Maximum Chemical Oxygen Demand Research Articles

Low-cost treatment method for organic matter and nutrients in landfill leachate.

In this study, the ability of low-cost composite adsorbents to treat organic compounds in terms of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) was investigated. The composite adsorbents were composed of washed sea sand (WSS), dewatered alum sludge (DAS), zero-valent iron (ZVI), and granular activated carbon (GAC). The removal efficiency of COD in landfill leachate by a composite adsorbent (composed of WSS (40%), DAS (40%), ZVI (10%), and GAC (10%) in weight) was 79.93 ± 1.95%. The corresponding adsorption capacity was 8.5 mg/g. During batch sorption experiments, the maximum COD removal efficiencies given by DAS, WSS, ZVI, and GAC were 16, 51.3, 42, and 100.0%, respectively. The maximum removal efficiencies of the above composite adsorbent for TN and TP were 84.9 and 97.4%, respectively, and the adsorption capacities were 1.85 and 0.55 mg/g, respectively. The Elovich isotherm model gave the best fit for COD, TN, and TP adsorption. This composite adsorbent can treat more than one contaminant simultaneously. The application of DAS and ZVI to make an efficient adsorbent for wastewater treatment would be a good re-use application for them, which would otherwise be landfilled directly after their generation.

Treatment and prevention of pollutants in the wastewater from a scheelite and fluorite processing plant

Mineral processing wastewater contains high levels of chemical oxygen demand (COD), suspended solids (SS) and heavy metal ions, and its substandard discharge will pose a threat to the ecological environment and human health. In this study, a combined method of coagulation and Fenton oxidation was used to remove pollutants from scheelite and fluorite processing wastewater. The experimental results showed that the overall removal rates of COD, SS, Pb2+ and Zn2+ from the wastewater samples reached 88.41 %, 99.73 %, 99.09 % and 99.31 %, respectively, after stepwise treatment with poly ferric sulfate (PFS) coagulation and Fenton oxidation. The main contributors of COD in the wastewater samples were sodium oleate (NaOL) and benzohydroxamic acid (BHA). The maximum COD removal by PFS coagulation was >90 % for NaOL solution, but <45 % for BHA solution. The COD removal effect of Fenton process on NaOL solution was also better than that of BHA. This indicated that the removal effect of COD was not only related to the experimental conditions but also to the structure of organic compounds. Based on the above research, a monitoring and management system of pollutants was established, and the effective removal of pollutants was confirmed by industrial tests in a plant. This study provides a certain theoretical basis and technical support for the efficient treatment of mineral processing wastewater and is of great significance for the protection of the ecological environment around the mine.

Treatment of debrominated wastewater by electrocoagulation using Mild Steel electrodes

Most process industries produce a large amount of effluent which includes bromine, which is valuable for further use. After the separation of valuable bromine from such industrial wastewater, a sizeable amount of debrominated wastewater (DWW) with a large amount of contaminates is left over. Considering the chemical oxygen demand (COD), total dissolved solid (TDS), turbidity, and color parameters, DWW cannot be discharged directly to water bodies. It mandatorily requires to be treated for the removal of various contaminants. Wastewater treatment includes traditional processes like chemical treatment, biological treatment, and physical treatment. Although they have been effective, each process has its limitations and can be energy-intensive and costly. Electrocoagulation (EC) is a highly effective treatment process that has been widely used to treat complex industrial wastewater. To treat DWW, The EC treatment was conducted in a 2-liter batch reactor using Mild Steel electrodes (MS) arranged as four parallel plates. After the treatment achieved maximum color, turbidity, COD, and TDS removal of 71.91%,100%, 36.36%, and 24.95%, respectively, at optimal current intensity 2 A, pH 9, and electrode spacing 1.5 cm. Energy consumption of 3 Wh/L was observed as a maximum at pH 11 and a maximum total metal consumption (TMC) of 2.11 g/L at pH 7. The highest foam and residue weight was 6.81 kg/m3 at pH 9 and the highest sedimentation rate was found at pH 11. Electrocoagulation treatment time was also examined for each parameter such as pH, electrode gap, and current intensity.

