Assessment of the surface water quality and primary health risk in urban wastewater and its receiving river Kathajodi, Cuttack of eastern India.

Kathajodi, the principal southern distributary of the Mahanadi River, is the vital source of irrigation and domestic water use for densely populated Cuttack city which receives anthropogenic wastes abundantly. This study assesses the contamination level and primary health status of urban wastewater, and its receiving river Kathajodi based on the physicochemical quality indices employing inductively coupled plasma mass spectroscopy and aligning with guidelines from the United States Environmental Protection Agency (USEPA) and WHO. The high WQI, HPI, and HEI in the catchment area (KJ2, KJ3, and KJ4) indicate poor water quality due to the influx of domestic waste through the primary drainage system and effluents of healthcare units. A high BOD (4.33-19.66 mg L-1) in the catchment indicates high organic matter, animal waste, bacteriological contamination, and low DO, resulting in deterioration of water quality. CR values beyond limits (1.00E - 06 to 1.00E - 04) in three locations of catchment due to higher Cd, Pb, and As indicate significant carcinogenic risk, while high Mn, Cu, and Al content is responsible for several non-carcinogenic ailments and arsenic-induced physiological disorders. The elevated heavy metals Cd, Cu, Fe, Mn, Ni, and Zn, in Kathajodi, could be due to heavy coal combustion, vehicle exhaust, and industrial waste. On the other hand, Cu, Fe, K, and Al could be from agricultural practices, weathered rocks, and crustal materials. Positive significant (p ≤ 0.05) Pearson correlations between physicochemical parameters indicate their common anthropogenic origin and similar chemical characteristics. A strong correlation of PCA between elements and physiological parameters indicates their role in water quality deterioration. Assessing the surface water quality and heavy metal contents from this study will offer critical data to policymakers for monitoring and managing public health concerns.

Target and Nontarget Screening to Support Capacity Scaling for Substance Use Assessment through a Statewide Wastewater Surveillance Network in New York.

Wastewater-based epidemiology (WBE) has been widely implemented around the world as a complementary tool to conventional surveillance techniques to inform and improve public health responses. Currently, wastewater surveillance programs in the U.S. are evaluating integrated approaches to address public health challenges across multiple domains, including substance abuse. In this work, we demonstrated the potential of online solid-phase extraction coupled with liquid chromatography-high-resolution mass spectrometry to support targeted quantification and nontargeted analysis of psychoactive and lifestyle substances as a step toward understanding the operational feasibility of a statewide wastewater surveillance program for substance use assessment in New York. Target screening confirmed 39 substances in influent samples collected from 10 wastewater treatment plants with varying sewershed characteristics and is anticipated to meet the throughput demands as the statewide program scales up to full capacity. Nontarget screening prioritized additional compounds for identification at three confidence levels, including psychoactive substances, such as opioid analgesics, phenethylamines, and cathinone derivatives. Consumption rates of 12 target substances detected in over 80% of wastewater samples were similar to those reported by previous U.S.-based WBE studies despite the uncertainty associated with back-calculations. For selected substances, the relative bias in consumption estimates was sensitive to variations in monitoring frequency, and factors beyond human excretion (e.g., as indicated by the parent-to-metabolite ratios) might also contribute to their prevalence at the sewershed scale. Overall, our study marks the initial phase of refining analytical workflows and data interpretation in preparation for the incorporation of substance use assessment into the statewide wastewater surveillance program in New York.

A novel green synthesis of MnO2-Coal composite for rapid removal of silver and lead from wastewater.

