentration levels of EOCs in sewage sludge was collected after literature review. Chemical analyses were also conducted for 50 pharmaceuticals and illicit drugs in sludge samples from Athens Sewage Treatment Plant. Risk assessment was based on both terrestrial and aquatic acute toxicity data, using both the maximum and the average measured concentrations of the target compounds. EC50/LC50 values were collected through literature review or using the ECOSAR program in cases that experimental values were not available. Triclosan seems to pose an environmental risk on the soil environment, as its RQ values exceeded 1, both in terrestrial and aquatic toxicity data based risk assessment. Calculations based on aquatic toxicity data showed that another eleven compounds had RQs higher than 1, most of them belonging to the classes of synthetic phenolic compounds and siloxanes. Tetradecamethylhexasiloxane presented the highest RQ, while high RQs were also calculated for decamethylcyclopentasiloxane and caffeine. No environmental risk for the terrestrial environment is expected due to the individual action of illicit drugs, perfluorinated compounds and benzotriazoles. The sludge source and the day of sampling affected the estimated threat due to nonylphenolic compounds; however these factors did not affect the estimated risk for siloxanes, caffeine and ofloxacin. Calculation of RQ values for the mixture of EOCs, using either the maximum or the average concentrations, far exceeded 1 (253 and 209, respectively), indicating a presumable threat for the terrestrial environment due to the baseline toxicity of these compounds. Countries that reuse sludge for agricultural purposes should include specific EOCs in national monitoring campaigns and study more thoroughly on their effects to the terrestrial environment.

Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems

Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The activated sludge system was operated under low organic loading conditions. The moving bed biofilm reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalized to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic.

Review on the occurrence, fate and removal of perfluorinated compounds during wastewater treatment

Perfluorinated compounds (PFCs) consist of a fully fluorinated hydrophobic alkyl chain attached to a hydrophilic end group. Due to their wide use in several industrial and household applications, they have been detected in numerous Sewage Treatment Plants (STPs) during the last ten years. The present review reports the occurrence of 22 PFCs (C4-C14, C16, C18 carboxylates; C4-C8 and C10 sulfonates; 3 sulfonamides) in municipal or/and industrial wastewater, originating from 24 monitoring studies. PFCs levels in sewage sludge have also been reported using data from 12 studies. Most of the above monitoring data originate from the USA, North Europe and Asia and concern perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), while limited information is available from Mediterranean area, Canada and Australia. PFCs concentrations range up to some hundreds ng/L and some thousands ng/g dry weight in raw wastewater and sludge, respectively. They are not significantly removed during secondary biological treatment, while their concentrations in treated wastewater are often higher compared to raw sewage. Their biodegradation during wastewater treatment does not seem possible; whereas some recent studies have noted the potential transformation of precursor compounds to PFCs during biological wastewater treatment. PFCs sorption onto sludge has been studied in depth and seems to be an important mechanism governing their removal in STPs. Concerning tertiary treatment technologies, significant PFCs removal has been observed using activated carbon, nanofiltration, reverse osmosis or applying advanced oxidation and reduction processes. Most of these studies have been conducted using pure water, while in many cases the experiments have been performed under extreme laboratory conditions (high concentrations, high radiation source, temperature or pressure). Future efforts should be focused on better understanding of biotransformation processes occurred in aerobic and anaerobic bioreactors and result to PFCs formation and on the application of advanced treatment technologies under conditions commonly found in STPs.

Sorption and biodegradation of selected benzotriazoles and hydroxybenzothiazole in activated sludge and estimation of their fate during wastewater treatment

Biodegradation of benzotriazole (BTR), 5-chlorobenzotriazole (CBTR), xylytriazole (XTR), 4-methyl-1H-benzotriazole (4TTR), 5-methy-1H-lbenzotriazole (5TTR) and 2-hydroxybenzothiazole (OHBTH) was studied in activated sludge batch experiments under aerobic and anoxic conditions, presence of organic substrate and different sludge residence times (SRTs). Their sludge-water distribution coefficients were also calculated in sorption experiments and ranged between 87 and 220 L kg(-1). Significant biodegradation of BTR, CBTR, XTR and OHBTH was observed in all biotic experiments. Half-life values ranged between 23 and 45 h (BTR), 18 and 47 h (CBTR), 14 and 26 h (XTR), 6.5 and 24 h (OHBTH). The addition of substrate did not suppress biodegradation kinetics; whereas in some cases accelerated biodegradation of microcontaminants. Except for CBTR, no effect of SRT on biodegradation constants was observed. Prediction of micropollutants removal in Sewage Treatment Plants (STPs) indicated that they will be partially removed, mainly due to aerobic biodegradation. Higher removal is expected at STPs operating at higher SRT and higher suspended solids concentrations.

