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An agro-waste corncob was used to prepare activated carbon and loaded with ZnO nanoparticles by using the impregnation method. The FTIR band at 492 cm−1 of zinc oxide nanoparticle-loaded corncob activated carbon (ZnO@CCAc-7) shows the spreading vibrational modes of ZnO. The crystallinity and crystal structure of different prepared materials were analysed using X-ray diffraction (XRD). The specific surface area of ZnO@CCAc-7 was observed to be 148.3 m2/g, which was nearly two times larger than that of efficient corncob activated carbon. The fundamental peaks of carbon, oxygen and ZnO nanoparticle with their atomic percent of C 66.66, O 27.10 and ZnO 6.24 were observed in the SEM-EDX spectrum. The thermal stability of the prepared adsorbent was also analysed using thermogravimetric analysis (TGA). The maximum COD reduction using ZnO@CCAc-7 adsorbent was obtained to be 76.4% at the peak values of pH 6, dose 1.50 g/50 mL, time 160 minutes and temperature 30 ͦC. The various adsorption models Hill, Khan, Redlich–Peterson, Toth, Koble–Corrigan and Freundlich were found close-fitted to the adsorption process. It was observed that the COD removal adsorption technique ensued to a pseudo-first-order rate of kinetics. The negative value of Gibb's free ΔG0 and positive values of the enthalpy change (∆H° = 25.64 kJmol-1) indicates that the process of COD removal using ZnO@CCAc-7 adsorbent was spontaneous and endothermic in nature. Furthermore, response surface methodology with a subset of Central composite design was also studied in detail to optimise the COD removal efficiency. [ABSTRACT FROM AUTHOR]

The biosorption capacity of untreated olive stones (OS) and olive stones chemically treated (TOS) to remove COD's landfill leachate was investigated in this study. Characterization of the both biosorbents was performed using XRD, SEM, FTIR and 13C NMR techniques. Leachate was taken from Hassi Bounif Sanitary Landfill (HBSL) in Oran (Western Algeria). So, Hassi Bounif Leachate (HBL) exhibited a basic pH between 7.83 and 8.2, high COD level varying from 5,200 to 8,000 mg.L-1, low BOD5/COD ratio from 0.1 to 0.16, and high NH3-N concentrations ranged from 2,300 to 2,800 mg.L-1. Accordingly, this leachate can be classified as an intermediate leachate that is likely to stabilize. Biosorption studies were carried out in a batch system and the effects of contact time, media pH, and biosorbent mass on the removal efficiency of COD were explored. Based on results obtained at pH=11, contact times of 55 and 105 min were achieved for biosorbent masses of 0.1 g for TOS and 0.3 g for OS, respectively, and were found to be the optimal operating conditions for HBL treatment. Thus, the highest COD removal efficiencies of 79.94 and 67.04% were reached for TOS and OS, correspondently. The pseudo-second order model was the best fitted to our experimental data with high regression coefficients (R2 ≥ 0.98). The Langmuir isotherm model adequately represented the COD removal process, with a maximum adsorption capacity of 90.91 mg.g-1 for TOS and 31.25 mg.g-1 for OS at T=50°C and pH=11. The thermodynamic parameters indicated that the biosorption process was feasible, spontaneous, and endothermic. These findings suggested that TOS might be employed as an inexpensive and effective biosorbent for COD removal from stabilized leachate. They can also provide baseline information and design assistance for a leachate treatment plant at the HBSL site, as well as for any sanitary landfill in Algeria. [ABSTRACT FROM AUTHOR]

To evaluate effects of microalga addition in the intensive Litopenaeus vannamei farming system, the amount of Picochlorum sp. in culture water was adjusted to be 1 × 104 cells/mL (KH_1), 2 × 104 cells/mL (KH_2), or 4 × 104 cells/mL (KH_4) respectively by artificial addition, and that without microalgal addition was set as the control. First, it was found that Picochlorum sp. addition was effective to reduce the total ammonia nitrogen (TAN), nitrite, phosphate, and chemical oxygen demand (COD) in culture water, and the water quality of KH_4 was the best among various groups after a 30-day culture, with reduction of 89.85% TAN, 78.17% nitrite, 50.00% phosphate, and 63.28% COD in comparison with the control. Second, addition of Picochlorum sp. had a significant impact on the microalgae community structure of shrimp culture system, and it has become the absolute dominant genus in KH_1, KH_2, and KH_4 group, with relative abundances of 86.57%, 95.48%, and 99.01% respectively, whereas Chaetoceros (51.05%) dominate in the control. Moreover, the growth performance of shrimp in KH_2 and KH_4 groups were better than those in the control (P < 0.05), and the superoxide dismutase (SOD) and lysozyme (LZM) activity in hepatopancreas increased by 31.73–78.05% and 16.93–73.74% for the Litopenaeus vannamei in KH_2 and KH_4. The results of this study indicated that artificial addition of Picochlorum sp. could be effective to improve the water quality and shrimp growth, and be a feasible environmental regulation method in shrimp aquaculture. [ABSTRACT FROM AUTHOR]

Algal oligosaccharides (AOS) have been shown to effectively promote plant growth. While there have been many studies on the use of AOS in promoting crop growth, few have investigated their potential in improving ecological floating bed wastewater treatment. Therefore, this paper aims to explore the effects and mechanisms of AOS in enhancing ecological floating bed wastewater treatment. Water spinach was cultivated in aquaculture wastewater treated with varying concentrations of AOS (0.025, 0.05, 0.1, and 0.2 mg/L), with an ecological floating bed without AOS serving as the control group. Results shows the addition of AOS can significantly enhancing ecological floating bed plant and microbial accumulation, resulting in profound improvement in ecological floating bed wastewater treatment efficiency. This is evident in the increased plant height, stem diameter, main root length, number of roots, leaf area, above water-surface fresh weight, below water-surface fresh weight, above water-surface dry weight, below water-surface dry weight, chlorophyll a, chlorophyll b, and chlorophyll content. The combination of 0.05 mg/L AOS with the ecological floating bed exhibits the most favorable results, with percentage increases in various indicators were 44.0%, 52.9%, 29.9%, 62.0%, 28.0%, 141.6%, 84.0%, 97.7%, 220.0%, 24.6%, 34.2%, 26.9% compared to the control group. The addition of AOS to the water spinach ecological floating bed system significantly enhances the removal efficiency of water turbidity, chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3−-N), total nitrogen (TN), and total phosphorus (TP) water quality indicators. This experiment also investigated the differences in microbial community structure between the control group and the group with the optimal concentration of AOS to study the mechanism of action of AOS. The combination of 0.05 mg/L AOS with the ecological floating bed demonstrates the optimal removal efficiency. This study offers crucial technical insights for further optimizing ecological floating bed technology and improving water purification efficiency. [ABSTRACT FROM AUTHOR]

Wastewater generated by edible oil industries is characterized by elevated levels of chemical oxygen demand (COD), oils, and grease (O&G), which poses significant challenges for treatment to comply with environmental standards. This study aims to assess the effectiveness of continuous flow electrocoagulation in treating such wastewater and optimizing water quality to meet these standards. A response surface methodology (RSM) approach is employed to evaluate the influence of critical operational parameters, including pH, electrode distance, electric current, and reaction time, on the removal efficiencies of COD and O&G. Numerous experiments are conducted under various conditions to identify the optimal configuration. The results revealed that under optimal conditions of pH 3.81, electrode spacing of 1.5 cm, an electric current of 5 A, and a contact time of 51.42 minutes, removal efficiencies of 91.2% for COD and 93.7% for O&G are achieved. Additionally, the maximum processing efficiency is reached during the second operational cycle, where the residual concentrations of COD and O&G are found to be 36.6 mg/L and 14.2 mg/L, resulting in removal efficiencies of 99.26% and 99.25%, respectively. These findings underscore that the proposed optimized electrocoagulation method can attain higher removal efficiencies for COD and O&G than those previously noted in comparable studies. Consequently, this method could be adopted by industries aiming to comply with stringent environmental regulations. Furthermore, the novel combination of operational parameters addresses a significant gap in wastewater treatment research, providing a sustainable solution for industries managing oily contaminants. However, further research may be necessary to evaluate large-scale applications' long-term operational stability and cost-effectiveness. [ABSTRACT FROM AUTHOR]

