Micropollutants In Wastewater Research Articles

A novel red mud adsorbent for phosphorus and diclofenac removal from wastewater

The ubiquitous occurrence of nutrients (e.g. phosphorus) and micropollutants (e.g. pharmaceuticals and endocrine disrupting chemicals) in wastewater and urban stormwater runoff sources may cause adverse effects on aquatic ecosystems and human health. Therefore, the removal of these pollutants from wastewater, treated effluent, and urban stormwater runoff is critically needed. In this study, a novel modified red mud with polypyrrole (RM-PPy) was successfully synthesized with improved functional groups (–OH, –N=, –NH–, N+), specific area (SBET 102.24 m2/g), and mesopore structure (i.e. average pore diameter of 3.29 nm), which are assumed to enhance the adsorptive removal of diclofenac (DCF) and phosphorus (P) in aqueous solution. The measured maximum adsorption capacity of RM-PPy towards diclofenac (195 mg/g) in single adsorbate system was higher than that (115.7 mg/g) in the binary adsorbates system (i.e. in the presence of P), indicating that the presence of pollutants such as P in water hampered the adsorptive removal of DCF. The adsorption of DCF and P was largely dependent on solution pH values. Higher adsorptive removals of DCF and P were observed at acidic conditions (pH 2–5). Adsorption isotherm of DCF and P was better fitted to Freundlich model compared to Langmuir isotherm model, suggesting multilayer coverage. Adsorption of DCF onto RM-PPy might take place via anion exchange and electrostatic interactions. For P adsorption, apart from anion exchange and electrostatic interactions, the chemical precipitation via ligand exchange between P and hydroxyl (–OH) in RM-PPy can be considered as one of the main adsorption mechanisms. Further studies on the competitive adsorption of other anionic micropollutants at environmentally relevant concentrations (ng/L–μg/L) in water samples by RM-PPy are needed to evaluate the potential application of RM-PPy for the removal of other anionic micropollutants (i.e. antibiotics) in treated wastewater and stormwater runoff.

Removal of Organic Micropollutants in Wastewater Treated by Activated Sludge and Constructed Wetlands: A Comparative Study

The aim of this study is to compare the removal of organic micropollutants (OMPs) in wastewater by activated sludge (AS) and constructed wetlands (CWs). This analysis was carried out in a wastewater treatment plant (WWTP) of a rural community where they implemented two technologies in parallel: AS and a pilot plant of horizontal subsurface flow (HSSF) constructed wetlands. In this case, these systems were fed by the same influent and the removal efficiencies of 14 OMPs, including analgesics/anti-inflammatories, anticonvulsants, stimulants, antifungals, fragrances, plasticizers, and transformation products, were evaluated in each system. Regarding the presence of OMPs in the wastewater, the concentrations of these compounds in the influent ranged from 0.16 to 7.75 µg/L. In general, the removal efficiencies achieved by the AS system were between 10%–95% higher than those values reported by HSSFs with values above 80% for naproxen, ibuprofen, diclofenac, caffeine, triclosan, methyl dihydrojasmonate, bisphenol-A, 2-hydroxyl ibuprofen, and carboxy ibuprofen (p < 0.05). This behavior can be related to the aerobic conditions that promote the AS system with oxidation-reduction potential (ORP) and dissolved oxygen (DO) values above −281 mV and 0.24 mg/L, respectively. However, the removal of galaxolide was greater in HSSF system than in AS with significant difference of 70% (p < 0.05). Despite these results, this study reveals that comparing both technologies, AS had the best removal performance of these OMPs studied.

Unfolding the action mode of light and homogeneous vs. heterogeneous photo-Fenton in bacteria disinfection and concurrent elimination of micropollutants in urban wastewater, mediated by iron oxides in Raceway Pond Reactors

In this work, iron oxides have been proposed as low-cost heterogeneous photo-Fenton catalysts for the simultaneous disinfection and reduction of microcontaminant load from urban wastewater in raceway pond reactors at near-neutral pH. The objective was not finding the best operating conditions but understanding the mechanisms of FeOx driven disinfection and the implications presented by the matrix constituents, namely organic matter and (bi)carbonates, as well as the possibility to apply this system after different secondary treatments in continuous flow mode. Notable bacterial inactivations were obtained in both batch and continuous flow modes by any iron oxide used, with total inactivation (5 log reduction) in the case of Hematite. The heterogeneous photo-Fenton process was proven to be the driving bacterial inactivation force in urban wastewaters. Additionally, monitoring the elimination of 25 emerging contaminants in the secondary effluents was performed. The operation mode (batch-continuous) was assessed, attaining a minimum of 35% micropollutant removal.

