COD Reduction Research Articles

Statistical evaluation of the coagulation-flocculation process by using Moringa oleifera seeds extract to reduce dairy industry wastewater turbidity

The use of coagulant aqueous extract obtained from M. oleifera seeds in the integration of coagulation/flocculation processes and membrane separation proved to be an environmentally friendly alternative for wastewater treatment from the dairy industry. Three saline solutions, KCl, MgCl2 and CaCl2, were tested to extract the active component from Moringa seeds. The greatest statistical effect on turbidity removal was attributed to the initial pH of the effluent, according to the t-Student at the 5 % significance level. The maximized turbidity and color removals were 96.8 and 90.3 %, respectively, at pH 11 and 300 mg L−1 of the coagulant extracted with CaCl2 0.9 mol L−1. Nanofiltration indicated that previously flocculated organic matter particles were reversibly retained by the membrane. Total fouling was only 35 %, resulting in 98 % recovery of the initial water flow, and a reduction in color, turbidity, COD, calcium, and hardness of 99.5; 98.9; 89.1; 85.5 and 85 %, respectively.

The Effects of Low-frequency Pulsed Electromagnetic Fields on the Cleaning of Household Wastewater

The effect of pulsed EMF with a pulse repetition frequency of 16 Hz on the decomposition of organic compounds in wastewater in the presence of activated sludge microorganisms has been studied. It is shown that aerobic purification of a mixture of wastewater and activated sludge in the presence of a continuous pulsed electromagnetic field with a frequency of 16 Hz and a magnetic induction of no more than 0.5 μT accelerates the process of ammonification by 25 %, nitrification and denitrification by 15 %, reduction of COD by approximately 20 %.The intensity of the increase in the biomass of activated sludge and the rate of its deposition were noted.

Ultrasonically assisted hydrothermal synthesis of tungsten(VI) oxide-TiO2 nanocomposites for enhanced photocatalytic degradation of non-narcotic drug paracetamol under natural solar light: insights into degradation pathway, mechanism, and toxicity assessment.

Photocatalytic degradation of pharmaceutical residues through natural solar radiation represents a green and economical treatment process. In this work, ultrasonically assisted hydrothermal synthesis of WO3-TiO2 nanocomposite was carried out at 140-150°C for 5h and calcinated at 600°C. The structural and optical properties of the synthesized material were investigated using techniques like XRD, FESEM/EDX, HRTEM, BET surface area, UV-DRS optical analysis, and photocurrent response. The band gap of TiO2 was successfully reduced from 3.0 to 2.54eV and thus making it effective under solar light. Complete degradation of paracetamol (50ppm and natural pH of 6.5) was achieved in 3.5h under natural sunlight at catalyst dose of 0.5g/l. The extent of mineralization was evaluated by measuring the COD reduction. Based on the degradation products identified by GC-MS/LC-TOF-MS, the degradation process under natural solar-light could be interpreted to initiate through OH. radical species. The toxicity removal of the treated paracetamol solution under natural solar-light was evaluated by the seed germination test using Spinacia oleracea seeds and exhibited 66.70% seed germination, confirming the reduction in toxicity. The enhanced photocatalytic efficiency of the nanocomposite is attributed to the higher surface area, low rutile content, lower band gap, and incorporation of WO3, which led to an extended absorption range and a slower rate of electron-hole recombination. The technical insights presented in this research offer a feasible approach for utilizing natural solar light driven photocatalysis for wastewater treatment in an efficient and sustainable way. The proposed degradation pathway, and seed germination test (toxicity removal) of the treated paracetamol solution under natural sunlight, has not been previously evaluated.

