Enhancing treatability of tannery wastewater by integrated process of electrocoagulation and fungal via using RSM in an economic perspective

Treatment of tomato paste wastewater by electrochemical and membrane processes: process optimization and cost calculation

This study investigated the treatment of wastewater from tomato paste (TP) production using electrocoagulation (EC) and electrooxidation (EO). The effectiveness of water recovery from the pretreated water was then investigated using the membrane process. For this purpose, the effects of independent control variables, including electrode type (aluminum, iron, graphite, and stainless steel), current density (25-75 A/m2), and electrolysis time (15-120 min) on chemical oxygen demand (COD) and color removal were investigated. The results showed that 81.0% of COD and 100% of the color removal were achieved by EC at a current density of 75 A/m2, a pH of 6.84 and a reaction time of 120 min aluminum electrodes. In comparison, EO with graphite electrodes achieved 55.6% of COD and 100% of the color removal under similar conditions. The operating cost was calculated to be in the range of $0.56-30.62/m3. Overall, the results indicate that EO with graphite electrodes is a promising pretreatment process for the removal of various organics. In the membrane process, NP030, NP010, and NF90 membranes were used at a volume of 250 mL and 5 bar. A significant COD removal rate of 94% was achieved with the membrane. The combination of EC and the membrane process demonstrated the feasibility of water recovery from TP wastewater.

Advancements in combined electrocoagulation processes for sustainable wastewater treatment: A comprehensive review of mechanisms, performance, and emerging applications

This review explores the potential and challenges of combining electrochemical, especially electrocoagulation (EC) process, with various - wastewater treatment methods such as membranes, chemical treatments, biological methods, and oxidation processes to enhance pollutant removal and reduce costs. It emphasizes the advantages of using electrochemical processes as a pretreatment step, including increased volume and improved quality of permeate water, mitigation of membrane fouling, and lower environmental impact. Pilot-scale studies are discussed to validate the effectiveness of combined EC processes, particularly for industrial wastewater. Factors such as electrode materials, coating materials, and the integration of a third process are discussed as potential avenues for improving the environmental sustainability and cost-effectiveness of the combined EC processes. This review also discusses factors for improvement and explores the EC process combined with Advanced Oxidation Processes (AOP). The conclusion highlights the need for combined EC processes, which include reducing electrode consumption, evaluating energy efficiency, and conducting pilot-scale investigations under continuous flow conditions. Furthermore, it emphasizes future research on electrode materials and technology commercialization. Overall, this review underscores the importance of combined EC processes in meeting the demand for clean water resources and emphasizes the need for further optimization and implementation in industrial applications.

Synthesis of graphite/rGO-modified fungal hyphae for chromium (VI) bioremediation process

Bioremediation is a promising technology that can eliminate the drawbacks of conventional treatment methods in removing harmful toxic metals including chromium(VI). Therefore, in this study, fungal hyphae modified with graphite and reduced graphene oxide were synthesized and assessed for their potential to bioremediate heavy metals for the first time in the literature. The effects of the carbon-based materials on microbial structure were characterized using scanning electron microscopy analysis. Thermogravimetric, RAMAN, X-ray diffraction, and enzymatic analyzes were performed to determine the role of functional groups. In addition, batch adsorption experiments utilizing response surface methodology were conducted to optimize operating parameters such as time (1-11 h), chromium (10-50 mg/L), and graphite/reduced graphene oxide (0.1-1 g/L). The maximum adsorption capacity with the graphene fungal hyphae was determined to be 568 mg.g-1, which is 9.7 times that of the crude fungal hyphae. The Cr(VI) removal for fungal hyphae-graphite and fungal hyphae-reduced graphene oxide biocomposites was 98.25% and 98.49%, respectively. The isothermal and kinetic results perfectly matched the 2nd order pseudo-model and Langmuir model in terms of the nature of the adsorption process. The laboratory scale test results indicate that fungal hyphae modified with graphite and reduced graphene oxide have a high adsorption capacity, suitable for the removal of chromium (VI) from wastewater.