Evaluation of the Different Fractions of Organic Matter in an Electrochemical Treatment System Applied to Stabilized Leachates from the Bordo Poniente Landfill in Mexico City

The presence of refractory compounds in stabilized leachates makes treatment complex. In leachate treatment systems, the lack of data on the characterization of leachates and effluents makes it difficult to track and explain the evolution of organic matter. In this study, the fractionation of chemical oxygen demand (COD) and humic substances, including humic acids (HA) and fulvic acids (FA), in addition to the application of spectroscopic techniques (Fourier transform infrared and ultraviolet–visible spectroscopy), were used to solve this data gap. A treatment system was proposed: electro-coagulation (EC) and electro-oxidation (EO). Optimal conditions (maximum COD removal) were EC, I: 4.3 A, stirring: 120 revolutions per minute, and pH: 7; EO, added NaCl: 1.0 g L−1, distance between electrodes: 0.75 cm, I: 2 A, and pH: 7. Under optimal conditions COD, HA, and FA % removals were achieved: EC: 64, 69, and 63; EO: 83, 40, and 55; respectively. In EC, the % of biodegradable COD increased from 26 to 39 and in EO it increased from 39 to 58. The biodegradability index increased from 0.094 to 0.26 with EC and reached 0.46 with EO. The generated data allowed us to establish the transformations of organic matter in the process, which was useful for understanding the processes and functioning as a tool for improving treatment systems.

Insight into the pollution characteristics of road and roof runoff in Changsha, China

Non-point source pollution from rainwater runoff presents a serious challenge for urban water management in many cities undergoing urbanization and experiencing climate change. To alleviate water resource conflicts in Changsha, China, this study comprehensively evaluated the pollution characteristics and first flush effect (FFE) of runoff from asphalt roads and colored steel plate roofs under seven rainfall events in April-May 2022. The runoff was collected and purified using bioretention ponds. The results showed that the peak runoff pollutant concentrations occurred within the first 20min of runoff generation and then decreased to relatively stable levels, with maximum total suspended solids (TSS) concentration and chemical oxygen demand (CODCr) reaching 873.5 and 207.32mg/L, respectively, for road runoff and 162 and 73.31mg/L for roof runoff, respectively. The main pollutants were TSS and CODCr, followed by ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3--N), total phosphorus (TP), and nitrite nitrogen (NO2--N). Concentrations of pollutants and FFE for roof runoff were lower than those for road runoff. Road runoff had a more obvious FFE for TP and NH4+-N, whereas the roof runoff showed the presence of TP and NO3--N. An important implication is that treating the first 30% of surface runoff from rainfall events with long antecedent dry days or high rainfall amounts is necessary to improve water quality before discharge or utilization. The study also found that road and roof runoff, after treatment with bioretention ponds, exhibit good water quality, thus, allowing their use as reclaimed water or for miscellaneous purposes in urban areas. Overall, this study provides useful information for designing management measures to mitigate runoff pollution and reuse in Changsha.

Optimization of synthetic domestic wastewater treatment performance in anoxic/aerobic sequencing batch reactor with zeolite addition

In this study, treatment performance was investigated based on chemical oxygen demand (COD), ammonium nitrogen (NH4 +-N), total inorganic nitrogen (TIN) and simultaneous nitrification and denitrification (SND) parameters in a zeolite-added anoxic/aerobic sequencing batch reactor. Response surface methodology (RSM) was used to model treatment performance, determine the impact of operating conditions, and optimize them. The effect of zeolite size, dosage and COD/NH4 +-N (C/N) ratio as operating parameters were evaluated in the central composite design (CCD). Variance analysis (ANOVA) results of the quadratic model, high coefficients of determination and low values of the root mean square error (RMSE) for dependent variables indicated the validity of the model in predicting experimental results. The desirability function showed that optimum conditions were 0.80 mm for zeolite size, 3.05 g/L for zeolite dosage and 9.8 for C/N. Under these conditions, the maximum COD, NH4 +-N, TIN removal efficiencies and SND efficiency were 92.85%, 93.3%, 77.33% and 82.96%, respectively. The results of the study showed that the most effective independent variable on dependent variables was the C/N ratio.