Effects of triclosan, diclofenac, and nonylphenol on mesophilic and thermophilic methanogenic activity and on the methanogenic communities

In this study, a toxicity assay using a mesophilic wastewater treatment plant sludge-based (SI) and a thermophilic manure-based inoculum (MI), under different biomass concentrations was performed to define the effects of diclofenac (DCF), triclosan (TCS), and nonylphenol (NP) on anaerobic digestion (AD) process. Additionally, the influence of DCF, TCS, and NP on the relative abundance of the methanogenic populations was investigated. Results obtained demonstrated that, in terms of methane production, SI inoculum was more resistant to the toxicity effect of DCF, TCS, and NP, compared to the MI inoculum. The IC50 values were 546, 35, and 363 mg L(-1) for SI inoculum and 481, 32, and 74 mg L(-1) for MI inoculum for DCF, TCS, and NP, respectively. For both inocula, higher biomass concentrations reduced the toxic effect of TCS (higher methane production up to 64%), contrary to DCF, where higher biomass loads decreased methane yield up to 31%. Fluorescence in situ hybridization analysis showed that hydrogenotrophic methanogens were more resistant to the inhibitory effect of DCF, TCS, and NP compared to aceticlastic methanogens.

Assessing single and joint toxicity of three phenylurea herbicides using Lemna minor and Vibrio fischeri bioassays

Single and joint toxicity of three substituted urea herbicides, namely monolinuron [3-(4-chlorophenyl)-1-methoxy-1-methylurea], linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] and diuron [1-(3,4 dichlorophenyl)-3,3 dimethyl urea], were studied. The duckweed Lemna minor and the luminescent bacterium Vibrio fischeri were used for the toxicity assessment and they were exposed to various concentrations of the herbicides, individually and in binary mixtures. The exposure time was 7d for the duckweed and 30 min for the bacterium. Estimation of EC50 values was performed by frond counting and reduction in light output for Lemna minor and Vibrio fischeri, respectively. Lemna minor was found to be much more sensitive than Vibrio fischeri to target compounds. The toxicity of the three herbicides applied solely was estimated to be in decreasing order: diuron (EC50=28.3 μg L(-1))≈linuron (EC50=30.5 μg L(-1))>monolinuron (EC50=300 μg L(-1)) for the duckweed and linuron (EC50=8.2 mg L(-1))>diuron (EC50=9.2 mg L(-1))>monolinuron (EC50=11.2 mg L(-1)) for the bacterium. Based on the environmental concentrations reported in the literature and EC50 values obtained from Lemna minor experiments, Risk Quotients (RQ) much higher than 1 were calculated for diuron and linuron. In Lemna minor experiments, combination of target compounds resulted to additive effects due to their same mode of phenylurea action on photosynthetic organisms. Regarding Vibrio fischeri, synergistic, additive and antagonistic effects were observed, which varied according to the concentrations of target compounds.

Consumption-based approach for predicting environmental risk in Greece due to the presence of antimicrobials in domestic wastewater

The main objective of the current study was to estimate the potential environmental risks associated with human consumption of antimicrobials in Greece. Consumption data was collected for the 24 most often used antimicrobials for the years 2008-2010, and their predicted environmental concentrations (PECs) in raw and treated wastewater were calculated using mass balances and literature data on human excretion and elimination efficiency during wastewater treatment. The ecotoxicological risk was estimated by calculating the ratio of PEC to predicted no-effect concentration (PNEC) for three categories of aquatic organisms (algae, daphnids, and fish). PNEC values were calculated based on experimental ecotoxicity data and data originated from the Ecological Structure Activity Relationship (ECOSAR). PEC values in raw sewage ranged between 0.02 μg L(-1) (erythromycin) and 27 μg L(-1) (amoxicillin), while in treated wastewater, the highest concentration was predicted for cefuroxime axetil (6.6 μg L(-1)). Based on acute toxicity data for algae, risk quotient (RQ) values higher than 1 were obtained for 7 out of the 24 target antimicrobials in raw and treated wastewater, while no significant risk was estimated for daphnids and fish. Regarding the possible risk due to the chronic toxicity of antimicrobials, RQ values higher than 80 were obtained for amoxicillin and clarithromycin in algae. The use of baseline toxicity data from ECOSAR showed that the environmental risk from exposure to mixtures of antimicrobials was low for all three aquatic species. However, further studies on toxicity of mixtures should be performed as calculation of toxicity ratio (TR) values showed that 90 % of the target antimicrobials seem to exhibit a specific mode of toxic action when present in mixtures rather than baseline toxicity. As a result, an underestimation of toxicity based on the ECOSAR model is possible for the mixture of target antimicrobials. For Greek rivers where low (dilution factor, D<10) and medium (D=10-100) dilution of wastewater occurs, moderate to high risk is expected due to the existence of individual antimicrobials such as amoxicillin, clarithromycin, ciprofloxacin, azithromycin, erythromycin, and levofloxacin in discharged treated wastewater.