Water scarcity affects more than 40% of the population; in addition, 70% of all water extracted from aquifers is used for irrigation, reducing its availability for human consumption. Therefore, irrigation of crops with wastewater helps reduce water scarcity. In Mexico, high chemical oxygen demand (COD)-value wastewater is generated by the cooking process of corn (Zea mays). In this work, the use of this effluent for the irrigation of potato crops (Solanum tuberosum) is proposed. Four treatments were applied: (A) water, (B) water with fertiliser, (C) 100% wastewater and (D) 50% wastewater, both residual effluent of the cooking corn process. In the determination of biomass, in the number of leaves, there were no differences between the treatments; instead, for the height of the plants, A and B were higher for day 32. Treatment B obtained the highest production of tubers, followed by treatment A. Treatment C achieved 80% of the production of treatment A, suggesting that the components of the wastewater can be used as nutrients by potato plants. Being necessary for a study on the affectation on soil fertility, the use of treated wastewater to irrigate crops represents a viable alternative to reduce the effluents commonly discharged into natural spaces. Furthermore, if the composition of the treated wastewater is known, a water resource added with the compounds present that can improve the crop can be offered as a source of water to mitigate its increasingly high scarcity worldwide. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the utilization rate of organic substrates contained in sanitary landfill leachates (SLLs) by fixed and suspended biomass reactors. Five bioreactors were designed, constructed, and tested for chemical oxygen demand (COD) removal. We applied three levels of organic loading in the influent for each bioreactor, including (1) a rotating biological contactor (RBC) (12, 20, and 25 g COD/m2/day); (2) a trickling filter (TF) (2.67, 5.33, and 8 kg COD/m3/day); (3) an upflow anaerobic sludge blanket (UASB) (13.31, 15.98, and 18.65 kg COD/m3/day); (4) an upflow anaerobic filter in two separated stages (UAF-2SS) (3.71, 2.76, and 1.8 kg COD/m3/day); and (5) an upflow anaerobic filter in three separated stages (UAF-3SS) (2.25, 3.45, and 4.44 kg COD/m3/day). Two equations for predicting the substrate utilization rate (SUR) of organic compounds by microorganisms were calibrated and validated, modeled under a nonsteady state condition. We modified Monod's equation to obtain the significant organic SUR and COD removal efficiency by the biomasses. These kinetic parameters were performed by the microorganisms fixing controlled experimental conditions for pH (8–9) and temperature for the UAFs (20°C, 27°C, and 34°C) and the remaining reactors (18°C– 20°C). The SUR and COD removal efficiency results were as follows: for UASB, −400 to −800 mg/L/h , 70% to 85%; for UAF-3SS, −100 to −300 mg/L/h , 85% to 95%; for UAF-2SS, −100 to −200 mg/L/h , 70% to 85%; and for RBC and TF, −50 to −250 mg/L/h , 70% to 80%. The results were mainly influenced by the structural arrangement of the organic compounds being biodegraded and the geometric configurations of the bioreactors in multiple separated stages, allowing the influence of the solubility of the recalcitrant substances, which varied from 7 to 14:1 COD dilition, to obtain subinhibitory levels for the microbial metabolism and achieve a high COD removal efficiency. Practical Applications: Two of the five bioreactors evaluated in this study, the upflow anaerobic filter in two separated stages and the upflow anaerobic filter in three separated stages, are proposed and designed as innovative reactors for treating groundwater from tropical aquifers contaminated with hydrocarbons. Additionally, UAFs were configured in a coupled bioreactor arrangement (i.e., a sequencing batch reactor followed by UAFs) to restore water quality by removing organic compounds in tropical rivers. By comparing the five bioreactors, the capacity for the chemical oxygen demand removal was significant related to the organic substrate utilization rate (SUR) for treating sanitary landfill leachates with low recalcitrance levels (i.e., rapidly biodegradable). Rapidly biodegradable SLLs can be associated with La Cortada-SLL percolated from the cells/trenches excavated for the disposal of municipal solid waste (MSW) (i.e., Pamplona Municipality, Colombia) due to the contents of a high fraction of putrescible wastes (67%) and a high biochemical oxygen demand/chemical oxygen demand ratio (62%). This level ratio produced a suitable SUR obtained from the microbial metabolism starting with the upflow anaerobic sludge blanket reactor (−400 to −1,200 mg/L/h) followed by the remaining bioreactors (−150 to −350 mg/L/h). Upflow anaerobic filters in multiple separated stages reactors constitute a feasible technical option for overcoming medium to high recalcitrance levels in SLLs obtained from cells/trenches excavated storing around 25% components fraction (e.g., metals, plastics, rubber, leather, textiles). [ABSTRACT FROM AUTHOR]

In this study, the treatability of olive mill wastewater by iron-activated persulphate (PS) oxidation was investigated. Central Composite Design (CCD) was applied to optimise the process parameters and establish a mathematical model for total phenol, chemical oxygen demand (COD), and colour removal from olive mill wastewater. The effect of process variables (PS dose, Fe2+ dose, initial pH, and reaction time) on pollutant removal efficiency was evaluated. The correlation coefficients of the quadratic polynomial equations were high for COD, total phenol, and colour removal by PS oxidation, and the model was found to be applicable. Optimum conditions determined by the developed model for maximum COD removal were pH 5, PS dose 206.7 mM, Fe2+ dose 70 mM, and reaction time 95 min. The COD, total phenol, and colour removal efficiencies estimated by the applied model were 46.74%, 94.62%, and 96.04%, respectively. The removal efficiencies obtained under optimum conditions as a result of the validation experiments were 45.5%, 93.8%, and 95.5% for COD, total phenol, and colour removal, respectively. The results of the study showed that PS oxidation in which Fe2+ is used as an activator is a suitable alternative for olive mill wastewater treatment. [ABSTRACT FROM AUTHOR]

• Chlorella proteinosa was cultivated in an MPBR for secondary effluents treatment. • Highest TN removal rate of 23.8 mg/L/day was achieved at a lowest HRT of 8 hr. • Highest microalgae biomass productivity reached 20.2 mg/L/day at the HRT of 8 hr. • Bacterial nitrogen respiration was reduced by 95.5 % from an HRT of 24 hr to 8 hr. Further treatment of secondary effluents before their discharge into the receiving water bodies could alleviate water eutrophication. In this study, the Chlorella proteinosa was cultured in a membrane photobioreactor to further remove nitrogen from the secondary effluents. The effect of hydraulic retention time (HRT) on microalgae biomass yields and nutrient removal was studied. The results showed that soluble algal products concentration reduced in the suspension at low HRT, thereby alleviating microalgal growth inhibition. In addition, the lower HRT reduced the nitrogen limitation for Chlorella proteinosa 's growth through the phase-out of nitrogen-related functional bacteria. As a result, the productivity for Chlorella proteinosa increased from 6.12 mg/L/day at an HRT of 24 hr to 20.18 mg/L/day at an HRT of 8 hr. The highest removal rates of 19.7 mg/L/day, 23.8 mg/L/day, and 105.4 mg/L/day were achieved at an HRT of 8 hr for total nitrogen (TN), ammonia, and chemical oxygen demand (COD), respectively. However, in terms of removal rate, TN and COD were the largest when HRT is 24 hr, which were 74.5% and 82.6% respectively. The maximum removal rate of ammonia nitrogen was 99.2% when HRT was 8 hr. [Display omitted] [ABSTRACT FROM AUTHOR]

• Separable polymers are formed from organic contaminants in raw coking wastewater. • Simultaneous abatement and recovery of organics from coking wastewater is realized. • About 89% of PDS is saved compared to conventional degradation-based process. • Polymerization mechanism is probed by the molecular structure of organic-polymers. • More energy efficient compared to degradation-based processes. Industrial wastewater should be treated with caution due to its potential environmental risks. In this study, a polymerization-based cathode/Fe3+/peroxydisulfate (PDS) process was employed for the first time to treat a raw coking wastewater, which can achieve simultaneous organics abatement and recovery by converting organic contaminants into separable solid organic-polymers. The results confirm that several dominant organic contaminants in coking wastewater such as phenol, cresols, quinoline and indole can be induced to polymerize by self-coupling or cross-coupling. The total chemical oxygen demand (COD) abatement from coking wastewater is 46.8% and the separable organic-polymer formed from organic contaminants accounts for 62.8% of the abated COD. Dissolved organic carbon (DOC) abatement of 41.9% is achieved with about 89% less PDS consumption than conventional degradation-based process. Operating conditions such as PDS concentration, Fe3+ concentration and current density can affect the COD/DOC abatement and organic-polymer yield by regulating the generation of reactive radicals. ESI-MS result shows that some organic-polymers are substituted by inorganic ions such as Cl–, Br–, I–, NH 4 +, SCN– and CN–, suggesting that these inorganic ions may be involved in the polymerization. The specific consumption of this coking wastewater treatment is 27 kWh/kg COD and 95 kWh/kg DOC. The values are much lower than those of the degradation-based processes in treating the same coking wastewater, and also are lower than those of most processes previously reported for coking wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

This study presents a comprehensive investigation into the efficacy of advanced oxidation treatment methods, focusing on the photo-Fenton process for removing organic pollutants from wastewater. Despite prior research, significant knowledge gaps persist regarding the optimal operational conditions for maximizing pollutant removal efficiency. This manuscript fills those gaps through extensive batch experiments, meticulously evaluating the impacts of irradiation time, pH levels, and ferrous sulfate and hydrogen peroxide concentrations on treatment outcomes. Our results indicate that an irradiation time of 140 minutes and a pH of 3.1 are critical for achieving remarkable pollutant removal efficiencies: 91.57% for color, 85.14% for chemical oxygen demand (COD), and 79.87% for total organic carbon (TOC) over a 180-minute treatment period with optimal dosages. To further enhance understanding, we employed predictive models utilizing response surface methodology (RSM) and central composite design (CCD), rigorously assessing their statistical performance. The models demonstrated strong alignment with experimental data and existing literature, showcasing their reliability. This research not only provides novel insights into optimizing wastewater treatment processes but also holds significant practical value for industries aiming to implement effective strategies for mitigating organic pollution. By addressing critical knowledge gaps, this study lays a foundation for improved environmental remediation practices, offering a vital framework for industries committed to sustainable wastewater management. [ABSTRACT FROM AUTHOR]