Reclamation of forward osmosis reject water containing hexavalent chromium via coupled electrochemical-physical processes

Forward osmosis is a water separation process that uses the natural energy of osmotic pressure to separate water from dissolved solutes through a semipermeable membrane. One of the major challenges using this process is the rejection water which contains high content of pollutants, hindering its practical application. Herein, for the first time, this work introduces a coupled electrochemical-physical process including iron-electrocoagulation/filtration/sedimentation as a cost-effective treatment to the forward osmosis reject water containing hexavalent chromium to be reclaimed. The synergistic treatment was optimized through a central composite design and response surface methodology to enhance hexavalent Cr removal and minimize operating costs, electrical energy consumption, and settled sludge volume. A 90.0% chromium removal was achieved under optimized conditions: electrolysis time of 59.7 min and current of 1.24 A (J = 6.32 mA cm-2). In addition, operating costs of 0.014 USD m-3, electrical energy consumption of 0.005 kWh m-3, and settled sludge volume of 445 mL L-1 were obtained.

Removal of chromium from tannery industry wastewater using iron-based electrocoagulation process: experimental; kinetics; isotherm and economical studies

Chromium is a hazardous compound from industrial processes, known for its toxicity, mutagenicity, teratogenicity, and carcinogenicity. Chemical methods are efficient but cost-effective alternatives with reduced sludge are sought. Electro-coagulation, utilizing low-cost iron plate electrodes, was explored for factual tannery wastewater treatment in this manuscript. Operating parameters such as initial chromium concentration, voltage, electrode number, operating time, agitation speed and current density has been studied to evaluate the treatment effeciency. Under optimal conditions (15 V, 0.4 mA/cm2, 200 rpm, 330 ppm chromium, 8 iron electrodes with a total surface area of 0.1188 m2, 3 h), chromium elimination was 98.76%. Iron anode consumption, power use, and operating cost were 0.99 gm/L, 0.0143 kW-h/L, and 160 EGP/kg of chromium eliminated, respectively. Kinetics studies were pursued first-order reaction (97.99% correlation), and Langmuir isotherms exhibited strong conformity (Langmuir R2: 99.99%). A predictive correlation for chromium elimination (R2: 97.97%) was developed via statistical regression. At HARBY TANNERY factory in Egypt, industrial sewage treatment achieved a final chromium disposal rate of 98.8% under optimized conditions.

Zero waste discharge in tannery industries - An achievable reality? A recent review

In the recent times, more attention is on industrial waste management due to the unaffordable space for dump yards and landfills and the increased charges for waste dumping. Even though the vegan revolution and plant-based meat products are booming, the traditional slaughterhouses and the wastes produced by them continue to be a concern. Waste valorisation is an established procedure striving to create a closed chain process in industries where there is no refuse. Although a highly polluting industry, slaughterhouse industry wastes have been recycled to economically viable leather since ancient times. However, the tannery industry is causing pollution in par with or even more than the slaughterhouses. Effective management of the liquid and solid wastes from the tannery is of utmost concern because of its toxicity. The hazardous wastes generated enter the food chain, causing long term impacts in the ecosystem. Several leather waste transformation processes are widely used in the industries, and they are yielding good products of economic value. However careful exploration into the processes and products of waste valorisation are often ignored as long as the transformed waste product is of higher value than the waste. The most efficient and environmentally friendly waste management technique should convert the refuse into a value-added utilization without any toxic leftovers. Zero waste concept is an extension of the zero liquid discharge concept, where the solid waste is also treated and reused to such an extent that there is no residue to be sent to the landfill. This review initially presents the existing methods for the de-toxification of tannery wastes and examines the possibility of solid waste management within the tannery industry to attain zero waste discharge.

Study of the effect of current intensity on the structural performance of electrogenerated mesoporous aluminum phosphate: application for adsorption

To keep up with the development of contaminants in the water supply, it is required to create new adsorbents or improve current ones. The adsorption capacity of AlPO₄ electrocoagulated with varying current intensities was examined. AlPO₄ was produced by electrolysis in a NaCl solution using aluminum electrodes and a 0.1 M phosphate buffer at varying current intensities. Current efficiency was enhanced. X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy were used to analyze the adsorbents (FTIR). The specific surface area was estimated by the quantity of methylene blue adsorbed by particles in an aqueous solution. Numerous operating factors must be addressed, including pH, starting concentration, adsorbent dose, and contact duration. The electrostatic interaction between positively charged MB molecules and negatively charged adsorbents drives adsorption at alkaline pH. When describing equilibrium adsorption, the Langmuir model is more accurate. Modeling using an adsorption isotherm may further improve the predicted specific surface area. At 0.2 amperes, the observed specific surface area was 2.86 m²/g.

