Purpose This research explores how integrating Lean Six Sigma (LSS) methodologies with Circular Economy (CE) principles can enhance operational efficiency and sustainability in wastewater treatment (WWT) systems. Design/methodology/approach Using a case study approach, this research evaluates a municipal WWT plant as a bounded system. It applies established tools, such as Failure Mode and Effects Analysis (FMEA), regression analysis and hypothesis testing, to assess process performance. While these tools are widely recognized, their domain-specific adaptation to climate resilience and CE challenges in WWT systems remains limited, particularly within a structured, single-case empirical framework. Findings The results show that traditional quality improvement tools can be effectively adapted to achieve environmental goals. The proposed framework achieved a 6.5% reduction in energy use in the secondary treatment stage, corresponding to annual savings of 575,665 kWh and approximately $48,891. It also contributed to reduced greenhouse gas (GHG) emissions by recovering methane (CH4) and supported long-term resilience through hydraulic capacity forecasting. Research limitations/implications Although based on a single case, the study offers insights that can guide broader application across WWT sectors and geographies, laying the groundwork for future empirical validation. Practical implications This research provides a flexible framework for industry professionals to integrate LSS and CE strategies into infrastructure operations. Originality/value The study bridges a research gap by introducing a novel LSS–CE framework tailored to sustainability and climate resilience in WWT systems.

In this article, the needle plate corona discharge plasma water treatment device is used to treat nicosulfuron in water. In this article, the effects of treatment duration, discharge gap, discharge voltage, initial pH and concentration of persulfate in the synergistic system on the degradation rate of nicosulfuron in the corona discharge system and corona discharge synergistic persulfate system were investigated, and the reaction kinetics were also analyzed. The research found that the use of plasma technology alone had a certain degradation effect on nicosulfuron in water. However, when combined with persulfate to form a synergistic system, the degradation rate of nicosulfuron could be significantly enhanced. And finally, the degradation pathway of nicosulfuron was inferred by using Fukui function and Mulliken Buju analysis.

The depik (Rasbora tawarensis) is one of the leading fishery commodities in Central Aceh Regency and is endemic to Laut Tawar Lake. Due to overfishing and environmental degradation, the depik is now endangered, necessitating domestication. The success of the domestication stage is influenced by providing feed that meets the fish's needs, such as Artemia encapsulated with spirulina to enhance the nutritional quality of the Artemia. This study aims to evaluate the effect. of spirulina dosage as an Artemia enrichment material on the growth performance of depik. The applied research design was a completely randomized design with four treatments replicated four times. The treatments included Artemia without bioencapsulation (Treatment 1/P1), Artemia bioencapsulation with 0.5 g of spirulina powder per liter of water (Treatment 2/P2), Artemia bioencapsulation with 1 g of spirulina powder per liter of water (Treatment 3/P3), and Artemia bioencapsulation with 2 g of spirulina powder per liter of water (Treatment 4/P4). The parameters observed were absolute length growth (ALG), absolute weight growth (AWG), specific growth rate (SGR), and survival rate. Based on the ANOVA test, different doses of spirulina had a significant effect (P < 0.05) on the growth and survival of depik fry. The higher the dose given, the higher the growth and survival performance produced. Based on the Duncan test, the best treatment was shown in Treatment 4, namely the provision of bioencapsulated Artemia with 2 g of spirulina powder as feed for the depik fry.

Abstract Synthetic dyes are extensively used in the textile industry and represent a major source of environmental pollution due to the discharge of colored effluents into aquatic ecosystems. Conventional physical and chemical treatment methods are often ineffective in completely removing these dyes and may generate secondary pollutants or increase toxicity. Consequently, environmentally friendly and sustainable biological alternatives are required. This study aimed to isolate, characterize, and evaluate indigenous fungi from dye-contaminated environments for the decolorization of Remazol Red (RR) dye. Fungal isolates were obtained from the Cibuluh River, Cisadane River, and textile industry wastewater treatment plants. Initial screening was performed on solid media containing RR dye, resulting in 45 fungal isolates, of which 15 demonstrated strong resistance and decolorization capability at elevated dye concentrations. Five promising isolates (TB1, TB3, TB4, SB1, and SB2) were further evaluated in liquid media containing RR at concentrations ranging from 100 to 1000 mg/L. Among the tested isolates, TB1, TB3, and TB4 exhibited the highest decolorization efficiencies, achieving nearly complete dye removal at lower concentrations and maintaining substantial activity even at higher levels within five days of incubation. Visual observations and spectrophotometric analyses confirmed effective dye removal. Morphological and molecular identification based on ITS sequencing revealed that SB1 was closely related to Aspergillus tamarii, SB2 to Aspergillus awamori, TB1 to Aspergillus niger, TB4 to Trametes polyzona, and TB3 to Cladosporium cladosporioides. This study highlights the strong potential of indigenous fungi as cost-effective and sustainable agents for textile dye bioremediation.