Synergistic effect of TiO2 nanostructured cathode in microbial fuel cell for bioelectricity enhancement

Nano-bedecking of electrode with nanoparticles is an effective method to improve power generation of microbial fuel cells (MFCs). In this study, different concentrations (0.25 mg cm−2, 0.50 mg cm−2, 0.75 mg cm−2 and 1.0 mg cm−2) of TiO2 nanoparticles of size 10–25 nm were overlaid on the carbon cloth (CC) using spray pyrolysis technique and used as catalytic cathode in a dual-chambered microbial fuel cell treating distillery wastewater. Results evidenced that TiO2 nanoparticles modified cathode increased the power generation and recorded a highest power and current density of 162.5 ± 2 mW m−2 and 1.4 ± 0.005 A m−2, respectively. Carbon cloth coated with 0.50 mg cm−2 TiO2 nanoparticles showed 2.8 and 7.3 times higher current and power density as compared to uncoated cathode. MFC operated at a hydraulic retention time (HRT) and organic loading rate (OLR) of 72 h and 59.2 g COD L−1 d−1 showed a maximum chemical oxygen demand (COD) removal of 72.3% which was 15.3% higher than the control MFC. Likewise, the coulombic efficiency of control and modified MFC was 33% and 44%, respectively. The maximum NO3−- N, NO2−- N and NH4+- N removal efficiency of 77.3%, 49.9% and 59.4% were observed for TiO2 nanoparticles modified electrode which was 19.3%, 11.4% and 10.5% higher than control. TiO2 modified cathode was effective in enhancing the bioelectricity generation in MFCs.

Parametric optimization of additive manufactured biocarrier submerged in sequencing batch reactor for domestic wastewater treatment

The high nutrient concentration in domestic wastewater effluent can endanger the aquatic life via eutrophication. Thus, research have been carried out to prevent harm to aquatic life. In regard biofilm reactors have been successful by far with few limitations. Bio-carrier fabrication of desired shape is one of the limitations. Recently, the invention of additive manufacturing (AM) of object made it feasible to fabricate the desired shape. In this study additive manufactured bio‒carrier (AMB) was printed using AM technique, with high surface area to volume ratio as well as density higher than water. The submerged attach growth sequencing batch biofilm reactor (SAGSBBR) for organic and nutrient removal from domestic wastewater (DWW) was conducted to determine the optimum bio‒carrier filling ratio (FR) and cycle time (CT) by using response surface methodology (RSM) with CT ranging between 12 h and 24 h and FR ranging between 0 and 20%. The maximum chemical oxygen demand (COD), ammonia-nitrogen (NH4+‒N), and total phosphorus (TP) removal was 96.8 mg/L, 93.32 mg/L, and 88.89 mg/L respectively, which was achieved in submerged attached growth sequential biofilm batch reactor with 10% FR (SAGSBBR‒10). The optimization study determined the optimal solution of CT and FR to be 17.07 h and 12.38% respectively, with desirability of 0.987. The predicted mean of responses for the optimal solution were 96.64%, 94.40% and 89.94% for COD removal, NH4+‒N removal and TP removal, respectively. The rate of biomass attachment at the first stage in SAGSBBR‒10 and SAGSBBR‒20 was about 11.39 mg/carrier.d and 8.64 mg/carrier.d, whereas the highest accumulation achieved was 98.27 mg/carrier and 80.15 mg/carrier respectively. Thus, this study can assist us to achieve sustainable development goal (SDG) 6.