Laccase-Carbon nanotube nanocomposites for enhancing dyes removal

Abstract Adsorption can effectively remove recalcitrant micro-pollutants in wastewater. However, its industrial application is constrained by the adsorption saturation. This work introduces a novel technique to directly immobilize the laccases onto the CNTs (Laccase-Carbon nanotubes) to improve its adsorption performance. Comprehensive investigations were carried out to compare and understand the adsorption performance at various operational conditions for Carbon nanotube and Laccase-Carbon nanotubes. By calculating the adsorption thermodynamics, adsorption kinetics and particle diffusion kinetics, the removal improvement mechanisms were revealed. The results showed that Laccase-Carbon nanotubes performed much better regarding the dye removal rate (96% within 3 h) and better stability than Carbon nanotubes (84% within 3 h), under various operating conditions (carbon nanotube concentration (0.02–0.08 g/L), laccase ratio (0.25–1.25), dye concentration (10–60 mg/L), temperature (15–35 °C), and rotating speed (0–250 rpm)). Besides, the isothermal adsorption model and adsorption kinetic indicated that Laccase-carbon nanotubes possessed greater adsorption capacity than carbon nanotubes, which may maybe due to the fact that adsorbed dyes onto carbon nanotubes were timely eliminated by laccases, achieving regeneration of adsorption capacity. Moreover, based on the particle diffusion kinetic, the diffusion rate of dyes onto the surface or into the internal of Laccase-Carbon nanotubes was clearly higher than that of carbon nanotubes. Additionally, Scanning Electron Microscope, BET-specific surface area and Fourier Transform Infrared Spectroscopy were utilized to observe the microstructure of enzyme immobilization. This biomimetic nanocomposite sheds light upon conventional wastewater treatment processes for recalcitrant micro-pollutants.

Precipitation effects on parasite, indicator bacteria, and wastewater micropollutant loads from a water resource recovery facility influent and effluent.

The variability of fecal microorganisms and wastewater micropollutants (WWMPs) loads in relation to influent flow rates was evaluated for a water resource recovery facility (WRRF) in support of a vulnerability assessment of a drinking water source. Incomplete treatment and bypass discharges often occur following intense precipitation events that represent conditions that deviate from normal operation. Parasites, fecal indicator bacteria, and WWMPs concentrations and flow rate were measured at the WRRF influent and effluent during dry and wet weather periods. Influent concentrations were measured to characterize potential bypass concentrations that occur during wet weather. Maximum influent Giardia and C. perfringens loads and maximum effluent Escherichia coli and C. perfringens loads were observed during wet weather. Influent median loads of Cryptosporidium and Giardia were 6.8 log oocysts/day and 7.9 log cysts/day per 1,000 people. Effluent median loads were 3.9 log oocysts/day and 6.3 log cysts/day per 1,000 people. High loads of microbial contaminants can occur during WRRF bypasses following wet weather and increase with increasing flow rates; thus, short-term infrequent events such as bypasses should be considered in vulnerability assessments of drinking water sources in addition to the increased effluent loads during normal operation following wet weather.

Induction of Microbial Oxidative Stress as a New Strategy to Enhance the Enzymatic Degradation of Organic Micropollutants in Synthetic Wastewater.

Organic micropollutants (OMPs) are pervasive anthropogenic contaminants of receiving waters where they can induce various adverse effects to aquatic life. Their ubiquitous environmental occurrence is primarily attributed to discharge from wastewater treatment plants due to incomplete removal by common biological wastewater treatment processes. Here, we assess a new strategy for promoting the degradation of six representative OMPs (i.e., sulfamethoxazole, carbamazepine, tylosin, atrazine, naproxen, and ibuprofen) by intentionally stimulating the production of microbial oxidoreductases to counter oxidative stress caused by oxygen perturbations. Mixed microbial cultures from a dairy farm wastewater were subjected to cyclic perturbations of dissolved oxygen (DO). A distance-based redundancy analysis was used to show that DO perturbations correlate with the abundance of Pseudomonadaceae and Rhodocyclaceae families, activities of peroxidases and cytochromes, and the degradation of OMPs. DO perturbation of 0.25 and 0.5 cycles/h led to most abundance of Pseudomonadaceae and Rhodocyclaceae families, showed higher activity of peroxidase and cytochrome, and gave largest removal of OMPs (removal of 92 ± 3% for sulfamethoxazole, 84 ± 3% for naproxen, 82 ± 3% for ibuprofen, 66 ± 2% for carbamazepine, 57 ± 15% for tylosin, and 88 ± 1% for atrazine).

