Municipal Wastewater Effluent Research Articles

Desalination RO reject brine as a novel-based porous geopolymer for phosphorus removal from contaminated media

Desalination reverse osmosis reject brine-based porous geopolymer (RO/GP) was produced and investigated as an improved adsorbent for phosphorus (P) removal from tainted seawater, brackish water, river water, and municipal wastewater effluent. The RO reject brine/geopolymer was produced by reacting metakaolin and fly ash with a Na-alkali activator and anhydrous RO brine as a sacrificial template. The influence of RO reject brine content on water absorption, porosity, mechanical, and structural properties were examined. The developed RO-based geopolymers exhibited the greatest porosity (58.3–84.2 % vol%), a significant ratio of open porosity to total porosity (67.7–92.1 %), and outstanding compression strength (3.6–10.4 MPa). The produced RO/GP structure has an adsorption capacity of 92.4 mg-P/g. The sequestration reaction of phosphorus by RO/GP is of pseudo-second-order kinetic behavior via Chi-squared (χ2), RMSE, and determination coefficient (R2) values. Regarding their agreement with Langmuir behavior, the phosphorus adsorption uptakes occur in homogeneous and monolayer states. The reaction is exothermic, spontaneous, and favorable. The RO/GP exhibits significant affinity for phosphorus co-existing with Cl−, Na+, SO42−, K+, HCO3−, and Ca2+. The RO/GP shows high safety during the adsorption investigation, with a total cost of 0.32 $/kg-P.

Biochar from recovered cellulose as new admixture in constructed wetlands for micropollutant removal: A circular approach

This study aimed to evaluate the suitability of biochar produced by pyrolysis from recovered wastewater cellulose and activated biologically as an admixture in Constructed Wetlands (CWs) when applied as a post-treatment step to remove micropollutants (MPs) from municipal wastewater effluent. Two planted vertical flow mesocosm CWs with cellulose-based admixtures of different origins (plant residue and recovered toilet paper) were fed with a municipal wastewater effluent representative for rural catchments. The results showed an average MPs elimination of 89.1 % for the activated biochar produced from recovered cellulose when 15 relevant compounds are considered and a reduction of the risk from compounds cocktail below the maximum acceptable level having diclofenac, carbamazepine, PFOS, ciprofloxacin and clarithromycin as main risk drivers (Risk Quotient > 1). The implementation of a circular approach to reduce MPs was finally conducted for the Blies catchment (Saarland region in Germany) characterized by low population density and small, sensitive water bodies. This approach demonstrates the feasibility of combining cellulose recovery with a fine sieve in large wastewater treatment plants (WWTPs) and providing biochar produced from recovered cellulose as an admixture to small WWTP where CW is an affordable solution for MP mitigation.

The Effects of Wastewater Reuse on Smallmouth Bass (Micropterus dolomieu) Relative Abundance in the Shenandoah River Watershed, USA.

Municipal and industrial wastewater effluent is an important source of water for lotic systems, especially during periods of low flow. The accumulated wastewater effluent flows-expressed as a percentage of total streamflow (ACCWW%)-contain chemical mixtures that pose a risk to aquatic life; fish may be particularly vulnerable when chronically exposed. Although there has been considerable focus on individual-level effects of exposure to chemical mixtures found in wastewater effluent, scaling up to population-level effects remains a challenging component needed to better understand the potential consequences of exposure in wild populations. This may be particularly important under a changing climate in which wastewater reuse could be essential to maintain river flows. We evaluated the effects of chronic exposure to wastewater effluent, as measured by ACCWW%, on the relative abundance of young-of-year (YOY), juvenile, and adult smallmouth bass (Micropterus dolomieu) populations in the Shenandoah River Watershed (USA). We found that increases in ACCWW% in the previous year and during the prespawn period were negatively correlated with the relative abundance of YOY, resulting in an average 41% predicted decrease in abundance (range = 0.5%-94% predicted decrease in abundance). This lagged effect suggests that adult fish reproductive performance may be compromised by chemical exposure during periods of high ACCWW%. No relationships between ACCWW% and juvenile or adult relative abundance were found, suggesting that negative effects of ACCWW% on YOY abundance may be offset due to compensatory mechanisms following higher ACCWW% exposure. Understanding the effects of wastewater effluent exposure at multiple levels of biological organization will help in the development of management strategies aimed at protecting aquatic life. Environ Toxicol Chem 2024;43:1138-1148. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Development of dissolved organic matter-based indicators to understand the degradation of organic contaminants in reverse osmosis concentrate from potable reuse systems

