Comparison between the conventional anaerobic digestion of sewage sludge and its combination with a chemical or thermal pre-treatment concerning the removal of pharmaceuticals and personal care products

Distinctive effects of graphene oxide and reduced graphene oxide on methane production kinetics and pharmaceuticals removal in anaerobic reactors

Graphene oxide (GO) addition to anaerobic digestion has been suggested to enhance direct electron transfer. The impact of GO (0.075 g GO g-1 VS) and biologically and hydrothermally reduced GO (bio-rGO and h-rGO, respectively) on the methane production kinetics and removal of 12 pharmaceuticals was assessed in Fed-batch reactors. A decrease of 15 % in methane production was observed in the tests with GO addition compared with the control and the h-rGO. However, bio-rGO and h-rGO substantially increased the methane production rate compared to the control tests (+40 %), in the third fed-batch test. Removal of pharmaceuticals was enhanced only during the bio-reduction of GO (1st fed-batch test), whereas once the GO was bio-reduced, it followed a similar trend in the control and h-rGO tests. The addition of GO can enhance the methane production rate and, therefore, reduce the anaerobic treatment time.

Occurrence, spatiotemporal trends, fate, and treatment technologies for microplastics and organic contaminants in biosolids: A review

This review provides a comprehensive overview of the occurrence, fate, treatment and multi-criteria analysis of microplastics (MPs) and organic contaminants (OCs) in biosolids. A meta-analysis was complementarily analysed through the literature to map out the occurrence and fate of MPs and 10 different groups of OCs. The data demonstrate that MPs (54.7% occurrence rate) and linear alkylbenzene sulfonate surfactants (44.2% occurrence rate) account for the highest prevalence of contaminants in biosolids. In turn, dioxin, polychlorinated biphenyls (PCBs) and phosphorus flame retardants (PFRs) have the lowest rates (<0.01%). The occurrence of several OCs (e.g., dioxin, per- and polyfluoroalkyl substances, polycyclic aromatic hydrocarbons, pharmaceutical and personal care products, ultraviolet filters, phosphate flame retardants) in Europe appear at higher rates than in Asia and the Americas. However, MP concentrations in biosolids from Australia are reported to be 10 times higher than in America and Europe, which required more measurement data for in-depth analysis. Amongst the OC groups, brominated flame retardants exhibited exceptional sorption to biosolids with partitioning coefficients (log Kd) higher than 4. To remove these contaminants from biosolids, a wide range of technologies have been developed. Our multicriteria analysis shows that anaerobic digestion is the most mature and practical. Thermal treatment is a viable option; however, it still requires additional improvements in infrastructure, legislation, and public acceptance.

Advanced steam-explosion pretreatment mediated anaerobic digestion of municipal sludge: Effects on methane yield, emerging contaminants removal, and microbial community

Advanced steam explosion pretreatment, i.e., the Thermal hydrolysis process (THP) is applied mainly to improve the sludge solubilization and subsequent methane yield in the downstream anaerobic digestion (AD) process. However, the potential of THP in pretreating the high solids retention time (SRT) sludges, mitigating the risk of emerging organic micropollutants and effects on anaerobic microbiome in digester remains unclear. In this study, sludge from a sequencing batch reactor (SBR) system operating at a SRT of 40 days was subjected to THP using a 5 L pilot plant at the temperature ranges of 120-180 °C for 30-120 min. The effect of THP on organics solubilization, methane yield, organic micropollutant removal, and microbial community dynamics was studied. The highest methane yield of 507 mL CH4/g VSadded and volatile solids (VS) removal of 54% were observed at 160°C- 30min THP condition, i.e., 4.1 and 2.6 times higher than the control (123 mL CH4/gVSadded, 20.7%), respectively. The experimental values of hydrolysis coefficient and methane yield have been predicted using Modified Gompertz, First order, and Logistics models. The observed values fitted well with all three models showing an R2 value between 0.96 and 1.0. THP pretreated sludges showed >80% removal of Trimethoprim, Enrofloxacin, Ciprofloxacin, and Bezafibrate. However, Carbamazepine, 17α-ethinylestradiol, and Progesterone showed recalcitrant behavior, resulting in less than 50% removal. Microbial diversity analysis showed the dominance of Proteobacteria, Firmicutes, Chloroflexi, and Bacteroidetes, collectively accounting for >70-80% of bacterial reads. They are mainly responsible for the fermentation of complex biomolecules like polysaccharides, proteins, and lipids. The THP-mediated anaerobic digestion of sludge shows better performance than the control digestion, improved methane yield, higher VS and micropollutants removal, and a diverse microbiome in the digester.

Risk control of antibiotics, antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) during sewage sludge treatment and disposal: A review

Sewage sludge is an important reservoir of antibiotics, antibiotic resistance genes (ARGs), and antibiotic resistant bacteria (ARB) in wastewater treatment plants (WWTPs), and the reclamation of sewage sludge potentially threats human health and environmental safety. Sludge treatment and disposal are expected to control these risks, and this review summarizes the fate and controlling efficiency of antibiotics, ARGs, and ARB in sludge involved in different processes, i.e., disintegration, anaerobic digestion, aerobic composting, drying, pyrolysis, constructed wetland, and land application. Additionally, the analysis and characterization methods of antibiotics, ARGs, and ARB in complicate sludge are reviewed, and the quantitative risk assessment approaches involved in land application are comprehensively discussed. This review benefits process optimization of sludge treatment and disposal, with regard to environmental risks control of antibiotics, ARGs, and ARB in sludge. Furthermore, current research limitations and gaps, e.g., the antibiotic resistance risk assessment in sludge-amended soil, are proposed to advance the future studies.

Presence of pharmaceuticals and their metabolites in wild-living aquatic organisms - Current state of knowledge

In the last decades an increasing number of studies has been published concerning contamination of aquatic ecosystems with pharmaceuticals. Yet, the distribution of these chemical compounds in aquatic environments raises many questions and uncertainties. Data on the presence of selected pharmaceuticals in the same water bodies varies significantly between different studies. Therefore, since early 1990 s, wild organisms have been used in research on environmental contamination with pharmaceuticals. Indeed, pharmaceutical levels measured in biological matrices may better reflect their overall presence in the aquatic environments as such levels include not only direct exposure of a given organisms to a specific pollutant but also processes such as bioaccumulation and biomagnification. In the present paper, data concerning occurrence of pharmaceuticals in aquatic biota was reviewed. So far, pharmaceuticals have been studied mainly in fish and molluscs, with only a few papers available on crustaceans and macroalgae. The most commonly found pharmaceuticals both in freshwater and marine organisms are antibiotics, antidepressants and NSAIDS while there is no information about the presence of anticancer drugs in aquatic organisms. Furthermore, only single studies were conducted in Africa and Australia. Hence, systematization of up-to-date knowledge, the main aim of this review, is needed for further research targeting.

