Self-cleaning foulant attachment on near-infrared responsive photocatalytic membrane for continuous dynamic removing antibiotics in sewage effluent environment

Bifunctional photocatalytic nanofiltration (PNF) membrane has become a reliable frontier technique for removing refractory organic micropollutants. However, the active mitigated fouling mechanism from the microscopic perspective during its long-term operation of purifying real micro-polluted water is rarely studied. Herein, with an integrated use of QSense Explorer and confocal laser scanning microscope techniques, self-cleaning foulant attachment on an activated and customized near-infrared responsive polymeric PNF (termed as nPNF) membrane with good service performance for continuous dynamic removing antibiotics in sewage effluent environment was firstly elucidated. Time-dependent changes in dissipation oscillation frequency, sensed mass and the visualized foulant spatial distribution all indicated that there were only sporadic foulant attachment, an extremely low fouling layer thickness and irreversible fouling rate on/of the activated nPNF membrane top surface, thereby endowing it with excellent self-cleaning characteristic. This is probably because the reactive oxygen species (mainly •O2- and •OH) concurrently destroys the integrity of fouling layer and its internal adhesion structure, transforming part of the irreversible fouling on nPNF membrane surface into reversible one that is easy to wash off. These new horizons provided useful insight on the fate of selected antibiotics in the to-be-removed stage and self-cleaning foulant attachment of PNF membrane.

A synthesis on the sub-lethal toxicity of atenolol, a beta-blocker, in teleost fish

Blood pressure medications like atenolol are detected in aquatic ecosystems. The objectives here were to (1) map the global presence of atenolol in surface water and sewage; (2) present current knowledge regarding removal efficiency and degradation of atenolol; (3) identify biological endpoints sensitive to exposure; (4) reveal molecular biomarkers that may be useful for exposure studies in fish; (5) determine whether toxicology studies are within environmental relevance. In fish, atenolol exposure affects endocrine and immune systems, metabolism, and epigenetics. Fewer than half of all studies measuring biological responses use environmentally-relevant concentrations. Heart rate appeared most sensitive to atenolol exposure relative to other endpoints. Data are lacking for behavioral responses to atenolol. Molecular biomarkers for atenolol may include those associated with acute kidney injury, cholestasis, and hypertriglyceridemia. Head kidney and liver may therefore be useful for detecting atenolol-induced effects. This review synthesizes knowledge regarding atenolol-induced toxicity in fish.

Effects of potential microplastics in sewage effluent on Nile Tilapia and photocatalytic remediation with zinc oxide nanoparticles

The aim of the present study was a qualitative assessment of potential microplastics (MPs) in the sewage effluent collected from a local sewage treatment plant located in Riyadh City, Saudi Arabia. The composite samples of domestic sewage effluent were subjected to UV (ultraviolet) light-induced zinc oxide nanoparticles (ZnONPs) mediated photocatalysis. The first phase of the study included the synthesis of the ZnONPs with an extensive characterization. The synthesized nanoparticles were 220 nm in size with a characteristic spherical/hexagonal shape. These NPs were then used at three different concentrations (10 mM, 20 mM, and 30 mM) for the UV light-induced photocatalysis. A shift in the Raman spectra on photodegradation mirrored the surface changes of the functional groups shown by the FTIR spectra; presence of functional groups containing oxygen and C-C bonds associated with oxidation and chain scission. SEM micrographs showed photodegraded particles. Complementary elemental maps from the EDS analysis showed the presence of C, O, and Cl suggesting the potential presence of MPs. The O/C ratio was used to assess potential oxidation degree. In addition, an evaluation of the toxicological effects of the potential MPs in the sewage effluent on Nile tilapia (Oreochromis niloticus) exposed to the effluent at two concentrations (50% and 75%) elicited a marked response in the endpoints evaluated; EROD activity, MDA (malondialdehyde), 8-oxo-2'-deoxyguanosine levels in and AChE (acetylcholinesterase) activity in the brain. Thus, the key results provide new insights into the use of clean technologies to combat global MP pollution in aquatic ecosystems.

Lipidomic, metabolomic, and behavior responses of zebrafish (Danio rerio) exposed to environmental levels of the beta blocker atenolol