Water pollution from phenols remains a critical concern due to their persistence, toxicity, and industrial prevalence. Graphene oxide (GOx), with its functional groups and large surface area, offers strong adsorption potential. Using density functional theory (DFT), reduced density gradient (RDG), and quantitative structure–activity relationship (QSAR), we examined how protonation and substituents influence phenol adsorption. Deprotonated phenolates bind more strongly to GO than neutral species via electrostatics and H-bonding. Substituents alter affinity: halogens enhance it, bulky alkyls hinder it, and nitro groups show electron-withdrawing effects. Bisphenolate A displayed multidentate binding. QSAR models reproduced DFT energies with R2 > 0.99, enabling fast prediction. These results highlight how pH speciation and substituents govern adsorption on GO, guiding the design of efficient water treatment materials.

This study aims to optimize the physical, mechanical, and thermal properties of 100% Ground Granulated Blast Furnace Slag (GGBFS) based geopolymer wood-composite panels. Pine fibers were utilized as the primary reinforcement matrix, while glass and hemp fibers were introduced as secondary reinforcements at varying proportions (3%, 6%, 9% by weight). The research investigated the effects of fiber pretreatments (hot water vs. 1% NaOH) and reinforcement hybridization. Results indicate that GGBFS successfully geopolymerized, forming a hybrid N-A-S-H and C-A-S-H gel network. Quantitative analysis revealed that 9% glass fiber reinforcement yielded the highest mechanical performance, achieving a Modulus of Rupture (MOR) of 10.05 N/mm2 and Internal Bond (IB) strength of 1.32 N/mm2, alongside superior water resistance (1.0% Thickness Swelling). Conversely, while hemp fiber inclusion reduced mechanical strength (MOR: 5.77 N/mm2 at 9%), it significantly enhanced thermal insulation, reducing thermal conductivity to 0.10 W/m·K. It was observed that aggressive NaOH pretreatment caused alkali-induced degradation of pine fibers, negatively impacting the composite’s integrity compared to hot water treatment. This study demonstrates the feasibility of tailoring 100% slag-based geopolymer composites for either structural (glass-reinforced) or insulating (hemp-reinforced) applications using industrial by-products.

The Nworie River in southeastern Nigeria is a vital freshwater source for domestic, recreational, and agricultural use. However, it is increasingly threatened by pollution from untreated sewage, urban runoff, and indiscriminate waste disposal. This study assessed the microbial quality of the river to evaluate potential ecological and public health risks. Water and sediment samples were collected from six different sites between April and June 2023 using standard plankton nets and Van Veen grab samplers. Microbial assessment employed serial dilution and membrane filtration methods, with inoculation on Nutrient Agar, MacConkey Agar, Eosin Methylene Blue Agar, Salmonella Shigella Agar, and Potato Dextrose Agar. Colony counts were expressed as cfu/ml and compared with Federal Ministry of Environment (FMEnv) standards. Results revealed elevated microbial loads: total bacteria ranged from 2.00 × 10⁴ to 4.05 × 10⁵ cfu/ml, coliforms from 6.00 × 10⁴ to 1.30 × 10⁵ cfu/ml, and fungi from 2.00 × 10⁴ to 1.40 × 10⁵ cfu/ml, all exceeding FMEnv permissible limits. Klebsiella species were detected at three sites (up to 2.00 × 10⁵ cfu/ml), while Escherichia coli was absent across all samples. These findings indicate severe microbial contamination, highlighting significant health risks for communities dependent on the river. The study underscores the urgent need for improved wastewater management, public sensitization, proper water treatment strategies,and exploration of microbial bioremediation as a sustainable solution.