Reverse osmosis (RO)-based treatment of municipal wastewater effluent allows for potable reuse, but this process generates reverse osmosis concentrate (ROC) that needs further treatment before disposal. This study investigated the application of UV-based advanced oxidation processes (AOPs) to degrade nine contaminants of emerging concern (CECs) from real ROC waste streams, using UV-only and UV-AOPs with hydrogen peroxide, free chlorine, and persulfate. Dissolved organic matter (DOM) in ROC was characterized using fluorescence excitation emission matrix data and analyzed by a four-component parallel factor (PARAFAC) analysis model. UV-only treatment showed considerable removal of CECs that displayed high values of quantum yields and molar absorption coefficients. UV-AOP treatment of ROC exhibited heavy scavenging of reactive species during CEC degradation. A probe-based approach established that hydroxyl radical was the dominant reactive species in all UV-AOPs. A kinetic analysis of PARAFAC components of DOM showed that the visible humic-like and protein-like components exhibited the higher reaction kinetics compared to UV humic-like and nutrient-like components. The strong linear correlation of protein-like component and seven of the nine CECs across multiple AOPs indicated that they have similar reactivity, enabling the establishment of chemical-reactivity based surrogates for prediction CEC fate in ROC wastes.

Spectrophotometric determination of phenol impurity in phenoxyethanol and phenol index of drinking water and municipal wastewater effluent after salting-out assisted liquid phase microextraction (SA-LPME)

In this study, a novel and convenient analytical method based on salting-out-assisted liquid phase microextraction (SA-LPME) has been developed. A spectrophotometric technique was employed to quantify the concentration of phenol in drinking water and treated wastewater, as well as the phenol impurity in 2-phenoxyethanol (PE). To accomplish this, a solution containing dissolved PE was supplemented with 4-aminoantipyrine (4-AAP) and hexacyanoferrate. Subsequently, NaCl was added to induce the formation of a two-phase system, consisting of fine droplets of PE as an extractant phase in the aqueous phase. The resulting red derivative was then extracted into the extractant phase and separated through centrifugation. Finally, the absorbance of the extracted derivative was measured at 520 nm. The Response Surface Methodology (RSM) based on the Box-Behnken Design (BBD) was employed to optimize the influential factors, namely 4-Aminoantipyrine (4-AAP), buffer (pH = 10), hexacyanoferrate, and NaCl. By utilizing the optimal conditions (buffer: 50 μL, 4-AAP (1% w/v): 80 μL, hexacyanoferrate (10% w/v): 65 μL, and NaCl: 0.7 g per 10 mL of the sample), the limit of detection was determined to be 0.7 ng mL−1 and 0.22 μg g−1 for water and PE samples, respectively. The relative standard deviation (RSD) and correlation of determination (r2) obtained fell within the range of 2.4–6.8% and 0.9983–0.9994, respectively. Moreover, an enrichment factor of 65 was achieved for a sample volume of 10 mL. The phenol concentration in two PE samples (PE-1, PE-2), provided by a pharmaceutical company (Pars Sadra Fanavar, Iran), were determined to be 0.83 ± 0.05 μg g−1 and 2.70 ± 0.14 μg g−1, respectively. Additionally, the phenol index in drinking water and treated municipal wastewater was found to be 3.60 ± 1.06 ng mL−1 and 4.60 ± 1.17 ng mL−1, respectively. These mentioned samples were spiked in order to evaluate the potential influence of the matrix. The relative recoveries from PE-1, PE-2 samples, drinking water, and treated municipal wastewater samples were measured as 104.5%, 97.5%, 101.6%, and 107.8%, respectively, indicating no matrix effect.