Is there a risk for the aquatic environment due to the existence of emerging organic contaminants in treated domestic wastewater? Greece as a case-study

The ecological threat associated with emerging pollutants detected in wastewater was estimated in country level. Treated wastewater was analyzed for pharmaceuticals and illicit drugs; whereas the concentrations of all emerging contaminants determined in Greek Sewage Treatment Plants were recorded through literature review. Toxicity data was collected after literature review or using ECOSAR and risk quotients (RQs) were calculated for treated wastewater and 25 Greek rivers, for 3 different aquatic organisms (fish, daphnia magna, algae). According to the results, monitoring data was available for 207 micropollutants belonging to 8 different classes. RQ>1 was calculated for 30 compounds in secondary treated wastewater. Triclosan presented RQ>1 (in algae) for all studied rivers; decamethylcyclopentasilane (in daphnia magna), caffeine (in algae) and nonylphenol (in fish) presented RQ>1 in rivers with dilution factors (DF) equal or lower to 1910, 913 and 824, respectively. The class of emerging contaminants that present the greatest threat due to single or mixture toxicity was endocrine disrupters. The mixture of microcontaminants seems to pose significant ecological risk, even in rivers with DF equal to 2388. Future national monitoring programs should include specific microcontaminants that seem to possess environment risk to surface water.

Sorption of Perfluorinated Compounds onto different types of sewage sludge and assessment of its importance during wastewater treatment

The distribution coefficient (Kd) and the organic carbon distribution coefficient (KOC) were determined for four Perfluorinated Compounds (PFCs) to three different types of sludge taken from a conventional Sewage Treatment Plant (STP). Batch experiments were performed in six different environmental relevant concentrations (200ngL(-1)to 5μgL(-1)) containing 1gL(-1) sludge. Kd values ranged from 330 to 6015, 329 to 17432 and 162 to 11770Lkg(-1) for primary, secondary and digested sludge, respectively. The effects of solution's pH, ionic strength and cation types on PFCs sorption were also evaluated. Sorption capacities of PFCs significantly decreased with increased pH values from 6 to 8. Furthermore, the divalent cation (Ca(2+)) enhanced PFCs sorption to a higher degree in comparison with the monovalent cation (Na(+)) at the same ionic strength. The obtained Kd values were applied to estimate the sorbed fractions of each PFC in different stages of a typical STP and to calculate their removal through treated wastewater and sludge. In primary settling tank, the predicted sorbed fractions ranged from 3% for Perfluorooctanoic Acid (PFOA) to 55% for Perfluoroundecanoic acid (PFUdA), while in activated sludge tank and anaerobic digester sorption was more than 50% for all target compounds. Almost 86% of initial PFOA load is expected to be detected in treated wastewater; while Perfluorodecanoic acid (PFDA), PFUdA and Perfluorooctanesulfonate (PFOS) can be significantly removed (>49%) via sorption to primary and excess secondary sludge. In anaerobic digester, the major part (>76%) of target PFCs is expected to be sorbed to sludge, while almost 3% of initial PFOA load will be detected in sludge leachates.

Fate of selected emerging micropollutants during mesophilic, thermophilic and temperature co-phased anaerobic digestion of sewage sludge

The removal of endocrine disrupting compounds (EDCs) and non-steroidal anti-inflammatory drugs (NSAIDs) was studied in three lab-scale anaerobic digestion (AD) systems; a single-stage mesophilic, a single-stage thermophilic and a two-stage thermophilic/mesophilic. All micropollutants underwent microbial degradation. High removal efficiency (>80%) was calculated for diclofenac, ibuprofen, naproxen and ketoprofen; whereas triclosan, bisphenol A and the sum of nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate were moderately removed (40-80%). NSAIDs removal was not affected by the type of AD system used; whereas slightly higher EDCs removal was observed in two-stage system. In this system, most microcontaminants were removed in thermophilic digester. Biotransformation of NP1EO and NP was affected by the temperature applied to bioreactors. Under mesophilic conditions, higher removal of NP1EO and accumulation of NP was noticed; whereas the opposite was observed under thermophilic conditions. For most analytes, higher specific removal rates were calculated under thermophilic conditions and 20 days SRT.