Optimized Artificial Intelligent Model to Boost the Efficiency of Saline Wastewater Treatment Based on Hunger Games Search Algorithm and ANFIS

Chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies of saline wastewater treatment indicate the efficiency of the electrochemical oxidation process. Therefore, the main target of this paper is to simultaneously increase COD and TOC removal efficiencies using artificial intelligence and modern optimization. Firstly, an accurate model based on ANFIS was established to simulate the electrochemical oxidation process in terms of reaction time, pH, salt concentration, and DC applied voltage. Compared with ANOVA, thanks to ANFIS modelling, the RMSE values are decreased by 84% and 86%, respectively, for COD and TOC models. Additionally, the coefficient of determination values increased by 3.26% and 7.87% for COD and TOC models, respectively. Secondly, the optimal reaction time values, pH, salt concentration, and applied voltage were determined using the hunger games search algorithm (HGSA). To prove the effectiveness of the HGSA, a comparison with a slime mold algorithm, sine cosine algorithm, and Harris’s hawks optimization was conducted. The optimal values were found at a pH of 8, a reaction time of 36.6 min, a salt concentration of 29.7 g/L, and a DC applied voltage of 9 V. Under this condition, the maximum COD and TOC removal values were 97.6% and 69.4%, respectively. The overall efficiency increased from 76.75% to 83.5% (increased by 6.75%).

Improved Biohythane Production from Rice Straw in an Integrated Anaerobic Bioreactor under Thermophilic Conditions

This study evaluated the feasibility of continuous biohythane production from rice straw (RS) using an integrated anaerobic bioreactor (IABR) at thermophilic conditions. NaOH/Urea solution was employed as a pretreatment method to enhance and improve biohythane production. Results showed that the maximum specific biohythane yield was 612.5 mL/g VS, including 104.1 mL/g VS for H2 and 508.4 mL/g VS for CH4, which was 31.3% higher than the control RS operation stage. The maximum total chemical oxygen demand (COD) removal stabilized at about 86.8%. COD distribution results indicated that 2% of the total COD (in the feed) was converted into H2, 85.4% was converted to CH4, and 12.6% was retained in the effluent. Furthermore, carbon distribution analysis demonstrated that H2 production only diverted a small part of carbon, and most of the carbon flowed to the CH4 fermentation process. Upon further energy conversion analysis, the maximum value was 166.7%, 31.7 times and 12.8% higher than a single H2 and CH4 production process. This study provides a new perspective on lignocellulose-to-biofuel recovery.

Purification efficiency of Pyropia-processing wastewater and microalgal biomass production by the combination of Chlorella sp. C2 cultivated at different culture temperatures and chitosan

To elucidate the impacts of culture temperature on nutrient removal efficiency of Pyropia-processing wastewater (PPW) and microalgal biomass production, Chlorella sp. C2 was employed and cultivated in raw PPW under different temperatures. Results showed that, after incubating for 7 days, higher biomass (0.50 g/L) and total lipids (21.84 %) were attained at 35 °C. The maximal chemical oxygen demand (COD), phycobiliprotein, total nitrogen and total phosphorus removal rates were observed at 30–35 °C and separately reached 62.41 %, 92.61 %, 92.19 % and 98.33 %. Interestingly, COD removal efficiencies of Chlorella cells, cultivated for 3, 5 and 7 days at 30–35 °C, 15–25 °C and 10 °C respectively, could reach >75 % with assistance from 60–80 mg/L chitosan. Meanwhile, the clarification efficiency of chitosan on algal cells reached >95 %. It suggests that Chlorella strain cultured at altered temperatures could efficiently remove PPW nutrients assisted by moderate chitosan, simultaneously achieving the rapid harvest of microalgae.