Microbiological quality assessment of treated municipal wastewater effluents for crop irrigation purposes

Massive crop production demands enormous volumes of water for irrigation. Water scarcity has led growers to look for suitable alternative water sources. Treated wastewater for agricultural purposes has been documented; however, high microbial loads pose a high risk to consumers of contaminated produce. This study evaluated the microbiological quality of treated wastewater from three artificial canals belonging to two treated municipal wastewater plants in Sinaloa, Mexico. Fecal coliforms, Escherichia coli, and Salmonella were quantified by standard methods in 60 treated wastewater samples. Fecal coliforms and E. coli were quantified from 4.0x102 to 3.9x107 CFU/100 mL and 1.0x102 to 1.0x107 CFU/100 mL, respectively. Salmonella was isolated from 45 samples, with the highest value of 16.14 MPN/L. Most of the examined samples exceeded the national and international microbial limits in water for agricultural purposes. Therefore, treated municipal wastewater from central Sinaloa, Mexico, is unsuitable for agricultural irrigation.

Solar-driven photocatalytic removal of anti-microbial drugs – Comparison of the efficiency of selected photocatalysts

The growing interest in the environmental contamination by antibiotics is observed due to their adverse effects on aquatic fauna, formation and spread of antibiotic-resistant bacteria, and antibiotic-resistant genes. Heterogeneous photocatalysis has been found a promising method to remove these recalcitrant micropollutants from the broadly understood aquatic environment. The most efficient functional materials for photocatalytic applications are nano-sized semiconductor oxides. ZnO is recently mentioned to be an alternative to TiO2, a commonly used photocatalyst, for environmental applications, but there is still a lack of information on its operation efficiency, especially in more complex matrices. This study aimed to compare the efficiency of TiO2-P25 and ZnO in the removal of selected veterinary sulfonamides (SAs), namely: sulfadiazine (SDZ), sulfamethoxazole (SMX), and sulfamethazine (SMT) from distilled water (DW), river water (RW), and municipal wastewater effluent (MWWE). TiO2-P25 has been found the most efficient photocatalyst to remove target SAs from DW, while in the case of RW and MWWE ZnO was more efficient in the degradation of studied antibiotics. The removal efficiency of the studied SAs decreased in the following order: SMT>SDZ>SMX. Doubling the photocatalysts concentration increased the efficiency of SAs degradation, but the final effect depends on the complexity of the matrix used.

Life cycle performance and associated environmental risks of constructed wetlands used for micropollutant removal from municipal wastewater effluent

Wastewater treatment systems produce environmental impacts in their construction and operation, and nature-based treatment processes offer opportunities to reduce the environmental burdens. Constructed wetlands represent such a solution that can remove micropollutants from municipal effluent. This study evaluates life cycle impacts and environmental risk of constructed wetlands for improved treatment performance. The assessment of laboratory- and pilot-scale installation performance provides insights into sustainability of scaling fundamental research to technology demonstration. The normalised life cycle assessment showed that the laboratory installation generated higher environmental impacts than the pilot, due to the cooling tank and its associated electric power (∼60% of the total burdens for five impact categories). The avoided environmental impacts through the micropollutants' elimination ranged from 50% to 99.9% (for freshwater ecotoxicity and human toxicity, respectively). A sensitivity and uncertainty analysis highlighted how the substrate and electricity demands represented the highest environmental impacts, thus extending lifespan of a full-scale system whilst maintaining treatment performance represents the most notable opportunity to improve the environmental performance. The findings support measures to enhance sustainability through design, procurement and operation stages of development. Constructed wetlands represent a sustainable nature-based form of wastewater treatment, and this study offers lessons to further enhance their environmental performance.