The presence of Ag(I) and Pb(II) ions in wastewater poses a significant threat to human health in contemporary times. This study aims to explore the development of a novel and economical adsorbent by grafting MnO2 particles onto low-rank coal, providing an innovative solution for the remediation of water contaminated with silver and lead. The synthesized nanocomposites, referred to as MnO2-Coal, underwent thorough characterization using FTIR, XRD, BET, and SEM to highlight the feasibility of in-situ surface modification of coal with MnO2 nanoparticles. The adsorption of Ag(I) and Pb(II) from their respective aqueous solution onto MnO2-Coal was systematically investigated, with optimization of key parameters such as pH, temperature, initial concentration, contact time, ionic strength, and competing ions. Remarkably adsorption equilibrium was achieved within a 10 min, resulting in impressive removal rates of 80-90 % for both Ag(I) and Pb(II) at pH 6. The experimental data were evaluated using Langmuir, Freundlich, and Temkin isotherm models. The Langmuir isotherm model proved to be more accurate in representing the adsorption of Ag(I) and Pb(II) ions onto MnO2-Coal, exhibiting high regression coefficients (R2 = 0.99) and maximum adsorption capacities of 93.57 and 61.98 mg/g, along with partition coefficients of 4.53 and 71.92 L/g for Ag(I) and Pb(II), respectively, at 293 K. Kinetic assessments employing PFO, PSO, Elovich, and IPD models indicated that the PFO and PSO models were most suitable for adsorption mechanism of Pb(II) and Ag(I) on MnO2-Coal composites, respectively. Moreover, thermodynamic evaluation revealed the spontaneous and endothermic adsorption process for Ag(I), while exothermic behavior for adsorption of Pb(II). Importantly, this approach not only demonstrates cost-effectiveness but also environmental friendliness in treating heavy metal-contamination in water. The research suggests the potential of MnO2-Coal composites as efficient and sustainable adsorbents for water purification applications.

Removal, transformation and ecological risk assessment of pesticide in rural wastewater by field-scale horizontal flow constructed wetlands of treated effluent.

Constructed wetlands (CWs) are widely used in sewage treatment in rural areas, but there are only a few studies on field-scale CWs in treating wastewater-borne pesticides. In this study, the treatment and metabolic transformation of 29 pesticides in rural domestic sewage by 10 field-scale horizontal flow CWs (HF-CWs), each with a treatment scale of 36‒5000 m3/d and operated for 2‒10 years, in Guangzhou, Southern China was investigated. The risk of pesticides in treated effluent and main factors influencing such risk were evaluated. Results demonstrated that HF-CWs could remove pesticides in sewage and reduce their ecological risk in effluent, but the degree varied among types of pesticides. Herbicides had the highest mean removal rate (67.35 %) followed by insecticides (60.13 %), and the least was fungicides (53.22 %). In terms of single pesticide compounds, the mean removal rate of butachlor was the highest (73.32 %), then acetochlor (69.41 %), atrazine (68.28 %), metolachlor (58.40 %), and oxadixyl (53.28 %). The overall removal rates of targeted pesticides in each HF-CWs ranged from 11 %‒57 %, excluding two HF-CWs showing increases in pesticides in treated effluent. Residues of malathion, phorate, and endosulfan in effluent had high-risks (RQ > 5). The pesticide concentration in effluent was mainly affected by that in influent (P = 0.042), and source control was the key to reducing risk. The main metabolic pathways of pesticide in HF-CWs were oxidation, with hydroxyl group to carbonyl group or to form sulfones, the second pathways by hydrolysis, aerobic condition was conducive to the transformation of pesticides. Sulfones were generally more toxic than the metabolites produced by hydrolytic pathways. The present study provides a reference on pesticides for the purification performance improvement, long-term maintenance, and practical sustainable application of field-scale HF-CWs.

Release characteristics and risk assessment of volatile sulfur compounds in municipal wastewater treatment plants.

In recent years, the malodorous gases generated by sewage treatment plants have gradually received widespread attention due to their sensory stimulation and health hazards. The emission concentration, sensory evaluation and health risk assessment of volatile sulfur compounds (VSCs) were all explored in two municipal wastewater treatment plants (WWTPs) with oxidation ditch and anaerobic/oxic treatment process, respectively. The VSCs concentration showed the highest amount in the primary treatment unit in both the two WWTPs (73.3% in Plant A and 93.0% in Plant B), while the H2S took the main role in the composition of VSCs. However, H2S took a larger percentage in Plant A (84.5% âˆ¼ 87.0%) rather than Plant B (61.2% âˆ¼ 83.5%), which may be due to the different operating conditions and sludge properties in different treatment process. Besides, H2S also gained the first rank in the sensory evaluation and health risk assessment, which may cause considerable sensory irritation and health risk to workers and surrounding residents. Furthermore, the influencing factor analyses of VSCs emission showed that the temperature of water and air, ORP of sludge made the greatest effect on VSCs release. This study provides theoretical and data support for the research of VSCs emission control in WWTPs.

Assessment of characteristics and treatment processes of wastewater from slaughterhouses in the state of Minas Gerais, Brazil.