Insights into iron sulfide activated sulfite pretreatment for enhancing short-chain fatty acids production from sludge fermentation: Performance and mechanism.

Similar to other developing countries, Hanoi, the capital of Vietnam disposes of urban sludge, including sludge from water and wastewater treatment plants, drainage systems, at a landfill. With increasing population growth and urbanization, the volume of generated sludge continues to rise, necessitating proper treatment of the resulting sludge landfill leachate. This study assessed the characteristics of sludge landfill leachate and investigated appropriate treatment methods. The results indicate that the leachate contained high turbidity and TSS levels, along with a substantial organic content, as reflected by an average COD of 222 mg/L and BOD₅ of 110 mg/L. Nitrogen levels were also high, with NH4+ at 102 mg/L and TN at 108 mg/L. Based on these characteristics, the study implemented a combined coagulation and biological treatment approach. The pretreatment of the leachate by coagulation led to COD reduction, thereby reducing the efficiency of the subsequent biological treatment. Therefore, the selected treatment process involved an initial AO (anoxic-oxic) biological treatment using biofilm carriers to remove organic matter and nitrogen, followed by coagulation using PAC at a dosage of 200 mg/L. The treated sludge landfill leachate met local discharge standard of Hanoi. This study provides essential data for designing sludge landfill leachate treatment system in Hanoi, Vietnam.

Metal-organic frameworks (MOFs), owing to their highly tunable structures, large specific surface areas, rich pore architectures, and diverse functionalities, have emerged as promising candidates for addressing environmental and energy challenges. With continuous advances in green synthesis techniques, eco-friendly applications of MOFs are progressively transitioning from laboratory research to real-world engineering. This review systematically summarizes recent progress in MOF applications across multiple green technology domains, including environmental remediation, sustainable energy conversion and storage, agricultural and food sciences, and healthcare. Emphasis is placed on the mechanisms and performance of MOFs in air pollution control, water treatment, photo/electrocatalytic water splitting and hydrogen storage, lithium-ion batteries and supercapacitors, pesticide delivery systems, food packaging materials, drug delivery, and bioimaging. Furthermore, key challenges facing practical MOF applications, such as material stability, regenerability, scalability in synthesis, and environmental safety, are critically analyzed. Prospects for future research directions are also outlined. This review aims to provide theoretical support and research guidance for the advanced application of MOFs in green chemistry, low-carbon energy, smart agriculture, and precision medicine, thereby promoting their further engineering implementation and industrialization within the framework of sustainable development.

A new hydrogel nanocomposite, sodium alginate-g-poly(acrylic acid)/montmorillonite (SA-g-P(AA)/MMT), was created using free radical polymerization. The purpose was to test its ability to remove Azur B dye. Detailed analysis using techniques like FTIR, XRD, FESEM, and EDX confirmed the synthesis of the material, revealing characteristic functional groups, a change in the MMT's crystalline structure, and a porous surface morphology. The poly(acrylic acid) was effectively grafted onto sodium alginate, and montmorillonite was incorporated. This process resulted in a porous and amorphous structure ideal for adsorption. Adsorption tests yielded excellent results, with a maximum removal efficiency of 97.13% achieved. The material demonstrated capacity of 1942.80 mg/g. Optimal conditions were found to be pH 1.2, 30 °C, and a 180 min. Kinetic studies determined that the adsorption process followed a pseudo-second-order mechanism. Thermodynamic analysis indicated that the process was spontaneous (ΔG = −14.35 kJ/mol) and endothermic (ΔH = 18.88 kJ/mol). The Temkin model (R² = 0.986) provided the best fit for the adsorption isotherm, indicating a heterogeneous surface with consistent binding energy. The nanocomposite also exhibited pH-responsive swelling, which enhanced its performance in acidic environments (swelling of 590% at pH 10). These findings confirm that SA-g-P(AA)/MMT nanocomposite is a pH-sensitive adsorbent, making it a promising material for water treatment. KEY WORDS: Azur B dye, Hydrogel, Clay, Nanocomposite, Adsorption, Water treatment Bull. Chem. Soc. Ethiop. 2026, 40(3), 533-550. DOI: https://dx.doi.org/10.4314/bcse.v40i3.4

