Contaminants In Wastewater Effluents Research Articles

Recent advances of Copper- BTC metal-organic frameworks for efficient degradation of organic dye-polluted wastewater: Synthesis, mechanistic insights and future outlook

Water borne emerging pollutants represents a significant challenge confronting the modern society. As a result of excessive use of dyes and pigments by the textile and other industries, substantial amount of these toxic and recalcitrant substances are widely dispersed into the aquatic sources that may raise serious health issues to all life forms besides causing potential disruption to the ecosystem. Treatments of these hazardous and non-biodegradable organic contaminants in wastewater effluents have become a focal point for researchers dedicated to environmental remediation. Notably, Metal organic frameworks (MOFs) and their composites have been reported to be promising materials for tackling such challenges. This review is dedicated to provide a concise overview by consolidating the diverse beneficial attributes of Cu-BTC MOF rendering it as a versatile material with applications spanning diverse domains, focusing on the reactivity, the role of the metal ion and its recent potential for addressing the elimination of toxic textile dye wastes from the wastewater effluent. Furthermore, it also documents the underlying mechanistic pathway governing the degradation mechanism and the superior electron transport property of Cu ̶ BTC, besides painting in detail the existing limitations that hinder their applicability at an industrial platform. Moreover, a set of future research outlooks serving as a roadmap for exploring the potentiality of Cu ̶ BTC MOFs have also been presented.

Application of Adsorption Thermodynamics and Column Studies for Pb2+, Cd2+ and Mn2+ Ions Removal in Multicomponents Model Solution Using Low-Cost Bentonite Clay Adsorbent

The presence of heavy metal contaminants in wastewater effluents has become a great threat to living creatures and the environment. In this study, the application of thermodynamics and column studies for Pb2+, Cd2+ and Mn2+ metal ions removal in multicomponent aqueous solution using low-cost bentonite clay was investigated. Evaluation of enthalpy (∆Ho), entropy (∆So) and Gibbs free energy (∆Go) revealed that heavy metals adsorption was endothermic and spontaneous as temperature increased from 30 to 65 oC. The column performance was determined at 0.05m adsorbent bed depth, 0.023 and 0.04 mL/s flow rates. The influent concentration was 10 and 50 ppm while the breakthrough time was between 0.83 and 8 hr. The maximum uptake of metal ions was 2.2 mg/g for Pb(II), Mn(II) was 0.4 mg/g and 1.7 mg/g for Cd(II). The result showed the potential of bentonite clay as a candidate for toxic metal ions adsorption in wastewater.

Dissolved organic nitrogen removal and its mechanisms during simulated soil aquifer treatment

Soil aquifer treatment systems are known to further remove contaminants in wastewater effluent when applied through infiltration into the ground. Dissolved organic nitrogen (DON) in the effluent, a precursor for nitrogenous disinfection by-products (DBPs) such as N-nitrosodimethylamine (NDMA), is of great concern upon subsequent use of the groundwater infiltered into the aquifer. In this study, the vadose zone of the soil aquifer treatment system was simulated using 1 m laboratory soil columns under unsaturated conditions representing the vadose zone. The final effluent of a water reclamation facility (WRF) was applied to these columns to investigate the removal of N species with a focus on DON, as well as NDMA precursors. DON removal achieved was up to 99 % with an average of 68 % and was accompanied by a 52 % nitrate increase suggesting the occurrence of ammonification and nitrification through the soil columns. Around 62 % of total DON removal was seen at <10 cm travel distance, which was in accordance with higher adenosine triphosphate (ATP) concentrations at the top of the column due to more oxygen and organic matter availability. Total Dissolved N removal was drastically lowered to 4.5 % in the same column without microbial growth, which highlights the importance of biodegradation. The columns were capable of removing 56 % of the fluorescent dissolved organic matter (FDOM). Soil columns could remove NDMA precursors up to 92 % through the column with the initial concentration of 89.5 ng/L, possibly due to the removal of DON fractions. The results demonstrate the capability of the vadose zone in further treatment of DON and other organic matter before reaching the groundwater through infiltration or indirect discharge to surface water. Differences in applied water quality and the site-specific oxic conditions in SAT systems could lead to variable removal efficiencies.