Dynamics of Soil Microbial Communities During Diazepam and Oxazepam Biodegradation in Soil Flooded by Water From a WWTP

The demand for energy and chemicals is constantly growing, leading to an increase of the amounts of contaminants discharged to the environment. Among these, pharmaceutical molecules are frequently found in treated wastewater that is discharged into superficial waters. Indeed, wastewater treatment plants (WWTPs) are designed to remove organic pollution from urban effluents but are not specific, especially toward contaminants of emerging concern (CECs), which finally reach the natural environment. In this context, it is important to study the fate of micropollutants, especially in a soil aquifer treatment (SAT) context for water from WWTPs, and for the most persistent molecules such as benzodiazepines. In the present study, soils sampled in a reed bed frequently flooded by water from a WWTP were spiked with diazepam and oxazepam in microcosms, and their concentrations were monitored for 97 days. It appeared that the two molecules were completely degraded after 15 days of incubation. Samples were collected during the experiment in order to follow the dynamics of the microbial communities, based on 16S rRNA gene sequencing for Archaea and Bacteria, and ITS2 gene for Fungi. The evolution of diversity and of specific operating taxonomic units (OTUs) highlighted an impact of the addition of benzodiazepines, a rapid resilience of the fungal community and an evolution of the bacterial community. It appeared that OTUs from the Brevibacillus genus were more abundant at the beginning of the biodegradation process, for diazepam and oxazepam conditions. Additionally, Tax4Fun tool was applied to 16S rRNA gene sequencing data to infer on the evolution of specific metabolic functions during biodegradation. It finally appeared that the microbial community in soils frequently exposed to water from WWTP, potentially containing CECs such as diazepam and oxazepam, may be adapted to the degradation of persistent contaminants.

Fate of selected organic micropollutants during anaerobic sludge digestion

Organic micropollutants are incompletely removed from wastewater in Water Resource Recovery Facilities using conventional methods and can therefore enter the anaerobic sludge treatment together with primary and secondary sludge. This review compiles literature data on the fate of selected micropollutants (Carbamazepine [CBZ], Diclofenac [DCF], Ibuprofen [IBP], Sulfamethoxazole [SMX], and Triclosan [TCS]) during anaerobic sludge treatment and how the fate is affected by chemical properties, phase distribution and operating conditions. CBZ was found to be persistent to anaerobic degradation in most studies, with some exceptions reporting a degradation efficiency of 60%. Removal efficiencies for DCF, IBP, and TCS varied widely (from no to [very] high removal). For SMX, most studies reported a removal above 80%. A correlation was found between the fate during anaerobic digestion and physicochemical properties (hydrophobicity and molecular structure). Sorption to sludge, affected in some cases by pH changes during digestion, is suggested to reduce bioavailability. IBP and TCS were mainly present in the liquid phase or solid phase, respectively, CBZ and DCF were present in similar proportions in both phases, while statements were contradictory for SMX. Parameters such as temperature and sludge age did not significantly influence the fate of investigated micropollutants during anaerobic digestion. PRACTITIONER POINTS: Most studies report no significant removal of CBZ during anaerobic sludge digestion. Removal efficiencies of DCF, IBP, and TCS vary from study to study between no removal and high or very high removal. Considering such heterogeneous removal efficiencies, it is recommended to conduct digestion trials to find out in which range the values will be for a specific sludge. SMX is very highly removed during anaerobic digestion in most studies. Parameters such as temperature and SRT do not significantly influence the fate of the five investigated micropollutants. Hydrophobicity, which has some effect on the liquid/solid phase distribution of micropollutants, and molecular structure influence the removal efficiencies.

Total and Metabolically Active Microbial Community of Aerobic Granular Sludge Systems Operated in Sequential Batch Reactors: Effect of Pharmaceutical Compounds

Two aerobic granular sludge (AGS) sequential batch reactors were operated at a mild (15 °C) temperature for 180 days. One of those bioreactors was exposed to a mixture of diclofenac, naproxen, trimethoprim, and carbamazepine. The AGS system, operating under pressure from emerging contaminants, showed a decrease in COD, BOD5, and TN removal capacity, mainly observed during the first 100 days, in comparison with the removal ratios detected in the control bioreactor. After an acclimatisation period, the removal reached high-quality effluent for COD and TN, close to 95% and 90%, respectively. In the steady-state period, trimethoprim and diclofenac were successfully removed with values around 50%, while carbamazepine and naproxen were more recalcitrant. The dominant bacterial OTUs were affected by the presence of a mixture of pharmaceutical compounds, under which the dominant phylotypes changed to OTUs classified among the Pseudomonas, Gemmobacter, and Comamonadaceae. The RT-qPCR and qPCR results showed the deep effects of pharmaceutical compounds on the number of copies of target genes. Statistical analyses allowed for linking the total and active microbial communities with the physico-chemical performance, describing the effects of pharmaceutical compounds in pollution degradation, as well as the successful adaptation of the system to treat wastewater in the presence of toxic compounds.

Novel framework of GIS based automated monitoring process on environmental biodegradability and risk analysis using Internet of Things

A proper method on real-time monitoring of organic biomass degradation and its evaluation for safeguarding the ecosystem is the need of the hour. The work process designed in this study is to demarcate the anaerobic digestion potential using kinetic modelling and web GIS application methods. Wastewater source that causes pollution are identified through satellite maps such as solid earth, drain system, surface of earth structure, land filling and land use. The grabbed data are utilized for identifying the concentration of sludge availability. Based on literature resource multi influencing factor techniques are introduced along with overlay method to differentiate digestion potential of sludge source. This study optimizes the biodegradation potential of domestic sewage at different sludge concentrations in a pilot model operated with the samples identified through topographical drainage survey. The materialization of devices is using the Internet of Things (IoTs), that is pragmatic to be the promising tendency. Kinetic study, methanogenic assay test are performed with three different cation binding agents to find its solubilization potential and methane evolution, which is further subjected to digestion potential in anaerobic conditions for possible application in the field of environmental science. Risk analysis reveals that land filling method will have highest impact on maintaining sustainable environment. The results outcome on natural biodegradation may be used for individual house hold wastewater management for the locality.

Mass loading, distribution, and removal of antibiotics and antiretroviral drugs in selected wastewater treatment plants in Kenya

The discharge of active pharmaceutical ingredients (APIs) into the aquatic environment from wastewater effluents is a concern in many countries. Although many studies have been conducted to evaluate the APIs removal efficiencies and emissions to the environment in wastewater treatment plants (WWTPs), most of these studies considered the aqueous and sludge phases, disregarding the suspended particulate matter (SPM) phase. To try to understand the role of the SPM, the occurrence of five most common antibiotics and three antiretroviral drugs (ARVDs) commonly used in Kenya were investigated in this study. APIs partitioning and mass loading in influents and effluents of three different WWTPs: trickling filters, stabilization ponds, and decentralized fecal sludge system, were evaluated. API concentration levels ranging from ˂LOQ (limit of quantification) to 92 μgL^-1 and ˂LOQ to 82.2 mgkg^-1 were observed in aqueous samples and solid samples respectively, with SPM accounting for most of the higher concentrations. The use of the aqueous phase alone for determination of removal efficiencies showed underestimations of API removal as compared to when solid phases are also considered. Negative removal efficiencies were observed, depending on the compound and the type of WWTP. The negative removals were associated with deconjugation of metabolites, aggregated accumulation of APIs in the WWTPs, as well as unaccounted hydraulic retention time during sampling. Compound characteristics, environmental factors, and WWTPs operation influenced WWTPs removal efficiencies. Wastewater stabilization ponds had the poorest removals efficiencies with an average of -322%. High total mass loads into the WWTPs influent and effluent of 22,729 and 22,385 mg day^-1 1000 PE^-1 were observed respectively. The results aims at aiding scientists and engineers in planning and designing of WWTPs. Findings also aim at aiding policy-making on pharmaceutical drug use and recommend proper wastewater management practices to manage the high mass loading observed in the WWTPs.