The state of Minas Gerais is one of Brazil's largest animal protein producers, and its slaughterhouses generate highly polluting wastewater, which needs to be treated for discharge or reuse. As a novelty, this review article focused on assessing the characteristics and methods to treat wastewater from slaughterhouses in the state of Minas Gerais, and verifying its compliance with environmental regulatory agencies. The aim was to present data that helps to better manage this residue in other Brazilian states and countries. By analyzing the literature data, it was found that raw slaughterhouse wastewater (SWW) showed a high concentration of organic matter. For most SWW, the BOD5/COD ratio was above 0.4, which implies that it can be treated biologically. Generally, treated wastewater was in accordance with legal discharge standards, considering COD and BOD5 removals above 70% and 75%, respectively. It was found that wastewater treatment plants (WWTPs) consisted of some type of pretreatment (screens, grease traps) to remove coarse solids and fatty material, eventually followed by a flotation step and finally by biological processes, mostly anaerobic and/or aerated (or facultative) ponds. However, the absence of an aerobic process at the end of the treatment in some WWTPs, in addition to a system allowing better removal of biological flocs, might be the reason for ammoniacal nitrogen and suspended solids values being above the allowed maximum in treated wastewater, respectively. Besides the discharge into water bodies, it was verified that fertigation using treated SWW is very common in the state of Minas Gerais.

Effects of municipal sludge composition on hydrothermal liquefaction products: Aqueous phase characterization and biodegradability assessment.

Hydrothermal liquefaction (HTL) aqueous phases derived from mixed sludge and digested sludge of two wastewater treatment plants (WWTP) were characterized considering variations in primary-secondary sludge ratios, an aspect previously overlooked in the literature. Mixed sludge was obtained by mixing primary and secondary sludge to simulate high primary sludge, average, and high secondary sludge cases. Aerobic and mesophilic/thermophilic anaerobic biodegradability tests were conducted. Higher chemical oxygen demand, total ammonium-N, orthophosphate-P, fatty acids, and N-heterocycles in HTL aqueous samples were detected as the secondary sludge ratio increased in mixed sludge. A similar trend was observed in the biodegradability tests. Characteristics of HTL aqueous derived from mixed sludge of WWTP 1 showed much higher variation, whereas WWTP 2 mixed sludge was not affected significantly by primary-secondary sludge ratios. Finally, the biodegradability levels of HTL aqueous samples were determined to be 69-78 % under aerobic, 58-70 % under mesophilic anaerobic, and 42-56 % under thermophilic anaerobic conditions.

Environmental risk assessment of selected pharmaceuticals in hospital wastewater in nothern Vietnam.

Pharmaceuticals are progressively employed in both human and veterinary medicine and increasingly recognized as environmental contaminants. This study investigated the occurrence of selected pharmaceuticals in influent and effluent of wastewater treatment plants of 12 hospitals in Hanoi and 3 northern cities of Vietnam during dry and rainy seasons. In addition, environmental risk of pharmaceuticals in both hospital influents and effluents were evaluated based on risk quotients (RQs). Nine selected pharmaceutical compounds including sulfamethoxazole (SMX), naproxen (NPX), diclofenac (DCF), ibuprofen (IBU), acetaminophen (ACT), carbamazepine (CBM), iopromide (IOP), atenolol (ATN), and caffeine (CAF) were frequently detected in most influent and effluent wastewaters of 12 investigated hospitals. Detected compound levels exhibited a wide range, from as low as 1 ng/L for DCF to as high as 61,772 ng/L for ACT. Among these compounds, ACT, CAF, SMX, and IOP were consistently detected at substantial concentrations in both influents and effluents. This investigation also highlighted potential risks posed by SMX, ACT, and CAF residues present in influents and effluents of hospital wastewater treatment plants (WWTPs) to aquatic ecosystem. These finding are expected to provide scientific-based evidence for the development of hospital waste management and environmental management programs in Vietnam.

Efficient magnetic solid-phase extraction, UPLC-MS/MS detection, and consumption assessment of five trace psychoactive substances.