Excess feeding increases adipogenesis but lowers leptin transcript abundance in zebrafish larvae

Although fish exposed to municipal wastewater effluents (MWWE) show higher lipid accumulation, whether this is due to adipogenesis is unclear. The objective here was to identify molecular markers of adipogenesis in zebrafish (Danio rerio) larvae for use as high throughput screening tools for environmental contaminants, including obesogens in MWWE. Zebrafish larvae were fed a commercial diet at a maintenance level (5 % body mass) or in excess (25 or 50 % body mass) from day 6 to 30 days post-fertilization (dpf) to stimulate adipogenesis. We monitored fat accumulation and markers of lipid metabolism, including peroxisome proliferator-activated receptor γ (ppar γ), fatty acid synthase (fas), ELOVL fatty acid elongase 2 (elovl2), diacylglycerol O-acyltransferase 2 (dgat2), leptin (lepa and lepb), leptin receptor (lepr), and lipoprotein lipase (lpl). Excess feeding led to a higher growth rate, protein content and an increase in igf1 transcript abundance. Also, these larvae had higher triglyceride levels and accumulated lipids droplets in the abdominal cavity and viscera. The molecular markers of adipogenesis, including fas, elovl2, and dgat2, were upregulated, while the transcript abundance of lpl, a lipolytic gene, was transiently lower due to excess feeding. The increased adiposity seen at 30 dpf due to excess feeding coincided with a lower lep but not lepr transcript abundance in zebrafish. Our results demonstrate that excess feeding alters the developmental programming of key genes involved in lipid homeostasis, leading to excess lipid accumulation in zebrafish larvae. Overall, fas, elovl2, lpl, and dgat2, but not lep or ppar γ, have the potential to be biomarkers of adipogenesis in zebrafish larvae.

Degradation of methotrexate by unactivated and solar-activated peroxymonosulfate in water: Moiety-specific reaction kinetics and transformation product-associated risks

Anticancer drugs have raised worldwide concern owing to their ubiquitous occurrence and ecological risks, necessitating the development of efficient removal strategies in water and wastewater treatment. Although peroxymonosulfate (PMS) is known to be a promising chemical in water decontamination, limited information is available regarding the removal efficiency of anticancer drugs by PMS and solar/PMS systems. This study first reports the moiety-specific reaction kinetics and mechanisms of methotrexate (MTX), an anticancer drug with widespread attention, by PMS (unactivated) and solar-activated PMS in water. It was found that MTX abatement by the direct PMS oxidation followed second-order kinetics, and the pH-dependent rate constants increased from 0.4 M−1 s−1 (pH 5.0) to 1.3 M−1 s−1 (pH 8.0), with a slight decrease to 1.1 M−1 s−1 at pH 9.0. The presence of chloride and bromide exerted no obvious influence on the removal of MTX by PMS. Furthermore, the chemical reactivity of MTX and its seven substructures with different reactive species was evaluated, and the degradation contributions of the reactive species involved were quantitatively analyzed in the solar/PMS system. The product analysis suggested similar reaction pathways of MTX by PMS and solar/PMS systems. The persistence, bioaccumulation, and toxicity of the transformation products were investigated, indicating treatment-driven risks. Notably, MTX can be removed efficiently from both municipal and hospital wastewater effluents by the solar/PMS system, suggesting its great potential in wastewater treatment applications. Overall, this study systematically evaluated the elimination of MTX by the unactivated PMS and solar/PMS treatment processes in water. The obtained findings may have implications for the mechanistic understanding and development of PMS-based processes for the degradation of such micropollutants in wastewater.

Optimization of ammonia and COD removal from municipal wastewater effluent by electrochemical continuous flow reactor equipped with Ti/RuO2 and Cu foam

The aim of the present work was to study an electrochemical continuous-flow reactor for the removal of ammonia nitrogen (NH4+N), its by-product, and Chemical Oxygen Demand (COD) from synthetic and real municipal wastewater effluent. In this study, Ti/RuO2 electrode was prepared by the thermal decomposition method for the removal of NH4-N and COD. Characterization of the Ti/RuO2 was accomplished using FE-SEM, EDS, AFM, and XRD. Cyclic voltammetry and Tafel curves were used for the electrochemical feature of the Ti/RuO2 electrode. Box-Behnken Design (BBD) method was used to optimize the operating conditions. The effects of four independent parameters including the initial concentration of NH4+ (10–30 mg/L as N), Cl− concentration (100–500 mg/L), HRT (30–100 min), and current (0.4–1.4 A) were examined using continuous experiments for the removal of NH4+N and COD. Characterization results confirmed that RuO2 was successfully coated on the surface of titanium mesh. Optimum conditions for Cl− concentration, HRT, and current were 490 mg/L, 100 min, and 1.36 A, respectively for an effluent concentration of 30 mg/L NH4+N and 30 mg/L of COD. Under these conditions, the removal efficiencies of NH4+N and COD were respectively 97.79 and 89.64 %, and the concentration of NO3−N was 1.93 mg/L. This work highlights the importance of an electrochemical continuous flow reactor for further removal of nitrogen and COD from the effluent of municipal wastewater treatment plants.