Remediation of real industrial hypersaline effluent using sequential approach of precipitation followed by cavitation based oxidative process

The current study aims to develop a cost-effective and efficient treatment method for the remediation of amine-containing real industrial effluent. The method consists of a precipitation to remove chloride ions and TDS, followed by cavitation-based AOPs involving US and chemical oxidants as H2O2, O3, Fenton’s reagent, NaClO, and nTiO2. Different parameters including precipitating agent type and dosage, oxidant loading/flow rate, and time were assessed to determine optimal conditions for effective treatment. Treatment schemes were evaluated based on cavitational yield (mg/J), treatment cost (Rs/L), and COD reduction to select an industrially feasible design for amine-containing real effluent treatment. The optimum conditions elucidated were H2O2 loading of 3 g/L, NaClO loading of 3 g/L, O3 flowrate of 3 LPH, nTiO2 loading of 3 g/L, and Fenton’s reagent ratio (H2O2/Fe2+) as 6:1. Under the optimum conditions, US+nTiO2 (70%) treatment schemes were the most efficient, achieving a maximum COD reduction compared to US+Fenton (65%), US+H2O2 (36%), US+O3 (49%) and US+NaClO (53%) schemes. Additionally, impact of chloride and TDS on the oxidation process in terms of COD reduction was assessed. Using Rotavap instead of precipitation, and subsequent use of the best oxidation method (US/HC+Fenton+CaO) achieved COD and TDS levels below 250 mg/L (discharge limit) at optimum conditions, with minimal operating costs of 0.23 $/L and 0.15 $/L, respectively. Overall, the study concluded that the sequential approach of precipitation/Rotavap and cavitation-assisted oxidation is an effective and sustainable method, providing a promising solution for the wastewater treatment in the metallurgical industry.

An efficient electrochemical degradation of toxic pollutants in wastewater using BiOBr/BiVO4 hierarchical structured electrode material

The electrochemical degradation of alizarin red dye was studied using bismuth oxyhalide attached to bismuth vanadate nanocomposite synthesized via a simple solvothermal method. The electrochemical degradation of alizarin red dye was treated at current densities of 3 and 5 mA cm−1 for 30 min under different supporting electrolyte mediums (NaCl and KCl). Also, the electrochemical degradation of BiOBr/BiVO4 electrode shows higher degradation percentages of 97 and 99 for NaCl and KCl electrolyte solutions, which are higher degradation percentages than pure BiVO4 electrode (88 and 91 for NaCl and KCl). Also, the BiOBr/BiVO4 electrode shows 100% COD reduction during the 30th min of alizarin red dye using both NaCl and KCl electrolyte solutions. This may indicate that the prepared BiOBr/BiVO4 electrode shows an efficient electrode material for the degradation of textile dyes.

Investigate the anaerobic degradation of high-acetone latex wastewater with magnetite supplement

This study evaluated the effects of acetone on the anaerobic degradation of synthetic latex wastewater, which was simulated from the wastewater of the deproteinized natural rubber production process, including latex, acetate, propionate, and acetone as the main carbon sources, at a batch scale in 5 cycles of a total of 60 days. Fe3O4 was applied to accelerate the treatment performance from cycle 3. Acetone was added in concentration ranges of 0%, 0.05%, 0.1%, 0.15%-included latex, and 0.15%-free latex (w/v). In the Fe3O4-free cycles, for latex-added vials, soluble chemical oxygen demand (sCOD) was removed at 43.20%, 43.20%, and 12.65%, corresponding to the input acetone concentrations varying from 0.05% to 0.15%, indicating the interference of acetone for COD reduction. After adding Fe3O4, all flasks reported a significant increase in COD removal efficiency, especially for acetone-only and latex-only vials, from 36.9% to 14.30%–42.95% and 83.20%, respectively. Other highlighted results of COD balance showed that Fe3O4 involvement improved the degradation process of acetate, propionate, acetone, and the other COD parts, including the intermediate products of latex reduction. Besides, during the whole batch process, the order of reduction priority of the carbon sources in the synthetic wastewater was acetate, propionate and acetone. We also found that the acetate concentration appeared to be strongly related to reducing other carbon sources in natural rubber wastewater. Microbial community analysis revealed that protein-degrading bacteria Bacteroidetes vadinHA17 and Proteinniphilum and methylotrophic methanogens might play key roles in treating simulated deproteinized-natural-rubber wastewater.