Wastewater-based epidemiology (WBE) has become an objective and updated surveillance strategy for monitoring and estimating consumption trends of psychoactive substances (PSs) in the population. Firstly, magnetic shrimp shell biochar-based adsorbent (DZMBC) was synthesized and employed for extraction trace PSs from municipal wastewater. Proper pyrolysis temperature and increased KOH activator content favored the pore structure and surface area, thus facilitating extraction. DZMBC delivered exceptional extraction performance such as pH stability, anti-interference property, fast magnetic separation ability, reusability, and reproducibility. Then, a method based on magnetic solid-phase extraction (MSPE) followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed, validated, and utilized for the quantitative determination of five PSs in real wastewater samples. Methodological validation results indicated a favorable linearity, low method limits of detection (1.00-4.75 ng/L), and good precisions (intra-day and inter-day relative standard deviations < 4.8%). Finally, an objective snapshot of Chongqing drug use and consumption pattern was obtained. Methamphetamine (MAMP) and 3,4-methylenedioxymethamphetamine (MDMA) were the prevalent illegal drugs in local. Both concentrations and per capita consumption of MDMA displayed a change (P < 0.05) between July and September, while no statistical differences were observed for each week.

Antibiotic ciprofloxacin removal from aqueous solutions by electrochemically activated persulfate process: Optimization, degradation pathways, and toxicology assessment.

Ciprofloxacin (CIP) is a commonly used antibiotic in the fluoroquinolone group and is widely used in medical and veterinary medicine disciplines to treat bacterial infections. When CIP is discharged into the sewage system, it cannot be removed by a conventional wastewater treatment plant because of its recalcitrant characteristics. In this study, boron-doped diamond anode and persulfate were used to degrade CIP in an aquatic solution by creating an electrochemically activated persulfate (EAP) process. Iron was added to the system as a coactivator and the process was called EAP+Fe. The effects of independent variables, including pH, Fe2+, persulfate concentration, and electrolysis time on the system were optimized using the response surface methodology. The results showed that the EAP+Fe process removed 94% of CIP under the following optimum conditions: A pH of 3, persulfate/Fe2+ concentration of 0.4 mmol/L, initial CIP concentration 30 mg/L, and electrolysis time of 12.64 min. CIP removal efficiency was increased from 65.10% to 94.35% by adding Fe2+ as a transition metal. CIP degradation products, 7 pathways, and 78 intermediates of CIP were studied, and three of those intermediates (m/z 298, 498, and 505) were reported. The toxicological analysis based on toxicity estimation software results indicated that some degradation products of CIP were toxic to targeted animals, including fathead minnow, Daphnia magna, Tetrahymena pyriformis, and rats. The optimum operation costs were similar in EAP and EAP+Fe processes, approximately 0.54 €/m3.

Human health risk assessment framework for new water resource recovery-based bio-composite materials.

A new type of bio-composite material is being produced from water-recovered resources such as cellulose fibres from wastewater, calcite from the drinking water softening process, and grass and reed from waterboard sites. These raw materials may be contaminated with pathogens and chemicals such as Escherichia coli, heavy metals, and resin compounds. A novel risk assessment framework is proposed here, addressing human health risks during the production of new bio-composite materials. The developed framework consists of a combination of existing risk assessment methods and is based on three main steps: hazard identification, qualitative risk mapping, and quantitative risk assessment. The HAZOP and Event Tree Analysis methodologies were used for hazard identification and risk mapping stages. Then, human health risks were quantitatively assessed using quantitative chemical risk assessment, evaluating cancer and non-cancer risk, and quantitative microbial risk assessment. The deterministic and the stochastic approaches were performed for this purpose. The contamination of raw materials may pose human health concerns, resulting in cancer risk above the threshold. Microbial risk is also above the safety threshold. Additional analysis would be significant as future research to better assess the microbial risk in biocomposite production. The framework has been effectively used for chemical and microbial risk assessment.

Emerging pollutants in textile wastewater: an ecotoxicological assessment focusing on surfactants.