Contribution of primary and secondary treatment on the removal of benzothiazoles, benzotriazoles, endocrine disruptors, pharmaceuticals and perfluorinated compounds in a sewage treatment plant

The occurrence and fate of 36 emerging contaminants, belonging to five different classes, (benzotriazoles, BTRs; benzothiazoles, BTHs; perfluorinated compounds, PFCs; non-steroidal anti-inflammatory drugs, NSAIDs and endocrine disruptors, EDCs) were investigated in raw, treated wastewater (both particulate and dissolved phases), and in sludge from a sewage treatment plant (STP) in Athens, Greece. The average concentrations of BTRs, BTHs, NSAIDs and EDCs in raw wastewater ranged between 11 ng L(-1) and 7.27 μg L(-1), while PFCs did not exceed 100 ng L(-1). In dewatered sludge, the average concentrations ranged between 0.8 ng g(-1) dw (perfluorohexanoic acid, PFHxA) and 3895 ng g(-1) dw (nonylphenol, NP). The distribution of emerging contaminants between particulate and dissolved phase was different among the compounds. BTRs and BTHs showed lower solid-liquid distribution coefficients (Kd) than all other compounds. For 9 over the 27 compounds detected in influents, the removal efficiency was higher than 70%, while the others either were removed to a lesser extent or detected at higher concentrations in effluents. Based on this, advanced treatment processes should be applied in the future for achieving adequate emerging contaminants removal in STPs. Regarding removal mechanisms, almost 60% of BTRs and 30 to 75% of BTHs were removed in bioreactors, while the contribution of primary and secondary clarifiers was of minor importance. Sorption to primary sludge was a significant mechanism affecting EDCs fate in STP.

Quantitative and qualitative greywater characterization in Greek households and investigation of their treatment using physicochemical methods

Data for the quantity of greywater produced in Greek households was collected from two different cities, while samples from different residences were taken for greywater's quality characterization. Laboratory experiments were also performed to investigate the use of coagulation on COD and TSS removal from two different types of greywater, while a combined treatment consisting of coagulation, sand filtration and adsorption on granular activated carbon (GAC) was applied to achieve adequate quality for greywater reuse. According to the results, average greywater production in Greek residences was 82.6 ± 49.3 L per inhabitant and day, while the major sources were shower/bathtub and laundry, contributing to 41% and 26%, respectively. On the other hand, blackwater production was estimated at 59.4 ± 29.6L per inhabitant and day. Greywater produced in shower/bathtub and hand basin had similar quality characteristics, while kitchen sink's greywater were more contaminated, presenting lower pH values and higher concentrations of TSS and total COD. Coagulation experiments with FeCl3 and Al2(SO4)3 showed that process efficiency was differentiated significantly according to the type of greywater and the coagulant used. The highest removal efficiency (COD: 81%; TSS: 79%) was achieved for greywater that did not contain wastewater from the laundry and for Al2(SO4)3×14 H2O dosage of 800 mg L(-1). The application of coagulation, sand filtration and GAC adsorption resulted to average concentrations of COD and TSS equal to 28 ± 11 and 11 ± 3 mg L(-1), respectively, in treated greywater.

Mass loading and fate of linear and cyclic siloxanes in a wastewater treatment plant in Greece

The occurrence and fate of 5 cyclic (D3 to D7) and 12 linear (L3 to L14) siloxanes were investigated in raw and treated wastewater (both particulate and dissolved phases) as well as in sludge from a wastewater treatment plant (WWTP) in Athens, Greece. Cyclic and linear siloxanes (except for L3) were detected in all influent wastewater and sludge samples at mean concentrations of (sum of 17 siloxanes) 20 μg L(-1) and 75 mg kg(-1), respectively. The predominant compounds in wastewater were L11 (24% of the total siloxane concentration), L10 (16%), and D5 (13%), and in sludge were D5 (20%) and L10 (15%). The distribution of siloxanes between particulate and dissolved phases in influents differed significantly for linear and cyclic siloxanes. Linear siloxanes showed higher solid-liquid distribution coefficients (log K(d)) than did cyclic compounds. For 10 of the 16 compounds detected in influents, the removal efficiency was higher than 80%. Sorption to sludge and biodegradation and/or volatilization losses are important factors that affect the fate of siloxanes in WWTPs. The mean total mass of siloxanes that enter into the WWTP via influent was 15.1 kg per day(-1), and the mean total mass released into the environment via effluent was 2.67 kg per day(-1).