Simultanous Electricity Production and Wastewater Ttreatment in a Microbial Fuel Cell Inoculeted with Anaerobic Sludge

In order to reduce the environmental pollution associated with the conventional energy sources and to achieve the increased global energy demand, alterative and renewable sustainable energy sources need to be developed. Microbial fuel cells (MFCs) represent a bio-electrochemical innovative technology for pollution control and a simultaneous sustainable energy production from biodegradable, reduced compounds. This study mainly considers the performance of continuous up flow dual-chambers MFC fueled with actual domestic wastewater and bio-catalyzed with anaerobic aged sludge obtained from an aged septic tank. The performance of MFCs was mainly evaluated in terms of COD reductions and electrical power output. Results revealed that the COD removal efficiency up to 89% was obtained for wastewaters having an average initial COD concentration of 350 mg/L. Stabilized power outputs were clearly observed achieving a maximum value of 170 mW/ m2.

Facilitating the electrochemical characterization and biofilm enrichment through anode modification in microbial fuel cells

Poor anodic performance is a significant obstacle for scalable applications of air-cathode microbial fuel cells (MFCs), and it can be significantly improved with graphite anodic surface modifications. Morphological and electrochemical performance of modified anode with reduced graphene oxide rGO), polyaniline (PANI), carbon nanotubes (CNTs), each mixed with plant powder, showed improvement in electron transfer rate and anodic biocapacitance over unmodified anode in MFC. PANI-modified anode showed maximum power generation (149.7 mW/cm2) over other variations in MFCs. The highest COD percentage removal was obtained by the PAIN-modified anode (91.9%) followed by the CNTs-modified anode (86.7%) and the rGO-modified anode (82.4%). Electrochemical analyses revealed the enhancement in redox current generation with low charge transfer resistance with enrichment in electrogens in anodic biofilm using such anode modifiers, especially PANI, than unmodified anode in MFC. Biological and physiological analyses also support favoring electrogenic microbial activities and community structure towards the electroactive response and secretion of extracellular polymeric substances (EPS) for mediating electrons with modified anode conditions. Thus, the PANI-modified anode can be a promising and a sustainable anode candidate for MFC's long-term stability and scalable applications. Likewise, it could potentially be utilized as an innovative approach for developing a high-performance anode with extended operation for COD reduction in wastewater.

Optimizing leachate treatment with titanium oxide-impregnated activated carbon (TiO2@ASC) in a fixed-bed column: characterization, modeling, and prediction study.

This research focused on the application of a fixed bed column filled with immobilized titanium oxide-loaded almond shell carbon (TiO2@ASC) for the treatment of leachate. The adsorption performance of synthesized TiO2@ASC in fixed bed column is analyzed using adsorption experiments and modeling study. The characteristics of synthesized materials are determined by several instrumental techniques like BET, XRD, FTIR, and FESEM-EDX. The flow rate, initial concentration of COD and NH3-N, and bed height were optimized to determine the effectiveness of leachate treatment. The linear bed depth service time (BDST) plots equations with a correlation coefficient of greater than 0.98 confirmed the model's accuracy for COD and NH3-N adsorption in column structure. The adsorption process was found to be well predicted by an artificial neural network (ANN) model with a root mean square error of 0.0172 and 0.0167 for COD and NH3-N reduction, respectively. The immobilized adsorbent was regenerated using HCl and was found to be reusable for up to three cycles, promoting material sustainability. This study is aimed to contribute towards SDG 6 and SDG11 by United Nations Sustainable Development Goals.