Water and several chemicals, including dyestuffs, surfactants, acids, and salts, are required during textile dyeing processes. Surfactants are harmful to the aquatic environment and induce several negative biological effects in exposed biota. In this context, the present study aimed to assess acute effects of five surfactants, comprising anionic and nonionic classes, and other auxiliary products used in fiber dyeing processes to aquatic organisms Vibrio fischeri (bacteria) and Daphnia similis (cladocerans). The toxicities of binary surfactant mixtures containing the anionic surfactant dodecylbenzene sulfonate + nonionic fatty alcohol ethoxylate and dodecylbenzene sulfonate + nonionic alkylene oxide were also evaluated. Nonionic surfactants were more toxic than anionic compounds for both organisms. Acute nonionic toxicity ranged from 1.3 mg/L (fatty alcohol ethoxylate surfactant) to 2.6 mg/L (ethoxylate surfactant) for V. fischeri and from 1.9 mg/L (alkylene oxide surfactant) to 12.5 mg/L (alkyl aryl ethoxylated and aromatic sulfonate surfactant) for D. similis, while the anionic dodecylbenzene sulfonate EC50s were determined as 66.2 mg/L and 19.7 mg/L, respectively. Both mixtures were very toxic for the exposed organisms: the EC50 average in the anionic + fatty alcohol ethoxylate mixture was of 1.0 mg/L ± 0.11 for V. fischeri and 4.09 mg/L ± 0.69 for D. similis. While the anionic + alkylene oxide mixture, EC50 of 3.34 mg/L for D. similis and 3.60 mg/L for V. fischeri. These toxicity data suggested that the concentration addition was the best model to explain the action that is more likely to occur for mixture for the dodecylbenzene sulfonate and alkylene oxide mixtures in both organisms. Our findings also suggest that textile wastewater surfactants may interact and produce different responses in aquatic organisms, such as synergism and antagonism. Ecotoxicological assays provide relevant information concerning hazardous pollutants, which may then be adequately treated and suitably managed to reduce toxic loads, associated to suitable management plans.

Assessment of selected pharmaceuticals in Riyadh wastewater treatment plants, Saudi Arabia: Mass loadings, seasonal variations, removal efficiency and environmental risk.

Despite increasing interest in pharmaceutical emissions worldwide, studies of environmental contamination with pharmaceuticals arising from wastewater discharges in Saudi Arabia are scarce. Therefore, this study examined occurrence, mass loads and removal efficiency for 15 pharmaceuticals and one metabolite (oxypurinol) from different therapeutic classes in three wastewater treatment plants (WWTPs), in Riyadh city in Saudi Arabia. A total of 144 samples were collected from the influents and effluents between March 2018 and July 2019 and analyzed using Solid Phase Extraction followed by triple quadrupole LC-MS/MS. The average concentrations in the influents and effluents were generally higher than their corresponding concentrations found either in previous Saudi Arabian or global studies. The four most dominant compounds in the influent were acetaminophen, ciprofloxacin, caffeine, and diclofenac, with caffeine and acetaminophen having the highest concentrations ranging between 943 and 2282 µg/L. Metformin and ciprofloxacin were the most frequently detected compounds in the effluents at concentrations as high as 33.2 µg/L. Ciprofloxacin had the highest mass load in the effluents of all three WWTPs, ranging between 0.20 and 20.7 mg/day/1000 inhabitants for different WWTPs. The overall average removal efficiency was estimated high (≥80), with no significant different (p > 0.05) between the treatment technology applied. Acetaminophen and caffeine were almost completely eliminated in all three WWTPs. The samples collected in the cold season generally had higher levels of detected compounds than those from the warm seasons, particularly for NSAID and antibiotic compounds. The estimated environmental risk from pharmaceutical compounds in the studied effluents was mostly low, except for antibiotic compounds. Thus, antibiotics should be considered for future monitoring programmes of the aquatic environment in Saudi Arabia.

Contamination Pattern and Risk Assessment of Polar Compounds in Snow Melt: An Integrative Proxy of Road Runoffs.

To assess the contamination and potential risk of snow melt with polar compounds, road and background snow was sampled during a melting event at 23 sites at the city of Leipzig and screened for 489 chemicals using liquid chromatography high-resolution mass spectrometry with target screening. Additionally, six 24 h composite samples were taken from the influent and effluent of the Leipzig wastewater treatment plant (WWTP) during the snow melt event. 207 compounds were at least detected once (concentrations between 0.80 ng/L and 75 µg/L). Consistent patterns of traffic-related compounds dominated the chemical profile (58 compounds in concentrations from 1.3 ng/L to 75 µg/L) and among them were 2-benzothiazole sulfonic acid and 1-cyclohexyl-3-phenylurea from tire wear and denatonium used as a bittern in vehicle fluids. Besides, the analysis unveiled the presence of the rubber additive 6-PPD and its transformation product N-(1.3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6-PPDQ) at concentrations known to cause acute toxicity in sensitive fish species. The analysis also detected 149 other compounds such as food additives, pharmaceuticals, and pesticides. Several biocides were identified as major risk contributors, with a more site-specific occurrence, to acute toxic risks to algae (five samples) and invertebrates (six samples). Ametryn, flumioxazin, and 1,2-cyclohexane dicarboxylic acid diisononyl ester are the main compounds contributing to toxic risk for algae, while etofenprox and bendiocarb are found as the main contributors for crustacean risk. Correlations between concentrations in the WWTP influent and flow rate allowed us to discriminate compounds with snow melt and urban runoff as major sources from other compounds with other dominant sources. Removal rates in the WWTP showed that some traffic-related compounds were largely eliminated (removal rate higher than 80%) during wastewater treatment and among them was 6-PPDQ, while others persisted in the WWTP.