Preparation of a filter bed coupled with Mn-TiO2/ZnO nanocomposite for the treatment of micro-pollutants in municipal wastewater

Technical advancement is urgently required for the degradation of micro-pollutants in municipal wastewater. The present study aimed to describe the preparation of a filter-bed Mn-TiO2/ZnO nanocomposite and degradation of micro-pollutants in real-time municipal wastewater obtained from Kesare wastewater treatment plant in Mysore district, India. Activated carbon and sand were used for the preparation of the filter bed, and activated carbon was prepared using agricultural wastes (coconut shells). Meanwhile, the visible light-responsive Mn-TiO2/ZnO composite was prepared using the mild sol-gel technique. The composites were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and photocatalytic techniques. High crystallinity, considerable shift in the band gap energy, and adequate photocatalytic activity under the visible light range were observed. In addition, the filter bed coupled with the Mn-TiO2/ZnO nanocomposite functioned efficiently in the degradation of the common pollutants under LED irradiation as the driving source of energy.

Efficient degradation of pharmaceutical micropollutants in water and wastewater by FeIII-NTA-catalyzed neutral photo-Fenton process

Ferric-nitrilotriacetate complex (FeIII-NTA) has been adopted to catalyze the photo-Fenton degradation of emerging pharmaceutical micropollutants in water and wastewater at neutral pH. The generation of hydroxyl radicals (HO) in UVA/FeIII-NTA/H2O2 was identified by using electron spin resonance (ESR) trapping technique. The effects of critical parameters (e.g., NTA:FeIII molar ratio, FeIII-NTA and H2O2 dosages) on the steady-state HO concentrations were studied in terms of the degradation of carbamazepine (CBZ, as a model compound) in Milli-Q water. In addition, the degradation of pharmaceuticals mixtures (including CBZ, crotamiton (CRMT) and ibuprofen (IBP)) in wastewater effluents from a biological aerated filter (BAF) by UVA/FeIII-NTA/H2O2 was studied in continuous-flow mode. The results showed that the efficacies of FeIII-NTA in catalyzing photo-Fenton degradation of pharmaceuticals in wastewater effluents were comparable to those obtained by FeIII-ethylenediamine-N,N′-disuccinic acid (FeIII-EDDS), and far exceeded other FeIII-L complex (e.g., citric acid, malonic acid, oxalic acid and tartaric acid). More than 92% degradation efficiencies of CBZ, CRMT and IBP were obtained in continuous-flow mode under the given conditions of 0.178 mM FeIII-NTA (1:1), 4.54 mM H2O2, UVA intensity 4.05 mW cm−2, hydraulic retention time (HRT) 2 h, influent pH 7.6 (±0.2) and temperature 20 °C. The results presented herein suggest that FeIII-NTA-catalyzed neutral photo-Fenton reaction can be an alternative tertiary process for the treatment of pharmaceutical micropollutants in secondary wastewater effluents.

An Innovative Phenolic Resin and Its Application in Wastewater Treatment for Paracetamol Removal

Water scarcity has been a concern worldwide, especially since the presence of micropollutants in wastewater has increased. In this scenario, adsorption and advanced oxidative processes have gained increasing attention in environmental chemistry, emerging as promising alternatives for water decontamination. Drugs are a good example of those pollutants and, among all drugs, paracetamol is a widely used one and was used in the current study. Thus, alternative precursors of phenolic compounds, as a blend of Kraft black liquor and tannin, were used for an innovative activated phenolic resin (APR) production and investigated for paracetamol removal. When the APR was used in a photocatalytic process, the paracetamol removal mechanism was predominantly by adsorption rather than by photocatalysis. The paracetamol adsorption onto APR was almost 70 % higher than in the conventional thermally treated photocatalysts, encouraging a further assessment of paracetamol adsorption onto APR. The adsorption capacity reached a maximum value for an APR weight of 0.02 g, with an adsorption capacity of 19.43 mg g-1. Moreover, the paracetamol solution pH did not show noteworthy effect on the adsorption capacity in the pH range evaluated. Chemical structure characterization pointed out a variety of functional groups on the APR surface, which are characteristic of bio-phenolic compounds structure. The drug adsorption onto APR may be explained by the adsorbent - adsorbate p-p interactions and hydrogen bonding. At the maximum adsorption capacity, the use of APR as adsorbent provided a paracetamol removal of about 45 %, which can be increased to greater than 90 % by increasing the adsorbent weight. This confirmed the resin’s potential as an adsorbent for paracetamol removal.