Blood pressure medications are used to treat hypertension; however, low concentrations of beta-blockers in water systems can negatively impact aquatic wildlife. Here, we conducted a metabolic and behavioral study investigating atenolol, a beta-blocker frequently detected in global wastewater systems. The objectives were to determine the effects of low-level atenolol exposure on early stages of zebrafish. We measured survival, deformities, heartbeat, mitochondrial function, lipid and amino acid profiles, and locomotor activity to discern mechanisms of metabolic disruption. We hypothesized that atenolol disrupts lipid metabolism, which would negatively impact locomotor activity. Atenolol showed no overt toxicity to larval zebrafish up to 10 μg/L and deformities were infrequent (<5 %), and included cardiac edema and larvae with kinked tails. A hatch delay was observed at 2-day post-fertilization (dpf) for fish exposed to >5 μg/L atenolol. Heart rates were reduced in 2 and 3 dpf in fish treated with >500 ng/L atenolol. There was no change in oxygen consumption rates (basal and maximum respiration) of embryos when exposed to a range of atenolol concentrations, suggesting mitochondrial respiration was intact. Oil red staining for lipid content in larvae showed a global reduction in lipids with 10 μg/L exposure, prompting deeper investigation into the lipid profiles. Lipidomics quantified 86 lipids and revealed reduced abundance in Ceramide 18: 1 16:0 (Cer_NS d18:1_16:0), Ether linked Phosphatidylethanolamine 16:0 22:6 (EtherPE 16:0e_22:6), and Ether linked Phosphatidylcholine 16:0 22:6 (EtherPC 16:0e_22:6). We also quantified 12 amino acids and observed a subtle dose-dependent reduction in the levels of L-Histidine. Exposure to atenolol did not impact larval locomotor activity based on a Visual Motor Response test. Taken together, atenolol at environmentally relevant levels decreased heart rate of developing zebrafish and altered lipid content. As such, exposure to beta-blockers like atenolol may have negative consequences for developmental trajectories and growth of aquatic species.

Simultaneous degradation and separation of antibiotics in sewage effluent by photocatalytic nanofiltration membrane in a continuous dynamic process

Bifunctional photocatalytic nanofiltration (PNF) membrane is increasingly concerned in practical micro-polluted water purification, but there are still several bottlenecks that inhibit its practicality. In this context, the feasibility of a novel metal-free and visible light-responsive surface-anchored PNF membrane for simultaneously removing target antibiotics in real sewage effluent in a continuous dynamic process was explored. The results showed that the optimal PNF-4 membrane was expectedly consisted of an inside tight sub-nanopore structured separation layer and an outside thinner, smoother, super hydrophilic mesoporous degradation layer, respectively. Consequently, the activated PNF-4 membrane could synergistically reduce trimethoprim and sulfamethoxazole concentrations to below two orders of magnitude, accompanying with almost constant high water permeability, suggesting that the hydrophilic modification of the mesoporous degradation layer basically offsets its inherent hydraulic resistance. Also, after repeating the fouling-physical rinsing process three times lasted for 78 h, only sporadic adherent contaminants remained onto the top surface, together with the minimal total and irreversible fouling ratios (as low as 7.2% and 1.2%, respectively), strongly demonstrated that PNF-4 membrane displayed good self-cleaning performance. Undoubtedly, this will significantly reduce its potential cleaning frequency and maintenance cost in long-term operation. Meanwhile, the acute and chronic biotoxicities of its permeate to Virbrio qinghaiensis sp. -67 were also reduced sharply to 2.22% and 0.45%, respectively. All of these evidences suggest that the dual functions of PNF-4 membrane are synergetic in an uninterrupted permeating process. It will provide useful insights for continuously enhancing the practicality and effectiveness of PNF membrane in actual micro-polluted water purification scenarios.

Phosphorus compounds in the dissolved and particulate phases in urban rivers and a downstream eutrophic lake as analyzed using 31P NMR

Phosphorus (P) discharges from human activities result in eutrophication of lakes. We investigated whether the forms of phosphorus (P) in rivers with high effluent loads flowing through urban areas of Sapporo, Japan, were transformed when transported downstream into a eutrophic lake, namely Lake Barato. We hypothesized that the inorganic P supplied from the rivers might be transformed to organic forms in the lake. The results showed that soluble reactive phosphorus (SRP) and particulate inorganic phosphorus (PIP) dominated in the river discharge to the lake. Suspended solids in the rivers were rich in iron (Fe) so PIP was associated with Fe. A comparison of the concentrations at the river mouth and 4.5 km downstream showed that the concentrations of SRP and PIP were lower at 4.5 km downstream than at the river mouth, whereas the concentrations of organic P (i.e., dissolved organic phosphorus and particulate organic phosphorus) were similar. The results from solution ³¹P nuclear magnetic resonance spectroscopy of lake water showed that pyrophosphate was only present in the particulate fraction, while orthophosphate diesters (DNA-P) were only present in the dissolved fraction. Riverine samples contained orthophosphate (ortho-P) only, while lake samples contained ortho-P, orthophosphate monoesters, and DNA-P. The results suggest that the P forms, particularly those of dissolved P, shifted from inorganic to organic forms as the water was discharged from the river to the lake.

Bacterial diversity and predicted enzymatic function in a multipurpose surface water system - from wastewater effluent discharges to drinking water production

BACKGROUND

Rivers and lakes are used for multiple purposes such as for drinking water (DW) production, recreation, and as recipients of wastewater from various sources. The deterioration of surface water quality with wastewater is well-known, but less is known about the bacterial community dynamics in the affected surface waters. Understanding the bacterial community characteristics -from the source of contamination, through the watershed to the DW production process-may help safeguard human health and the environment.