Flood-induced seedling mortality along riverbanks is a global issue, primarily caused by oxygen deficiency and associated secondary stresses during submergence. To address this problem, our study introduced an innovative approach by enhancing dissolved oxygen (DO) in floodwater to alleviate flooding stress. We conducted a pot experiment using one-year-old seedlings of two Carya illinoinensis cultivars, ‘Mahan’ and ‘Pawnee’, under three treatments: control (CK), high-oxygen flooding (HO), and low-oxygen flooding (LO). Morphological, growth, and physiological responses of both cultivars were systematically evaluated to comprehensively assess their flooding tolerance. The results demonstrated that aeration significantly mitigated both physiological damage and growth inhibition caused by flooding. After 60 days of flooding, compared with the LO treatment, the HO treatment reduced the leaf injury rate (by 11.11% in ‘Mahan’ and 0% in ‘Pawnee’) and the injury index by 26.43–31.75% in both cultivars. It also increased the growth rate in plant height (GRH) by 18.18–166.67%, total biomass (TB) by 15.69–18.17%, and root-to-shoot ratio (RSR) by 18.18–34.94%. Moreover, the HO treatment led to reductions in malondialdehyde (MDA) content by 7.55–7.87%, soluble protein (SP) content by 2.14–20.50%, and activities of superoxide dismutase (SOD) and catalase (CAT) by 16.86–17.16% and 17.20–23.73%, respectively. Membership function analysis further revealed that plants in the HO treatment exhibited superior overall stress resistance compared to those in the LO treatment, with the resistance ranking as follows: ‘Mahan’-HO > ‘Mahan’-LO > ‘Pawnee’-HO > ‘Pawnee’-LO. In summary, this study explores how elevated dissolved oxygen alleviates key flood stress symptoms, thus providing a theoretical foundation for flood-resistant management of C. illinoinensis in the Yangtze River Basin and a novel intervention framework for other terrestrial plants facing periodic flooding.

Comparative performance of activated sludge and waste stabilization ponds for the removal of pollutants and pathogens in full-scale wastewater treatment plants in Egypt.

In this study, manganese oxide films were successfully deposited on Graphite sheets using a sol-gel dip-coating method. The films were subsequently employed as anode electrodes for the electrochemical oxidation of produced water (PW) in the polishing stage of the treatment. Electrodes were fabricated by optimizing key parameters affecting the synthesis of manganese oxide colloids, including precursor concentration, withdrawal speed, and calcination temperature, through a dip-coating process on Graphite sheets followed by thermal treatment and calcination. The electrochemical performance of the electrodes was evaluated through cyclic voltammetry (CV) and their chemical oxygen demand (COD) removal efficiency during the electrochemical oxidation of PW. A comparison of the electrochemical efficiencies of fabricated electrodes under different fabrication conditions in the treatment process showed that the optimal conditions included an initial manganese acetate concentration of 0.3M, five coating layers, a withdrawal speed of 5.5mm/min, and calcination at 300°C for 60min, which led to the formation of a crystal structure of Mn2O3. The results showed the specific capacity of 92.161 mF/cm2, 86.96% COD removal at 30mA/cm2 after 120min and an estimated lifetime of 500h. The structural and morphological characterization of the optimized electrode using X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the uniform deposition of Mn2O3 nanoparticles on the Graphite substrate. The findings indicate that the proposed MnOx electrode exhibits both high efficiency and stability, making it a promising candidate for the electrochemical oxidation of produced water as well as for applications in electrochemical supercapacitors.

The desire to protect aquatic ecosystems and drinking water supplies from the adverse effects of nutrients, trace organic contaminants, and other constituents in municipal wastewater has led to a need for additional treatment, particularly in watersheds with insufficient dilution. Constructed wetlands have emerged as viable alternatives to advanced wastewater treatment processes for effluent polishing due to their low cost and ancillary benefits. Starting in the late 1980s, experiences gained from several decades of operating wetlands in small communities increased confidence that these nature-based treatment systems could be effective and reliable. As a result, investments were made in larger constructed wetlands, with surface areas greater than a million square meters (1 Mm2) and flows often exceeding 1 m3 s-1, on effluent-dominated rivers and as part of potable water reuse projects. More recently, new wetland designs have improved the constructed wetland system performance by taking advantage of sunlight-mediated processes in the water column and microbial processes on subsurface porous media. Research that provides additional insight into contaminant removal mechanisms, demonstrates long-term viability, and further improves treatment performance could expand the application of constructed wetlands to other difficult-to-solve water quality challenges, including the treatment of municipal water reuse concentrate and the mitigation of nonpoint source pollution.