Occurrence of Micropollutants in Wastewater and Evaluation of Their Removal Efficiency in Treatment Trains: The Influence of the Adopted Sampling Mode

The monitoring of micropollutants in water compartments, in particular pharmaceuticals and personal care products, has become an issue of increasing concern over the last decade. Their occurrence in surface and groundwater, raw wastewater and treated effluents, along with the removal efficiency achieved by different technologies, have been the subjects of many studies published recently. The concentrations of these contaminants may vary widely over a given time period (day, week, month, or year). In this context, this paper investigates the average concentration and removal efficiency obtained by adopting four different sampling modes: grab sampling, 24-h time proportional, flow proportional and volume proportional composite sampling. This analysis is carried out by considering three ideal micropollutants presenting different concentration curves versus time (day). It compares the percentage deviations between the ideal concentration (and removal efficiencies) and the differently measured concentrations (removal efficiencies) and provides hints as to the best sampling mode to adopt when planning a monitoring campaign depending on the substances under study. It concludes that the flow proportional composite sampling mode is, in general, the approach which leads to the most reliable measurement of concentrations and removal efficiencies even though, in specific cases, the other modes can also be correctly adopted.

Investigation into Micropollutant Removal from Wastewaters by a Membrane Bioreactor.

Direct potable reuse of wastewater is attractive as the demand for potable water increases. However, the presence of organic micropollutants in industrial and domestic wastewater is a major health and environmental concern. Conventional wastewater treatment processes are not designed to remove these compounds. Further many of these emerging pollutants are not regulated. Membrane bioreactor based biological wastewater treatment has recently become a preferred method for treating municipal and other industrial wastewaters. Here the removal of five selected micropollutants representing different classes of emerging micropollutants has been investigated using a membrane bioreactor. Acetaminophen, amoxicillin, atrazine, estrone, and triclosan were spiked into wastewaters obtained from a local wastewater treatment facility prior to introduction to the membrane bioreactor containing both anoxic and aerobic tanks. Removal of these compounds by adsorption and biological degradation was determined for both the anoxic and aerobic processes. The removal as a function of operating time was investigated. The results obtained here suggest that removal may be related to the chemical structure of the micropollutants.

Evaluation of transformation products from chemical oxidation of micropollutants in wastewater by photoassisted generation of sulfate radicals

In this research, the degradation of seven different micropollutants (MPs) and the formation of their transformation products (TPs) have been assessed during the application of different advanced oxidation processes: photolytic and photocatalytic activation of peroxymonosulfate (PMS) and persulfate (PS). The results were compared with those obtained from the photolytic experiments using hydrogen peroxide (H2O2) as oxidant. A significant abatement of almost all MPs was achieved, even with very low UV-C contact time (9 and 28 s). The degradation of atenolol (ATN) and caffeine (CFN) ranged from 84 to 100% with a dose of 0.5 mM of any oxidant. The efficiencies for bisphenol-A (BPA), carbamazepine (CBZ), diclofenac (DCF), ibuprofen (IBP), and sulfamethoxazole (SMX) varied depending on the oxidation system and operating conditions (oxidant dose and UV-C contact time), leading to the photolysis of PMS to higher efficiencies than PS and H2O2. In all cases, the abatement of MPs ranged from 63 to 83%, even with the lowest PMS dosage. Moreover, the addition of Fe(II) as a catalyst enhanced the removal efficiency, reaching almost total removal, especially over CBZ, DCF, and IBP. The Dissolved Organic Carbon (DOC) removal ranged between 44 and 62%, suggesting the transformation of MPs in intermediate compounds. The identification of transformation products was carried out for each micropollutant and each oxidation treatment, being observed some transformation products specific of oxidation by sulfate radicals. For example, m/z 165.0432 only appeared after PMS/Fe(II)/UV-C on the degradation of BFA, m/z 251.082 appeared after photolytic activation of PMS and PS on CBZ removal, and m/z 128.0452 was observed after any sulfate radical oxidation treatment, but not after photolysis of H2O2.