Acidogenesis is a key step in the anaerobic biotransformation of organic micropollutants

Understanding the role of the different anaerobic digestion stages on the removal of organic micropollutants (OMPs) is essential to mitigate their release from wastewater treatment plants. This study assessed the fate of 21 OMPs during hydrolysis and acidogenesis to elucidate the contribution of these stages to the overall anaerobic removal. Moreover, the removal mechanisms and factors influencing them were investigated. To this purpose, a fermentation reactor was operated and fed with two different substrates: starch (to jointly evaluate hydrolysis and acidogenesis) and glucose (to isolate acidogenesis). Results indicate that sulfamethoxazole was highly biotransformed (>80 %), while galaxolide, celestolide, tonalide, erythromycin, roxithromycin, trimethoprim, octylphenol and nonylphenol achieved a 50-80 % biotransformation. Since no significant differences in the biotransformation efficiencies were found between starch and glucose fermentation, it is stated that the enzymatic activities involved in starch hydrolysis do not significantly contribute to the cometabolic biotransformation of OMPs, while acidogenesis appears as the major player. Moreover, a higher biotransformation (≥15 percentage points and p ≤ 0.05) was found for galaxolide, celestolide, tonalide, erythromycin and roxithromycin during acidogenesis in comparison with the efficiencies reported for the acetogenic/methanogenic step. The biotransformation of some OMPs was explained considering their chemical structure and the enzymatic activities.

Thermal hydrolysis of sewage sludge partially removes organic micropollutants but does not enhance their anaerobic biotransformation

Pretreatment technologies prior to anaerobic digestion (AD) have been developed with the aim of enhancing biogas productivity and reducing the presence of pathogens in digested sludge. Among them, thermal hydrolysis (TH) appears as the most promising one. In wastewater treatment plants (WWTPs) sludge is the end point of many organic micropollutants (OMPs), which was proved to lead to important environmental and human risks since sludge is commonly used in agriculture. The objective of this work is to determine the fate OMPs in TH and subsequent AD. Sewage sludge was pretreated in a TH pilot plant at 170 °C for 20 min. Afterwards, two anaerobic digesters with a working volume of 14 L fed with fresh and pretreated sludge were operated in parallel in mesophilic conditions. TH proved to be an effective technology to partially or totally remove the dissolved fraction of OMPs as well as the fraction sorbed into those suspended solids that are solubilised after this pretreatment. However, it did not affect the OMPs sorbed concentration into solids that are not solubilised. Globally, the OMPs removal efficiency during TH appears to be linked to the solids solubilisation during this process. Afterwards, the OMPs biotransformation efficiency in AD of fresh and pretreated sludge was determined. Noticeable differences between the microbiome of both reactors was determined, but the anaerobic biotransformation was not substantially different for most of the OMPs. However, it affected musk fragrances, which presented considerably lower biotransformation efficiency in the reactor fed with pretreated sludge. Therefore, TH was proved effective in partially removing OMPs but not in enhancing their bioavailability and subsequent anaerobic biotransformation.

Leaching of endocrine disrupting chemicals from marine microplastics and mesoplastics under common life stress conditions

Microplastics (MPs) and mesoplastics are able to sorb harmful substances and often contain additives, e.g., endocrine disrupting chemicals (EDCs), that can cause adverse effects to organisms. The present study aims to determine EDC concentrations and their endocrine activities in leachates of field-collected marine MPs and mesoplastics under stress conditions that are known to occur during the plastic life cycle. Estrogens were the dominant EDCs on plastic particles and were either concentrated from the surrounding water or originated from plastic manufacturing. Bisphenol A had the highest detection frequency (75%) with an average concentration of 475 ± 882 μg/kg, followed by bisphenol S, octylphenol and nonylphenol. Moreover, smaller marine MPs leached greater quantities of EDCs because the sorption from surrounding seawater is more efficient for smaller particles. It was found that normal life stresses such as microwaving (MW) and autoclaving (AC) can decrease EDC concentrations, but solar irradiation (solar) can increase EDC concentrations in leachates. Even though organisms with higher metabolic ability exhibited greater estrogenic effects, the comprehensive toxicity of plastic leachates after common life treatments was still limited (below the EC₁₀ value) if 0.1% is taken as the EDC uptake from plastic. In future studies, the accurate contribution of plastic bound EDCs needs to be further explored, and the monitoring of MPs and mesoplastics in the human diet remains important because the concentrations of these plastics may change in the future.

Co-digestion of microalgae and primary sludge: Effect on biogas production and microcontaminants removal

Microalgal-based wastewater treatment plants are conceived as low cost and low energy consuming systems. The operation of these plants involves the management of primary sludge and microalgal biomass. The aim of this study is to analyse the anaerobic co-digestion of both by-products in terms of biogas production and contaminants of emerging concern removal. The co-digestion of microalgae and primary sludge (25/75% on a volatile solids basis) was investigated in continuous reactors and compared to microalgae mono-digestion at a hydraulic retention time of 20days. Results showed how the co-digestion enhanced the anaerobic digestion of microalgal biomass, since primary sludge is a more readily biodegradable substrate, which increased the methane production by 65% and reduced the risk of ammonia toxicity. Regarding the contaminants, musk fragrances (galaxolide and tonalide) and triclosan showed the highest abundance on primary sludge (0.5-25μg/g TS), whereas caffeine, methyl dihydrojasmonate and triphenyl phosphate were barely detected in both substrates (<0.1μg/g TS). The removal of these contaminants was compound-depending and ranged from no removal to up to 90%. On the whole, microalgae mono-digestion resulted in a higher removal of selected contaminants than the co-digestion with primary sludge.

Removal of personal care products (PCPs) in wastewater and sludge treatment and their occurrence in receiving soils

Clean water is one of the main resources for key activities such as agriculture, power generation, and public and industrial supplies. However, once wastewater generated by these activities is released into the environment, it may represent a potential risk to ecosystems and even human health depending on the presence of certain types and levels of contaminants. This study is focused on personal care products (PCPs), a class of contaminants of emerging concern (CECs) which includes commonly used cosmetic and personal hygiene products (e.g., fragrances, UV filters, antimicrobials, surfactants, among others), and their comparison with legacy contaminants such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). We have monitored the concentrations of up to 66 target compounds in influent and effluent wastewater, sludge, and compost samples from a wastewater treatment plant (WWTP) at Jerez de la Frontera (SW Spain) over a 1-year period. Almost half of the target compounds (44%) were frequently detected in influent wastewater samples, with prevalence of synthetic fragrances and higher abundance of UV filters during warmer periods. Due to their relatively poor removal efficiencies (<70%), 30 target compounds were always detected in the final effluent. The highest levels here were observed for an UV filter (octocrylene) and three synthetic fragrances (traseolide, OTNE, and galaxolide), showing maximum concentrations of 4-7 μg L^-1 and 12-95 μg g^-1 in the dissolved and particulate fractions, respectively. Concentrations of these compounds increased in sludge, being up to 365 μg g^-1 for some fragrances and showing negligible decrease after anaerobic digestion. Windrow composting of this sludge, however, resulted in an efficient removal (up to 100%) for most analytes. On the other hand, levels between <1 and 651 ng g^-1 were measured in soils columns (0-150 cm) at the WWTP gardens irrigated with effluent wastewater. The occurrence of PCPs in these soils seemed to be heavily influenced by temperature, as maximum concentrations were measured in colder months, indicating a higher rate of microbial activity degradation and/or volatilization during warmer months.