RESULTS

The spatial and seasonal dynamics of bacterial communities, their predicted functions, and potential health-related bacterial (PHRB) reads within the Kokemäenjoki River watershed in southwest Finland were analyzed with the 16S rRNA-gene amplicon sequencing method. Water samples were collected from various sampling points of the watershed, from its major pollution sources (sewage influent and effluent, industrial effluent, mine runoff) and different stages of the DW treatment process (pre-treatment, groundwater observation well, DW production well) by using the river water as raw water with an artificial groundwater recharge (AGR). The beta-diversity analysis revealed that bacterial communities were highly varied among sample groups (R = 0.92, p <  0.001, ANOSIM). The species richness and evenness indices were highest in surface water (Chao1; 920 ± 10) among sample groups and gradually decreased during the DW treatment process (DW production well; Chao1: 320 ± 20). Although the phylum Proteobacteria was omnipresent, its relative abundance was higher in sewage and industrial effluents (66-80%) than in surface water (55%). Phyla Firmicutes and Fusobacteria were only detected in sewage samples. Actinobacteria was more abundant in the surface water (≥13%) than in other groups (≤3%). Acidobacteria was more abundant in the DW treatment process (≥13%) than in others (≤2%). In total, the share of PHRB reads was higher in sewage and surface water than in the DW treatment samples. The seasonal effect in bacterial communities was observed only on surface water samples, with the lowest diversity during summer.

CONCLUSIONS

The low bacterial diversity and absence of PHRB read in the DW samples indicate AGR can produce biologically stable and microbiologically safe drinking water. Furthermore, the significantly different bacterial communities at the pollution sources compared to surface water and DW samples highlight the importance of effective wastewater treatment for protecting the environment and human health.

Reevaluation of the contributions of reactive intermediates to the photochemical transformation of 17β-estradiol in sewage effluent

Photodegradation of the natural steroid 17β-estradiol (E2), an endocrine-disrupting hormone that has been widely detected in aquatic environments, was investigated in wastewater effluents at various pH ranges under simulated solar irradiation. The rate of E2 degradation in the sewage effluents was stable at pH 6.0-7.0 but suddenly increased from pH 8.0-10.0. The second-order reaction rate constants of E2 with ³EfOM* and CO₃^•- were measured to increase 11.0-fold and 18.0-fold from pH 6.0 to 10.0, respectively. Two main reasons are proposed for this sharp increase. First, the change in the ionization state of E2 made it susceptible to oxidation by triplet-state effluent organic matter (³EfOM*) and carbonate radicals (CO₃^•-). Second, the steady-state concentration of CO₃^•- increased with increasing pH. Indirect photolysis was suggested to be the main degradation pathway in the sewage effluents, and ³EfOM* was proposed to play a major role at pH 8.0-9.0, while CO₃^•- played a significant role at pH 10.0. In this study, EfOM was shown for the first time to inhibit the oxidation of E2 initiated by ³EfOM* and CO₃^•-. Thus, we suggest that EfOM plays a dual role in the photodegradation of E2: EfOM can not only be activated as ³EfOM* to degrade E2 but also can inhibit the degradation of E2 by reducing the E2 oxidation intermediate back to E2. The estrogenic activity of the photodegradation products was also studied. The in vitro estrogenic activity of E2 solutions decreased approximately as fast as the E2 photodegradation occurred in the effluent water at various pH values, suggesting that solar photodegradation in sewage effluents reduces the risk of endocrine disruption in waters impacted by E2 and subject to continuing inputs. The results of this study are important for predicting the environmental fate of endocrine-disrupting chemicals and developing methods for their removal from aquatic environments.

Potential environmental toxicity of sewage effluent with pharmaceuticals

Sewage effluent effects on the biochemical parameters of Astyanax bimaculatus organs were investigateted. Treated sewage was collected in a treatment plant; 43 compounds, among them, pharmaceuticals and hormones, were investigated. Caffeine, ciprofloxacin, clindamycin, ofloxacin, oxytetracycline, paracetamol, sulfadiazine, sulfamethoxazole, sulfathiazole and tylosin waste was detected in the collected material. Fish were divided into four groups: control, TSE (treated sewage effluent), TSE + P (TSE with increased concentration of five pharmaceuticals) and PTSE (TSE + P post-treated with O₃/H₂O₂/UV). Biochemical parameters were evaluated in different organs after 14-day exposure. TBARS levels increased significantly in the brain of animals in the TSE and TSE + P groups in comparison to the control. There was significant reduction in TBARS levels recorded for the liver, muscle and gills of animals in the PTSE group in comparison to those of animals in the other groups. AChE activity reduced in the muscle of animals in the groups showing the highest pharmaceutical concentrations. CAT activity in the liver of animals in groups exposed to pharmaceutical effluent was inhibited. GST activity increased in brain of animals in the TSE + P and PTSE groups, whereas reduced levels of this activity were observed in liver of animals in the TSE group. Increased GST activity was observed in the brain of animals in TSE + P and PTSE groups. Based on integrated biomarker response values, the TSE + P group presented greater changes in the analyzed parameters. Results point out that pharmaceutical waste can cause oxidative stress, as well as affect biochemical and enzymatic parameters in Astyanax sp. Post-treatment can also reduce damages caused to fish, even in case of the likely formation of metabolites. Based on these results, these metabolites can be less toxic than the original compounds; however, they were not able to fully degrade the pharmaceutical waste found in the sewage, which can interfere in fish metabolism.