Life cycle assessment of advanced wastewater treatment processes: Involving 126 pharmaceuticals and personal care products in life cycle inventory

Continuous exposure to pharmaceuticals and personal care products (PPCPs) is a critical concern given potential toxicity impacts on aquatic environments and human health, although concentrations of PPCPs in the environment are low. While several studies have focused on the fate and toxicity of organic micropollutants in wastewater, the environmental impacts of life cycle assessment induced by these organic micropollutants in advanced wastewater treatment processes are still unknown. To address this need, an environmental evaluation of three representative advanced wastewater treatment processes (ozonation, granular activated carbon adsorption and reverse osmosis) involving PPCPs removal was conducted using life cycle assessment and USEtox model in this study. Although a large amount of PPCPs can be eliminated during conventional waste highest characterization factors for freshwater toxicity, while 17α-ethinylestradiol, sertraline, and 17β-estradiol had the highest human toxicity characterization factors. From the perspective of LCA, reverse osmosis appeared to have the greatest environmental burden due to the high energy and material consumption during the treatment process. After involving 126 PPCPs in life cycle inventory, the ecotoxicity impact results were increased significantly in three advanced wastewater treatment processes. The contribution of effluent was improved in toxicity impact category, accounting more than 25% for the three processes. The effluent (including PPCPs) as the key factor was next only to electricity and chemicals in eutrophication, ecotoxicity and human toxicity impacts category particularly. Therefore, PPCPs should not be ignored in life cycle assessment of advanced wastewater treatment processes, although they are not typically monitored in wastewater. These results are valuable for conducting a comprehensive environmental evaluation of advanced wastewater treatment processes considering micro-pollutants removal. The identified PPCPs with high freshwater and human toxicity can be considered as the priority control index of organic micropollutants for wastewater treatment plants.

Metal-free g-C3N4 photocatalysis of organic micropollutants in urban wastewater under visible light

Heterogeneous photocatalysis under visible light was employed for the degradation of organic micropollutants (MPs) found in the biologically treated effluents of an urban wastewater treatment plant (UWWTP). The irradiation source consisted in 4 light emitting diodes (LEDs) with a nominal power of 400–500 W m–2 at 417 nm. Metal-free exfoliated graphitic carbon nitride (gCNT), which was synthetized through a simple thermal treatment using dicyandiamide as precursor, was employed as photocatalyst. The gCNT material was characterized using different techniques: N2 adsorption isotherms at 77 K, electron microscopy (scanning and transmission) and diffuse reflectance UV–Vis. The photocatalytic performance of the material was compared to the commercial TiO2-P25, confirming that gCNT led to a remarkable higher removal efficiency of the target MPs. Most of these MPs were removed in less than 10 min to levels below the limit of quantification (carbamazepine > isoproturon > clopidogrel > diclofenac > atenolol > bezafibrate > tramadol > venlafaxine > fluoxetine). Indirect photolysis, resulting from the secondary reactive oxidants generated during the irradiation of the aqueous matrix components, was found to partially contribute for the elimination of the occurring MPs. In addition, the gCNT photocatalyst was immobilized on glass rings for use under continuous mode operation, a minimum residence time of 25 min being required to attain significant removal efficiencies. Phytotoxicity experiments showed that heterogeneous photocatalysis did not enhance the toxicity of the wastewaters.

Fecal contamination of storm sewers: Evaluating wastewater micropollutants, human-specific Bacteroides 16S rRNA, and mitochondrial DNA genetic markers as alternative indicators of sewer cross connections