Osmotic Microbial Fuel Cell for Groundwater Softening, Defluoridation, Salinity Reduction, and Energy Production

Despite being the major source of freshwater, groundwater is contaminated with hardness, fluorides, salinity, and so on, and hence, its application for domestic/industrial purposes is severely limited. Existing remediation technologies demand both chemical and energy inputs. Therefore, in this study, an osmotic microbial fuel cell (OsMFC) was developed as an energy-positive and chemical-free technology to achieve simultaneous groundwater softening, defluoridation, salinity reduction, and bioelectricity production. High-quality water was extracted from wastewater in the OsMFC and was applied to reduce groundwater contaminants by dilution. The effects of feed/draw solution (FS/DS) ratio, membrane area, reactor volume, and time on water flux, energy production, and reduction efficiencies of Na+, Cl−, total hardness (TH), and F− were studied. The increase in FS/DS ratio and membrane area resulted in considerable improvement in the water flux, energy production, and contaminant reduction. However, an increase in the reactor volume had little effect on the overall performance. A maximum water flux of 9.81 litres per square meter per hour [LMH (L/m2/h)] with reduction efficiencies of 75.81%, 76.27%, 72.22%, and 65.76% for Na+, Cl−, TH, and F−, respectively, were obtained with an extended operating time of 168 h. Maximum chemical oxygen demand (COD) removal of 86.6% and current density of 0.34 mA/m3 were achieved simultaneously. The study demonstrated a sustainable approach of extracting high-quality water from wastewater and its application in groundwater remediation along with energy production.

Treating mechanical washing wastewater with iron-in-oil characteristics by changing the fate of iron.

The mechanical washing wastewater contained a large amount of oil, and the iron wrapped in the oil was slowly released into water. This caused the effluent quality to fluctuate, causing common polymeric aluminum chloride (PAC) to ineffectively remove the water-in-oil. The method uses Ca2+ to demulsify and ClOx- to destroy the water-in-oil structure, which releases Fe from the oil droplets. The active oxygen produced by NaClOx further converts Fe2+ into Fe3+ and then combines with NaOH to form Fe(OH)3-flocs core, which improves the flocculation efficiency of PAC. The optimal ratio was approximately 400 μL of NaClOx, 200 μL of 1 mol L-1 CaO, and 12 mL of 12.8 g L-1 PAC. The oil removal rate reached 99.88% and the residue density was 178.42 mg L-1. The maximum Fe and chemical oxygen demand (COD) removal rates were close to 49.2 and 99.89%, respectively. In field applications, wastewater should be acidified first, and acidification oxidation is more effective than direct oxidation. In short, a novel way for treating mechanically washed wastewater with iron-in-oil characteristics by changing the environmental fate of iron is provided.

A combined bio-system to improve effluent water quality from sewage wastewater plants for agricultural reuse

AbstractA continuous lab-scale integrated bio-system was conducted to treat sewage wastewater from Abu-Rawash wastewater treatment plant (WWTP). The bio-system showed high efficiency in removing chemical oxygen demand (COD), biological oxygen demand (BOD5), and total suspended solids (TSS). The experimental analysis results indicated that the maximum COD removal and methane yields were 97.6 and 13.74 mmol CH4/Kg COD at a hydraulic retention time (HRT) of 6 h, respectively. Zn, Mn, and Fe were removed at a high rate of up to 96.6%. The sponge bio-carriers have improved overall treatment performance and substantially improved mixed liquor volatile suspended solids/mixed liquor suspended solids (MLVSS/MLSS) ratio at an appreciated range, and the total pathogenic organisms were removed up to 99.8% in the second stage. Because the innovative bio-system enables a rapid startup process, is simple to use, and is inexpensive, it can provide an economically feasible alternative for wastewater management and could be extended to full-scale applications for agricultural purposes.