Aiming to preserve and protect the environment, physical and chemical quality of young and mature leachate samples from Fez controlled landfill were studied and assessed. Therefore, leachate samples were taken and analyzed during the period of January-September 2022. The physico-chemical characterization of both young and mature leachates revealed a significant load of organic matter (biological and chemical oxygen demands: BOD5 and COD) and minerals (NTK and PO43-). In addition, the metallic trace elements (MTEs) concentrations recorded for Cr, Fe, Al and Ni exceeded the threshold levels required in national standards, and their quantitative distribution followed the same pattern at both sites studied: Ni > Fe > Cr > Al > Zn > Pb. The Principal Component Analysis (PCA) enabled to reduce the database to a smaller dimension by gathering as much information on their trends and correlations. Two components were selected which account for the sum of 64.06% of the factors. [ABSTRACT FROM AUTHOR]

BACKGROUND: High water consumption and the toxic pollutants found in industrial wastewater are key challenges in achieving a more sustainable development. In this sense, it is crucial to develop sustainable ways to reduce the organic pollutants found in wastewater and to promote its reuse. RESULTS: In this study, a simple, low‐cost, and environmentally friendly path for dairy wastewater decontamination through photocatalysis using rod‐shaped α‐Fe2O3/TiO2 type II heterojunctions is reported. The photoreaction of the model solution was evaluated under UVA‐visible irradiation with different amounts of α‐Fe2O3 over TiO2, lactose as pollutant concentrations, Cl− and SO42− anions effects, and oxidant ambient showing up to 42% lactose degradation without the addition of oxidant ambient. Optimized parameters (1.0%wt α‐Fe2O3/TiO2, [catalyst] = 0.5 g L−1, [lactose] = 0.7 g L−1, [H2O2] = 10 mM, [O2] = constant) were used on dairy wastewater, which showed a 63% total organic carbon reduction and a 56% chemical oxygen demand reduction. The composite was easily recovered by decantation with a turbidity reduction of ~ 99%. The photocatalyst reusability was assessed over three successive uses and it maintained its activity with a loss of only 10%. CONCLUSION: This study offers a promising approach for the development of innovative sustainable nanotechnology to efficiently degrade organic pollutants commonly found in dairy wastewater and improve its quality within a shorter timeframe. Our approach could contribute to the development of efficient and cost‐effective complementary technologies for the Sequencing Batch Reactor in the treatment of dairy wastewater, thus contributing to the sustainability of the dairy industry. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The radiolytic degradation of 4-hydroxybenzoate (4-HBA–) in aerated, oxygen-free and N2O-saturated aqueous solutions at concentrations of 0.10 and 0.25 mmol/dm3 were gamma irradiated at different doses in a source of Co-60. The results show that ·OH adds predominantly to the 3 position of the aromatic ring, and elimination of the acid group leads to the degradation of 4-HBA–. With an N2O-saturated 0.10 mmol/dm3 4-HBA– solution, total degradation occurred at 1.6 kGy, and with a 0.25 mmol/dm3 solution, total degradation occurred at 3.5 kGy. In the aerated and oxygen-free 0.25 mmol/dm3 4-HBA– solutions, the behavior was similar, degradation occurring at a dose of 13.1 kGy. At the concentration of 0.10 mmol/dm3, total degradation occurred at 7.0 kGy, with small amounts of radiolytic products and byproducts. We propose a mechanism for the degradation of 4-HBA– caused by water radicals produced in the three environments, leading to formation of the identified stable products. Oxidation was followed by chemical oxygen demand (COD), which decreased as the 4-HBA− concentration increased. The kinetics showed a pseudo-first-order behavior. The rate constant of degradation was similar for the solutions with and without oxygen. HIGHLIGHTS Study of radiolytic degradation of 4-hydroxybenzoate in aqueous solutions.; Distribution of radiolitic products from the degradation of 4-hydroxybenzoate in aqueous solutions.; Formation and degradation of primary and secondary products from irradiated 4-hydroxybenzoate.; Degradation kinetics, mechanisms, and chemical oxygen demand in the degradation of 4-HBA−.; Mechanistic scheme for gamma radiation degradation of 4-hydroxybenzoate.;

Background: Wastewater from poultry slaughterhouses is a serious environmental threat if they are incompletely treated. Recently, the utilization of microalgal species has gained significant attention for treating such wastewater. Chlorella vulgaris is one of the most efficient microalgae for treating poultry slaughterhouse wastewater due to its exceptional capacity for N, P, and chemical oxygen demand (COD) removal. This study aimed to investigate the impact of initial total nitrogen concentration, total phosphorus, photoperiod, and cultivation time on reducing the organic load and enhancing the production of biomass in slaughterhouse wastewater. Methods: Samples were collected from the effluent of a poultry slaughterhouse and underwent qualitative analysis. C. vulgaris was cultivated in the BBM culture medium. Experiments were designed using the response surface method. The designed experiments were then carried out and the obtained data were subjected to analysis of variance (ANOVA), resulting in fitted models for the data on organic load removal and biomass production. Numerical optimization was performed to optimize COD removal and increase algal biomass. Finally, the models were validated. Results: The results demonstrated that the quadratic model has a good fit for COD removal and biomass increase data. In the optimal conditions, including TN = 600 mg/L, TP = 34 mg/L, culture duration = 15 d, and photoperiod = 12.6 hr, the COD removal efficiency and algal biomass production were 93.88% and 92.37%, respectively. Conclusion: Chlorella vulgaris exhibits significant potential for the removal of the organic load from poultry slaughterhouse effluent. Also, substantial algal biomass is generated, which can be used in various areas such as livestock feed and sanitary uses.

Abstract In this investigation, the modeling of the Aksaray industrial wastewater treatment plant was performed using artificial neural networks with various architectures in the MATLAB software. The dataset utilized in this study was collected from the Aksaray wastewater treatment plant over a 9-month period through daily records. The treatment efficiency of the plants was assessed based on the output values of chemical oxygen demand (COD) output. Principal component analysis (PCA) was applied to furnish input for the Feedforward Backpropagation Artificial Neural Networks (FFBANN). The model’s performance was evaluated using the Mean Squared Error (MSE), the Mean Absolute Error (MAE) and correlation coefficient (R2) parameters. The optimal architecture for the neural network model was determined through several trial and error iterations. According to the modeling results, the ANN exhibited a high predictive capability for plant performance, with an R2 reaching up to 0.9997 when comparing the observed and predicted output variables.

AbstractWater resources are precious resources around the world, but pollution is becoming increasingly severe. While the degree of damage to water caused by organic pollutants is reflected by chemical oxygen demand, which is also an important indicator for hydrological monitoring. Therefore, accurate measurement of chemical oxygen demand is necessary. The rapid development of water quality detection by ultraviolet visible spectrum analysis as an efficient, convenient, and pollution-free new water quality detection method has been achieved. When we were processing ultraviolet visible spectral absorbance data, various environmental factors can affect the chemical oxygen demand light absorption value, thus affecting the accuracy of detection. So there are some goals, such as more comprehensively extracting the feature wavelength and reducing the interference to achieve better detection results. It is expected that the model can be applied to a portable water quality detection device. It is necessary to consider detection time, reduce model training parameters, and improve detection speed. Therefore, this article proposes Competitive Adaptive Weighted Sampling-Convolutional Neural Network-Long Short-Term Memory and Competitive Adaptive Weighted Sampling-Convolutional Long Short-Term Memory models for detecting chemical oxygen demand in water. To verify the effectiveness of the proposed model, the model was trained on the experimental dataset and the detection results of all models involved in the article were compared. It can be confirmed that the application of these two proposed algorithms results in less detection time and higher accuracy in concentration detection. [ABSTRACT FROM AUTHOR]

In this study, we synthesized a novel electrode for electrocatalytic adsorption by fabricating ACF‐TiO2 via the sol‐gel method and binding it with IrO2‐TaO2. The electrode's effectiveness in treating oilfield produced water (OPW) was evaluated using batch techniques. Comprehensive characterization, including scanning electron microscopy (SEM), energy‐dispersive spectrometry (EDS), Brunauer‐Emmett‐Teller (BET) analysis, and Fourier‐transform infrared (FTIR) spectroscopy, confirmed uniform TiO2 loading onto the ACF surface, preserving structural integrity. BET analysis indicated increased mesopore volume and enhanced organic adsorption capacity without compromising microporous structure. Additionally, FTIR analysis revealed the emergence of functional groups conducive to adsorption and catalytic reactions. Freundlich isotherms and pseudo‐first‐order kinetics best fit the adsorption data. Remarkably, even after five cycles, the electrode maintained high removal efficiencies for chemical oxygen demand (COD) and oil content at 91.35 % and 91.12 %, respectively. We further investigated the complex phenomena of material adsorption, electrochemical oxidation, and desorption during electrocatalytic adsorption, highlighting the importance of solid‐phase adsorption and liquid‐phase electrocatalytic oxidative decomposition in OPW treatment. Comparison with similar electrodes and DSA electrodes demonstrated the superior performance and practicality of the IrO2‐TaO2‐ACF(TiO2) electrode. Its cost‐effectiveness and regeneration method further enhance its applicability in real‐world scenarios, emphasizing its potential in water treatment. [ABSTRACT FROM AUTHOR]