A set of fecal indicator bacteria and alternative markers were tested for their use to identify priority sectors of two urban watersheds in the Greater Montreal region with unintended household sewage connections to storm drainage systems. Analyses were performed for thermotolerant (fecal) coliforms (FC), Escherichia coli, human-specific Bacteroidales (HF183) and mitochondrial DNA (Hmt) markers, carbamazepine (CBZ), caffeine (CAF), theophylline (THEO) and acetaminophen (ACE). A high incidence of human fecal contamination was observed, illustrating the need for a method to appropriately prioritize sectors for the rehabilitation of sewer cross-connections. Concentrations of alternative markers were not significantly different between the residential and industrial/commercial/institutional (ICI) sectors. However, median E. coli concentrations were higher in the residential as compared to ICI sectors (p < 0.05). Hmt marker, CAF, and THEO were well correlated to E. coli in the ICI sector (r > 0.61, p < 0.05). Considering all sites, only CAF and THEO were correlated to E. coli (r > 0.59, p < 0.05), possibly as a result of higher E. coli inputs from other sources such as domestic animals or fauna in the residential sector. Thresholds were determined to relate alternative markers to E. coli for use in an index for prioritizing sectors with sewer cross-connections. HF183, Hmt, CAF, THEO, and ACE were identified as suitable markers for identifying sewer cross-connections and are more reliable than E. coli alone, most importantly in residential sectors.

Kinetics and modeling of artificial sweeteners degradation in wastewater by the UV/persulfate process

The frequent detection of artificial sweeteners (ASs) in wastewater and surface water gives rise to concerns about their removal, Acesulfame (ACE) and sucralose (SUC) are two ASs that are difficult to remove. The ultraviolet/persulfate (UV/PS) advanced oxidation technology (AOT) is being considered as an effective process for the degradation of micropollutants in wastewater. However, the study of the degradation of ASs in real wastewater by the UV/PS is minimal. This study investigated the kinetics and modeling of ACE and SUC degradation in wastewater by the UV/PS process. Both ACE and SUC could be degraded effectively using this process. The degradation of ACE was mainly attributed to UV photolysis (51%), HO∙ (26%) and SO4∙- (16%), while that of SUC was mainly attributed to HO∙ (68%) and SO4∙- (27%). The second-order rate constants of ASs with SO4∙- were significantly lower than that with HO∙. Three major transformation products (TPs) of ACE and four major TPs of SUC were identified. Additionally, the effects and mechanisms of the water matrices, such as HCO3−, Cl−, NO3− and natural organic matter (NOM), on ASs degradation were investigated through response surface methodology (RSM). NOM and Cl− significantly inhibited the degradation of ACE in the UV/PS system, whereas NOM and HCO3− played a main inhibition role on the degradation of SUC. A water matrices parameter model for predicting ASs degradation in real wastewater was established by RSM for the first time, and the removal of ACE and SUC was well predicted by the model.

Influences of multi influent matrices on the retention of PPCPs by nanofiltration membranes

Nanofiltration (NF) has great potential in removing trace organic micropollutants in wastewater, especially pharmaceuticals and personal care products (PPCPs). However, little information is available on PPCPs rejections under complex feed water matrices, which better represent real wastewater treatment conditions. In this paper, the PPCPs rejection behaviors and the dominating mechanisms by NF membranes were studied under multi mixed influent matrices which contained various inorganic ions, humic acids and sodium alginate. The results showed that the DF30 membrane had the highest rejection of negatively charged indomethacin (95.4%) and diclofenac sodium (94.1%) in pure water. Our study also showed that electrostatic effect and steric hindrance were the primary rejection mechanisms of PPCPs by DF30 membrane in pure water. The predominant fouling of DF30 membrane could be explained by the complete blocking model in the filtration of mixed influent matrices containing both inorganic ions and organic matters. The components in membrane bioreactor (MBR) effluent was beneficial to retention of positively and neutrally charged PPCPs, but had no significant effects on retention of negatively charged PPCPs. Risk quotients of the six target PPCPs in NF effluent were all lower than 0.1, likely indicating low risk to aquatic organisms. This work has potential implications for a deeper understanding of PPCPs rejections by NF in wastewater treatment.

Photo-assisted Degradation of Sulfamethazine by Ferrocene-catalyzed Heterogeneous Fenton-like System