Sewage Effluent Causes Metal Pollution of a Sub-tropical River System in Zimbabwe

Metal pollutants are persistent in the environment and of concern to human health. The aim of the study was to assess the distribution of metals (Cr, Fe, Pb, Mg and Cu) in Sebakwe River. Water and sediment samples were collected from upstream reference sites (4 and 5) and influenced downstream sites (1, 2 and 3) of the sewage effluent discharge point. Pb concentrations in water were significantly higher (p < 0.05) in sites 1 and 2 downstream of the sewage discharge point. In the sediments, the sites downstream of the effluent discharge point had significantly higher concentrations of Cu (p < 0.05) and Cr (p < 0.05). A comparison of metal concentration in water with World Health Organization and Standards Association of Zimbabwe standards revealed that the levels of Pb in water were above the recommended limits, posing a health risk to Pb poisoning for people living along Sebakwe River.

Medically-derived radionuclides levels in seven heterogeneous urban wastewater treatment plants: The role of operating conditions and catchment area

In nuclear medicine radionuclides are administered to patients both for diagnosis or treatment. Subsequently, the excreta from patients, enriched in radionuclides, enter the sewerage networks and reach wastewater treatment plants (TPs). Characterization of inflow wastewaters, sewage effluents and sewage sludges in the seven different urban WWTPs in the Barcelona Metropolitan Area (BMA) has been done and ¹³¹I, ^99mTc, ¹¹¹In, ⁶⁷Ga and ¹²³I concentrations were determined by gamma-spectroscopy. In order to explain the diversity of nuclear medicine short-lived radionuclide concentrations found in the BMA, mean sewage sludge ages and wastewater hydraulic retention times were determined, NM services located and patient management guidelines described. Results were found to vary greatly among the different TPs in inflow wastewaters, sewage effluents and sewage sludges. ¹³¹I and ^99mTc activity concentrations showed the highest values in most of the inflow wastewaters, sewage effluents and sewage sludges. In the integrated analysis of the present findings, a large-sized TP (320,000 m³/d) from the BMA urban wastewater treatment system shows higher levels and detection frequencies of medically-derived radionuclides. The maximums detected in the sludges from this TP, are partly explained by the relatively low sewage sludge ages. Furthermore, inflow wastewater hydraulic retention times and sludge ages in the TPs are long enough for decay of the short-lived nuclear medicine radionuclides studied (t_1/2 ≤ 8d) in such a way that TPs work as abatement systems and decrease the levels of radioactivity both in the effluent and in the final sludge. An integrated analysis of 7 TPs from the same system has been carried out to go further into the dynamics of medically-derived radionuclides in it.

River catchment responses to anthropogenic acidification in relationship with sewage effluent: An ecotoxicology screening application

Rising environmental pressures on water resources and resource quality associated with urbanisation, industrialisation, mining and agriculture are a global concern. In the current study the upper Olifants River catchment as case study was used, to show that acid mine drainage (AMD) and acid precipitation were the two most important drivers of possible acidification during a four-year study period. Over the study period 59% of the precipitation sampled was classified as acidic with a pH value below 5.6. Traces of acidification in the river system using aquatic organisms at different trophic levels were only evident in areas of AMD point sources. Data gathered from the ecotoxicology screening tools, revealed that discharge of untreated and partially treated domestic sewage from municipal sewage treatment works and informal housing partially mitigate any traces of acidification by AMD and acid precipitation in the main stem of the upper Olifants River. The outcome of the study using phytoplankton and macroinvertebrates as indicator organisms revealed that the high loads of sewage effluent might have played a major role in the neutralization of acidic surface water conditions caused by AMD and acid precipitation. Although previous multi-stage and microcosm studies confirmed the decrease in acidity and metals concentrations by municipal wastewater, the current study is the first to provide supportive evidence of this co-attenuation on catchment scale. These findings are important for integrated water resource management on catchment level, especially in river systems with a complex mixture of pollutants.