Wastewater from the food industry is considered harmful to human health and aquatic life, as well as polluting water and soil. This research is centered around finding an affordable and easy physicochemical method for dealing with waste generated by the food industry. To accomplish this goal, a new bio-based flocculant called 4-benzyl-4-(2-oleamidoethylamino-2-oxoethyl) morpholin-4-ium chloride was created using sustainable sources, specifically crude olive pomace oil. Its chemical structure was confirmed using various spectroscopic techniques such as FTIR, 1H-NMR, mass spectra, and 13C-NMR. This new bio-based cationic flocculant was combined with alum to act as a coagulant in the waste treatment process. Also, a study was conducted to determine the optimal conditions for the coagulation-flocculation process parameters, namely, pH and alum dosage, on COD and removal efficiency. The results showed that the optimal conditions for flocculation were achieved at pH 5.8, with 680 mg/L alum and 10 mg/L of commercial flocculant dose compared to only 5 mg/L of a new bio-based cationic flocculant. A comparison was made between the new bio-cationic flocculant and a commercial CTAB one for treating wastewater in the food industry. The study found that the new bio-based cationic flocculant was more effective in reducing the chemical oxygen demand, achieving a reduction of 61.3% compared to 54.6% for using a commercial cationic flocculant. Furthermore, using a new bio-based cationic flocculant costs only 0.49 $/g, which is less than the present cationic flocculant, which costs 0.93 $/g. The adoption of this new flocculant provides a sustainable alternative to existing industrial wastewater treatment processes [ABSTRACT FROM AUTHOR]

The present work deals with developing a method for revalorizing steel residues to create sunlight-active photocatalysts based on iron oxides. Commercial-grade steel leftovers are oxidized under different combinations of pH and temperature (50–90 °C and 3 ≥ pH ≤ 5) in a low energy-intensive setup. The material with the highest production efficiency (yield > 12%) and magnetic susceptibility (χm = 387 × 10−6 m3/kg) was further explored and modified by diffusion of M2+ (Zn and Co) ions within the structure of the oxide using a hydrothermal method to create ZnFe2O4, CoFe2O4 and combined Co–Zn ferrite. (Co–Zn)Fe2O4 displayed a bandgap of 2.02 eV and can be activated under sunlight irradiation. Electron microscopy studies show that (Co–Zn)Fe2O4 consists of particles with diameters between 400 and 700 nm, homogeneous size, even distribution, and good dispersibility. Application of the developed materials in the sunlight catalysis of black liquors from cellulose extraction resulted in a reduction of the Chemical Oxygen Demand (− 15% on average) and an enhancement in biodegradability (> 0.57 BOD/COD) after 180 min of reaction. Since the presented process employs direct solar light, it opens the possibility to large-scale water treatment and chemical upgrading applications. [ABSTRACT FROM AUTHOR]

To explore the sustainable development of grinding fluid in barrel finishing, the idea of water resource reuse in grinding fluid has been proposed. The influence of the graphene oxide (GO) and the sodium dodecyl benzene sulfonate (SDBS) as main components in the grinding fluid on the chemical oxygen demand (COD) was analyzed. Repreparing new grinding fluids by utilizing the water resources in grinding fluid after finishing will not cause a sharp increase in COD value. GO which absorbs SDBS can be taken away from grinding fluid by physical separation. It will decrease the COD value of grinding fluid. However, SDBS exists in the form of colloids in the grinding fluid and cannot be removed through physical separation, which also affects the COD value. Based on water quality indicators (the COD, pH, total hardness, metal aluminum, anionic surfactants, and total dissolved solids), the water quality index (WQI) of the reusing grinding fluid after finishing by the physical separation is significantly reduced. It indicates that reusing water resources in grinding fluid is a feasible way to reuse grinding fluid. [ABSTRACT FROM AUTHOR]

This study presents the synthesis of a new nanocomposite named Zn3V2O8/hydroxyapatite (ZnV/HAP) to assess its photocatalytic efficiency for degrading Congo red dye (CR) under visible light. The nanocomposite was analyzed using various techniques, including FT-IR, XRD, UV-vis DRS, SEM, TEM, EDAX, XPS, and BET analysis. The photocatalyst's performance was enhanced by a shift in its band gap to 1.7 eV, compared to similar materials. ZnV/HAP exhibits superior photocatalytic performance compared to ZnV particles. The rate constant for the degradation of CR by ZnV/HAP was determined to be 0.0063 min−1. The degrading efficiency of the ZnV/HAP composite is 94%. The enhanced charge separation in the ZnV/HAP composite is attributed to the strong contacts between the interfacial surfaces, which are responsible for their higher activity. A method was found to facilitate this heightened activity, with hydroxyl and superoxide radicals serving as crucial reactive species that significantly contribute to the photocatalytic process. The phytotoxicity investigation conducted on Vigna radiata plants demonstrated the photocatalytic effectiveness of the ZnV/HAP combination. In addition, the deteriorated CR dye solution exhibited a color removal efficiency of 94.62% for total organic carbon (TOC) and 92.86% for chemical oxygen demand (COD). The findings demonstrate that the synthesized ZnV/HAP is a viable substitute for visible-light-driven photocatalysts. Furthermore, the antimicrobial efficacy of ZnV/HAP was assessed against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger, demonstrating remarkable antibacterial and antifungal properties comparable to the positive control medication. [ABSTRACT FROM AUTHOR]

The use of coagulants, such as ferric chloride hexahydrate, in wastewater treatment processes is known to induce pipe corrosion and to contribute to the discoloration of treated water. This study explores alternative approaches to sludge dewatering by evaluating the effectiveness of polymeric aluminum chloride (PAC) as a coagulant and polyoxyethylene alkyl ether (POAE) as a surfactant. The impacts of coagulation/flocculation were assessed using time to filtration (TTF) and a pressure filter press. The effects of certain coagulant and surfactant dosages were studied. The inputs were in the range of 105–1750 mg/L for PAC and 28–152 mg/L for POAE, which were determined based on zeta potential (ZP) measurements. The optimal concentrations were 876 mg/L for PAC and 114 mg/L for POAE, resulting in a TTF of less than 1 min. Moreover, the effect of pH on anaerobic sludge dewaterability was investigated. At a low pH below 8, the ZP reached the maximum value, and a higher pH resulted in a reduction in ZP. Under low-pH adjustments, it was observed that the dewatering performance of the POAE surfactant improved more significantly than that of the PAC coagulant. In addition, the effect of pressure was analyzed using a pressure filter under conditions favoring POAE, with relatively lower dosages and greater cost-effectiveness. In order to evaluate the solubility of organic matter under pressurized conditions, the filtrate's removal efficiency, chemical oxygen demand (COD), and total phosphorus (TP) were investigated. Solubilization did not occur at an increased pressure of around 10 bars. The findings presented in this study provide technical assistance for sludge treatment. [ABSTRACT FROM AUTHOR]

Effective nitrogen removal from anaerobic co-digestion is a major challenge to achieving dual-carbon goals. This study explored the acclimatization process of a lab-scale two-stage partial nitritation and anammox process of a stepwise increase in the percentage of raw anaerobic co-digestion liquor from kitchen waste, human feces, and municipal sludge in a venous industrial park in China, which has not been reported yet. Under limited dissolved oxygen (below 0.5 mg/L) and high ammonia levels (200–1500 mg/L), based on adjusting aeration rates, partial nitritation rapidly started up in 50 days. After acclimatization, partial nitritation still performed efficiently and stably, with the final total nitrogen loading rate (TNLR) of 1.24 ± 0.09 gN/L/d, nitrite accumulation rate of 99 ± 4%, and ratio of eff. nitrite/ammonia of 1.32 ± 0.13. In the anammox process, the final total nitrogen removal efficiency, total nitrogen removal rate, and TNLR reached 94 ± 5%, 1.27 ± 0.03 gN/L/d, and 1.36 ± 0.05 gN/L/d, respectively. Chemical oxygen demand (COD) was also reduced in both reactors, with COD removal rates of 0.7 gCOD/L/d in the partial nitritation and 0.4 gCOD/L/d in the anammox process. Overall, the PNA system demonstrated its feasibility in adapting to high ammonia, salinity, and iron levels, when treating anaerobic co-digestion liquor, particularly regarding resource recovery in venous industrial parks. [ABSTRACT FROM AUTHOR]