Antibiotics are acknowledged micropollutants in wastewaters and surface waters. They are of particular concern because they can trigger an increase in resistant bacteria. Therefore, novel and efficient technology for the removal of antibiotics is urgently needed. In this study, heterogeneous Fenton-like reaction based on ferrocene (Fc) had been constructed, sulfamethazine (SMZ) was selected as target compound due to its abundance in water. The degradation kinetics, transformation pathway, and degradation products of SMZ in this system were investigated. The results showed that Fc+H2O2+UV had better degradation efficiency for SMZ than did Fc, Fc+UV, H2O2, and H2O2+UV, Fc+H2O2 systems. Radical scavenger experiments confirmed that the photogenerated OH was largely responsible for the photolytic enhancement of SMZ in the Fc+H2O2+UV system. Additionally, the electron spin resonance technique revealed that photogenerated O2- was found in the system, indicating that Fc can generate electrons under light conditions. H2O2 underwent electron disproportionation to produce OH, which promoted the degradation of SMZ. The degradation products of SMZ in the Fc+H2O2+UV system were identified by LC/LTQ-Orbitrap MS. The hydroxylation of SMZ, the removal of SO2, and the products of breaking C-S, S-N, and N-C bonds were observed. Common soluble components (such as DOM, Cl-, and Br-) in water can quench OH, thus inhibiting the photodegradation of SMZ. However, the ionic strength had no significant effect on the degradation of SMZ in the Fc+H2O2+UV system, which showed that this technique positively affected the treatment of wastewater containing high-salinity antibiotics.

Temporal variability of parasites, bacterial indicators, and wastewater micropollutants in a water resource recovery facility under various weather conditions

Wastewater discharges lead to the deterioration of receiving waters through treated effluents and by-passes, combined and sanitary sewer overflows, and cross-connections to storm sewers. The influence of weather conditions on fecal indicator bacteria, pathogens and wastewater micropollutants on raw and treated sewage concentrations has not been extensively characterized. However, such data are needed to understand the effects of by-pass discharges and incomplete treatment on receiving waters. A water resource recovery facility was monitored for pathogenic parasites (Cryptosporidium oocysts, Giardia cysts), fecal indicator bacteria (Escherichia coli, Clostridium perfringens), and wastewater micropollutants (caffeine, carbamazepine, 2-hydroxycarbamazepine, acesulfame, sucralose, and aspartame) during 6 events under different weather conditions (snowmelt and trace to 32 mm 2-day cumulative precipitation). Greater intra- and inter-event variability was observed for Giardia, E. coli and C. perfringens than for studied WWMPs. Even with the addition of inflow and infiltration, daily variations dominated concentration trends. Thus, afternoon and early evening were identified as critical times with regards to high concentrations and flows for potential by-pass discharges. Peak concentrations of Giardia were observed during the June wet weather event (1010 cysts/L), with the highest flowrates relative to the mean monthly flowrate. Overall, Giardia, E. coli and C. perfringens concentrations were positively correlated with flowrate (R > 0.32, p < 0.05). In raw sewage samples collected under high precipitation conditions, caffeine, carbamazepine and its metabolite 2-OH-carbamazepine were significantly correlated (p < 0.05) with Giardia, E. coli, and C. perfringens demonstrating that they are useful markers for untreated sewage discharges. Data from the study are needed for estimating peak concentrations discharged from wastewater sources in relation to precipitation or snowmelt events.

Pharmaceuticals and pesticides in secondary effluent wastewater: Identification and enhanced removal by acid-activated ferrate(VI)

The emergence of resistance to antibacterial drugs and pesticides in water is unprecedented. This may have adverse consequences to human health and ecological systems. This paper first sought the identification of a wide range of pharmaceuticals and pesticides in two secondary effluent wastewaters (SEW) of different quality characteristics, followed by their removal by ferrate(VI) (Fe(VI), FeO42−). Screening for 22 pharmaceuticals and 32 pesticides, revealed that 11 pharmaceuticals and 3 pesticides in SEW of plant A, and 14 pharmaceuticals and 5 pesticides in SEW of plant B were present at concentrations higher than the liquid chromatography mass spectrometry method quantitation limit. The concentrations of pharmaceuticals and pesticides ranged from 0.15 ng/L-413.03 ng/L. Investigation of the removal of these pharmaceuticals and pesticides by Fe(VI) showed that some had recalcitrant activity towards their oxidation. Acid-activated Fe(VI) resulted in enhanced oxidation (12.6%–56.2% degradation efficiency) of 6 and 7 pharmaceuticals in SEW of plant A and plant B, respectively, at a shorter time than Fe(VI) without activation (i.e. 3–5 min versus 15–30 min). The degradation of 1 and 3 pesticides in SEW of plant A and plant B respectively, has also been enhanced by activating Fe(VI) (13.8%–86.2% degradation efficiency). Results on testing of organic matter characterization of treated SEW with and without acid-activated Fe(VI) treatment are also presented. Acid-activated Fe(VI) treatment has potential in enhancing the removal of micropollutants in real wastewater.