Anion-exchange resins (AER) are widely applied in water treatment, although their chemical-intensive regeneration remains a bottleneck for the consumption of chemicals and generation of wastes. This study presents a thermo-regenerable AER composite (TR@AER) prepared via the interpenetration of poly(acrylic acid-co-acrylamide) (p(AA-co-AM)) within the AER matrix. TR@AER exhibits thermoresponsive hydrophilicity and surface charge, evidenced by a decrease in contact angle from 88.1° (25 °C) to 76.7° (50 °C) and a drop in ζ-potential from +36.9 mV (25 °C) to +31.1 mV (50 °C). In situ variothermal FTIR and molecular dynamics simulations reveal that this dual response is triggered by the dissociation of hydrogen bonds between -COOH and -CONH2 groups in p(AA-co-AM). The dissociation simultaneously drives the hydrophobic-to-hydrophilic transition and deprotonation of -COOH groups in p(AA-co-AM), which subsequently interact with quaternary ammonium (-NR3+) moieties of AER and alter surface charge characteristics. This enables a switchable adsorption and desorption of organic contaminants. At 25 °C, TR@AER rapidly adsorbs diclofenac and ibuprofen through synergistic electrostatic and hydrophobic interactions. Heating to 50 °C disrupts these interactions, significantly enhancing desorption. The desorption efficiency correlates with p(AA-co-AM) content in TR@AER. At the optimal p(AA-co-AM) loading (26-37 wt%), diclofenac desorption reached 92.2% and ibuprofen desorption reached 96.0% at 50 °C, representing 1.7- and 1.8-fold that of 25 °C, respectively. By circumventing chemical-intensive regeneration protocols, this work highlights an innovative strategy for stimuli-responsive adsorbent design with excellent regeneration capabilities.

Globally, an estimated 11.2billion tons of municipal solid waste are generated annually. The increasing volume and complexity of waste, together with rapid urbanization, pose major risks to human health through diarrheal disease outbreaks. In many urban centers of low- and middle-income countries, solid waste management (SWM) practices remain inadequate. In Mbale City, Uganda, diarrheal disease ranks among the top five causes of morbidity and mortality, with over 28,000 cases reported in 2018. This study assessed the association between diarrheal disease and SWM practices and perceptions among residents of Industrial Division, Mbale City. A descriptive cross-sectional study employing both quantitative and qualitative approaches was conducted among 424 adult respondents (≥ 18 years) during the entire month of February 2020 in the Industrial Division of Mbale City. Quantitative data were collected using a structured questionnaire, while qualitative data were obtained through Focus Group Discussions (FGDs) and Key Informant (KI) interviews with community leaders and municipal officials. Data were entered into Epidemiological Data Software (EpiData) and analyzed using STATA. Potential confounders were identified from literature and expert consultation, including age, sex, education, water source, sanitation, and family size. Bivariable and multivariable logistic regression analyses were performed to assess associations between diarrhea and predictor variables. Qualitative data were analyzed using thematic content analysis. Diarrheal disease was defined as the passage of three or more loose or watery stools in 24h (WHO). The prevalence of diarrheal disease among adults in Industrial Division was 36.8%. After adjusting for confounders (age, sex, education, water source, water treatment, and toilet type), only the type of solid waste generated was significantly associated with diarrhea: households generating textiles had lower odds compared to those generating paper waste (AOR = 0.46; 95% CI: 0.24-0.90). Other significant factors included household size, source of drinking water, and toilet ownership. While overall SWM practices were moderate, key risk factors for diarrheal disease included unsafe water sources, lack of household toilets, and larger household sizes. The findings underscore the urgent need for improved sanitation, safe water supply, and community awareness on proper waste handling. Local authorities should strengthen community sensitization on SWM, ensure continuous water quality surveillance, promote construction of household toilets, and integrate family planning initiatives into urban public health programs.