A novel aerobic denitrifying bacterium Bacillus cereus J1 was isolated from a sewage treatment plant. Its characteristics under two distinct nitrogen sources were systematically investigated. According to the results of whole-genome sequencing, we inferred that strain J1 removes nitrogen through processes such as aerobic denitrification, dissimilatory nitrate reduction to ammonium, and ammonium assimilation. The degradation process of COD and total inorganic nitrogen (TIN) correlated to the zero-order degradation kinetics equation, and the maximum removal rate of NO3−−N reached 3.17 mg/L/h and that of NH4+−N was 3.79 mg/L/h. Utilizing single-factor experiments and response surface methodology, the optimal conditions for nitrate removal were determined as a shaking speed of 115 rpm, COD/nitrogen mass (C/N ratio) of 12.25, and salinity of 3.44 g/L, with the C/N ratio exerting the most significant influence. Similarly, for the maximum ammonium removal, the ideal conditions involved a shaking speed of 133 rpm, C/N ratio of 29, and salinity of 13.30 g/L, with the shaking speed exerting the most significant influence. These findings demonstrate that large amounts of ammonium and nitrate can be quickly removed with the help of Bacillus cereus J1, indicating that strain J1 may be applied to alleviate nitrogen pollution in aquatic environments. [ABSTRACT FROM AUTHOR]

It is well known that numerous operational, material and design variables act upon the performance of a plant-based microbial fuel cell which is an emerging sustainable and versatile energy device like hydrogen fuel cells. However, due to the high complexity of these bioelectrochemical systems, new solutions are required to optimize performance and uncover hidden relationships between dominant fuel cell variables. For this purpose, a database of 229 observations was created for plant-based microbial fuel cells (PMFCs) with 159 descriptor variables and a target variable (maximum power density) based on experimental results from 51 recent publications. Then, some machine learning solutions like principal component analysis (PCA), classification trees and SHapley Additive exPlanations (SHAP) analysis were applied. The PCA indicated mainly two routes involving low and high chemical oxygen demand (COD) towards high maximum power density which consists of the plant family, wastewater type, support media, construction design, separator type, anode and cathode electrodes and light source. SHAP analysis revealed that the most important factors for high performance are operating temperature, natural light, soil support medium, and constructed wetland design. Finally, the classification tree successfully demonstrated nine routes towards high maximum power density which exclude the use of graphite plate cathode electrodes. [Display omitted] • Machine learning was applied to determine high power density routes in PMFC. • Principal component analysis indicated two routes to high maximum power density. • Shapley analysis revealed the most important factors for high-performance. • Most influential variables were found as temperature, natural light, soil support. [ABSTRACT FROM AUTHOR]

This study comparatively evaluated effluent reuse from two TWs—a horizontal subsurface flow (HF) and a vertical subsurface flow (VF)—used for rural wastewater treatment in Central Chile during the initial operation stage. The two TWs were planted with Zantedeschia aethiopica and were operated for 10 months at a pilot scale. The water quality of the influent and effluents was measured and compared with reuse regulations. The results showed similarities in the behavior of the effluents from the two TWs, presenting differences only in the chemical oxygen demand (COD) and different forms of nitrogen, suggesting the necessity of complementary treatment stages or modifications to the operation. The effluents from the HF better fulfilled the reuse standards for irrigation, as the VF faced problems associated with its size. However, a complementary disinfection system is necessary to improve pathogen removal in the effluents coming from the two TWs, especially to be reused as irrigation water for crops. Finally, this work showed the potential for applying subsurface TWs for wastewater treatment in rural areas and reusing their effluents as irrigation water, practice that can contribute to reducing the pressure on water resources in Chile, and that can be used as an example for other countries facing similar problems. [ABSTRACT FROM AUTHOR]

【Objective】The deposition and decomposition of solid particles in aquaculture wastewater will lead to the deterioration of aquaculture water and affect the health of fish. The study was conducted to understand the sedimentation rule of solid particles in aquaculture wastewater of Nile tilapia (Oreochromis niloticus) and its influence on the aquaculture water body, with an aim to provide a theoretical basis for the research and development and design of aquaculture wastewater treatment system.【Method】 The aquaculture wastewater of Nile tilapia pond was treated by static sedimentation. Samples of aquaculture wastewater at different depths were collected at different sedimentation times, and the particle size distribution, soluble organic components and water quality indexes of aquaculture wastewater were analyzed.【Result】Static sedimentation had no significant effect on the quality of aquaculture wastewater (P>0.05), and only reduced the mass concentrations of total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) in aquaculture wastewater surface. Suspended solids and algae in aquaculture wastewater could be separated by static sedimentation (P<0.05). After static sedimentation for 5.0 h, the TSS, chlorophyll a mass concentration, turbidity and chromaticity of two-meter-high water decreased by 3 854 mg/L, 42 mg/L, 0.23 NTU and 309 degrees respectively, and the TSS and chlorophyll a mass concentrations in aquaculture water decreased with the extension of sedimentation time. The results of particle size distribution showed that the settleable particles larger than 100 μm could be effectively separated by static sedimentation, but the fine particles lower than 30 μm could not be separated. The sedimentation velocity of solid particles was related to its particle size distribution range and mass concentration. The sedimentation velocity of solid particles decreased with the decrease of particle size distribution range and the increase of mass concentration. The results of three-dimensional fluorescence spectrum showed that the soluble organic compounds in the wastewater of Nile tilapia were mainly fulvic acid-like, and the soluble organic components in the wastewater could not be completely changed by static sedimentation.【Conclusion】Short time static sedimentation can effectively remove settleable particles in aquaculture wastewater, and the mass concentrations of TSS and chlorophyll a decrease with the extension of sedimentation time. However, static sedimentation cannot completely change the soluble organic components in the wastewater, nor can it significantly reduce the mass concentrations of nitrogen, phosphorus and other pollutants in aquaculture wastewater. [ABSTRACT FROM AUTHOR]

This research aims to analyze the efficiency of processing liquid waste from the laundry industry using the Free Water Surface Constructed Wetland (FWS) system with Azolla microphylla plants. The research method used is experimental research by manipulating independent variables and controlling other relevant variables, as well as observing the effect on the dependent variable. Laundry waste samples were taken from Berkah Laundry, Puri Gading, Bekasi. The results showed that the biomass of Azolla microphylla plants increased significantly from day 0 to day 12, with a growth rate between 0.0289 - 0.0477 grams/day and plant density between 185.19 ind/m2 - 277.78 ind/m2. The influent BOD concentration of laundry liquid waste during the acclimatization stage ranged from 5.89 - 10.54 mg/L, while the effluent BOD ranged from 4.35 - 6.98 mg/L, with the highest efficiency reaching 33.8%. The constructed wetland system with Azolla microphylla plants has proven to be effective in reducing pollutant content in liquid waste, with a BOD removal efficiency of 11.1% - 17.7% and COD of 14.5% - 39%. The conclusion of this research is that the use of artificial wetlands with Azolla microphylla plants can be an effective and environmentally friendly alternative solution for processing liquid waste from the laundry industry. The implications of this research show the potential for applying constructed wetland technology in the clothes washing industry to reduce the negative impact of waste on the environment. [ABSTRACT FROM AUTHOR]

Laundry businesses in Indonesia have high economic development opportunities. However, laundry wastewater in Indonesia does not yet have a good environmental culture and regulations for service users. Constructed wetland can be used as a sustainable biological processing technology, uses low energy, and does not require high costs to process laundry wastewater. The aim of this research is to analyze the ability of horizontal sub-surface flow constructed wetlands in a batch system with different numbers of aquatic bamboo plants (Equisetum hyemale) in degrading chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) in laundry wastewater. The research results showed that reactor 2 HSSF CW with a total of 200 E. hyemale plants produced higher removal efficiency compared to reactor 1 HSSF CW with a total of 120 E. hyemale plants where reactor 2 produced COD and BOD5 removal efficiency respectively. amounted to 88.22% and 90.30% while reactor 1 produced COD and BOD5 removal efficiencies of 86.04% and 88.10% respectively. Based on these results, reactor 1 and reactor 2 horizontal sub-surface flow constructed wetlands with E. hyemale plants produced effective performance in reducing COD and BOD5 concentrations in laundry wastewater. [ABSTRACT FROM AUTHOR]

In the field of electrochemical ozone production, electrodes need to have exceptional catalytic activity, long-term stability, and cost-effectiveness. In this case, TiO2-NTs/SnO2-Sb2O5-NiO electrodes were fabricated using a combination of anodization, electrochemical deposition, spin coating and annealing techniques. The coating of electrodes was analyzed using EDS, XRD and SEM techniques. According to the obtained cyclic voltammetry (CV) data, the TiO2-NTs/SnO2-Sb2O5-NiO electrode revealed a less positive potential for oxygen evolution compared to other constructed electrodes. The conversion of Ti to Ti-NTs improved the ozone production efficiency and resulted in higher concentrations of water-soluble ozone. To evaluate the performance of the electrodes and the corresponding electrocatalytic activity, a textile dye was used as a pollutant. The most effective modified electrode proved to have an impressive decomposition rate of 96% for the cationic yellow 28 dye within a 60-min timeframe. Furthermore, this modified electrode could substantially remove chemical oxygen demand (COD) of up to 53.6% during 60-min electrolysis. [ABSTRACT FROM AUTHOR]