Molecular characterization of dissolved organic matter in urban stormwater pond and municipal wastewater discharges transformed by the Florida red tide dinoflagellate Karenia brevis

Karenia brevis blooms occur almost annually in southwest Florida, imposing significant ecological and human health impacts. Currently, 13 nutrient sources have been identified supporting blooms, including nearshore anthropogenic inputs such as stormwater and wastewater outflows. A 21-day bioassay was performed, where K. brevis cultures were inoculated with water sourced from three stormwater ponds along an age gradient (14, 18, and 34 yrs.) and one municipal wastewater effluent sample, with the aim of identifying biomolecular classes and transformations of dissolved organic matter (DOM) compounds used by K. brevis. All sample types supported K. brevis growth and showed compositional changes in their respective DOM pools. Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) catalogued the molecular composition of DOM and identified specific compound classes that were biodegraded. Results showed that K. brevis utilized species across a wide range of compositions that correspond to amino sugars, humic, and lignin-like biomolecular classes. The municipal wastewater and the youngest stormwater pond (SWP 14) effluent contained the largest pools of labile DOM compounds which were bioavailable to K. brevis, which indicates younger stormwater pond effluents may be as ecologically important as wastewater effluents to blooms. Conversely, generation of DOM compounds of greater complexity and a wide range of aromaticity was observed with the older (SWP 18 and SWP 34) stormwater pond treatments. These data confirm the potential for stormwater ponds and/or wastewater to contribute nutrients which can potentially support K. brevis blooms, revealing the need for improved nutrient retention strategies to protect coastal waters from the potential ill effects of urban effluent.

Performance of different peroxide sources and UV-C radiation for the degradation of microcontaminants in tertiary effluent from a municipal wastewater treatment plant

Microcontaminants present in environmental aqueous matrices represent an emerging concern due to their recalcitrance to conventional wastewater treatment. This study aimed to (i) investigate the degradation of a mixture containing benzophenone-3, fipronil and propylparaben in a tertiary municipal wastewater effluent (100 µg L−1 each) by UV-C, UV-C/H2O2, UV−C/S2O82− and UV−C/HSO5− , and (ii) compare the degradation profile of this mixture with that of naproxen (a compound that reacts preferentially by electron transfer). Regarding the mixture, degradation increased from 50% (UV-C) to 74–87% by coupling UV-C with peroxides under the best peroxide concentration (400 μmol L−1) due to the generation of hydroxyl (HO•) and sulfate (SO4•−) radicals. In addition, the degradation efficiency was strongly dependent on the structure of the target compound, pH and peroxide source. Although high pseudo-first-order rate constants (kobs) were obtained at pH 3.0 for all peroxides, higher kobs were obtained at pH 7.0 (natural matrix pH) in the presence of H2O2. Kobs calculated for mixture degradation using different peroxides at pH 7 showed the following order: UV-C/H2O2 > UV−C/HSO5− >UV−C/S2O82−. In contrast, an opposite profile was observed for naproxen degradation (UV−C/S2O82− >UV−C/HSO5− > UV-C/H2O2). Finally, the analysis of energy efficiency and treatment costs showed that UV-C/H2O2 is highly cost-effective.