Using medically-derived iodine-131 to track sewage effluent in the Laurentian Great Lakes

Tracking sewage wastewater in a large lake is difficult. Concentrations of pharmaceuticals that can be used as indicator compounds are quickly diluted and not easy to measure. In this study, we examined the potential of using medically-derived iodine-131 (¹³¹I, t_½ = 8.02 d) as a tracer for Milwaukee sewage effluent in Lake Michigan. ¹³¹I activities in sewage effluent from two Milwaukee wastewater treatment plants (WWTPs) were measured in conjunction with ¹³¹I activities in water, sediment and biota in the Milwaukee Outer Harbor and Lake Michigan. ¹³¹I discharge rates from both WWTPS ranged from 34 ± 15 to 1807 ± 24 MBq d^-1, with average and median ¹³¹I discharges of 278 and 129 MBq d^-1. A budget of ¹³¹I in the Milwaukee Outer Harbor - based on measured sediment and water column inventories - showed that ∼11% of the ¹³¹I discharged to the harbor was scavenged to bottom sediments, ∼19% decayed in the harbor water column, and ∼70% was flushed out of the harbor to Lake Michigan. From this budget, we derived a harbor flushing rate of 3.1 days. In Lake Michigan, ¹³¹I activity was found in Cladophora algae (undetected to 91 ± 2 Bq kg^-1) along ∼40 km of shoreline. Benthic trawl samples showed ¹³¹I activity up to 8 km from shore. Calculated ¹³¹I length scales were 30 km alongshore and 3.4 km offshore and corresponded to sewage effluent dispersion rates of ∼2.6 km d^-1 and ∼0.3 km d^-1 in along- and offshore directions. Using ¹³¹I as a tracer of sewage effluent from other coastal municipalities to the Laurentian Great Lakes appears feasible, particularly for larger (>10⁵) population centers.

Monitoring for a specific management objective: protection of shorebird foraging habitat adjacent to a waste water treatment plant

Intertidal invertebrates are often used in environmental monitoring programs as they are good indicators of water quality and an important food source for many species of fish and birds. We present data from a monitoring program where the primary aim is to report on the condition of the potential invertebrate prey abundance, biomass and diversity for migrating shorebirds on mudflats adjacent to a waste water treatment plant in a Ramsar listed wetland in Victoria, Australia. A key threat to the foraging habitat at this site has been assessed as a reduction in potential prey items as a result of the changes to the waste water treatment processes. We use control charts, which summarise data from intertidal mudflats across the whole shoreline of the adjacent waste water treatment plant, to elicit a management response when trigger levels are reached. We then examine data from replicate discharge and control sites to determine the most appropriate management response. The monitoring program sits within an adaptive management framework where management decisions are reviewed and the data is examined at different scales to evaluate and modify our models of the likely outcomes of management actions. This study provides a demonstration of the process undertaken in a year when trigger levels were reached and a management decision was required. This highlights the importance of monitoring data from a range of scales in reducing uncertainty and improving decision making in complex systems.

Removal and attenuation of sewage effluent combined tracer signals of phosphorus, caffeine and saccharin in soil

Contaminants in septic tank effluent (STE) are expected to be removed by the soil system before discharging to the environment. However, potential contaminants such as phosphorus (P), caffeine and artificial sweeteners do find their way to watercourses impacting aquatic eco systems. In this study, the attenuation of STE P, caffeine and saccharin were investigated in untreated soil and in soil with reduced microbial activity, in aqueous solutions and in the complex matrix of STE. Time series sorption and desorption experiments using batch equilibrium and a column experiment of STE P attenuation were conducted. The results revealed that the soil distribution coefficients (K_d) were: P 81.57 > caffeine 22.16 > saccharin 5.98 cm³/g, suggesting greater soil affinity to P adsorption. The data revealed that 80% of saccharin and 33% of caffeine attenuation was associated with microbial activities rather than adsorption processes. However, a complete removal of saccharin and caffeine did not occur during the equilibration period, suggesting their leaching potential. The dominant mechanism of P attenuation was adsorption (chemical and physical), yielding P retention of >73% and 35% for P in aqueous solution and in STE matrix, respectively, for batch equilibrium. The soil in the column acted as effluent P sink retaining 125 μg P/g soil of effluent P. The attenuation of P, caffeine and saccharin in the aqueous solution was greater than in STE, suggesting that the complex composition of STE reduced soil adsorption ability, and that other substances present in STE may be competing for soil binding sites. The data revealed that caffeine and P had similarities in the interaction with soils and thus caffeine may be considered as a STE tracer of anthropogenic source of P in receiving waters.