The single-cycle transient high-concentration organic load shock test was conducted on the micropressure swirl reactor (MPSR) and sequencing batch reactor (SBR) to assess their capability to different levels of transient organic load shock (OLS), including pollutant removal, sludge characteristics, and microbial characteristics. The results indicated that the impact-resistance of biological treatment systems was related to reactor structure and microbial community distribution. When subjected to transient chemical oxygen demand (COD) load of 0.81, 1.28, and 1.70 g / (L · d a y) , respectively, both reactors exhibited effective organic removal capabilities. Compared with MPSR, within a certain shock range, nitrification in the SBR was less affected by shock and had a higher effect on nitrogen and phosphorus removal. However, when shock load reached 1.70 gCOD/(L·day) , the denitrification was sufficient in the MPSR, and microorganisms continued to secrete polysaccharides (PS), which was beneficial for adsorbing pollutants and resisting impacts. Under steady-state conditions, the SBR exhibited excellent nitrification with a relative abundance of 60.7% for nitrifying functional groups such as Thiothrix. Compared with the SBR, the MPSR displayed a higher microbial community diversity, with a variety of phosphorus-removing bacteria and denitrifying bacteria genera occupying aerobic and anoxic partitions within the same space, which was profitable for effective denitrification and phosphorus removal under high OLS. Besides, the enrichment of Flavobacterium and Zoogloea sp. at high concentrations significantly enhanced the MPSR's resistance to OLS. This study provides a theoretical basis for effective measures by different processes in response to organic load shocks. [ABSTRACT FROM AUTHOR]

River water quality often follows a long-memory stochastic process with power-type autocorrelation decay, which can only be reproduced using appropriate mathematical models. The selection of a stochastic process model, particularly its memory structure, is often subject to misspecifications owing to low data quality and quantity. Therefore, environmental risk assessment should account for model misspecification through mathematically rigorous and efficiently implementable approaches; however, such approaches have been still rare. We address this issue by first modeling water quality dynamics through the superposition of an affine diffusion process that is stationary and has a long memory. Second, the worst-case upper deviation of the water quality value from a prescribed threshold value under model misspecifications is evaluated using either the divergence risk or Wasserstein risk measure. The divergence risk measure can consistently deal with the misspecification of the memory structure to the worst-case upper deviation. The Wasserstein risk measure is more flexible but fails in this regard, as it does not directly consider the memory structure information. We theoretically compare both approaches to demonstrate that their assumed uncertainties differed substantially. From the application to the 30-year water quality data of a river in Japan, we categorized the water quality indices to be those with truly long memory (Total nitrogen, NO3-N, NH4-N, and SO 4 2 - ), those with moderate power-type memory (NO2-N, PO4-P, and Total Organic Carbon), and those with almost exponential memory (Total phosphorus and Chemical Oxygen demand). The risk measures are successfully computed numerically considering the seasonal variations of the water quality indices. [ABSTRACT FROM AUTHOR]

Brassware industry constitutes the second most polluting industrial sector in Fez city, Morocco, owing to its high heavy metal load. The aim of this study is to examine and evaluate the performance of vertical flow constructed wetlands in treating brassware effluents using various plant species. Ten treatment systems were planted with four types of plants: Chrysopogon zizanioides, Typha latifolia, Phragmites australis, and Vitex agnus-castus, while another system remained unplanted. These systems underwent evaluation by measuring various parameters, including pH, electrical conductivity, suspended solids, chemical oxygen demand, biological oxygen demand, sulfates, orthophosphates, total Kjeldhal nitrogen, ammonium, nitrates, nitrites, and heavy metals such as silver, copper, and nickel, using standard methods over of ten weeks. The results obtained demonstrate effectiveness of these systems. When planted with Ch. zizanioides, the systems achieved elimination rates of 83.64%, 98.55%, 91.48%, 86.82%, 80.31%, 96.54%, 98%, and 98.82% for suspended solids, ammonium, nitrites, BOD5, sulfates, orthophosphates, silver, and nickel, respectively. System with V. agnus-castus showed significant reductions in nitrate and copper, with rates of 84.48% and 99.10%, respectively. Considerable decrease in pH and electrical conductivity values was observed in all systems, with a notable difference between planted and control systems regarding effectiveness of treatment for other parameters. The novelty of this study lies in the application of constructed wetlands for the treatment of brassware effluents in the city of Fez, Morocco. Consequently, a comparison was conducted to assess the removal efficiency of Chrysopogon zizanioides (L.) Roberty and Vitex agnus-castus L., in comparison to Typha latifolia L. and Phragmites australis (Cav.) Trin. These four plant species were specifically chosen for their high elimination capacity and resistance to the toxicity of the pollutants. Notably, this study represents an unexplored aspect in the existing literature. Nevertheless, T. latifolia and P. australis have been extensively utilized in constructed wetlands for treating diverse wastewaters. The findings from this study can also be extrapolated to pilot-scale constructed wetlands, offering valuable insights for the removal of pollutants from brassware wastewater. [ABSTRACT FROM AUTHOR]

A diatomite-modified Fe2O3 (Fe2O3/Dia) catalyst was prepared to catalyze the ozonation degradation of sulfachloropyridazine sodium (SPDZ). The chemical oxygen demand (COD) was used as the index of pollutant degradation. The catalytic ozonation experiment showed that the COD removal rate of SPDZ was 87% under Fe2O3/Dia catalysis, which was much higher than that obtained when using Fe2O3 as the catalyst. The characteristics of the Fe2O3/Dia catalyst were investigated, and the successful synthesis of the Fe2O3/Dia composite catalyst was proved by XRD, XPS, SEM, FTIR, BET and other characterization methods. The catalytic mechanism of degradation by ozone with Fe2O3/Dia was analyzed. According to free-radical trapping experiments and an in situ electron paramagnetic spectrometer characterization analysis, the main oxidizing species in the catalytic Fe2O3/Dia ozone system is ·OH. The intermediates in the degradation process of SPDZ were detected and analyzed in detail by liquid chromatography-coupled mass spectrometry. The degradation mechanism and three degradation paths of SPDZ were proposed. [ABSTRACT FROM AUTHOR]

The treatment of palm oil mill effluent (POME) poses a significant challenge for Malaysia's palm oil industry, necessitating compliance with the Department of Environment (DOE) regulations prior to discharge. This study introduces an eco-friendly synthesis method utilizing mangosteen (Garcinia mangostana L.)-leaf aqueous extract to fabricate copper oxide (CuO), zinc oxide (ZnO) nanoparticles (NPs), and their nanocomposite (CuO-ZnO NCs). The physicochemical properties of these nanomaterials were characterized using various analytical tools and their effectiveness in reducing the chemical oxygen demand (COD) of palm oil mill effluent (POME) was assessed under the illumination of two types of light sources: monochromatic blue- and polychromatic white-light emitting diodes (LEDs). CuO-ZnO NCs demonstrated superior performance, with the lowest energy bandgap (1.61 eV), and achieved a COD removal efficiency of 63.27% ± 0.010 under blue LED illumination, surpassing the DOE's discharge limit of 100 mg/L. This study offers a cost-effective and environmentally friendly method for synthesizing heterojunction materials, which show great potential as photocatalysts in reducing POME COD to permissible levels for discharge. [ABSTRACT FROM AUTHOR]

In this study, we employed the response surface method (RSM) and the long short‐term memory (LSTM) model to optimize operational parameters and predict chemical oxygen demand (COD) removal in the electrocoagulation‐catalytic ozonation process (ECOP) for pharmaceutical wastewater treatment. Through RSM simulation, we quantified the effects of reaction time, ozone dose, current density, and catalyst packed rate on COD removal. Then, the optimal conditions for achieving a COD removal efficiency exceeding 50% were identified. After evaluating ECOP performance under optimized conditions, LSTM predicted COD removal (56.4%), close to real results (54.6%) with a 0.2% error. LSTM outperformed RSM in predictive capacity for COD removal. In response to the initial COD concentration and effluent discharge standards, intelligent adjustment of operating parameters becomes feasible, facilitating precise control of the ECOP performance based on this LSTM model. This intelligent control strategy holds promise for enhancing the efficiency of ECOP in real pharmaceutical wastewater treatment scenarios. Practitioner Points: This study utilized the response surface method (RSM) and the long short‐term memory (LSTM) model for pharmaceutical wastewater treatment optimization.LSTM predicted COD removal (56.4%) closely matched experimental results (54.6%), with a minimal error of 0.2%.LSTM demonstrated superior predictive capacity, enabling intelligent parameter adjustments for enhanced process control.Intelligent control strategy based on LSTM holds promise for improving electrocoagulation‐catalytic ozonation process efficiency in pharmaceutical wastewater treatment. [ABSTRACT FROM AUTHOR]