Variation of antibiotics in sludge pretreatment and anaerobic digestion processes: Degradation and solid-liquid distribution

Degradation and solid-liquid distribution of antibiotics in three sludge pretreatments (ultrasonic, alkaline and thermal hydrolysis pretreatment) and subsequent anaerobic digestion processes were investigated. The contamination of fluoroquinolones (FQs) was most serious in the raw sludge, while sulfonamides (SAs) were negligible. Obvious solubilization of antibiotics was observed after sludge pretreatments. The intracellular antibiotics were released after thermal hydrolysis pretreatment, meanwhile tetracyclines (TCs) were thermally decomposed. Compared to TCs and macrolides (MLs), FQs were hardly degraded in anaerobic digestion with removal efficiencies lower than 42.02%, and the residual FQs were mostly adsorbed on the digested sludge. The limiting step for FQs reduction was the biodegradation, rather than desorption of adsorbed antibiotics. Addition of pretreatments had no obvious effect on the degradation and distribution of antibiotics in the anaerobic digested sludge, except that the thermal hydrolysis enhanced the migration of antibiotics to the liquid phase.

Enhanced Photocatalytic Activity of {110}-Faceted TiO₂ Rutile Nanorods in the Photodegradation of Hazardous Pharmaceuticals

Rutile TiO₂ with highly active facets has attracted much attention owing to its enhanced activity during the photocatalytic degradation of pollutants such as pharmaceuticals in wastewater. However, it is difficult to obtain by controlling the synthetic conditions. This paper reports a simple hydrothermal synthesis of rutile TiO₂ nanorods with highly exposed {110} facets. The obtained rutile was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. The main contribution to the photocatalytic activity comes from rutile nanorods with highly dominant active {110} facets, which were studied in the photodegradation of reactive cinnamic acid and more recalcitrant ibuprofen. The contribution of active species was also investigated. The present work further confirmed the hydrothermal synthesis route for controlling the preparation of highly crystalline and active rutile nanocrystals.

Removal of the veterinary antimicrobial sulfamethazine in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor subjected to step changes in the applied organic loading rate

A bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor treating synthetic swine wastewater was operated under different applied organic loading rates (OLR) through both variations in feed strength and in hydraulic retention time (HRT). The influence of step changes in OLR on the removal of the veterinary antimicrobial sulfamethazine (SMZ) was assessed. The highest observed SMZ removal efficiency, 75 ± 6%, was achieved with an OLR of 2.7 ± 0.4 kg O₂ m^-3 d^-1 when a significant increase in COD removal rate was observed. The SMZ removal rate was positively correlated (r = 0.899) to the COD removal rate in all of the experimental conditions in which the HRT was kept at 24 h, indicating a cometabolic transformation of the antimicrobial. Decreasing the HRT caused a significant decrease in SMZ removal efficiency without affecting the HAIB reactor performance in terms of stability, COD removal or metabolic intermediates production. Functionally equivalent steady states were observed in four different operational phases with similar operating conditions but with widely different behavior in relation to SMZ removal. The experimental results showed the potential of anaerobic technology in removing environmentally relevant concentrations of SMZ, and the possibility of enhancing reactor performance by controlling operating conditions.

Occurrence and elimination of antibiotics in three sewage treatment plants with different treatment technologies in Urumqi and Shihezi, Xinjiang

Fourteen antibiotics, including five quinolones (QNs), five sulfonamides (SAs), and four tetracyclines (TCs), were selected to investigate their occurrence and elimination in three sewage treatment plants (STPs) by employing different treatment technologies in Urumqi (two STPs) and Shihezi (one STP), China. The STP in Shihezi was chosen as representative to investigate the distribution of antibiotics in a sludge-sewage system. Results showed that the concentrations of most detected antibiotics ranged from tens to hundreds of nanograms per liter in influent samples and under 100 ng L^-1 in effluent samples. QNs and TCs were dominant species with concentrations of 2.33 mg kg^-1 to 3.34 mg kg^-1 and 0.36 mg kg^-1 to 0.47 mg kg^-1 in sludge samples, respectively. The elimination rates of target antibiotics by various STPs ranged from 17% to 100%. The STP with anaerobic/anoxic/aerobic and membrane bio-reactor technology removed antibiotics more efficiently than those with anaerobic/anoxic/oxic and oxidation ditch technology. The elimination capacities of treatment units from the three STPs were also investigated. SAs were mainly degraded in biological treatment units; conversely, QNs and TCs were significantly eliminated in sedimentary treatment units. Ozonation effectively removed remaining antibiotics but not UV and chlorination disinfection in this study.

Effects of 17β-estradiol (E2) on aqueous organisms and its treatment problem: a review

Natural estrogens, estrone (E1), 17β-estradiol (E2) and estriol (E3) are endocrine disrupting chemicals (EDCs) that are discharged consistently and directly into surface waters with wastewater treatment plants (WWPTs) effluents, disposal sludges and in storm-water runoff. The most common and highest potential natural estrogen that causes estrogen activity in wastewater influent is E2. This review describes and attempts to summarize the main problems involved in the removal of E2 from WWTP by traditional processes, which fundamentally rely on activated sludge and provide an insufficient treatment for E2, as well as advanced oxidation processes (AOPs) that are applied in tertiary section treatment works. Biological processes affect and play an important role in the degradation of E2. However, some investigations have reported that operations that rely on high retention times have low efficiencies. Although advanced treatment technologies are available, their cost and operational considerations do not make them sustainable solutions. Therefore, E2 is still being released into aqueous areas, as shown in this study that investigates results from different countries. E2 is present on the watch list of substances in the Water Framework Directive (WFD) of the European Union since 2013 and the minimum acceptable concentration of it is 0.4 ng/L.

Popular pharmaceutical residues in hospital wastewater: quantification and qualification of degradation products by mass spectroscopy after treatment with membrane bioreactor

The occurrence of drugs in wastewater has been considered an imminent risk to the population, for the treatments used are usually ineffective. The presence of four popular drug residues (metformin, paracetamol, tetracycline, and enalapril) in hospital effluents, by using ultra-fast liquid chromatography tandem mass spectrometry (UFLC-MS/MS) with electrospray (ESI) ionization, and removal/degradation by membrane bioreactor (MBR) system are investigated in this study. For analysis method, all standard calibration curves showed satisfactory linearity (R (2) ≥ 0.993) within a relatively wide range. The recovery was between 70.4 and 105.0 %, and the relative standard deviation (RSD) values were within the ranges of 8.2 and 13.5 %. The effluent samples were collected at the end of the process treated in a bench-scale MBR treatment system and preconcentrated on solid-phase extraction (SPE) cartridges. Following that procedure, the chemical analysis demonstrated that the MBR system was effective in enalapril 94.3 ± 7.63 %, tetracycline 99.4 ± 0.02 %, and paracetamol 98.8 ± 0.86 % removal. However, the polar metformin was less effectively removed (35.4 ± 12.49 %). Moreover, the degradation products were investigated using high-resolution mass spectrometry (HRMS) by quadrupole-time of flight (Q-TOF), which has been indicated a tetracycline metabolite. In order to investigate the environmental impact, the wastewater potential risk was evaluated. The risk quotient (RQ) by measure environmental concentration (MEC) and its predicted no effect concentration (PNEC) ratio (RQ = MEC/PNEC) was between 0.003 (enalapril) to 0.815 (paracetamol). Finally, this work demonstrates that UFLC-MS/MS (ESI-Q) is a sensitive and selective method for drug analysis in wastewater and with ESI-Q-TOF has the accuracy required for determining the degradation products of these compounds. Also, it indicated that membrane bioreactor systems represent a new generation of processes that have proved to outperform conventional treatment showing better effluent quality. The removal capacity studied in this work demonstrates the efficiency of this process.