Wastewater sources of per- and polyfluorinated alkyl substances (PFAS) and pharmaceuticals in four Canadian Arctic communities

Effective removal of organic contaminants in wastewater effluent poses a challenge to small communities worldwide, particularly in the Arctic due to infrastructure challenges and harsh climates. To understand better the efficacy of current treatment options and risks posed by pharmaceuticals and pesticides on receiving waters in the Arctic, four representative human communities in Nunavut, Canada were evaluated. Per- and polyfluorinated alkyl substances (PFASs) were also investigated in one community. These communities have treatment ranging from primary lagoons, engineered wetlands, and natural lakes. Pharmaceuticals and pesticides were measured using the organic diffusive gradients in thin film (o-DGT) passive sampler in summer 2018. Of the 34 compounds studied, seven pharmaceuticals were found at least once: atenolol, carbamazepine, metoprolol, naproxen, sulfapyridine, sulfamethoxazole, and trimethoprim. With the exception of 5210 ng naproxen/L in Iqaluit, most receiving waters showed negligible amounts of contamination. Iqaluit had the poorest overall system performance while Baker Lake had the best. Measured pharmaceutical concentrations do not appear to pose a significant acute hazard to receiving waters at this time, based on known toxicological endpoints. PFAS concentrations were found to be over 100-fold greater in Cambridge Bay wastewater than previously reported Arctic seawater. Results suggest that wastewater may be an important point source of PFASs in Arctic communities. The o-DGT passive samplers performed well in marine Arctic settings. We recommend further testing of wastewater efficiencies in Arctic communities along with evaluations of seasonal variations.

Selection and evaluation of water pretreatment technologies for managed aquifer recharge (MAR) with reclaimed water

Managed aquifer recharge with reclaimed water is a promising strategy for indirect potable reuse. However, residual contaminants in the treated wastewater effluent could potentially have adverse effects on human health. Hence, adequate water pretreatment is required. A multi-criteria approach was used to select and evaluate suitable water pretreatment technologies that can remove these critical contaminants in wastewater effluent for MAR identified in a previous study (Yuan et al., 2017). The treatment efficiency targets were calculated based on the concentrations and the suggested limits of critical contaminants. Treatment efficiency credits were then assigned to each treatment option for the removal of critical contaminants based on literature data. Treatment units that resulted in the highest efficiency credit scores were selected and combined into treatment train options, which were evaluated in terms of treatability, cost, and sustainability. This paper proposes an approach for the selection and evaluation of water treatment options, which will be helpful to guide the future implementation of MAR projects with reclaimed water.

Identification of critical contaminants in wastewater effluent for managed aquifer recharge

Managed aquifer recharge (MAR) using highly treated effluent from municipal wastewater treatment plants has been recognized as a promising strategy for indirect potable water reuse. Treated wastewater effluent can contain a number of residual contaminants that could have adverse effects on human health, and some jurisdictions have regulations in place to govern these. For those that do not, but where reuse may be under consideration, it is of crucial importance to develop a strategy for identifying priority contaminants, which can then be used to understand the water treatment technologies that might be required. In this study, a multi-criteria approach to identify critical contaminants in wastewater effluent for MAR was developed and applied using a case study site located in southern Ontario, Canada. An important aspect of this approach was the selection of representative compounds for each group of contaminants, based on potential for occurrence in wastewater and expected health or environmental impacts. Due to a lack of MAR regulations in Canada, the study first proposed potential recharge water quality targets. Predominant contaminants, potential additional contaminants, and potential emerging contaminants, which together comprise critical contaminants for MAR with reclaimed water, were then selected based on the case study wastewater effluent monitoring data and literature data. This paper proposes an approach for critical contaminant selection, which will be helpful to guide future implementation of MAR projects using wastewater treatment plant effluents.