The effect of wastewater effluent derived ligands on copper and zinc complexation

The shift toward bioavailability-based standards for metals such as copper and zinc not only improves the ecological relevance of the standard but also introduces significant complexity into assessing compliance. This study examined differences in the copper and zinc complexation characteristics of effluents from a range of different sewage treatment works and in relation to so-called 'natural' samples. This information is essential to determine whether the inclusion of effluent-specific complexation characteristics within the regulatory framework could enhance the environmental relevance of compliance criteria. The data show that for copper, binding affinity was not greater than that measured for materials derived from the receiving water environment, with a mean log K of between 4.4 and 5.15 and mean complexation capacity ranging from 38 to 120 μg/mg dissolved organic carbon (DOC) for effluents compared with a log K of 5.6 and complexation capacity of 37 μg/mg DOC for the Suwannee River fulvic acid. For zinc, however, effluents exhibited a much higher complexation capacity, with effluent means ranging from 3 to 23 μg/mg DOC compared with the Suwannee River fulvic acid, for which the complexation capacity could not be determined. Synthetic ligands in sewage effluent, such as ethylenediaminetetraacetic acid (EDTA), are implicated as contributing to these observed differences. This suggests that the current biotic ligand models for zinc might overstate the risk of harm in effluent-impacted waters. The data also show that the copper and zinc complexation characteristics of effluent samples obtained from the same sewage treatment works were less different from one another than those of effluents from other treatment works and therefore that sewage source has an important influence on complexation characteristics. The findings from this study support the case that the contribution to complexation from effluent-derived ligands could enhance the environmental relevance of bioavailability-based compliance criteria, in particular for zinc, owing to the additional complexation capacity afforded by effluent-derived ligands.

Nontargeted homologue series extraction from hyphenated high resolution mass spectrometry data

BACKGROUND

A large proportion of polar anthropogenic compounds routinely released into the environment comprises homologue series, i.e., sets of chemicals differing in a repeating chemical unit. Using analytical techniques such as liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS), these compounds are readily measurable as signal sets with characteristic differences in mass and typically retention time. However, and despite such distinct characteristics, no computational approach for the direct, simultaneous and untargeted detection of all such signal sets comprising both LC and HRMS information has to date been presented.

RESULTS

A fast two-staged approach has been developed to extract LC-HRMS signal patterns which can be indicative of homologous analytes. In a first stage, a k-d tree representation of picked LC-HRMS peaks is used to extract all feasible 3-tuples of peaks with restrictions in, e.g., mass defect differences. A second stage then recombines these 3-tuples to larger series tuples while ensuring smooth changes in their retention time characteristics. This unsupervised approach was evaluated for ten effluent samples from Swiss sewage treatment plants (STPs), in both positive and negative electrospray-ionization.

CONCLUSIONS

Beside recovering all continuous series of previously identified homologues, substantial fractions of nontargeted peaks could subsequently be assigned into very diverse peak series, although assignments were often not unique. The latter ambiguities were resolved by a self-organizing map technique and revealed both distinctive series meshing and rivaling combinatorial solutions in the presence of isobaric or gapped series peaks. When comparing STPs, several ubiquitous yet partially low-frequent series mass differences emerged and may prioritize future identification efforts. The presented algorithm is freely available as part of the R package nontarget and as a user-friendly web-interface at www.envihomolog.eawag.ch.Graphical AbstractSearch for systematic series indicative of homologous compounds is based on a partitioned representation of LC-HRMS signal characteristics. This nontargeted search first extracts series triplets in a nearest-neighbour walk and then recombines them to larger ones. For illustration, the two dimensions involving mass defect characteristics are represented by one only.

Multi-century record of anthropogenic impacts on an urbanized mesotidal estuary: Salem Sound, MA

Salem, MA, located north of Boston, has a rich, well-documented history dating back to settlement in 1626 CE, but the associated anthropogenic impacts on Salem Sound are poorly constrained. This project utilized dated sediment cores from the sound to assess the proxy record of anthropogenic alterations to the system and compared the proxy records to the known history. Proxies included bulk stable isotopes of organic matter, magnetic susceptibility, and trace metal concentrations. Our data reveal clear changes in organic matter composition and concentration associated with land use changes and twentieth century sewage disposal practices. Further, metals data correspond with local industrial activity, particularly the historic tanning industry in Peabody, MA. Although conservation practices of past decades have improved the state of Salem Sound, the stratigraphic record demonstrates that the environment is still affected by anthropogenic influences, and has not attained conditions consistent with pre-anthropogenic baseline. The approach and results of this study are applicable to coastal embayments that are being assessed for remediation, especially those with scant historic or monitoring data.

Nutrient fluxes from domestic wastewater: A national-scale historical perspective for the UK 1800-2010

Nutrient emissions in human waste and wastewater effluent fluxes from domestic sources are quantified for the UK over the period 1800-2010 based on population data from UK Census returns. The most important drivers of change have been the introduction of the water closet (flush toilet) along with population growth, urbanization, connection to sewer, improvements in wastewater treatment and use of phosphorus in detergents. In 1800, the population of the UK was about 12 million and estimated emissions in human waste were 37kt N, 6.2kt P and 205ktorganicC/year. This would have been recycled to land with little or no sewage going directly to rivers or coastal waters. By 1900, population had increased to 35.6 million and some 145kt N were emitted in human waste but, with only the major urban areas connected to sewers, only about 19kt N were discharged in sewage effluent. With the use of phosphorus in detergents, estimated phosphorus emissions peaked at around 63.5ktP/year in the 1980s, with about 28ktP/year being discharged in sewage effluent. By 2010, population had increased to 63 million with estimated emissions of 263kt N, 43.6kt P and 1460ktorganicC/year, and an estimated effluent flux of 104kt N, 14.8kt P and 63kt organic C. Despite improvements in wastewater treatment, current levels of nutrient fluxes in sewage effluent are substantially higher than those in the early 20th century.