Photocatalytic-ozonation process in oxytetracycline degradation in aqueous solution: composite characterization, optimization, energy consumption, and by-products

In this research, we synthesized BiOI/NH2-MIL125(Ti) via solvo-thermal method to investigation of oxytetracycline (OTC) degradation in photocatalytic-ozonation process. The results of the XRD, FESEM, EDAX, FTIR, UV–Vis, TEM, XPS, and BET analyzes indicated that the catalyst BiOI/MOF was synthesized with excellent quality. Design of experiment (DOE), ANOVA statistical analysis, interaction of parameters and predicated optimum condition was done based on CCD. The effect of catalyst dose (0.25–0.5 mg/l), pH (4–8), reaction time (30–60 min) and O3 concentration (20–40 mN) at 10 mg/l of OTC on PCO/O3 process was optimized. Based on P-value and F-value coefficients (0.0001, 450.3 respectively) the model of OTC (F-value = 2451.04) and (P-value = 0.0001) coefficients, the model of COD removal was quadratic model. Under optimum condition pH 8.0, CD = 0.34 mg/l, RT = 56 min and O3 concentration = 28.7 mN, 96.2 and 77.2% of OTC and COD removed, respectively. The reduction of TOC was 64.2% in optimal conditions, which is less than the reduction of COD and OTC. The kinetics of reaction followed pseudo-first-order kinetic (R2 = 0.99). Synergistic effect coefficient was 1.31 that indicated ozonation, presence of catalyst and photolysis had a synergistic effect on OTC removal. The stability and reusability of the catalyst in six consecutive operating steps was acceptable and 7% efficiency decreased only. Cations (Mg2+, and Ca2+), SO42− had no influence on performing the process, but other anions, organic scavengers, and nitrogen gas, had an inhibitory effect. Finally, the OTC degradation probably pathway includes direct and indirect oxidation that decarboxylation, hydroxylation, demethylation and were the main mechanism in OTC degradation.

Combination of electrochemically activated persulfate process and electro-coagulation for the treatment of municipal landfill leachate with low biodegradability

To handle complex wastewater with limited biodegradability, hybrid treatment systems are necessary. The current study represents the combined effectiveness of sulfate-radical associated electro-chemical advanced oxidation process (SR-EAOP) and electro-coagulation (EC) for the treatment of stabilized landfill leachate. For SR-EAOP, Pt/Ti was employed as the anode and an iron plate as the cathode; while EC treatment was performed by switching the polarity. Hence, both electrochemical treatment was carried out in single reactor. Initially, the effects of pH, applied voltage, persulfate and Fe2+ dosage, on the performance of SR-EAOP was examined. Sulfate radical was generated in the electrolytic system via cathodic reduction of persulfate (PS) and ferrous (Fe2+) ion activation. Auxiliary processes such as anodic oxidation via Pt/Ti anode and indirect electro-chemical oxidation were also contributed for pollutant degradation. Combined process SR-EAOP followed by EC (SR-EAOP + EC) has better leachate treatment efficacy in comparison with EC + SR-EAOPs. The SR-EAOP + EC based combined treatment mechanism achieved an efficient COD reduction of 88.67% than that of EC + SR – EAOP process (74.51% COD reduction). Characterization studies have been carried out for post-treated dried-sludge using Field Emission scanning electron microscope (FE-SEM) and X-ray powder diffraction (XRD) techniques. The combined process treatment (SR-EAOP + EC) can be applied as pre-treatment for leachate decontamination.