Distribution of selected antiandrogens and pharmaceuticals in a highly impacted watershed

Endocrine disruption and high occurrences of intersex have been observed in wild fish associated with municipal wastewater treatment plant (WWTP) effluents in urbanized reaches of rivers around the globe. These reproductive effects have often been attributed to the presence of estrogen receptor agonists in effluents. However, recent studies have isolated a number of androgen receptor antagonists (antiandrogens) that may also contribute to the endocrine disruption observed at sites that are influenced by WWTP outfalls. This study aimed to characterize the spatial and temporal distribution of antiandrogenic personal care products (triclosan, chlorophene, dichlorophene, oxybenzone, 1-naphthol, and 2-naphthol), along with a herbicide (atrazine) and representative pharmaceuticals (carbamazepine, ibuprofen, naproxen, and venlafaxine) in the Grand River watershed in southern Ontario. Surface water sampling of 30 sites associated with six municipal WWTP outfalls was conducted during a summer low flow. Monthly samples were also collected immediately upstream and downstream of a major WWTP from August to November 2012.Atrazine was consistently found in all surface water sampling locations. Many of the target pharmaceuticals and triclosan were detected in WWTP effluents, especially those that did not nitrify. Under low flow conditions, the concentrations of triclosan and several pharmaceuticals increased directly downstream of the WWTPs then decreased rapidly with distance downstream. Chlorophene was either found at trace levels or below detection limits in the effluents while dichlorophene, oxybenzone, 1-naphthol, and 2-naphthol were not detected in any samples. Chlorophene was detected in surface water during the low flow summer period and once during the monthly sampling from August to November. However, the primary source of chlorophene did not appear to be associated with WWTP effluent. This study documents the spatial and temporal occurrence of several antiandrogens and pharmaceuticals in a highly impacted Canadian watershed. It supports previous observations that there is a diversity of contaminants in wastewater effluents and other sources that have the potential to alter endocrine function in wild fish.

Effective decolorization of congo red in aqueous solution by adsorption and photocatalysis using novel magnetic alginate/γ-Fe2O3/CdS nanocomposite

AbstractMagnetic alginate/γ-Fe2O3/CdS composite photocatalyst (m-alginate/Fe2O3/CdS composite) was synthesized via a simple hydrothermal method, and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and vibrating sample magnetometer (VSM). The photocatalytic activity of m-alginate/Fe2O3/CdS composite was evaluated via the adsorption-photocatalytic removal of aqueous organic dye, i.e. congo red (CR). The m-alginate/Fe2O3/CdS composite can be easily manipulated and separated by a magnetic field, leading to the convenience and feasibility in the removal of aqueous hazardous dye. In addition, the kinetics of photocatalysis of CR has also been performed and found to follow the pseudo-first-order kinetics. These results suggest that m-alginate/Fe2O3/CdS composite can be used as an effective photocatalyst for the removal of hazardous pollutants such as dyes, and the adsorption-photocatalysis of these organic contaminants in wastewater effluents can s...

Effect of Wastewater Quality Parameters on Oxidation by Tin Oxide Anodes

The use of tin oxide anodes (TOAs) has been proposed for the disinfection of wastewater effluents and concurrent treatment of emerging contaminants. The common water quality constituents suspended solids, chemical oxygen demand (COD), alkalinity, ammonia-nitrogen, nitrite-nitrogen, and nitrate-nitrogen were investigated for their effect on oxidation performance by TOAs. Relative oxidant generation rates were not affected by increasing concentrations of suspended solids, COD, alkalinity, ammonia-nitrogen, or nitrate-nitrogen. Although nitrite-nitrogen did compete for oxidants generated by TOAs, nitrite is not usually present in oxygenated effluents. Chemical oxygen demand, ammonia, and nitrite were oxidized in the TOA systems, primarily through a non-hydroxyl radical mechanism. This research demonstrates that a majority of the common water quality constituents did not negatively affect TOA oxidation performance. Tin oxide anodes represent a potentially low cost and low maintenance option for single-step disinfection and treatment of emerging contaminants in wastewater effluents.