Heterogeneous electro-Fenton treatment of coking wastewater using Fe/AC/Ni cathode: optimization of electrode and reactor organic loading

ABSTRACT A self-developed iron-loaded activated carbon-based nickel foam electrode (Fe/AC/Ni cathode) was used to construct electro-Fenton reaction system to treat coking wastewater. To meet the gap between laboratory beaker experiments and field trials for practical applications, we proposed and validated a method for obtaining organic loads, the essential parameters used in the design of electrochemical systems for wastewater treatment. The three influencing factors most relevant to organic loading, the effective surface area of cathode, chemical oxygen demand (COD) concentration of influent, and treatment time, were selected and investigated for their effects on the COD removal rate of coking wastewater by single-factor experiments and further optimized by response surface method. The appropriate electrode area load (La) and reactor volume load (Lv) were calculated by their corresponding intrinsic relationships with the three factors. The optimum application conditions were effective surface area of cathode 28.5 cm2, COD concentration of influent 1.76 kg·m−3, and treatment time 160.43 min. Under these conditions, the maximum COD removal rate was 98.51%. The La and Lv were 8.905 mgCOD·cm−2·h−1 and 0.634 kgCOD·m−3·h−1, respectively. The characterization experiment results showed that the Fe/AC/Ni cathode had a significant effect on the treatment of refractory organic contaminants in coking wastewater.

Study of novel Ti/nanoTiO2-CuO electrode preparation for electrocatalytic degradation of drug pollutant from aqueous solution

The main aim of this study is to prepare a novel electrode through the Ti/nanoTiO2 electrode modification by the introduction of CuO nanoparticles using the electrophoretic deposition (EPD) technique. Field emission scanning electron microscope-energy dispersive spectrometer (FESEM-EDX), X-ray diffraction (XRD), linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chrono-potentiometry (CP), and chrono-amperometry (CA) analyses were used to characterize the surface and electrochemical properties of the Ti/nanoTiO2-CuO electrode, respectively. According to the performed analyses, superior results were seen which confirmed the improved charge transfer rate, electrical conductivity, stability, and electro-catalytic activity of the novel Ti/nanoTiO2-CuO electrode. Electrochemical removal of the Ciprofloxacin (CIP) as a model pollutant was carried out to evaluate the electro-catalytic performance of the novel prepared electrode. Furthermore, the important operational parameters in the electrochemical removal process including pH, current, reaction time, and electrolyte concentration were modeled and optimized by central composite design. Under the optimal conditions, the maximum CIP removal and chemical oxygen demand (COD) efficiencies were 85.91% and 81.25%, respectively. The reusability test indicated that the prepared electrode had relatively good stability. Ultimately, according to the results, the Ti/nanoTiO2-CuO electrode can be employed as a promising anode in the electro-catalytic removal of drug pollutants.

Enhanced Degradation of the Substrate Using Modified Upflow Anaerobic Sludge Blanket Reactor–Static Granular Bed Reactor Series with Varying Hydraulic Retention Time at Lab Scale

The performance of a modified upflow anaerobic sludge blanket (MUASB) reactor with a modified three-phase separator and a rope matrix, combined with SGBR in series was analyzed for the treatment of synthetic wastewater. The performance of the reactor series in terms of chemical oxygen demand (COD) removal was evaluated by varying the operational hydraulic retention times (HRT) from 12 to 30 h. The optimum HRT for the reactor series was found to be 24 h, with a corresponding organic loading rate (OLR) of 8 kg COD/m3/day. The maximum overall COD removal of the reactor series of 98.75% ±0.62% was obtained with the corresponding overall biogas production of 0.339%±0.01 m3/kg CODdigested. The reactor series was found to be stable during the operational period in terms of volatile fatty acids (VFAs)/alkalinity ratio. The analytical hierarchy process was used for choosing a better treatment option among the alternatives based on the selected criteria. MUASB–static granular bed reactor (SGBR) series was found to be superior to the MUASB and the SGBR individually based on COD removal. The payback period for the reactor series was calculated to be 8 years (approximately). The MUASB-SGBR series was found to be robust, stable, and economical, with better performance in terms of COD removal.