Trace organic contaminants in biosolids: Impact of conventional wastewater and sludge processing technologies and emerging alternatives

This paper critically reviews the fate of trace organic contaminants (TrOCs) in biosolids, with emphasis on identifying operation conditions that impact the accumulation of TrOCs in sludge during conventional wastewater and sludge treatment and assessing the technologies available for TrOC removal from biosolids. The fate of TrOCs during sludge thickening, stabilisation (e.g. aerobic digestion, anaerobic digestion, alkaline stabilisation, and composting), conditioning, and dewatering is elucidated. Operation pH, sludge retention time (SRT), and temperature have significant impact on the sorption and biodegradation of TrOCs in activated sludge that ends up in the sludge treatment line. Anaerobic digestion may exacerbate the estrogenicity of sludge due to bioconversion to more potent metabolites. Application of advanced oxidation or thermal pre-treatment may minimise TrOCs in biosolids by increasing the bioavailability of TrOCs, converting TrOCs into more biodegradable products, or inducing complete mineralisation of TrOCs. Treatment of sludge by bioaugmentation using various bacteria, yeast, or fungus has the potential to reduce TrOC levels in biosolids.

Pharmaceuticals and personal care products in untreated and treated sewage sludge: Occurrence and environmental risk in the case of application on soil - A critical review

This review is based on 59 papers published between 2002 and 2015, referring to about 450 treatment trains providing data regarding sludge concentrations for 169 compounds, specifically 152 pharmaceuticals and 17 personal care products, grouped into 28 different classes. The rationale of the study is to provide data to evaluate the environmental risk posed by the spreading of treated sludge in agriculture. Following discussion of the legislative scenario governing the final disposal of treated sludge in European countries and the USA, the study provides a snapshot of the occurrence of selected compounds in primary, secondary, mixed, digested, conditioned, composted and dried sludge originating in municipal wastewater treatment plants fed mainly with urban wastewater as well as in sludge-amended soil. Not only are measured values reported, but also predicted concentrations based on Kd values are reported. It emerges that in secondary sludge, the highest concentrations were found for fragrances, antiseptics and antibiotics and an attenuation in their concentrations occurs during treatment, in particular anaerobic digestion and composting. An in-depth literature survey of the (measured and predicted) Kd values for the different compounds and treated sludge are reported and an analysis of the influence of pH, redox conditions, sludge type was carried out. The data regarding measured and predicted concentrations of selected compounds in sludge-amended soil is then analyzed. Finally an environmental risk assessment posed by their occurrence in soil in the case of land application of sludge is examined, and the results obtained by different authors are compared. The most critical compounds found in the sludge-amended soil are estradiol, ciprofloxacin, ofloxacin, tetracycline, caffeine, triclosan and triclocarban. The study concludes with a focus on the main issues that should be further investigated in order to refine the environmental risk assessment.

Effects of Benzalkonium Chloride, Proxel LV, P3 Hypochloran, Triton X-100 and DOWFAX 63N10 on anaerobic digestion processes

In this study, the individual and synergistic toxicity of the following xenobiotics: Benzalkonium Chloride (BKC), Proxel LV (PRX), P3 Hypochloran (HPC), Triton X-100 (TRX), and DOWFAX 63N10 (DWF), on anaerobic digestion (AD) process, was assessed. The experiments were performed in batch and continuous (up-flow anaerobic sludge blanket, UASB) reactors with biochemical-industrial wastewater, as substrate. In batch experiments, half-maximal inhibitory concentrations (IC50) for the tested xenobiotics were found to be 13.1, 1003, 311.5 and 24.3 mg L(-1) for BKC, PRX, DWF and TRX, respectively while HPC did not affect the AD process. Furthermore, the xenobiotics mixture tested did not present any synergistic inhibitory effect on the AD process. In continuous experiments, BKC and xenobiotics' mixture induced even stronger (more than 85%) of inhibition, expressed as IC50, compared to the levels observed from the batch reactors. Oppositely, TRX showed no inhibition in continuous mode, while inhibition was detected at batch mode.

Beyond land application: Emerging technologies for the treatment and reuse of anaerobically digested agricultural and food waste

Effective treatment and reuse of the massive quantities of agricultural and food wastes generated daily has the potential to improve the sustainability of food production systems. Anaerobic digestion (AD) is used throughout the world as a waste treatment process to convert organic waste into two main products: biogas and nutrient-rich digestate, called AD effluent. Biogas can be used as a source of renewable energy or transportation fuels, while AD effluent is traditionally applied to land as a soil amendment. However, there are economic and environmental concerns that limit widespread land application, which may lead to underutilization of AD for the treatment of agricultural and food wastes. To combat these constraints, existing and novel methods have emerged to treat or reuse AD effluent. The objective of this review is to analyze several emerging methods used for efficient treatment and reuse of AD effluent. Overall, the application of emerging technologies is limited by AD effluent composition, especially the total solid content. Some technologies, such as composting, use the solid fraction of AD effluent, while most other technologies, such as algae culture and struvite crystallization, use the liquid fraction. Therefore, dewatering of AD effluent, reuse of the liquid and solid fractions, and land application could all be combined to sustainably manage the large quantities of AD effluent produced. Issues such as pathogen regrowth and prevalence of emerging organic micro-pollutants are also discussed.

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.

Pharmaceutical residues in sewage sludge: effect of sanitization and anaerobic digestion

The fate of pharmaceutical residues in treatment of WWTP sludge was evaluated during mesophilic anaerobic digestion (AD) and six sanitization technologies (pasteurization, thermal hydrolysis, advanced oxidation processes using Fenton's reaction, ammonia treatment, thermophilic dry digestion, and thermophilic anaerobic digestion). Sludge spiked with a selection of 13 substances was used and in total 23 substances were detected. A correlation between substance lipophilicity and sludge partitioning was found after sample centrifugation, with e.g., SSRI drugs (90-99%) and estrogens (96-98%) mainly found in the solid phase. A correlation between lipophilicity and persistence of pharmaceutical residues during AD was also detected, indicating that hydrophobic substances are less available to degrading microorganisms. Overall, AD was found to be the most effective technology in reducing a wide spectrum of organic substances (in average ca 30% reduction). Similar effects were obtained for both AD treatments, suggesting that temperature (mesophilic or thermophilic) is less important for micropollutant reduction. Advanced oxidation processes using Fenton's reaction also affected several compounds, including substances showing general stability over the range of treatments such as carbamazepine, propranolol, and sertraline. Pasteurization, ammonia treatment, and thermophilic dry digestion exhibited relatively modest reductions. Interestingly, only thermal hydrolysis efficiently removed the ecotoxicologically potent estrogenic compounds from the sludge.