Advancements of sequencing batch biofilm reactor for slaughterhouse wastewater assisted with response surface methodology

Slaughterhouse wastewater (SWW) contains a significant volume of highly polluted organic wastes. These include blood, fat, soluble proteins, colloidal particles, suspended materials, meat particles, and intestinal undigested food that consists of higher concentrations of organics such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrogen and phosphorus hence an efficient treatment is required before discharging into the water bodies. The effluent concentrations and performance of simultaneous sequential batch biofilm reactor (SBBR) with recycled plastic carrier media support are better than the local single-stage sequential batch reactor (SBR), which is lacking in the literature in terms of COD, NH₃, NO₃, and PO₄ treatment efficiency. The present study reports a novel strategy to remove the above mentioned contaminants using an intermittently aerated SBBR with recycled plastic carrier media support along with simultaneous nitrification and denitrification. The central composite design was evaluated to optimize the treatment performance of seven different process variables including; different alternating conditions (Oxic/anoxic) for aeration cycles (3/2 h in a 6 h cycle, 6/5 h in a 12 h cycle and 9/8 h in an 18 h cycle) and hydraulic retention time (6, 12 and 18 h). The average removal efficiencies are 94.5% for NH₃, 93% for NO₃ and 90.1% for PO₄, and 99% for COD. The study reveals that the denitrification in the post-anoxic phase was more efficient than the pre-anoxic phase for pollutant removal and maintaining higher quality effluent. The effluent concentrations and performance of simultaneous SBBR with recycled polyethylene carrier support media were better than local SBR system in terms of COD, NH₃, NO₃ and PO₄ treatment efficiency. Results stipulated the suitability of SBBR for wastewater treatment and reusability as a sustainable approach for wastewater management under optimum conditions.

Development of electrocoagulation process for wastewater treatment: optimization by response surface methodology

Electrocoagulation (EC) is a process used by supply of electric current with sacrificial electrodes for the removal of pollutant from wastewater. The study was experimentally investigated taking into account various factors such as pH (3–7.5), current (0.03–0.09 A), distance between the electrodes (1–2 cm), electrolytic concentration (1–3 g/L), and electrolysis time (20–60 min) which is impact on the % removal efficiency of color, chemical oxygen demand (COD), turbidity and determination of energy consumption used for aluminum (Al) electrode used. The surface response design process based on the central composite design (CCD) has been used to optimize different operational parameters for treatment of hospital wastewater using EC process. The % color, COD and turbidity removal, and energy consumption under different conditions were predicted with the aid of a quadratic model, as were the significance and their interaction with independent variables assessed by analysis of variance (ANOVA). The optimal conditions were obtained through mathematical and statistical methods to reach maximum % color, COD, and turbidity removal with minimum energy consumption. The results showed that the maximum removal of color (92.30%), COD (95.28%), and turbidity (83.33%) were achieved at pH–7.5, current–0.09A, electrolytic concentration–3g/L, distance between electrodes–2 cm and reaction time 60 min. This means that, the process of EC can remove pollutants from various types of wastewaters and industrial effluent under the various operating parameters.

•

EC effective technology used to treat wastewater generated from hospital.

•

Al was used as an electrode for hospital wastewater treatment using EC process.

•

EC can eliminate pollutants from wastewater under various operating parameters.

•

CCD used to optimize operational parameters for treatment of hospital wastewater.