Removal of pollutants from wastewater using activated carbon from durian peel

The efforts in reducing food waste can lead to better water management with less land required for food production and indirectly having a positive impact on the livelihoods and the environment. In order to support the practice of reducing food waste in Brunei Darussalam, one must find ways to recycle or reuse them, particularly waste generated from fruit peels. This paper investigates the feasibility of utilising Durian (Durio zibethinus) rinds to remove pollutants in wastewater, namely Chemical Oxygen Demand (COD), and Nitrates by the process called adsorption. Durian is a local fruit and has high consumption in the country. Hence, it produces a large amount of waste, particularly in the form of peels or rinds. In the present research, the fruit peels are treated by dehydration and carbonisation method prior to utilisation. The variable parameters will be investigated such as the effect on particle size, adsorbent dosage, pH, contact time, and agitation. The maximum COD removal percentage was found to be 68.2 % with an adsorption capacity of 690 mg/g. Overall, carbonised samples gave a better outcome than dehydrated samples. Possibly due to the presence of a unique pore structure in carbonised samples that allows organic matter to be adsorbed on the surface.

Electrochemical degradation of ofloxacin using PbO2/Pb-based lead acid battery electrode: Parametric optimization and kinetics study

In this study, PbO2/Pb-based electrode used in commercial lead-acid battery was applied for electrochemical oxidation (ECO) of ofloxacin (OFX) in aqueous phase. Surface topography of PbO2/Pb electrode material was analysed to access surface morphology composed of Pb and oxygen elements of PbO2 through scanning electron microscopy analysis and energy dispersive X-ray analysis. Electrochemical characterization like linear sweep voltammetry analysis, oxygen evolution potential determined as 1.25 V for PbO2/Pb electrode. A high oxidation peak current obtained in cyclic voltammetry analysis suggest that oxidation of OFX with help of produced hydroxyl (●OH) reactive species. Parametric optimization of various process parameters in ECO process was conducted to determine maximum efficacy of process. Maximum OFX removal (85 %) was obtained under the optimum conditions of (initial concentration of OFX:100 ppm, current density: 50 mA/cm2, Na2SO4 electrolyte concentration: 0.1 M Na2SO4 and pH:4). Maximum Chemical oxygen demand (COD) removal (65 %) is obtained when 18 kWh (kg COD removed) −1 of electrical energy was used in ECO process for OFX degradation. Reusability test conducted for used PbO2/Pb electrode indicates that the electrode is stable and can be used repeatedly up to 5 repeated cycles with a minimum 20 % loss in removal %.

Influence of co-substrate existence, temperature, pH, and salt concentration on phenol removal, desalination, and power generation using microbial desalination cells

Microbial desalination cells (MDCs) exhibited an economical value with large promises as a useful desalination treatment solution. MDCs threefold applications to efficiently treat wastewater and to produce electricity and simultaneously accomplish desalination were investigated in this work. The study examined the influence of various performance parameters including co-substrate, temperature, pH, and salt concentrations on the response of three-chamber MDCs with respect to energy recovery and contaminant removal (Phenol). The system evaluation criteria encompassed chemical oxygen demand (COD), phenol removal efficiency, Coulombic efficiency, desalination efficiency, and other system parameters such as voltage generation and power density. The maximum COD and phenol removal efficiencies obtained at temperature = 37 °C, pH = 7, and salt concentration = 10,000 ppm, were 80% and 74%, respectively. The maximum Coulombic efficiency was 5.3% and was observed at temperature = 18 °C, pH = 7, and salt concentration = 10,000 ppm. The results show that the presence of a co-substrate improved power density; the maximum power density obtained was 52.9 mW/m2. The principal component analysis elucidated the impact of pH on COD and phenol removal rates. With our findings confirmed trends in the improvement of the voltage generation, COD and phenol removal efficiencies with the addition of a co-substrate, the temperature and pH increase.