Trace levels of sewage effluent are sufficient to increase class 1 integron prevalence in freshwater biofilms without changing the core community

Most river systems are impacted by sewage effluent. It remains unclear if there is a lower threshold to the concentration of sewage effluent that can significantly change the structure of the microbial community and its mobile genetic elements in a natural river biofilm. We used novel in situ mesocosms to conduct replicated experiments to study how the addition of low-level concentrations of sewage effluent (nominally 2.5 ppm) affects river biofilms in two contrasting Chalk river systems, the Rivers Kennet and Lambourn (high/low sewage impact, respectively). 16S sequencing and qPCR showed that community composition was not significantly changed by the sewage effluent addition, but class 1 integron prevalence (Lambourn control 0.07% (SE ± 0.01), Lambourn sewage effluent 0.11% (SE ± 0.006), Kennet control 0.56% (SE ± 0.01), Kennet sewage effluent 1.28% (SE ± 0.16)) was significantly greater in the communities exposed to sewage effluent than in the control flumes (ANOVA, F = 5.11, p = 0.045) in both rivers. Furthermore, the difference in integron prevalence between the Kennet control (no sewage effluent addition) and Kennet sewage-treated samples was proportionally greater than the difference in prevalence between the Lambourn control and sewage-treated samples (ANOVA (interaction between treatment and river), F = 6.42, p = 0.028). Mechanisms that lead to such differences could include macronutrient/biofilm or phage/bacteria interactions. Our findings highlight the role that low-level exposure to complex polluting mixtures such as sewage effluent can play in the spread of antibiotic resistance genes. The results also highlight that certain conditions, such as macronutrient load, might accelerate spread of antibiotic resistance genes.

Particulate and colloidal silver in sewage effluent and sludge discharged from British wastewater treatment plants

Differential filtration was used to measure silver (>2 nm) entering and leaving nine sewage treatment plants (STPs). The mean concentration of colloidal (2-450 nm) silver, which includes nanosilver, was found to be 12 ng L(-1) in the influent and 6 ng L(-1) in the effluent. For particulate silver (>450 nm) the mean values were 3.3 μg L(-1) for influent and 0.08 μg L(-1) for effluent. Thus, removal was around 50% and 98% for colloidal and particulate silver respectively. There was no significant difference in performance between the different types of STP investigated (three examples each of activated sludge, biological filter and biological filter with tertiary treatment located across England, UK). In addition, treated sewage sludge samples (biosolids) were taken from several STPs to measure the total silver likely to be discharged to soils. Total silver was 3-14 mg kg(-1) DW in the sludge (median 3.6), which if the sludge were added at the recommended rate to soil, would add 11 μg kg(-1) yr(-1) to the top 20 cm soil layer. Predicted concentrations using the LF2000-WQX model for all the rivers of England and Wales for nanosilver were typically in the 0-1 ng L(-1) range but levels up to 4 ng L(-1) are possible in a high discharge and low flow scenario. Predicted concentrations for the total particulate forms were mostly below 50 ng L(-1) except for a high discharge and low flow scenario where concentrations could reach 135 ng L(-1).

Distribution and pollutant load of hexabromocyclododecane (HBCD) in sewage treatment plants and water from Japanese Rivers

Hexabromocyclododecane diastereoisomers (α-, β-, γ-, δ-, and ε-HBCD) were investigated in river water, sewage influent, and sewage effluent from the Yodo River basin, Japan. The mean annual values of HBCDs ranged from 0.19 to 14ngL(-1) in river water. We observed that the concentrations of HBCDs in the brackish water area were low compared with that in the fresh water area. It was implied that, when the flow of the river stagnated in the estuarine area, HBCDs settled with suspended matter because of their hydrophobic character. In the sewage treatment plants, HBCDs ranged from 16 to 400ngL(-1) in sewage influent, whereas they ranged from 0.39 to 12ngL(-1) in sewage effluent. Over 90% of HBCDs were removed from the wastewater in the sewage treatment plants. By using these results, we estimated the pollutant load of HBCDs that flows into Osaka Bay from the study area. It was estimated that approximately 15kg of HBCDs flow into Osaka Bay from the study area in a year. This value is five orders of magnitude lower than the 2010 market demand for HBCDs (3019 metrictons) in Japan.