A critical review in electrocoagulation technology applied for oil removal in industrial wastewater

EC process, which stands for Electrocoagulation, is considered a widespread wastewater remediation method that is investigated widely for an extensive variety of wastewater resources, based on its flexibility, easy setup, eco-friendly nature, and low footprint. The critical operative factors in the EC process and the crucial relation between EC and the typical chemical coagulation approach had been thoroughly evaluated because they are the main variables that govern the process of contaminant elimination. As a result, the EC process requires further investigations for scale-up simulations in the manufacturing scopes and optimization of operational parameters. Furthermore, the current paper studies the novel integrated separation methods with the combined EC process and also their limitations for improved wastewater remediation process for cleaner wastes, recycling processes, and water recovery. In this paper, the EC enhancement processes toward oil removal from wastewater have been reviewed which includes a concise representation of the source and features of oily wastewater. Additionally, the advanced remediation methods for oil-contained wastewater and the electrocoagulation process are presented. This review summarized the present utilization of electrocoagulation to eliminate oil from wastewater. Besides the process optimization and modeling investigations, the parameters that significantly affect the electrocoagulation remediation effectiveness are evaluated. Finally, the cutting-edge and sophisticated methods of electrocoagulation process for oil removal are presented.

Treatment of vegetable oil wastewater by a conventional activated sludge process coupled with electrocoagulation process

The present work aims to study chemical oxygen demand (COD), oil-grease, and color removal from vegetable oil wastewater by combined electrocoagulation and activated sludge processes. For this purpose, the sample was pretreated using electrocoagulation by various optimization parameters such as electrode type (Al-Al and Fe-Fe), current density (100-400 A/m² ), pH (2-8), and electrolysis time (15-180 min). The results showed that 89.3% of COD, 100% of oil-grease, and 66.2% of color were removed by electrocoagulation under the conditions of 300-A/m² current density, pH 2, and 180-min reaction time with Al-Al electrode pairs. Then, the effluent of electrocoagulation was treated by an activated sludge process. The results depicted that the activated sludge process was also effective for vegetable oil wastewater treatment and it enhanced 98.9% COD and 79.2% color removal efficiency. The effluent of the combined process was very clear, and its quality exceeded the direct discharge standard of the water pollution control regulation. The laboratory-scale test results indicate that the combined electrocoagulation and activated sludge process is feasible for the treatment of vegetable oil wastewater. PRACTITIONER POINTS: Vegetable oil wastewater was treated by combination of electrocoagulation and activated sludge processes. The combined electrocoagulation and activated sludge processes supplied 99.9% COD, 100% oil-grease, and 93.0% color removal efficiency. The laboratory-scale test results indicate that the combined EC-SBR processes were feasible for the treatment of vegetable oil wastewater.

Removal of microplastics from wastewater through electrocoagulation-electroflotation and membrane filtration processes

Wastewater treatment plants (WWTPs) are one of the major vectors of microplastics (MPs) pollution for the recipient water bodies. Therefore, the recovery of MPs from WWTPs is extremely important for decreasing their accumulation and impact in aquatic systems. In this present study, the electrocoagulation-electroflotation (EC/EF) and membrane filtration processes were investigated in removing MPs from wastewaters. The effectiveness of different electrode combinations (Fe-Al and Al-Fe), current density (10-20 A/m²), pH (4.0-10.0) and operating times (0-120 min) on the removal of two different polymer particles in water were investigated to obtain maximum treatment efficiency. The effect of pressure (1-3 bar) on membrane filtration removal efficiency was also investigated. The maximum removal efficiencies were obtained as 100% for both polymer types with electrode combination of Al-Fe, initial pH of 7, current density of 20 A/m² and reaction time of 10 min. The membrane filtration method also displayed a 100% removal efficiency. In addition, these laboratory-scale results were compared with the one-year average data of a plant treating with real-scale membranes. The results indicated that the proposed processes supplied maximum removal efficiency (100%) compared to conventional secondary and tertiary treatment methods (2-81.6%) in the removal of microplastics.

Treatment of cardboard factory wastewater using ozone-assisted electrocoagulation process: optimization through response surface methodology

Cardboard factory wastewater is usually known by high chemical oxygen demand (COD), color, phenols, lignin, and its derivatives, and usual treatment techniques are not able to treat such wastewaters. This study aimed to investigate the efficiency of ozone-assisted electrocoagulation process (EC/O₃) for the treatment of real cardboard wastewater. The parameters influencing COD removal in the EC/O₃ process were optimized using response surface methodology. Regard to the statistical model, the optimum conditions were obtained at current density 9.6 mA/cm², time 20 min, and pH 12. At optimal condition, EC/O₃ process removed 74.7% and 97.5% of COD and color, which was higher compared to ozonation and EC processes separately. The COD removal followed pseudo-first-order kinetic with the coefficient correlation of 0.97 and the reaction rate constant of 0.073 1/min. To sum up, the combined electrocoagulation process with ozonation could be used satisfactorily for removing pollutants from real cardboard wastewater.