Tannery effluents contain high amounts of polluting chemicals, such as salts and heavy metals released often to surface waters. New economic and eco-friendly purification methods are needed. Two adsorbing materials and five salt-tolerant fungal isolates from mangrove habitat were studied. Purification experiments were carried out using the pollutant adsorbents biochar and the biomass of vetiver grass (Chrysopogon zizanioides) roots and the fungi Cladosporium cladosporioides, Phomopsis glabrae, Aspergillus niger, Emericellopsis sp., and Scopulariopsis sp., which were isolated from mangrove sediment. They efficacy to reduce pollutants was studied in different combinations. Salinity, turbidity, total dissolved solids, total suspended solids, phenols, nitrogen, ammonia. Biological and chemical oxygen demand (BOD, COD) and several heavy metals were measured. The adsorbents were efficient reducing the pollutants to 15–50% of the original. The efficiency of the combination of biochar and roots was generally at the same level as the adsorbents alone. Some pollutants such as turbidity, COD and ammonium were reduced slightly more by the combination than the adsorbents alone. From all 14 treatments, Emericellopsis sp. with biochar and roots appeared to be the most efficient reducing pollutants to < 10–30%. BOD and COD were reduced to ca 5% of the original. The treatment was efficient in reducing also heavy metals (As, Cd, Cr, Mn Pb, Zn). The fungal species originating from the environment instead of the strains present in the tannery effluent reduced pollutants remarkably and the adsorbents improved the reduction efficiency. However, the method needs development for effluents with high pollutant concentrations to fulfil the environmental regulations. [ABSTRACT FROM AUTHOR]

Traditionally constructed wetlands face significant limitations in treating tailwater from wastewater treatment plants, especially those associated with sugar mills. However, the advent of novel modified surface flow constructed wetlands offer a promising solution. This study aimed to assess the microbial community composition and compare the efficiencies of contaminant removal across different treatment wetlands: CW1 (Brick rubble, lignite, and Lemna minor L.), CW2 (Brick rubble and lignite), and CW3 (Lemna minor L.). The study also examined the impact of substrate and vegetation on the wetland systems. For a hydraulic retention time of 7 days, CW1 successfully removed more pollutants than CW2 and CW3. CW1 demonstrated removal rates of 72.19% for biochemical oxygen demand (BOD), 74.82% for chemical oxygen demand (COD), 79.62% for NH4 +-N, 77.84% for NO3--N, 87.73% for ortho phosphorous (OP), 78% for total dissolved solids (TDS), 74.1% for total nitrogen (TN), 81.07% for total phosphorous (TP), and 72.90% for total suspended solids (TSS). Furthermore, high-throughput sequencing analysis of the 16S rRNA gene revealed that CW1 exhibited elevated Chao1, Shannon, and Simpson indices, with values of 1324.46, 8.8172, and 0.9941, respectively. The most common bacterial species in the wetland system were Proteobacteria, Spirochaetota, Bacteroidota, Desulfobacterota, and Chloroflexi. The denitrifying bacterial class Rhodobacteriaceae also had the highest content ratio within the wetland system. These results confirm that CW1 significantly improves the performance of water filtration. Therefore, this research provides valuable insights for wastewater treatment facilities aiming to incorporate surface flow-constructed wetland tailwater enhancement initiatives. [ABSTRACT FROM AUTHOR]

The leachate generated in municipal solid waste landfills tends to have extremely elevated levels of organic and inorganic pollutants influenced by the age and variety of landfills. This research aims to conduct a comparative analysis between two landfills, Krubong Landfill Sites (KLS) and Bukit Bakri Landfill Sites (BBLS). Based on the standard limit set by the Malaysia Environment Quality Act (MEQA), the average values of the leachate parameters at KLS and BBLS were recorded. These parameters include pH (8.84 for KLS and 9.08 for BBLS), temperature (30.22°C for KLS and 30.06°C for BBLS), Chemical Oxygen Demand (COD) (3695 mg L-1 for KLS and 11289 mg L-1 for BBLS), Biological Oxygen Demand (BOD) (1695 mg L-1 for KLS and 3325 mg L-1 for BBLS), and ammonia nitrogen (1107 mg L-1 for KLS and 1390 mg L-1 for BBLS). The findings of this research suggest that the age of the landfill indeed influences the characteristics of leachate and soil. KLS, being a mature landfill, demonstrated low biodegradability. On the other hand, BBLS, being a young landfill, exhibited high biodegradability. The highest heavy metal concentration in the soil sample of KLS was Barium (Ba), with 409 ppm, followed by Zirconium (Zr) at 297 ppm and Vanadium (V) at 114 ppm. For BBLS, Zirconium (Zr) and Thorium (Th) were 209 ppm, Rubidium (Rb) was detected at 86 ppm, and Chromium (Cr) was 57 ppm. In overall essence, the age of a landfill significantly influences its characteristics. Newly established landfills tend to contain a greater quantity of organic matter compared to older ones. [ABSTRACT FROM AUTHOR]

The research investigated changes in surface water quality (SWQ) in the canals and rivers of Can Tho province in the Mekong Delta in southern Vietnam. Surface water was sampled at 34 points through months of the end of the rainy and flood season (October 2023), the beginning of the dried season (December 2023), and the middle of the dried season (February 2024). The SWQ parameters were compared with limited values of the national technical standard on SWQ and the Vietnamese water quality index. We used principal component analysis (PCA) to find sources causing surface water pollution and cluster analysis (CA) to identify the similarities in SWQ parameters among sampling points. The research showed that Can Tho's average SWQ value ranged at a good level. The SWQ in the dry season is worse than in the rainy season. Pollution from suspended solids, organic matter, nutrients, and coliform was found in Can Tho's surface water. The PCA resulted in the three key sources of PCs 1, 2, and 3 being elucidated by 65.3% of SWQ changes. Twelve current monitoring parameters, including temperature, pH, dissolved oxygen, total suspended solids, total organic carbon, biological oxygen demand, chemical oxygen demand, ammonium, nitrite, nitrate, phosphate, and coliform, are influencing SWQ. It is suggested from the CA results that the 34 monitoring points could decrease to 30 points in the case of financial issues. The results are beneficial in reviewing the sampling points and monitoring parameters for SWQ in Can Tho. [ABSTRACT FROM AUTHOR]

Taitema Lake, situated at the terminus of the Tarim River Basin in Northwest China, represents a crucial ecological resource impacted by climate variability and anthropogenic interventions. In this study, we investigate the dynamic changes in Taitema Lake's area and water quality resulting from the implementation of an ecological water transfer project in 2000. Leveraging Landsat remote sensing data and comprehensive water quality monitoring, we analyzed the relationship between lake area variations and shifts in water quality parameters. Notably, our findings reveal a significant increase in Taitema Lake's area from 9.4 km2 in 2000 to 320 km2 in 2013. Concurrently, water quality indicators exhibited marked fluctuations, with total salt content ranging from 45,323.6 mg/L in 2000 to 970.4 mg/L in 2010 before increasing to 14,586.3 mg/L by 2014. Furthermore, a linear regression analysis highlights the moderate positive correlation between lake area and mineralization (R2 = 0.506) and sodium levels (R2 = 0.4907). Additionally, chloride (R2 = 0.5681) and sulfate (R2 = 0.6213) concentrations demonstrated a strong negative correlation with the lake area, indicative of a dilution effect. Furthermore, a comparison of water quality indicators between the years of minimum (2008) and maximum (2013) lake area underscores improvements in pH, chemical oxygen demand, and anionic surfactant concentrations as the lake area increased. Our study provides valuable insights into the effectiveness of ecological water management strategies in restoring and maintaining the ecological health of Taitema Lake, thereby informing evidence-based decision-making for the sustainable management of freshwater resources in arid environments. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) have attracted a great deal of attention as a promising technology for recovering electricity from organic substances by harnessing the metabolic activities of microorganisms. The objective of this study is to assess the efficacy of a LiTa0.5Nb0.5O3/g-C3N4 (LTN/g-C3N4) heterojunction as a photocathode catalyst within a single-chamber microbial fuel cell operating under both light irradiation and dark conditions. X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy dispersive X-Ray spectroscopy (EDS) were used to conduct a comprehensive analysis of the composite catalyst, revealing its exceptional purity and unique properties. After 120 h of exposure to visible light, the maximal power density of the MFC containing LTN/g-C3N4-modified carbon cloth was determined to be 667.7 mW/m3. The power density achieved with the presence of light was approximately three times greater than the power density obtained without light in the MFC (235.64 mW/m3). In addition, the study determined that the removal efficiencies of chemical oxygen demand (COD) were 88.4% and 66.5% when exposed to light and in the absence of light, respectively. These findings highlight the potential of the non-precious LTN/g-C3N4 photocatalyst as a viable alternative for effective wastewater treatment and power generation in microbial fuel cells with a single chamber configuration. [ABSTRACT FROM AUTHOR]