Ultrasound pretreatment for enhanced biogas production from olive mill wastewater

This study investigates applicability of low frequency ultrasound technology to olive mill wastewaters (OMWs) as a pretreatment step prior to anaerobic batch reactors to improve biogas production and methane yield. OMWs originating from three phase processes are characterized with high organic content and complex nature. The treatment of the wastewater is problematic and alternative treatment options should be investigated. In the first part of the study, OMW samples were subjected to ultrasound at a frequency of 20kHz with applied powers varying between 50 and 100W under temperature controlled conditions for different time periods in order to determine the most effective sonication conditions. The level of organic matter solubilization at ultrasound experiments was assessed by calculating the ratio of soluble chemical oxygen demand/total chemical oxygen demand (SCOD/TCOD). The results revealed that the optimum ultrasonic condition for diluted OMW is 20kHz, 0.4W/mL for 10min. The application of ultrasound to OMW increased SCOD/TCOD ratio from 0.59 to 0.79. Statistical analysis (Friedman's tests) show that ultrasound was significantly effective on diluted OMW (p<0.05) in terms of SCOD parameter, but not for raw OMW (p>0.05). For raw OMW, this increase has been found to be limited due to high concentration of suspended solids (SS). In the second part of the study, biogas and methane production rates of anaerobic batch reactor fed with the ultrasound pretreated OMW samples were compared with the results of control reactor fed with untreated OMW in order to determine the effect of sonication. A nonparametric statistical procedure, Mann-Whitney U test, was used to compare biogas and methane production from anaerobic batch reactors for control and ultrasound pretreated samples. Results showed that application of low frequency ultrasound to OMW significantly improved both biogas and methane production in anaerobic batch reactor fed with the wastewater (p<0.05). Anaerobic batch reactor fed with ultrasound pretreated diluted OMW produced approximately 20% more biogas and methane compared with the untreated one (control reactor). The overall results indicated that low frequency ultrasound pretreatment increased soluble COD in OMW and subsequently biogas production.

Anaerobic digestibility of estrogens in wastewater sludge: effect of ultrasonic pretreatment

BACKGROUND

Estrogenic compounds have been detected in the secondary effluents and in the biosolids from conventional wastewater treatment plants, which are not designed for their removal. Furthermore, existing limited studies on anaerobic digestibility of estrogens report conflicting results. The objective of the present work was to determine the fate and anaerobic digestibility of estrogenic compounds in various types of sludge including primary sludge (PS), waste activated sludge (WAS), and anaerobically digested sludge (seed).

METHODS

Estrone (E1) and 17-β estradiol (E2) were chosen as the model estrogenic compounds. Initially batch adsorption was conducted to determine the extent of adsorption and isotherm of E1 on various sludge. Thereafter, batch anaerobic digestion of E1 and E2 was conducted in various sludge using So/X ratio of 4 gCOD/gVSS in 250 ml bottles. The effect of earlier optimized ultrasonication dosage on the anaerobic digestion of E1 and E2 was also characterized. Estrogenicity of the digested samples was determined by the YES assay.

RESULTS

Most of E1 and E2 was adsorbed on the biosolids and the Freundlich isotherm fitted the experimental data well. No anaerobic digestion of E1 and E2 was found in any of the sludge tested, and the estrogenicity of the sludge measured by YES assay increased during digestion due to the formation of E2 from E1 in a reduced environment. Ultrasonication decreased the initial mass of E1 and E2 by 20% in the sonicated digester as compared to control digester, however, there was no further decrease in E1 and E2 during digestion.

CONCLUSIONS

Most of the estrogenic compounds partitioned onto the solids and remained there during digestion. Ultrasonication pretreatment reduced the estrogen burden for the digester due to advance oxidation, but no further removal of the estrogens occurred in the digester.

Effect of mild-temperature H2O2 oxidation on solubilization and anaerobic digestion of waste activated sludge

Efficient sludge management is among the most challenging issues in wastewater treatment today, and anaerobic digestion is regarded as a viable solution. Mild-temperature H202 oxidation was examined for enhanced solubilization and biogas production of waste activated sludge (WAS). The effects of pretreatment factors (i.e. temperature and H202 concentration) on the degree of WAS disintegration (DD) and biogas yield (BY) were assessed by response surface analysis within the design space of 60-90 degrees C and 0-200mM H202. Significant sludge disintegration (up to 23.0% DD) and visibly enhanced BY (up to 26.9%) were shown in the pretreatment trials. Two response surface models to describe how DD and BY respond to changes in the pretreatment conditions were successfully constructed (R2 > 0.95, p < 0.05). The models showed totally different response surface shapes, indicating the DD and BY were influenced by pretreatment conditions in very different ways. DD was dominantly affected by temperature and showed higher model responses at the high-temperature region, while the BY response peaked in the low-temperature and mid-level H2O2 region. This observation implies that the enhanced solubilization of WAS was not directly translated into an increase in biogas production. Our results showed that WAS can be efficiently disintegrated by H202 oxidation under mild-temperature conditions for enhanced anaerobic digestibility. Within the explored region of pretreatment conditions, the maximum BY was estimated to be 82.1 mL/gCODadded (32.8% greater than the untreated control) at (60.0 degrees C, 74.2 mM H2O2).

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.

Impact of secondary treatment types and sludge handling processes on estrogen concentration in wastewater sludge

Endocrine-disrupting compounds (EDCs), such as estrogen, are known to be present in the aquatic environment at concentrations that negatively affect fish and other wildlife. Wastewater treatment plants (WWTPs) are major contributors of EDCs into the environment. EDCs are released via effluent discharge and land application of biosolids. Estrogen removal in WWTPs has been studied in the aqueous phase; however, few researchers have determined estrogen concentration in sludge. This study focuses on estrogen concentration in wastewater sludge as a result of secondary treatment types and sludge handling processes. Grab samples were collected before and after multiple treatment steps at two WWTPs receiving wastewater from the same city. The samples were centrifuged into aqueous and solid phases and then processed using solid phase extraction. Combined natural estrogens (estrone, estradiol and estriol) were measured using an enzyme-linked immunosorbent assay (ELISA) purchased from a manufacturer. Results confirmed that activated sludge treatments demonstrate greater estrogen removal compared to trickling filters and mass concentration of estrogen was measured for the first time on trickling filter solids. Physical and mechanical sludge treatment processes, such as gravity thickeners and centrifuges, did not significantly affect estrogen removal based on mass balance calculations. Dissolved air flotation thickening demonstrated a slight decrease in estrogen concentration, while anaerobic digestion resulted in increased mass concentration of estrogen on the sludge and a high estrogen concentration in the supernatant. Although there are no state or federally mandated discharge effluent standards or sludge application standards for estrogen, implications from this study are that trickling filters would need to be exchanged for activated sludge treatment or followed by an aeration basin in order to improve estrogen removal. Also, anaerobic digestion may need to be replaced with aerobic digestion for sludge that is intended for land application.

Photolysis and photocatalysis of ibuprofen in aqueous medium: characterization of by-products via liquid chromatography coupled to high-resolution mass spectrometry and assessment of their toxicities against Artemia salina

The degradation of the pharmaceutical compound ibuprofen (IBP) in aqueous solution induced by direct photolysis (UV-A and UV-C radiation) and photocatalysis (TiO2 /UV-A and TiO2 /UV-C systems) was evaluated. Initially, we observed that whereas photocatalysis (both systems) and direct photolysis with UV-C radiation were able to cause an almost complete removal of IBP, the mineralization rates achieved for all the photodegradation processes were much smaller (the highest value being obtained for the TiO2 /UV-C system: 37.7%), even after an exposure time as long as 120 min. Chemical structures for the by-products formed under these oxidative conditions (11 of them were detected) were proposed based on the data from liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) analyses. Taking into account these results, an unprecedented route for the photodegradation of IBP could thus be proposed. Moreover, a fortunate result was achieved herein: tests against Artemia salina showed that the degradation products had no higher ecotoxicities than IBP, which possibly indicates that the photocatalytic (TiO2 /UV-A and TiO2 /UV-C systems) and photolytic (UV-C radiation) processes can be conveniently employed to deplete IBP in aqueous media.