Fate of selected pharmaceuticals and synthetic endocrine disrupting compounds during wastewater treatment and sludge anaerobic digestion

The concentrations of nine emerging contaminants, including pharmaceutically active compounds (PhACs) (ibuprofen, IBF; naproxen, NPX; diclofenac, DCF; ketoprofen, KFN) and endocrine disrupting chemicals (triclosan, TCS; bisphenol, BPA; nonylphenol, NP; nonylphenol monoethoxylate, NP1EO; nonylphenol diethoxylate, NP2EO), were determined in wastewater and sludge samples of two wastewater treatment plants (WWTPs) in Greece. Average concentrations in raw and treated wastewater ranged from 0.39 (KFN) to 12.52 μg L(-1) (NP) and from <LOD (IBF) to 0.80 μg L(-1) (DCF), respectively. A significant part of nonylphenols (NPs) and TCS in influent wastewater was bound to the particulate phase, while PhACs and BPA were mainly detected in the aqueous phase. Removal of target compounds during wastewater treatment ranged between 39% (DCF) and 100% (IBF). Except of DCF and BPA, similar removal efficiencies were observed in both WWTPs and no effect of WWTP's size and operational conditions was noticed. Use of mass balances showed that accumulation on sludge was a significant removal mechanism for NPs and TCS, while biodegradation/biotransformation was the major mechanism for the other compounds. Sampling of raw and digested sludge demonstrated that IBF and NPX are significantly removed (>80%) during anaerobic digestion, whereas removal of EDCs was lower, ranging up to 55% for NP1EO.

Occurrence of different classes of perfluorinated compounds in Greek wastewater treatment plants and determination of their solid-water distribution coefficients

The concentrations of eighteen perfluorinated compounds (PFCs: C5-C14 carboxylates, C4, C6-C8 and C10 sulfonates and 3 sulfonamides) were determined in wastewater and sludge samples originating from two different wastewater treatment plants (WWTPs). The analytes were extracted by solid phase extraction (dissolved phase) or sonication followed by solid phase extraction (solid phase). Qualitative and quantitative analyses were performed by LC-MS/MS. According to the results, perfluoropentanoic acid (PFPeA), perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were dominant in wastewater and sludge samples from both plants. The average concentrations in the raw and treated wastewater ranged up to 75.7 ng L(-1) (perfluorotridecanoic acid, PFTrDA) and 76.0 ng L(-1) (PFPeA), respectively. Concentrations of most PFCs were higher in effluents than in influents, indicating their formation during wastewater treatment processes. In sewage sludge, the average concentrations ranged up to 6.7 ng g(-1) dry weight (PFOS). No significant seasonal variations in PFCs concentrations were observed, while higher concentrations of PFOA, PFOS and perfluorononanoic acid (PFNA) were determined in the WWTP receiving municipal and industrial wastewater. Significantly different distribution coefficient (Kd) values were determined for different PFCs and different type of sludge, ranging between 169 L kg(-1) (PFHxS) to 12,922 L kg(-1) (PFDA).

Review on the fate of emerging contaminants during sludge anaerobic digestion

Several research papers have been published during the last years investigating the occurrence, fate and effects of emerging contaminants (ECs) on sludge anaerobic digestion (AD). Literature review revealed that research has been mainly focused on specific groups of compounds (linear alkylbenzene sulphonates, nonylphenol ethoxylates, some pharmaceuticals, estrogens, phthalates), while there are fewer or no data for others (personal care products, perfluorinated compounds, brominated flame retardants, organotins, benzotriazoles, benzothiazoles, nanoparticles). AD operational parameters (sludge residence time, temperature), sludge characteristics (type of sludge, adaptation on the compound), physicochemical properties of ECs and co-metabolic phenomena seem to affect compounds' biodegradation. The use of sludge pretreatment methods does not seem to enhance ECs removal; whereas encouraging results have been reported when AD was combined with other treatment methods. Future efforts should be focused on better understanding of biotransformation processes and sorption phenomena occurred in anaerobic digesters, as well as on identification of (bio)transformation products.