The selection of sites for permanent environmental monitoring of natural water bodies should rely on corresponding source apportionment studies. Tools like the water quality index (WQI) assessment may support this objective. This study aims to analyze a decade-long dataset of measurements of 26 chemical components at 26 observation points within the Irtysh River Basin, aiming to identify priority zones for stricter environmental regulations. It was achieved through the WQI tool integrated with geoinformation systems (GISs) and multivariate statistical techniques. The findings highlighted that both upstream sections of tributaries (Oba and Bukhtarma rivers) and the mainstream of the basin are generally in good condition, with slight fluctuations observed during flooding periods. Areas in the basin experiencing significant impacts from mining and domestic wastewater treatment activities were identified. The rivers Glubochanka (GL) and Krasnoyarka (KR) consistently experienced marginal water quality throughout the observation period. Various contaminant sources were found to influence water quality. The impact of domestic wastewater treatment facilities was represented by twofold elevated concentrations of chemical oxygen demand, reaching 22.6 and 27.1 mg/L for the KR and GL rivers, respectively. Natural factors were indicated by consistent slight exceedings of recommended calcium levels at the KR and GL rivers. These exceedances were most pronounced during the cold seasons, with an average value equal to 96 mg/L. Mining operations introduced extremal concentrations of trace elements like copper, reaching 0.046–0.051 mg/L, which is higher than the threshold by 12–13 times; zinc, which peaked at 1.57–2.96 mg/L, exceeding the set limit by almost 50–100 times; and cadmium, peaking at levels surpassing 1000 times the safe limit, reaching 0.8 mg/L. The adverse impact of mining activities was evident in the Tikhaya, Ulba, and Breksa rivers, showing similar trends in trace element concentrations. Seasonal effects were also investigated. Ice cover formation during cold seasons led to oxygen depletion and the exclusion of pollutants into the stream when ice melted, worsening water quality. Conversely, flooding events led to contaminant dilution, partially improving the WQI during flood seasons. Principal component analysis and hierarchical cluster analysis indicated that local natural processes, mining activities, and domestic wastewater discharge were the predominant influences on water quality within the study area. These findings can serve as a basis for enhanced environmental regulation in light of updated ecological legislation in Kazakhstan, advocating for the establishment of a comprehensive monitoring network and the reinforcement of requirements governing contaminating activities. [ABSTRACT FROM AUTHOR]

In order to reveal the impact of hydrodynamic conditions on the transport and diffusion of pollutants in Liaodong Bay in China, this article uses MIKE21 to establish a numerical model to simulate the hydrodynamic mechanisms of tidal currents and residual currents in Liaodong Bay. The model has been calibrated using observation data from 10 stations, and the simulation results of the tidal currents, Euler residual currents, Lagrangian residual currents, and particle tracking in Liaodong Bay have been calculated. Subsequently, a comparative analysis is conducted based on the abovementioned data and measured data, exploring the impact of hydrodynamic conditions on the transport and diffusion of COD in Liaodong Bay. The research results in this article indicate that high concentration COD areas are mainly concentrated in the coastal areas around the estuary of the Liao River and the Daliao River, and river input is the main source of COD in Liaodong Bay. The Euler residual circulation can form COD enrichment in some areas, which is significantly higher than the background concentration, and the large-scale transportation of COD after entering Liaodong Bay is determined by the Lagrangian residual current. The particle tracking results in the estuarine area can effectively characterize the actual transportation of pollutants. The results of the Lagrangian residual flow and particle tracking in the bay indicate that river pollutants are mainly transported to the west bank after entering Liaodong Bay. The distribution of a COD concentration of 1.5 mg/L confirms this finding. The research findings presented in this paper offer valuable insights into the spatial distribution and transportation mechanisms of pollutants. These results hold significant implications for pollution prevention and mitigation strategies in comparable bay environments. [ABSTRACT FROM AUTHOR]

This study optimized the organic matter solubilization of faecal sludge (FS). FS was treated in a microwave oven at varying microwave power and treatment times. Changes in total solids (TS), volatile solids (VS), total chemical oxygen demand (TCOD), and soluble chemical oxygen demand (sCOD) were measured. A response surface methodology (RSM) optimized organic matter solubilization during microwave treatment. A central composite design was employed, and the observed responses were used to fit a second-order response surface model. Microwave treatment at 14,000 kJ/kg. TS reduced FS volume by 58%. The VS/TS ratios remained similar before and after microwave treatment. The solubilization of organic matter (measured by the sCOD/TCOD ratio) increased after microwave treatment, showing an initial linear increase with specific energy followed by a decrease. The highest solubilization was 38%, achieved at a microwave power level of 630 W for 3 min. Organic matter solubilization was more sensitive to contact time than microwave power. RSM determined the optimized conditions to be 617.7 W and 2.4 min, within the experimental design boundaries. These findings align with similar observations from other studies using wastewater sludge. The results suggest that microwave treatment can achieve multiple FS treatment objectives. Optimal operating conditions should be identified if the aim is to solubilize organic matter in FS. [ABSTRACT FROM AUTHOR]

This study investigates the densification/granulation of activated sludge with poor settleability, treating real industrial wastewater from a tank truck cleaning company. The wastewater is low in nutrients, acidic in nature, and high and variable in chemical oxygen demand (COD, ranging from 2770 mg·L−1 to 14,050 mg·L−1). A microbial selection strategy was applied to promote slow-growing glycogen-accumulating microorganisms (GAO) by the implementation of an anaerobic feast/aerobic famine strategy in a sequencing batch reactor (SBR). After 60 to 70 days, the uptake of carbon during the anaerobic phase exceeded 80%, the sludge morphology improved, and the sludge volume index (SVI) dropped below 50 mL·g−1. 16S rRNA gene sequencing showed the enrichment of the GAOs Defluviicoccus and Candidatus Competibacter. Stable sludge densification was maintained when using a constant organic loading rate (OLR) of 0.85 ± 0.05 gCOD·(L·d)−1, but the sludge quality deteriorated when switching to a variable OLR. In view of the integration of densified/granular sludge in a membrane bioreactor configuration, the filtration properties of the densified SBR sludge were compared to the seed sludge from the full-scale plant. The densified sludge showed a significantly lower resistance due to pore blockage and a significantly higher sustainable flux (45 vs. 15 L·(m2·h)−1). [ABSTRACT FROM AUTHOR]

The tofu industry generates substantial liquid waste that poses environmental challenges due to its high chemical oxygen demand (COD), total suspended solids (TSS), and pH levels. This study aimed to determine the effectiveness of Eco Enzymes in reducing these chemical parameters in the tofu industry waste in Klumutan Village, Saradan District. Utilizing a Quasi-Experimental method, the research employed purposive sampling of liquid waste from tofu production. The findings revealed that the application of Ecoenzyme at doses of 5%, 10%, and 15%, with detention times of 10, 15, and 20 days, significantly reduced COD, TSS, and pH levels. The results showed that both the dosage and detention time had a substantial impact on the effectiveness of Ecoenzyme in treating the waste. The implications of this study suggest that Eco Enzymes can be an effective, eco-friendly solution for improving wastewater management in the tofu industry, thereby contributing to environmental sustainability. [ABSTRACT FROM AUTHOR]

The swine industry generates millions of gallons (thousands of cubic meters) of wastewater every day, posing significant environmental risk due to high concentrations of organics and nutrients. This study aims to investigate the effectiveness of attached-growth anaerobic bioreactors for treating swine wastewater by utilizing sulfate-reducing bacteria, focusing on the impact of chemical oxygen demand (COD)/sulfate mass ratios on organics degradation. A series of lab-scale anaerobic bioreactors were employed to treat swine wastewater for a 14-day period. The study evaluated changes in pH, acidity, alkalinity, COD, sulfate, and various nutrients along with total suspended solids (TSS) and volatile suspended solids (VSS) before and after treatment. At a COD/sulfate mass ratio of 2:1, the bioreactors achieved optimum removal efficiencies of 80% for TSS, 83% for VSS, 86–88% for COD, 82–87% for sulfate, 73% for sulfide, and 73% for sulfite. The nutrient removal efficiency was 67% for nitrate and 72% for nitrite. The acidity and alkalinity were effectively controlled, with alkalinity values reaching up to 2161 ± 92.5 mg/L and pH within the range of 7–7.24. The findings demonstrated that anaerobic bioreactor at a COD/sulfate mass ratio of 2:1 significantly enhanced the degradation of organic matter coupling with sulfate reduction in swine wastewater, providing an efficient and sustainable treatment method. [ABSTRACT FROM AUTHOR]

Real textile wastewater (RTWW) poses significant environmental challenges. RTWW typically contains high levels of organic compounds, such as dyes, as well as inorganic substances like salts. These contaminants can harm aquatic life when released into water bodies without appropriate treatment. RTWW was subjected to a series of sequential treatments: exchange resins for removing ions, advanced oxidation with bicarbonate-activated peroxide to degrade organic matter, and a biological treatment based on the Zahn–Wellens test to remove remaining chemical oxygen demand (COD) The advanced oxidation process based on the activation of H2O2 with NaHCO3 (catalyzed with cobalt impregnated on a pillared clay, Co/Al–PILC)) was optimized using central composite design (CCD) and response surface methodology (RSM). After the process integration, reductions in ion concentrations, chemical oxygen demand (COD), and total organic carbon content (TOC) were achieved. Reduced hardness (99.94%) and ions (SO42− and acid black 194 dye of 99.88 and 99.46%, respectively), COD (96.64%), and TOC (96.89%), guaranteeing complete treatment of RTWW, were achieved. Additionally, the biodegradability index of RTWW increased from 0.28 ± 0.01 to 0.90 ± 0.01, and phytotoxicity was reduced, going from a phytotoxic that inhibited the germination of lettuce seeds to a phytostimulant after biological treatment with activated sludge. [ABSTRACT FROM AUTHOR]