Removal and factors influencing removal of sulfonamides and trimethoprim from domestic sewage in constructed wetlands

Twelve pilot-scale constructed wetlands with different configurations were set up in the field to evaluate the removal and factors that influence removal of sulfonamides (sulfadiazine, sulfapyridine, sulfacetamide, sulfamethazine and sulfamethoxazole) and trimethoprim from domestic sewage. The treatments included four flow types, three substrates, two plants and three hydraulic loading rates across two seasons (summer and winter). Most target antibiotics were efficiently removed by specific constructed wetlands; in particular, all types of constructed wetlands performed well for the degradation of sulfapyridine. Flow types were the most important influencing factor in this study, and the best removal of sulfonamides was achieved in vertical subsurface-flow constructed wetlands; however, the opposite phenomenon was found with trimethoprim. Significant relationships were observed between antibiotic degradation and higher temperature and redox potential, which indicated that microbiological pathways were the most probable degradation route for sulfonamides and trimethoprim in constructed wetlands.

Effect of microwave hydrolysis on transformation of steroidal hormones during anaerobic digestion of municipal sludge cake

Fate and removal of 16 steroidal (estrogenic, androgenic and progestogenic) hormones were studied during advanced anaerobic digestion of sludge cake using microwave (MW) pretreatment. Effect of pretreatment temperature (80, 120, 160 °C), operating temperature (mesophilic at 35 ± 2 °C, thermophilic at 55 ± 2 °C) and sludge retention time (SRT: 20, 10, 5 days) were studied employing eight lab-scale semi-continuously fed digesters. To determine the potential effect of MW hydrolysis, hormones were quantified in total (sorbed + soluble) and supernatant (soluble) phases of the digester influent and effluent streams. Seven of 16 hormones were above the method reporting limit (RL) in one or more of the samples. Hormone concentrations in total phase of un-pretreated (control) and pretreated digester feeds ranged in <157-2491 ng/L and <157-749 ng/L, respectively. The three studied factors were found to be statistically significant (95% confidence level) in removal of one or more hormones from soluble and/or total phase. MW hydrolysis of the influent resulted in both release (from sludge matrix) and attenuation of hormones in the soluble phase. Accumulation of estrone (E1) as well as progesterone (Pr) and androstenedione (Ad) in most of the digesters indicated possible microbial transformations among the hormones. Compared to controls, all pretreated digesters had lower total hormone concentrations in their influent streams. At 20 days SRT, highest total removal (E1+E2+Ad +Pr) was observed for the thermophilic control digester (56%), followed by pretreated mesophilic digesters at 120 °C and 160 °C with around 48% efficiency. In terms of conventional performance parameters, relative (to control) improvements of MW pretreated digesters at a 5-d SRT ranged in 98-163% and 57-121%, for volatile solids removal and methane production, respectively.

Occurrence and removal of antibiotics in a municipal wastewater reclamation plant in Beijing, China

In this study, we investigated the occurrences and fates of eight quinolones (QNs), nine sulfonamides (SAs), and five macrolides (MCs) in a wastewater reclamation plant (WRP) in Beijing, China. Among all the 22 antibiotics considered, quinolones were the dominant antibiotics in all samples (4916ngL(-1) in influents, 1869ngL(-1) in secondary effluents, 123ngL(-1) in tertiary effluents, and 9200μgkg(-1) in sludge samples), followed by sulfonamides (2961ngL(-1) in influents, 1053ngL(-1) in secondary effluents, 25.9ngL(-1) in tertiary effluents, and 63.7μgkg(-1) in sludge samples) and macrolides (365ngL(-1) in influents, 353ngL(-1) in secondary effluents, 24.7ngL(-1) in tertiary effluents, and 32.7μgkg(-1) in sludge samples). The removal efficiencies of the target antibiotics were limited (-32 to 78%) in the conventional treatment. This study indicated that quinolones were mainly removed from the secondary clarifier, and sulfonamides were degraded in the oxic tank; while macrolides were considered as persistent during the conventional treatment. After the advance treatment, the target antibiotics could be effectively removed at high rates (85-100%), and the risks of antibiotic contamination significantly decreased. However, risk assessment showed that the risk of ofloxacin and erythromycin on organisms in recycled water needed further investigations.

Degradation of sulfonamides antibiotics in lake water and sediment

Degradation of three sulfonamides (SAs), namely sulfamethoxazole (SMX), sulfamethazine (SMZ), and sulfadimethoxine (SDM) in surface water and sediments collected from Taihu Lake and Dianchi Lake, China was investigated in this study. The surface water (5-10 cm) was collected from the east region of Taihu Lake, China. Two sets of degradation experiments were conducted in 3-L glass bottles containing 2 L of fresh lake water and 100 μg/L of individual SAs aerated by bubbling air at a rate of approximately 1.2 L/min, one of which was sterilized by the addition of NaN3 (0.1%). Sediment samples were taken from Taihu Lake and Dianchi Lake, China. For the sediment experiment, 5 g of sediment were weighed into a 50-mL glass tube, with 10 mg/kg of individual SAs. Different experimental conditions including the sediment types, sterilization, light exposure, and redox condition were also considered in the experiments. The three SAs degraded in lake water with half-lives (t 1/2) of 10.5-12.9 days, and the half-lives increased significantly to 31.9-49.8 days in the sterilized water. SMZ and SDM were degraded by abiotic processes in Taihu and Dianchi sediments, and the different experimental conditions and sediments characteristics had no significant effect on their declines. SMX, however, was mainly transformed by facultative anaerobes in Taihu and Dianchi sediments under anaerobic conditions, and the degradation rate of SMX in non-sterile sediment (t 1/2 of 9.6-16.7 days) were higher than in sterilized sediment (t 1/2 of 18.7-135.9 days). Under abiotic conditions, degradation of SMX in Dianchi sediment was faster than in Taihu sediment, probably due to the higher organic matter content and inorganic photosensitizers concentrations in Dianchi sediment. High initial SAs concentration inhibited the SAs degradation, which was likely related to the inhibition of microorganism activities by high SAs levels in sediments. Results from this study could provide information on the persistence of commonly used sulfanomides antibiotics in lake environment.

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.

Fate of estrogenic hormones in wastewater and sludge treatment: A review of properties and analytical detection techniques in sludge matrix

Estrogenic hormones (estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2)) are the major contributor to the total estrogenicity in waterways. Presence of these compounds in biosolids is also causing concern in terms of their use as soil amendment. In comparison with wastewater treatment, removal of estrogenic compounds in sewage sludge has received less attention. This paper presents a literature review regarding the source and occurrence of these pollutants in our environment. The removal pathways of estrogenic compounds in engineered systems, such as full-scale wastewater treatment plants (WWTPs), are also discussed. Review of the fate studies revealed that activated sludge system with nutrient removal shows very high (>90%) removal of estrogenic hormones in most of the cases. Although, aerobic digestion showed better attenuation of estrogenic compounds, anaerobic digestion increased the overall estrogenicity of biosolids. Finally, this paper highlights the challenges involved in analytical determination of these compounds in sewage sludge matrix.

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.