Acoustic cavitation for the process intensification of biological oxidation of CETP effluent containing mainly pharmaceutical compounds: Understanding into effect of parameters and toxicity analysis

The current work investigates the efficacy of acoustic cavitation (AC) based pretreatment as a process intensification method for improving the conventional biological oxidation (BO) treatment of the effluent from common effluent treatment plant (CETP) mainly containing pharmaceutical compounds. The effluent acclimatized with cow dung-based sludge was utilized for the aerobic oxidation with an optimum condition of 1:3 ratio of sludge to effluent and 6 h as duration. COD reduction of 19.58% was achieved with the conventional biological oxidation, which was demonstrated to be improved by incorporating acoustic cavitation-based pretreatment approaches under optimized conditions of 125 W and 70% duty cycle for only AC as well as oxidant loadings as 1000 mg/L for H2O2, 250 mg/L Fe(II) with 1000 mg/L H2O2 for Fenton, 1000 mg/L for KPS and 0.5 L/min for the O3 during the combination approaches. The improved COD reduction after the use of pretreatment approaches followed by the BO of 6 h duration was 29.26%, 72.42%, 85.47%, 45.68% and 69.26% for the AC, AC + H2O2, AC + Fenton, AC + KPS and AC + O3 based approaches respectively. The toxicity assay of the effluent before and after every pretreatment approach using bacterial strains ofStaphylococcus aureusandPseudomonas aeruginosaensured the biodegradability of the treated effluent as no toxic intermediates could be seen. Overall, the present work elucidated the effectiveness of acoustic cavitation-based pretreatment approaches for the improvement of conventional BO of CETP effluent.

Characterization and optimization of Rhodotorula toruloides and Ankistrodesmus falcatus co-culture in palm oil mill effluent for efficient COD removal and lipid production

Palm oil mill effluent (POME) with high COD can be utilized as a growth medium for microbial oil production, enabling simultaneous lipid production and effective green waste management. Thus, this study aimed to investigate the potential of co-cultivation of R. toruloides and A. falcatus to produce lipid and reduce COD in POME. The individual growth profiles of both cultures were assessed in POME and standard media. The cultures were co-cultivated in POME, and their lipid production, biomass growth, and COD removal were monitored. Response surface methodology (RSM) was used to determine the optimal POME concentration, yeast-to-microalgae ratio, and co-cultivation duration for the co-cultivation. The results demonstrated that co-cultivating the yeast and microalga in POME led to a significant increase in COD reduction and remarkable lipid production compared to pure cultures, resulting in fold increases of 2 and 1, respectively. The optimum conditions for achieving optimum COD removal and lipid production were obtained using a POME concentration of 59.88%, a yeast-to-microalgae ratio of 9:25, and a growth duration of 18 days, yielding 72.27% COD reduction, and 0.012 mg/L/d lipid productivity. This study highlights the potential of co-cultivating oleaginous yeast and microalga as a promising strategy for eco-friendly waste management in the oil palm industry and sustainable integrated biofuel production.

Degradation of polyvinylpyrrolidone-coated iron oxide nanoparticles through ozonation: Steric to electrosteric repulsion and electrostatic interactions

Surface degradation followed by aggregation of polyvinylpyrrolidone-coated iron oxide nanoparticles (PVP-IONPs) during ozonation make it possible to remove the toxic NPs from aqueous medium and reduce their environmental hazards. This study investigated the effect of concentration of NPs (50–150 mg/L), colloid pH (4−10), and ozonation time (10–30 min) on aggregates formation. The starting and ozonated NPs were characterized using DLS, XRD, VSM, UV-Vis, FTIR, XPS, SEM, and TEM. The optimal conditions (107.7 mg/L, pH 6.07, and 30 min ozonation) were determined by response surface method (RSM) to achieve maximum values of z-average (3.2 µm) and zeta potential (−6.64 mV). The steric repulsion changed to electrosteric and electrostatic interactions (van der Waals attraction) due to the degradation of the PVP coating, in which the clusters grew to form micrometer-sized aggregates. Irreversibility of NPs aggregation under optimal conditions of ozonation was confirmed by sonication of suspension; although the loose agglomerates formed at early periods were prone to breaking during sonication. A 77% reduction in COD of colloidal PVP-IONPs after ozonation under optimal conditions confirmed the significant degradation of PVP with ozone.