The persistent presence of endocrine-disruptive chemicals (EDCs) in surface waters has raised serious environmental and health concerns, necessitating the development of efficient and sustainable water treatment strategies. Advanced oxidation using visible light-driven photoactive bismuth oxyiodide nanoparticles is an emerging technique for efficient water treatment. The effects of reaction parameters such as pH and temperature on the formation of semiconductor BixOyIz nanoparticles remain underemphasized despite their critical role in tailoring size, morphology, elemental composition, specific surface area, and photocatalytic activity. Accordingly, this study aimed to develop a modified solvo-hydrothermal method to optimize the synthesis of BixOyIz nanoparticles under varying pH and temperature conditions, and to establish correlations between their physicochemical properties - characterized by XRD, SEM, EDX, TEM, FTIR, UV-vis DRS, XPS, PL, Raman, and BET - and their photocatalytic performance. The results revealed that the sensitivity of iodine to pH and temperature significantly influenced particle growth and specific surface area, while the overall photocatalytic activity was also determined by the various phases of bismuth oxides and hydroxides formed during synthesis. It was demonstrated that the particles synthesized at pH values between 1.5 and 5.5 showed the highest photocatalytic activity due to the combined effect of larger surface area and interstitial surface defects formed due to hydroxylation. Finally, the possible configuration mechanism of the synthesized nanoparticles and the kinetics of photocatalytic degradation were discussed.

ABSTRACT Water is a fundamental necessity for our existence, but its rapid contamination is causing devastating effects on the environment and health of living species worldwide. Adsorptive removal of pollutants is one of the popular water treatment techniques because of its simplicity, affordability, and the broad range of available adsorbents. Among the diverse range of adsorbents utilized for water applications, graphene‐based materials are gaining substantial attention in the water treatment applications owing to their unique physicochemical properties. Clay minerals are also quite popular adsorbents due to their low cost, abundant availability, and environmental compatibility. In this respect, GO‐intercalated bentonite (BNT) composite was developed via a facile solvent mixing method for the eradication of imidacloprid (IMD) pesticide from water. GO used in this study was fabricated from agricultural waste in order to increase the sustainability of the adsorption process. The synthesized adsorbent was further characterized via FTIR, BET, SEM, and TEM analysis. The experimental results showed that the addition of GO to BNT could improve the adsorptive removal of IMD in comparison to pristine BNT. The maximum removal of IMD using the fabricated composite was observed to be 92.83% under the optimized conditions (adsorbate concentration = 30 mg/L, adsorbent dose of 2 g/L, and 60‐min interaction time). The Langmuir isotherm and pseudo‐second‐order kinetic models provided a reliable description of the experimental data. Further, the resulting composite satisfactorily adsorbed IMD from real water samples, indicating the applicability of fabricated adsorbents in real wastewater as well.

This study presents a sustainable route for synthesizing zeolites by valorizing two abundant industrial residues: sugarcane bagasse ash and water treatment plant sludge. The synthesized material, primarily composed of sodalite as confirmed by XRD and SEM, was applied for the removal of Acid Red 27 (AR27), a synthetic dye widely used in the food, cosmetics, and household product industries. The adsorption kinetics followed a pseudo-second-order model, suggesting dependence on active site availability, while isotherm analysis indicated multilayer adsorption consistent with the BET model, with an adsorption capacity reaching 250mg·g-1. Experiments conducted with competitive anions suggest the adsorption mechanism in the first layer predominantly involved electrostatic interactions; the dye structure suggests π-π stacking for subsequent layers. Coexisting anions, particularly sulfate and bicarbonate, significantly hindered AR27 uptake due to competitive adsorption. Importantly, the adsorbent maintained its performance over three regeneration cycles using a diluted NaOH solution (0.01M). Compared to granular and powdered activated carbons, the synthesized zeolite exhibited superior performance, especially at medium to high contaminant loads. These findings highlight the potential of waste-derived zeolites as a low-cost, efficient, and environmentally friendly material for wastewater treatment, contributing to circular economy strategies and sustainable resource management.