A critical evaluation of liquid chromatography with hybrid linear ion trap—Orbitrap mass spectrometry for the determination of acidic contaminants in wastewater effluents

Acidic pesticide and pharmaceutical contaminants were pre-concentrated and extracted from wastewater samples (500mL) using solid-phase extraction. Analyte recoveries were 79–96%, with % RSD values in the range, 1.7–7.4%. Analyte identification and quantification were carried out using liquid chromatography–mass spectrometry (LC–MS) with hybrid linear ion trap (LIT) Orbitrap instrumentation. Using a resolution setting of 30,000 FWHM, full-scan MS analysis was performed using heated electrospray ionization (HESI) in negative mode. The high mass resolution capabilities of the Orbitrap MS were exploited for the determination of trace contaminants allowing facile discrimination between analytes and matrix. The dependant scan functions of the Orbitrap MS using higher collisional dissociation (HCD) and LIT MS were evaluated for the confirmation of analytes at trace concentration levels. Mass accuracy for target contaminants using this method was less than 2ppm. The limits of quantitation (LOQs) were in the range, 2.1–27ng/L. The inter-day accuracy and precision were measured over a five-day period at two concentrations. The % relative errors were in the range, 0.30–7.7%, and the % RSD values were in the range, 1.5–5.5%. Using this method, 2,4-D, mecoprop, ibuprofen, naproxene and gemfibrozil were identified in several wastewater treatment plants in Ireland.

Use of an accurate-mass database for the systematic identification of transformation products of organic contaminants in wastewater effluents

In this article, a systematic approach is proposed to assist and simplify the identification of transformation products (TPs) of organic contaminants. This approach is based on the use of characteristic fragmentation undergone by organic contaminants during MS/MS fragmentation events, and the relationship and consistency with the transformations experimented by these chemicals in the environment or during water treatment processes. With this in mind, a database containing accurate-mass information of 147 compounds and their main fragments generated by CID MS/MS fragmentation experiments was created using an LC–QTOF-MS/MS system. The developed database was applied to the identification of tentative TPs and related unexpected compounds in eight wastewater effluent samples. The approach comprises basically three stages: (a) automatic screening, (b) identification of possible TPs and (c) confirmation by MS/MS analysis. Parameters related to the search of compounds in the database have been optimized and their dependence with the exhaustiveness of the study evaluated. Eight degradation products, from the pharmaceuticals acetaminophen, amoxicillin, carbamazepine, erythromycin and azithromycin and from the pesticide diazinon, were identified with a high grade of accuracy. Three of them were confirmed by analysis of the corresponding analytical standards.

Chemical evaluation of contaminants in wastewater effluents and the environmental risk of reusing effluents in agriculture

Due to increasing interest in reusing wastewater in water-deficient regions, we suggest environmental risk assessment (ERA) as a suitable tool to evaluate potential risks from trace pollutants in irrigation water. We propose a simple method for screening environmental risks associated with reusing wastewater, which can predict potential risks in terrestrial ecosystems based on the concentration of pollutants in the effluent to be reused. This method was tested in a case study including 27 priority and emerging pollutants found in effluents from two Spanish wastewater-treatment plants (WWTPs). The results showed that secondary effluents from these Spanish WWTPs were likely to cause adverse effects, due particularly to the presence of some pharmaceuticals and heavy metals. A need for effective tertiary treatment prior to reuse of wastewater effluents in agriculture is highlighted.

Controlling various contaminants in wastewater effluent through membranes and engineered wetland

For effective wastewater reclamation and water recovery, the treatment of natural and effluent organic matters (NOM and EfOM), toxic anions, and micropollutants was considered in this work. Two different NOM (humic acid of the Suwannee River, and NOM of US and Youngsan River, Korea), and one EfOM from the Damyang wastewater treatment plant, Korea, were selected for investigating the removal efficiencies of tight nanofiltration (NF) and ultrafiltration (UF) membranes with different properties. Nitrate, bromate, and perchlorate were selected as target toxic anions due to their well known high toxicities. Tri-(2-chloroethyl)-phosphate (TCEP), oxybenzone, and caffeine, due to their different K ow and pK a values, were selected as target micropollutants. As expected, the NF membranes provided high removal efficiencies in terms of all the tested contaminants, and the UF membrane provided fairly high removal efficiencies for anions (except for nitrate) and the relatively hydrophobic micropollutant, oxybenzon. Through the wetlands, nitrate was successfully removed. Therefore, a fair process of combining membranes with an engineered wetland could be proposed for sustainable wastewater reclamation and optimum control of contaminats.