A critical review of state-of-the-art electrocoagulation technique applied to COD-rich industrial wastewaters

Electrocoagulation (EC) is one of the emerging technologies in groundwater and wastewater treatment as it combines the benefits of coagulation, sedimentation, flotation, and electrochemical oxidation processes. Extensive research efforts implementing EC technology have been executed over the last decade to treat chemical oxygen demand (COD)-rich industrial wastewaters with the aim to protect freshwater streams (e.g., rivers, lakes) from pollution. A comprehensive review of the available recent literature utilizing EC to treat wastewater with high COD levels is presented. In addition, recommendations are provided for future studies to improve the EC technology and broaden its range of application. This review paper introduces some technologies which are often adopted for industrial wastewater treatment. Then, the EC process is compared with those techniques as a treatment for COD-rich wastewater. The EC process is considered as the most privileged technology by different research groups owing to its ability to deal with abundant volumes of wastewater. After, the application of EC as a single and combined treatment for COD-rich wastewaters is thoroughly reviewed. Finally, this review attempts to highlight the potentials and limitations of EC. Related to the EC process in batch operation mode, the best operational conditions are found at 10 V and 60 min of voltage and reaction time, respectively. These last values guarantee high COD removal efficiencies of > 90%. This review also concludes that considerably large operation costs of the EC process appears to be the serious drawback and renders it as an unfeasible approach for handling of COD rich wastewaters. In the end, this review has attempted to highlights the potential and limitation of EC and suggests that vast notably research in the field of continuous flow EC system is essential to introduce this technology as a convincing wastewater technology.

Treatment of slaughterhouse wastewater by electrocoagulation and electroflotation as a combined process: process optimization through response surface methodology

The contamination of water with organic compounds has become an increasing concern in today's world. The cost-effective and sustainable treatment of industrial wastewaters is a major challenge. Advanced treatment techniques such as electrocoagulation-electroflotation offer economic and reliable solutions for the treatment of industrial wastewater. In this study, the electrocoagulation-electroflotation method was investigated for the simultaneous removal of chemical oxygen demand, total phosphorus, total Kjeldahl nitrogen, and color via response surface methodology. Factors such as electrode combination (Fe and Al), current density (10-20 mA/cm²), pH (3.0-9.0), and electrode distance (1-3 cm) were investigated in the treatment of wastewater to obtain maximum treatment efficiency. It was determined that chemical oxygen demand, total Kjeldahl nitrogen, total phosphorus, and color removal reached up to 94.0%, 77.5%, 97.0%, and 99.0%, respectively. Treatment costs were found as $0.71 with the Al-Fe electrode combination.

Caffeine removal using Elaeis guineensis activated carbon: adsorption and RSM studies

The palm (Elaeis guineensis), known as dendê, is an important oleaginous Brazilian plant with a high performance of oil production. In this work, a 2³ full experimental design was performed and the response surface method (RSM) was used to indicate the optimum parameter of caffeine adsorption on Elaeis guineensis endocarp activated carbon, since the endocarp is the main by-product from dendê oil production. It was set the adsorbent point of zero charge (pH_pzc), and the material was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The RSM results indicate removal efficiency (%) at the optimal conditions, 0.20 g of adsorbent, and caffeine initial concentration of 20 mg/L, and acidic medium was about 95%. Based on ANOVA and F test (F_calculated > F_standard), the mathematical/statistical model obtained fits well to the experimental data. The overall kinetic studies showed time was achieved after 5 h and caffeine adsorption followed the pseudo-second-order model suggesting chemisorption is a predominant mechanism. Redlich-Peterson and Sips models best represented the experimental data (0.967 < R² < 0.993). Thermodynamic revealed that caffeine adsorption was spontaneous at all temperatures studied, exothermic, and probably with changes in the adsorbate-adsorbent complex during the process. The tests conducted in different water matrixes corroborate the suitability of this adsorbent to be used in caffeine removal even in a complex solution.