Life Cycle Assessment of UV-C based treatment systems for the removal of compounds of emerging concern from urban wastewater.

In the last decades particular attention is being paid to the efficient and effective removal of compounds of emerging concern (CECs) present in wastewater before their eventual reuse or disposal. Several technologies have been developed for the degradation of CECs in aqueous matrix, in this regard advanced oxidation processes (AOPs) represent a nascent technological solution developed on a laboratory scale with applications on a prototype scale. The experimental evidences have shown that AOPs processes can oxidize numerous organic compounds in a much faster and more efficient way than that of the most common disinfection processes. The most common AOPs processes are those that involve the use of H2O2/UV, O3/UV, H2O2/O3, H2O2/O3/UV, Fenton and photo-Fenton. The aim of this work is to illustrate the results of a comparative LCA study of a laboratory scale UV-C photoreactor for the tertiary treatment of urban wastewater of three treatment systems (UV-C, UV-C + H2O2 e UV-C + TiO2). In particular, the specific objective is to evaluate, from an environmental point of view, an innovative advanced oxidation system based on nanostructures TiO2 immobilized on a stainless steel mesh. Compared to the UV-C photolysis reference system, the addition of hydrogen peroxide reduces the total environmental impact of the system by almost 75 %, while the use of the stainless-steel mesh coated by the nanostructures titanium dioxide reduces the UV-C environmental impact by 30 %. These results are due to the lower energy consumption of these last treatments compared to photolysis alone. The main impacts of the three systems are related to the electric power consumption of the centrifugal pump (63-64 %) and of the UV-C lamp (32-33 %). The LCA applied to these systems has shown that TiO2 assisted photocatalysis is not yet advantageous from an environmental point of view and that, therefore, the efficiency of the system needs to be improved.

A waste-based circular economy approach for phycoremediation of X-ray developer solution.

A waste-based circular economy approach is proposed for the phycoremediation of an X-ray developer (XD) solution. The present study emphasizes the utilization of food waste (FW) and agri-compost media (ACM) as growth media for D. armatus for the subsequent bioremediation potential of XD solution-coupled lipid production. A 3:1 dilution (FW/ACM: XD.) was found to be suitable for the phycoremediation study of XD solution towards the % removal of biological oxygen demand (BOD), chemical oxygen demand (COD) and silver. The phycoremediation studies of diluted XD solution in FW demonstrated a 74.50% BOD removal, 81.69% COD removal, and 54.70% removal of silver. The growth of D. armatus in diluted XD solution in food waste was 1.37% lipid content. The phycoremediation of diluted XD solution with ACM resulted in 83.05% BOD removal, 88.88% COD removal and 56.30% silver removal with the concomitant lipid production of 1.42%. The optimal bioremediation coupled lipid production of D. armatus was observed on the 19th day of D. armatus cultivation in the developer effluent, along with food waste and agri-compost media, for 31 days. The study suggests a sustainable utilization of waste (FW and ACM) as a nutritive medium to scrutinize the phycoremediation of XD solution with a concomitant lipid production that can open up new avenues in phycoremediation coupled energy commodities production.

Low-cost and resource-efficient monolithic photocatalyst with enhanced solar light utilization for the photocatalytic treatment of organic wastewater.