Phycoremediation of Laundry Wastewater Using Chlorella vulgaris (Beijerinck)

A study of the effect laundry wastewater on the microalga Chlorella vulgaris was carried out. The study was carried out using different treatments 0% (control), 5%, 10%, 20%, 30%, 40%, 50% of laundry wastewater. The microalgal growth responses were determined optically using absorbance on spectrophotometer at 750nm. Samples were analyzed for physicochemical parameters such as pH, temperature, total dissolved solids, conductivity, biochemical oxygen demand and chemical oxygen demand using standard methods. Descriptive statistics, inferential (One-way analysis of variance (ANOVA) and post-hoc test Duncan multiple range (DMR) were done using Microsoft excel 2010 and statistical package for social science SPSS 22. The results showed that different concentrations of laundry wastewater stimulated the growth of Chlorella vulgaris with 50% treatment having the highest yield (3.2), followed by 40% treatment (2.7) and the control (0%) had the least yield of 0.6. There was a significant increase in pH and temperature while there was a decrease in total dissolved solids, biochemical oxygen demand, chemical oxygen demand and conductivity. The level of reduction in COD was from 1340mg/L to 364mg/L, which indicated that Chlorella vulgaris has the potential to bioremediate laundry wastewater.

Development of microbial fuel cell for wastewater treatment and electricity generation using domestic wastes

Background: The energy crisis is a growing problem around the world, requiring the creation of alternative energy sources that can generate less carbon dioxide and benefit the ecosystem. Reutilization of wastewater is becoming the emerging energy solution. Wastewater contains a large amount of organic matter that can be oxidized in microbial fuel cells (MFCs) to produce electricity. MFCs use biodegradable materials to create energy in the presence of microorganisms. Methods: Purposive sampling technique was employed to collect samples from critical polluting sources. The samples were certainly maintained in a refrigerator at 4°C. Several mixes for sample were prepared and tested analytically- for physio-chemical and bacteriological characterizations of each substrate status at pre- and post-treatment stages. Electricity generating capacity of MFCs that employing different substrates was investigated experimentally using batch reactors. The cross-sectional methodology was employed to study possible power generation. Results: The maximum voltage output of 118.93, 144.84, and 89.76 mV were produced keeping the resistance unlimited for MFC1 (urine substrate), MFC2 (blackwater substrate), and MFC3 (graywater substrate), respectively. MFC that utilized graywater as a substrate brought the tiniest quantity of electricity; however, it stood the most stable. The highest COD reduction (65.83%) in the process was reported in urine substrate and the highest BOD5 removal (69.18%) was reported in black water substrate. Conclusion: The experimental results provided a promising indication of MFCs viability, providing hope for future power generation and alternative wastewater treatment option in developing countries.

Shear Enhanced Flotation Separation Technology in Winery Wastewater Treatment

The process of wine making is well known to produce large amounts of wastewater with highly variable characteristics. The disposal of untreated winery wastewater is strictly prohibited since it adversely affects the recipient environment. Due to the variability in characteristics of winery wastewater, developing a treatment system which can handle high organic and inorganic loads, especially during the vintage season, is a complex challenge. This study investigated the theory, methodology and implementation of a wastewater treatment technology called shear enhanced flotation separation (SEFS) as a potential primary treatment stage towards the treatment of winery wastewater. Winery effluent was subjected to a coagulation process in a high shear environment, with and without the introduction of air, followed by flocculation. Upon successful optimization of operating parameters, a polymeric-based coagulant AB121 and polyelectrolyte flocculant AB796 yielded the highest reduction in turbidity (95%) with typical values of 630 NTU for the raw wastewater and 25 NTU for the SEFS-treated effluent. A substantial reduction in total suspended solids (97%) was achieved with average raw winery wastewater values of 2275 mg/L compared to the 50 mg/L obtained for the SEFS-treated effluent. Furthermore, a notable reduction (54%) in COD (from 11,250 mg/L to 5220 mg/L) using SEFS technology was achieved.