The effect of thermal hydrolysis pretreatment on the anaerobic degradation of nonylphenol and short-chain nonylphenol ethoxylates in digested biosolids

The presence of micropollutants can be a concern for land application of biosolids. Of particular interest are nonylphenol diethoxylate (NP(2)EO), nonylphenol monoethoxylate (NP(1)EO), and nonylphenol (NP), collectively referred to as NPE, which accumulate in anaerobically digested biosolids and are subject to regulation based on the environmental risks associated with them. Because biosolids are a valuable nutrient resource, it is essential that we understand how various treatment processes impact the fate of NPE in biosolids. Thermal hydrolysis (TH) coupled with mesophilic anaerobic digestion (MAD) is an advanced digestion process that destroys pathogens in biosolids and increases methane yields and volatile solids destruction. We investigated the impact of thermal hydrolysis pretreatment on the subsequent biodegradation of NPE in digested biosolids. Biosolids were treated with TH, anaerobic digestion, and aerobic digestion in laboratory-scale reactors, and NPE were analyzed in the influent and effluent of the digesters. NP(2)EO and NP(1)EO have been observed to degrade to the more estrogenic NP under anaerobic conditions; therefore, changes in the ratio of NP:NPE were of interest. The increase in NP:NPE following MAD was 56%; the average increase of this ratio in four sets of TH-MAD samples, however, was only 24.6 ± 3.1%. In addition, TH experiments performed in pure water verified that, during TH, the high temperature and pressure alone did not directly destroy NPE; TH experiments with NP added to sludge also showed that NP was not destroyed by the high temperature and pressure of TH when in a more complex sludge matrix. The post-aerobic digestion phases removed NPE, regardless of whether TH pretreatment occurred. This research indicates that changes in biosolids processing can have impacts beyond just gas production and solids destruction.

Fate of steroid hormones and endocrine activities in swine manure disposal and treatment facilities

Manure may contain high concern endocrine-disrupting compounds (EDCs) such as steroid hormones, naturally produced by pigs, which are present at μgL(-1) levels. Manure may also contain other EDCs such as nonylphenols (NP), polycyclic aromatic hydrocarbons (PAHs) and dioxins. Thus, once manure is applied to the land as soil fertilizer these compounds may reach aquifers and consequently living organisms, inducing abnormal endocrine responses. In France, manure is generally stored in anaerobic tanks prior spreading on land; when nitrogen removal is requested, manure is treated by aerobic processes before spreading. However, little is known about the fate of hormones and multiple endocrine-disrupting activities in such manure disposal and treatment systems. Here, we determined the fate of hormones and diverse endocrine activities during manure storage and treatment by combining chemical analysis and in vitro quantification of estrogen (ER), aryl hydrocarbon (AhR), androgen (AR), pregnane-X (PXR) and peroxysome proliferator-activated γ (PPARγ) receptor-mediated activities. Our results show that manure contains large quantities of hormones and activates ER and AhR, two of the nuclear receptors studied. Most of these endocrine activities were found in the solid fraction of manure and appeared to be induced mainly by hormones and other unidentified pollutants. Hormones, ER and AhR activities found in manure were poorly removed during manure storage but were efficiently removed by aerobic treatment of manure.

The effectiveness of anaerobic digestion in removing estrogens and nonylphenol ethoxylates

The fate and behaviour of two groups of endocrine disrupting chemicals, steroid estrogens and nonylphenol ethoxylates, have been evaluated during the anaerobic digestion of primary and mixed sewage sludge under mesophilic and thermophilic conditions. Digestion occurred over six retention times, in laboratory scale reactors, treating sludges collected from a sewage treatment works in the United Kingdom. It has been established that sludge concentrations of both groups of compounds demonstrated temporal variations and that concentrations in mixed sludge were influenced by the presence of waste activated sludge as a result of transformations during aerobic treatment. The biodegradation of total steroid estrogens was >50% during primary sludge digestion with lower removals observed for mixed sludge, which reflected bulk organic solids removal efficiencies. The removal of nonylphenol ethoxylates was greater in mixed sludge digestion (>58%) compared with primary sludge digestion and did not reflect bulk organic removal efficiencies. It is apparent that anaerobic digestion reduces the concentrations of these compounds, and would therefore be expected to confer a degree of protection against exposure and transfer of both groups of compounds to the receiving/re-use environment.

Should we pretreat solid waste prior to anaerobic digestion? An assessment of its environmental cost

Many studies have shown the effectiveness of pretreatments prior to anaerobic digestion of solid wastes, but to our knowledge, none analyzes their environmental consequences/costs. In this work, seven different pretreatments applied to two types of waste (kitchen waste and sewage sludge) have been environmentally evaluated by using life cycle assessment (LCA) methodology. The results show that the environmental burdens associated to the application of pretreatments prior to anaerobic digestion cannot be excluded. Among the options tested, the pressurize-depressurize and chemical (acid or alkaline) pretreatments could be recommended on the basis of their beneficial net environmental performance, while thermal and ozonation alternatives require energy efficiency optimization to reduce their environmental burdens. Reconciling operational, economic and environmental aspects in a holistic approach for the selection of the most sustainable option, mechanical (e.g., pressurize-depressurize) and chemical methods appear to be the most appropriate alternatives at this stage.

Enhanced biomethanation of kitchen waste by different pre-treatments

Five different pre-treatments were investigated to enhance the solubilisation and anaerobic biodegradability of kitchen waste (KW) in thermophilic batch and continuous tests. In the batch solubilisation tests, the highest and the lowest solubilisation efficiency were achieved with the thermo-acid and the pressure-depressure pre-treatments, respectively. However, in the batch biodegradability tests, the highest cumulative biogas production was obtained with the pressure-depressure method. In the continuous tests, the best performance in terms of an acceptable biogas production efficiency of 60% and stable in-reactor CODs and VFA concentrations corresponded to the pressure-depressure reactor, followed by freeze-thaw, acid, thermo-acid, thermo and control. The maximum OLR (5 g COD L(-1) d(-1)) applied in the pressure-depressure and freeze-thaw reactors almost doubled the control reactor. From the overall analysis, the freeze-thaw pre-treatment was the most profitable process with a net potential profit of around 11.5 € ton(-1) KW.

Fate of endocrine-active compounds during municipal biosolids treatment: a review

For two decades, the fates of endocrine-disrupting compounds (EDCs) across various wastewater treatment processes have been studied using chemical and in vitro bioassay measurements. In comparison, little work has been conducted to track the fates of EDCs during municipal biosolids stabilization, particularly using bioassay approaches. This leads to knowledge gaps with respect to understanding which single or combined biosolid treatments facilitate EDC removal, and what the total endocrine-active potency of treated biosolids might be. These unknowns in turn heighten public opposition and distrust of biosolids reuse applications. This review aims to summarize what is currently known regarding EDC removal during commonly used full-scale biosolids treatment processes and highlights analytical challenges that are relevant when in vitro bioassays and chemical analyses are applied to biosolids samples.

Influence of feed characteristics on the removal of micropollutants during the anaerobic digestion of contaminated sludge

The removal of 13 polycyclic aromatic hydrocarbons, 7 polychlorobiphenyls and nonylphenol was measured during the continuous anaerobic digestion of five different sludge samples. The reactors were fed with one of the following: primary/secondary sludge (PS/SS), thermally treated PS, cellulose-added SS, or SS augmented with dissolved and colloidal matter (DCM). These various feeding conditions induced variable levels of micropollutant bioavailability (assumed to limit their biodegradation) and overall metabolism (supposed to be linked to micropollutant metabolism throughout co-metabolism). On the one hand, overall metabolism was higher with secondary sludge than with primary and the same was observed for micropollutant removal. However, when overall metabolism was enhanced thanks to cellulose addition, a negative influence on micropollutant removal was observed. This suggests that either the co-metabolic synergy would be linked to a specific metabolism or co-metabolism was not the limiting factor in this case. On the other hand, micropollutant bioavailability was presumably diminished by thermal treatment and increased by DCM addition. In both cases, micropollutant removal was reduced. These results suggest that neither overall metabolism nor bioavailability would absolutely limit micropollutant removal. Each phenomenon might alternatively predominate depending on the feed characteristics.