Developing low-cost, well-performing, and resource-efficient photocatalysts with enhanced solar light utilization can contribute to the practicability of photocatalytic techniques in organic wastewater treatment. This study fabricated and characterized a novel sunlight-driven BiOBr- and acetylene black (AB)-loaded monolithic photocatalyst. The fly ash-based geopolymer acts as photocatalyst support that can also provide adsorption sites and semiconductor metal oxide (Fe2O3). A conductive network in the geopolymer structure formed by AB can promote the separation of e--h+ pairs generated by active sites (BiOBr and Fe2O3). Moreover, the photothermal effect induced by AB can assist the photocatalytic reaction at the microinterface of the photocatalyst. This photocatalyst was suspended on the surface of an aqueous solution for sufficient contact with oxygen from the air and is thus beneficial for producing 1O2 and ·OH as the main active species. Within 30 min, it exhibited higher photothermal-photocatalytic activity with 96% removal efficiency of the target pollutant methylene blue (MB), which occurred at an initial concentration of 20 mg L-1. The demethylation and hydroxylation process induced by the active species constituted the primary degradation pathway for MB by Bi/AB/MFGP. Overall, this study provides a valuable reference for developing economical, effective, and practical photocatalysts and applying geopolymers in photocatalysis.

Environmental application of a cost-effective smartphone-based method for COD analysis: Applicability in the electrochemical treatment of real wastewater.

This study aims to develop a cheap method for the evaluation of quality of water or the assessment of the treatment of water by chemical oxygen demand (COD) measurements throughout the use of the HSV color model in digital devices. A free application installed on a smartphone was used for analyzing the images in which the colors were acquired before to be quantified. The proposed method was also validated by the standard and spectrophotometric methods, demonstrating that no significant statistical differences were attained (average accuracy of 97 %). With these results, the utilization of this smartphone-based method for COD analysis was used/evaluated, for first time, by treating electrochemically a real water matrix with substantial organic and salts content using BDD and Pt/Ti anodes. Aiming to understand the performance of both anodes, bulk experiments were performed under real pH by applying current densities (j) of 15, 30, and 60 mA cm-2. COD abatement results (which were achieved with this novel smart water security solution) clearly showed that different organic matter removal efficiencies were achieved, depending on the electrocatalytic material used as well as the applied current density (42 %, 45 %, and 85 % for Ti/Pt while 93 %, 97 % and total degradation for BDD by applying 15, 30, and 60 mA cm-2, respectively). However, when the persulfate-mediated oxidation approach was used, with the addition of 2 or 4 g Na2SO4 L-1, COD removal efficiencies were enhanced, obtaining total degradation with 4 g Na2SO4 L-1 and by applying 15 mA cm-2. Finally, this smartphone imaging-based method provides a simple and rapid method for the evaluation of COD during the use of electrochemical remediation technology, developing and decentralizing analytics technologies for smart water solutions which play a key role in achieving the Sustainable Development Goal 6 (SDG6).

Macro-nutrients recovery from liquid waste as a sustainable resource for production of recovered mineral fertilizer: Uncovering alternative options to sustain global food security cost-effectively.

Global food security, which has emerged as one of the sustainability challenges, impacts every country. As food cannot be generated without involving nutrients, research has intensified recently to recover unused nutrients from waste streams. As a finite resource, phosphorus (P) is largely wasted. This work critically reviews the technical applicability of various water technologies to recover macro-nutrients such as P, N, and K from wastewater. Struvite precipitation, adsorption, ion exchange, and membrane filtration are applied for nutrient recovery. Technological strengths and drawbacks in their applications are evaluated and compared. Their operational conditions such as pH, dose required, initial nutrient concentration, and treatment performance are presented. Cost-effectiveness of the technologies for P or N recovery is also elaborated. It is evident from a literature survey of 310 published studies (1985-2022) that no single technique can effectively and universally recover target macro-nutrients from liquid waste. Struvite precipitation is commonly used to recover over 95 % of P from sludge digestate with its concentration ranging from 200 to 4000 mg/L. The recovered precipitate can be reused as a fertilizer due to its high content of P and N. Phosphate removal of higher than 80 % can be achieved by struvite precipitation when the molar ratio of Mg2+/PO43- ranges between 1.1 and 1.3. The applications of artificial intelligence (AI) to collect data on critical parameters control optimization, improve treatment effectiveness, and facilitate water utilities to upscale water treatment plants. Such infrastructure in the plants could enable the recovered materials to be reused to sustain food security. As nutrient recovery is crucial in wastewater treatment, water treatment plant operators need to consider (1) the costs of nutrient recovery techniques; (2) their applicability; (3) their benefits and implications. It is essential to note that the treatment cost of P and/or N-laden wastewater depends on the process applied and local conditions.