The evaluation of bacterial-augmented floating treatment wetlands for concomitant removal of phenol and chromium from contaminated water

Contamination of aquatic ecosystems with organic and inorganic contaminants is a global threat due to their hazardous effects on the environment and human health. Floating treatment wetland (FTW) technology is a cost-effective and sustainable alternative to existing treatment approaches. It consists of a buoyant mat in which wetland plants can grow and develop their roots in a suspended manner and can be implemented to treat stormwater, municipal wastewater, and industrial effluents. Here we explored the potential of bacterial-augmented FTWs for the concurrent remediation of phenol and hexavalent chromium (Cr6+) contaminated water and evaluated treated water toxicity using Triticum aestivum L. (wheat) as a test plant. The FTWs carrying Phragmites australis L. (common reed) were inoculated with a consortium of four bacterial strains (Burkholderia phytofirmans PsJN, Acinetobacter lwofii ACRH76, Pseudomonas aeruginosa PJRS20, Bacillus sp. PJRS25) and evaluated for their potential to simultaneously remove phenol and chromium (Cr) from contaminated water. Results revealed that the FTWs efficiently improved water quality by removing phenol (86%) and Cr (80%), with combined use of P. australis and bacterial consortium after 50 days. The phytotoxicity assay demonstrated that the germination of wheat seed (96%) was significantly higher where bacterial-augmented FTWs treated water was used compared to untreated water. This pilot-scale study highlights that the combined application of wetland plants and bacterial consortium in FTWs is a promising approach for concomitant abatement of phenol and Cr from contaminated water, especially for developing countries like Pakistan where the application of advanced and expensive technologies is limited.

Deciphering the water quality impacts of COVID-19 human mobility shifts in estuaries surrounding New York City

The COVID-19 pandemic altered human mobility, particularly in large metropolitan areas. In New York City (NYC), stay-at-home orders and social distancing led to significant decreases in commuting, tourism, and a surge of outward migration. Such changes could result in decreased anthropogenic pressure on local environments. Several studies have linked COVID-19 shutdowns with improvements in water quality. However, the bulk of these studies primarily focused on short-term impacts during shutdown periods, without assessing longer-term impacts as restrictions eased. Here, we examine both concurrent lockdown and societal reopening impacts on water quality, using pre-pandemic baseline conditions, in two highly urbanized estuaries surrounding NYC, the New-York Harbor estuary and Long Island Sound (LIS). We compiled datasets from 2017 to 2021 of mass-transit ridership, work-from-home trends, and municipal wastewater effluent to assess changes in human mobility and anthropogenic pressure during multiple waves of the pandemic in 2020 and 2021. These were linked to changes in water quality assessed using high spatiotemporal ocean color remote sensing, which provides near-daily observations across the estuary study regions. To distinguish anthropogenic impacts from natural environmental variability, we examined meteorological/hydrological conditions, primarily precipitation and wind. Our results show that nitrogen loading into the New York Harbor declined significantly in the spring of 2020 and remained below pre-pandemic values through 2021. In contrast, nitrogen loading into LIS remained closer to the pre-pandemic average. In response, water clarity in New-York Harbor significantly improved, with less of a change in LIS. We further show that changes in nitrogen loading had higher impact on water quality than meteorological conditions. Our study demonstrates the value of remote sensing observations in assessing water quality changes when field-based monitoring is hindered and highlights the complex nature of urban estuaries and their heterogeneous response to changes in extreme events and human behavior.

Microplastic occurrence in selected aquatic species of the Persian Gulf: No evidence of trophic transfer or effect of diet

Microplastic (MP) contamination in the aquatic ecosystems is a growing global environmental issue that can cause detrimental effects on aquatic species. In this study, MPs in fish (six species, 195 specimens), molluscs (one species, 21 specimens), and crustaceans (three species, 264 specimens) with various biometry, trophic levels, feeding habits, and habitat characteristics were investigated in three habitats: a river, an estuary, and a harbor in the Persian Gulf. Gastrointestinal tracts, gills and skin of targeted samples were chemically digested and the MPs recovered were counted and analyzed with optical microscopy, Raman spectroscopy and SEM/EDX. MPs counted in species of the Bushehr Port (11.4 ± 4.4 MPs/10 g) were significantly higher than in the other locations. The total abundance of MPs ranged from 4.0 ± 2.3 MPs/10 g for Metapenaeus affinis to 28.0 ± 6.4 MPs/10 g for Sepia pharaonis. Importantly, no significant relationships were found between the number of MPs in different inedible tissues, trophic levels, and types of feeding habit. Nevertheless, MPs were more abundant (p < 0.05) in benthos (34.7 MPs/10 g) than benthopelagic (25.9 MPs/10 g) and pelagic species (22.6 MPs/10 g). A total of 96.6 % of the identified MPs were fibers, these were generally ≥1000 μm and were mainly black/grey. Fibers may come from municipal wastewater effluents and fishing activities. The findings of this study present new insights into MP contamination routes in aquatic species.