Sustainable wastewater treatment by RO and hybrid organic polyamide membrane nanofiltration system for clean environment

One of the environmental pollution is happened by the discharge of industrial wastewater that needs to be adequately filtered. Given that the effluent from the leather industry contains high levels of chromium, heavy metals, lipids, and Sulphur, it is one of the wastewater disposals that are most damaging. This experimental study focuses on reverse osmosis and hybrid organic polyimide membrane for nanofiltration for sustainable wastewater treatment. In the RO and organic polyamide Nano-porous membranes, a thin film of polyamide membrane was used for efficient filtration. Taguchi analysis optimized process parameters such as pressure, temperature, pH, and volume reduction factor. The outcome shows an 89% reduction in total wastewater hardness, an 88% reduction in sulfate, and an 89% efficiency reduction in COD. As a result, the proposed technology significantly increased filtration efficiency.

Industrial wastewater treatment using batch recirculation electrocoagulation (BRE) process: Studies on operating parameters

The environmental industry has demonstrated an increasing interest in employing electrocoagulation (EC) process to treat industrial wastewater/effluent for recycling/drinking purposes. An iron (Fe)/aluminum (Al) plate-based batch recirculation electrocoagulation technology for wastewater treatment in the distillery industry is discussed in this work. The impact of different operational parameters, including COD, wastewater pH, current, inter-electrode spacing, combination of electrodes, recirculation flow rate, concentration of electrolytes, and treatment duration on % color, % COD reduction efficiency, and energy consumption was examined. The experimental outcomes demonstrated that, the color removal was 100 %, COD removal was 99.90 %, and energy consumption was 7.73 kWh m−3 for COD of 3600 mg L−1, current of 0.56 Amp, combination of electrodes of Fe/Fe, inter-electrode spacing of 1 cm, wastewater pH of 7, flow rate of 15 L h−1, concentration of electrolytes of 5 g L−1, and treatment time of 180 min, respectively. It was found that, a longer treatment period, higher electrolyte concentrations and current, lower COD concentrations and recirculation flow rates, Fe/Fe electrode pairings, a pH of 7, and a smaller inter-electrode spacing all contributed to increased % COD reduction efficiency. The quantity of solid sludge formed were studied with the help of operational parameters, and the results were reported. Under the optimized process conditions, the wastewater treated can be fully recovered as clean water. As a consequence of this, the results of the experiments have shown that the batch recirculation electrocoagulation process has the potential to be a more promising solution to the problem of eliminating contaminants from wastewater and industrial effluent.

Enhancing anaerobic digestion of automotive paint sludge through biochar addition

The reduction of traditional fuel sources and the unpredictability of the global economy have led to a push for renewable energy alternatives. Waste recycling can significantly reduce greenhouse gas emissions. In this study, the effects of different proportions of biochar on the efficiency of mesophilic anaerobic digestion of automotive paint sludge were investigated over a period of one month. A combination of paint sludge and anaerobic sludge in a ratio of three to one was used, and biochar was added to the anaerobic digestion reactor in two different amounts of 10 and 26 g/l, with a control sample without biochar. The cumulative volume of biogas produced at the end of the one-month experiment was recorded for three samples: the control sample (without biochar), the second sample (with 2 g of biochar), and the third sample (with 5.2 g of biochar). The volumes of biogas produced were 300, 380, and 530 ml, respectively. Additionally, the COD reduction rates were 25%, 33%, and 48%, and the VS decrement rates were 21%, 27%, and 43%, respectively. The findings showed that adding biochar to the anaerobic digestion reactor containing automotive paint sludge increased biogas production. Additionally, gas chromatography results for an optimal sample of biogas extracted from the anaerobic digestion reactor indicated the presence of about 50% methane gas. These results highlight the potential for utilizing biochar in anaerobic digestion processes to improve renewable energy production and waste management.