Occurrence, fate and environmental risk assessment of endocrine disrupting compounds at the wastewater treatment works in Pietermaritzburg (South Africa)

Steroid hormone Endocrine Disrupting Compounds (EDCs) (natural estrogens (17-β-estradiol (E2), estrone (E1), estriol (E3), synthetic estrogen (17-α-ethinylestradiol (EE2)), natural androgen (testosterone) (tes) and natural progestogen (progesterone) (pro)) at an activated sludge wastewater works (WWW), were quantitated using Enzyme-linked immunosorbent assay (ELISA). The steroid hormone profile in the adjacent surface water was also determined. Pro was the most abundant (41%, 408 ng/L) in the influent, followed by tes (35%, 343 ng/L) and E2 (12%, 119 ng/L). E1 was the most abundant (35%, 23 ng/L) in effluent, followed by E2 (30%, 20 ng/L) and tes (17%, 11 ng/L). Chemical removal efficiencies of the steroid hormones by the WWW averaged 92%. High removal efficiency was observed for pro (98% ± 2) and tes (96% ± 1), compared to natural (72-100%) and synthetic estrogen (90% ± 3), with biodegradation being the major removal route for pro and tes. The lowest removal for E2 is in spring (65%), and maximum removal is in winter (95%). Natural (E2, E1) and synthetic estrogen (EE2) were major contributors to influent (E2 = 69%) and effluent (E2 = 73%) estrogenic potency. The estrogenic potency removal averaged 85% (range: 73-100). Risk assessment of the steroid hormones present in wastewater effluent, and surface water, indicated that EE2 and E2 pose the highest risk to human health and fish. EE2 was found to be much more resistant to biodegradation, compared to E2, in surface water. Estrone, as the breakdown product of E2 and EE2 in wastewater, appears to be suitable as an indicator of EDCs. The study suggests that a battery of tests: quantitative chemical assay, bioassay for estrogenic activity and risk assessment methods, collectively, are preferred in order to make meaningful, accurate conclusions regarding potential adverse effects of EDCs present in treated wastewater effluent or surface water, to the aquatic environment, human health, and wildlife systems.

Predicting concentrations of the cytostatic drugs cyclophosphamide, carboplatin, 5-fluorouracil, and capecitabine throughout the sewage effluents and surface waters of Europe

The present study evaluated the potential environmental concentrations of 4 cytostatic (also known as cytotoxic) drugs in rivers. The antimetabolite 5-fluorouracil (5FU) and its pro-drug capecitabine were examined based on their very high use rates, cyclophosphamide (CP) for its persistence, and carboplatin for its association with the metal element platinum. The study combined drug consumption information across European countries, excretion, national water use, and sewage removal rates to derive sewage effluent values across the continent. Results showed considerable variation in the popularity of individual cytostatic drugs across Europe, including a 28-fold difference in 5FU use and 15-fold difference in CP use. Such variations could have a major effect on the detection of these compounds in effluent or river water. Overall, capecitabine and CP had higher predicted levels in effluent than 5FU or carboplatin. Predicted effluent values were compared with measurements in the literature, and many non-detects could be explained by insufficient limits of detection. Linking the geographic based water resources model GWAVA with this information allowed water concentrations throughout 1.2 million km of European rivers to be predicted. The 90th percentile (worst case) prediction indicated that, with the exception of capecitabine, more than 99% of Europe's rivers (by length) would have concentrations below 1 ng/L for these cytostatic drugs. For capecitabine, 2.2% of river length could exceed 1 ng/L.

Usage of sewage effluent in irrigation of some woody tree seedlings. Part 3: Swietenia mahagoni (L.) Jacq

A pot experiment was investigated to study the effect of sewage irrigation treatments (primary and secondary effluents) compared with tap water on the growth and chemical constituents of mahogany seedlings (Swietenia mahagoni (L.) Jacq.) as well as soil chemical properties. The experiment was conducted at a greenhouse in the nursery of Timber Trees Research Department of Sabahia, Horticultural Research Station in Alexandria, Egypt, from June 2003 to December 2004 for three irrigation periods (6, 12 and 18 months). The sewage effluent waters were taken from oxidation ponds located in New Borg EL-Arab city and used directly for irrigation. The primary effluent treatment was superior than other treatments in improving the growth parameters (plant height, stem diameter, leaf area, leaves number, fresh and dry weights of leaves, shoots and roots and shoot/root ratio) and showed the highest concentration and total uptake of N, P, K, Cd, Ni, Pb and Fe in plant parts, followed by secondary effluent then tap water. The data revealed that soil salinity in terms of electrical conductivity of saturated paste (EC), CaCO3%, organic matter% and soluble anions and cations were influenced significantly by primary or secondary effluent treatment. The data also showed that the use of sewage effluent for irrigation increased N, P, K and DTPA-extractable-heavy metals (Cd, Cu, Ni, Pb, Fe, Mn and Zn). The effects of sewage effluent on growth parameters and elements content in plant parts and treated soil were more pronounced as water treatments were used for long period. The results suggested that the use of sewage effluent in irrigating mahogany trees grown on calcareous sandy loam soil was an important agriculture practice for improving soil properties, increasing fuel and timber production, and is an economic and safe way to dispose wastewaters.