Determination of fiber yield and quality in cotton cultivars, applied with biologically reclaimed greywater

Application of recycled municipal wastewater and industrial effluents using biological treatment methods to industrial crops is an ingenious practice to ensure the combined means of adopting sustainable industrial crops production through sustainable freshwater management. An investigation was made to study the effects of recycled greywater treated using the extended form of Effective Microorganisms in the sewage treatment plant, over the growth, biochemical contents, yield and fiber quality of MCU7 and SVPR2 cotton cultivars, grown under experimental conditions. The efficacy of the recycled greywater treatment was compared with ground well water as control and untreated greywater as on another treatment. Improved yield of lint fiber and cotton seeds were obtained with a ginning out turn (GOT) of 71.66% and 66.1% in the SVPR2 and MCU7 cultivars, respectively, when irrigated with recycled greywater. Similarly, both the cotton cultivars, supplied with the recycled greywater was found with a significantly higher (P ≤ 0.01) stable length (SL) and fiber strength, as well as significantly higher spinning consistency index (SCI) (P ≤ 0.05) and uniformity ratio, when compared with the other two treatments. The novelty approach, adopted in the experiment therefore can be concluded using the recycled greywater to the specific cotton cultivars in water-deficit agro-climatic conditions would be beneficial to sustain the cotton production, would be in turn benefiting the industries.

Appraisal of the Temporospatial Migration and Potential Ecotoxicity of Phthalic Acid Esters in Municipal Effluents, Rivers and Dam—A Catchment-Wide Assessment

Herein, the catchment-wide temporal dynamics and potential ecotoxicological risk of phthalic acid esters (PAEs) in aquatic ecosystems were assessed. Specifically, water samples were collected for a period of six consecutive months from seven selected sites, i.e., covering both dry and wet seasons for seasonal variabilities. The appraised PAEs comprised dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP), diphenyl phthalate (DPP), di-n-hexyl phthalate (DHP), bis(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DOP), diisodecyl phthalate (DiDP) and diisononyl phthalate (DiNP)) in municipal wastewater effluents, rivers and dam. Their concentrations were quantified using a gas chromatography–flame ionisation detector (GC–FID) via the liquid–liquid extraction mode. The appraised PAEs were ubiquitous in the selected sampling points, with DBP being the most abundant PAE homologue throughout the assessed localities. In particular, quantifiable concentrations were 18.9, 37.9 and 11.5 μg/L for DBP in wastewater effluents, rivers and the dam catchment, respectively, and for overall Σ10PAEs of minimum, mean and maximum of 0.492, 3.6 ± 9.82 and 63.2 μg/L, respectively. In addition, PAE concentrations in the effluents, rivers, and dam samples showed no significant differences with p &lt; 0.05. The overall prominent sequence for ∑PAEs registered: 53.3 &gt; 10.1 &gt; 10.0 &gt; 9.8 &gt; 4.3 &gt; 2.5 &gt; 1.8 &gt; 1.7 &gt; 1.1 &gt; 0.9% for DBP &gt; DEHP &gt; DiDP &gt; DOP &gt; DHP &gt; DPP &gt; BBP &gt; DMP &gt; DEP &gt; DiNP, respectively. The ecotoxicological risk assessment (risk quotient method) showed that DBP and DiDP posed high risk (RQ ≥ 1), and DOP, DEHP, DHP, DiNP and BBP posed median risk to aquatic organisms (0.1 ≤ RQ &lt; 1), while the risk from DMP and DEP was minimal (RQ &lt; 0.1). Additionally, DBP, DEHP, DOP, DPP and DiDP were higher than the water criterion (3 μg/L) of PAEs recommended by the United States Environmental Protection Agency (USEPA) for the protection of aquatic life. Findings from this study should go a long way in guiding regulators, custodians and catchment management forums, along with interested and affected parties, regarding the status and potential ecotoxicological effects of PAEs in the receiving environment.

Chemically Modified TiO2 Photocatalysts as an Alternative Disinfection Approach for Municipal Wastewater Treatment Plant Effluents

Among key issues in municipal wastewater treatment plants (MWTP) is the existence of pathogenic bacteria in the discarded effluents. Conventional disinfectants (ozone, UV irradiation, chlorine) have been insufficient in providing safe water due to the development of undesirable and noxious by-products. TiO2 comprises an attractive alternative to conventional methods because of its versatility and recently explored biocidal efficiency. As a result, within the framework of this study, chemically modified, visible active nanocrystalline TiO2 powders (N-TiO2, N,S-TiO2, and Ag@N-TiO2) were prepared via a low-cost, feasible sol-gel method for the treatment of real municipal wastewater effluents. Wastewater samples were acquired from the outlet of the treatment of Antiparos (Cyclades, Greece) MWTP during the summer period in which a great number of seasonal habitants and tourists usually visit the island, resulting in at least a doubling of the population. All synthesized powders were thoroughly characterized using various morphological and spectroscopic techniques, such as FE-SEM, XRD, micro-Raman, FTIR, DLS, UV-DRS, and XPS. Photocatalytic evaluation experiments were initially conducted towards Rhodamine B degradation under visible light irradiation. Among all studied powders, Ag@N-TiO2 indicated the highest efficiency, reaching total degradation (100%) of RhB within 240 min due to its smaller crystallite size (1.80 nm), enhanced surface area (81 m2g−1), and reduced energy band gap (Eg = 2.79 eV). The effect of the produced powders on the disinfection as assessed in terms of fecal indicator microorganisms (E. coli and total coliforms) inactivation was also examined in a semi-pilot scale-up photocatalytic reactor. Ag@N-TiO2 nanopowder was also found substantially more active for both groups of bacteria, leading to complete inactivation in less than 35 min, probably due to the higher production of H2O2/—OH, as emerged from the photocatalytic mechanism study. In addition, Ag@N-TiO2 nanoparticles demonstrated excellent photocatalytic and disinfection stability even after five subsequent recycling trials (8.34% activity loss and complete inactivation, respectively). The results of the present study demonstrate the feasibility for Ag@N-TiO2 to be utilized as a viable, eco-friendly approach for the photocatalytic pathogenic bacteria inactivation as an alternative disinfection approach for municipal wastewater treatment plant effluents with intense seasonal fluctuations in volume.

Identification, occurrence, concentration and composition profile of fiproles in municipal wastewater treatment plants

Although fipronil and several of its transformation products are ubiquitous in aquatic environments, limited information is available on the structural identities, detection frequencies, concentrations and composition profiles of fiproles (fipronil and its known and unknown transformation products) in municipal wastewater treatment plants (WWTPs). In this study, a suspect screening analysis was applied to identify and characterize fipronil transformation products in 16 municipal WWTPs from three cities in China. In addition to fipronil and its four transformation products (fipronil amide, fipronil sulfide, fipronil sulfone and desulfinyl fipronil), fipronil chloramine and fipronil sulfone chloramine were detected for the first time in municipal wastewater. Moreover, the cumulative concentrations of six transformation products were 0.236 ng/L and 3.44 ng/L in wastewater influents and effluents, and accounted for one-third (in influents) to half (in effluents) of fiproles. Of those transformation products, two chlorinated byproducts (fipronil chloramine and fipronil sulfone chloramine) were major transformation products in both municipal wastewater influents and effluents. Notably, the log Kow and bioconcentration factor (evaluated by EPI Suite software) of fipronil chloramine (log Kow = 6.64, and BCF = 11,200 L/kg wet-wt) and fipronil sulfone chloramine (log Kow = 4.42, and BCF = 382.9 L/kg wet-wt) were greater than that of their parent compound. Considering the persistence, bioaccumulation potential and toxicity, the high detection rates of fipronil chloramine and fipronil sulfone chloramine in urban aquatic systems need to be specifically considered in future ecological risk assessments.