Residual Chemical Oxygen Demand Research Articles

Application of combined hydrodynamic cavitation and Fenton reagent for COD reduction of cellulosic fiber industry effluents

The present work demonstrates the implementation of combined approach of hydrodynamic cavitation reactor and Fenton oxidation process for the treatment of three cellulosic fiber (CF) industry effluent streams using pilot scale reactor with operation at 500 L developed at an industrial site. In order to assess the techno-economic viability of the combined hydrodynamic cavitation (HC) and Fenton oxidation process, various sets of experimental runs were carried out. Effect of type of treatment approach, one step and stepwise addition of oxidants, number of cavitation passes, and finally the type of effluent varying in terms of initial chemical oxygen demand (COD) on the efficacy of treatment were studied. Based on the results, HC + Fenton oxidation scheme was demonstrated to be a viable option for the treatment of CF industry effluent streams. HC + Fenton treatment rapidly reduced COD, achieving almost 90 % reduction in just 10 min, highlighting its efficiency in industrial wastewater treatment. The treatment achieved substantial reduction in residual COD levels with actual value as up to 1000 mg/L COD in effluent-I, up to 150 mg/L COD in effluent-II, and up to 100 mg/L COD in effluent-III. The study also explored the operating cost expenditure (Opex) of the proposed system required to demonstrate it at a commercial level, including the cost of chemicals and electricity. The COD reduction cost evaluated were INR 140–230/kg COD depending on the effluent. The main highlight of the article is the practical demonstration at the manufacturing unit including the operating cost calculations.

Analysis of particle size distribution of organic carbon for landfill leachate—implications for sustainable treatment

AbstractBACKGROUNDLandfill leachate has a complex composition requiring experimental support to formulate a sustainable treatment strategy. This study utilized the particle size distribution (PSD) of the chemical oxygen demand (COD) content to assess the profile of biodegradable and inert COD fractions; it also emphasized the functions and benefits of ultrafiltration and nanofiltration modules coupled to an activated sludge process. The evaluation profited from the field data of a landfill site in Istanbul, where the leachate was actually treated in a membrane bioreactor (MBR) plant.RESULTSCOD and total nitrogen levels fluctuated between 10 100–31 200 mg L−1 and 1150–2800 mg L−1, respectively. PSD analysis for COD, conducted at two extremes, displayed similar results, where the majority of the COD was observed to accumulate at the low extremity of the particle size, 70–72% below 2 nm. Therefore, direct membrane filtration of leachate yielded low COD removals that were limited to 9% with ultrafiltration and to 31–35% with nanofiltration. COD fractionation indicated a ratio of 5% for the inert COD in leachate. The permeate COD of ultrafiltration in the existing plant was 2000 mg L−1, much higher than the inert fraction ratio, which was further reduced to 266 mg L−1 by nanofiltration.CONCLUSIONPSD analysis was an integral complement of respirometry for establishing the size‐biodegradation relationships of different COD fractions. It located the majority of soluble COD fractions below 0.55 nm, thus implying the necessity of a biological process. PSD also identified the generation of soluble residual metabolic products, indicating that residual COD escaping treatment would be equally significant to the removal potential of the biodegradable substrate. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Bioaugmentation Potential Investigation Using a Phenol Affinity Analysis of Three Acinetobacter Strains in a Multi-Carbon-Source Condition

Bioaugmentation potential and phenol substrate affinity in a multi-carbon-source condition for three Acinetobacter strains (Acinetobacter towneri CFII-87, Acinetobacter johnsonii CFII-99A and Acinetobacter sp. CFII-98) were demonstrated. First, the phenol biodegradation ability of the strains was analyzed in batch experiments with phenol as the sole carbon source. All strains degraded phenol at 100 and 500 mg·L−1 initial concentrations; the maximum specific growth rates were 0.59 and 0.30 d−1 for A. towneri CFII-87, 0.50 and 0.20 d−1 for A. johnsonii CFII-99A, and 0.64 and 0.29 d−1 for A. sp. CFII-98, respectively. For the two tested phenol concentrations, no lag phase was observed for the A. towneri CFII-87 strain, A. sp. CFII-98 presented 4 h and 8 h lag phase, while A. johnsonii CFII-99A presented 3 h and 12 h lag phases. Phenol carbon source dependency of the strains was tested in a multi-carbon-source condition (on phenol-rich synthetic wastewater), both for individual strains and for a consortium prepared as an equal mixture of the three strains. The strains A. towneri CFII-87 and A. sp. CFII-98 and the consortia degraded phenol in 16 h while there was no other significant carbon source consumption during the 48 h trial, as shown by the constant non-phenolic residual chemical oxygen demand (COD) and volatile suspended solids (VSS) concentration after the depletion of phenol. The strain A. johnsonii CFII-99A, however, consumed phenol within 24 h and a further decrease in non-phenolic COD and increase in biomass was also observed upon the depletion of phenol. The highest specific phenol removal rate of 282.11 mg phenol·g VSS∙h−1 was observed in the case of the strain A. towneri CFII-87, followed by A. sp. CFII-98, the consortium and A. johnsonii CFII-99A with 178.84, 146.76 and 141.01 mg phenol·g VSS∙h−1, respectively. Two bacterial strains (A. towneri CFII-87, A. sp. CFII-98) presented a strong affinity to phenol, utilizing it as a primary carbon source, and thus, their use in the bioaugmentation of wastewater bioreactors indicated the viable potential to increase the phenol removal rate of these systems.

Sustainable and optimized values for municipal wastewater: The removal of biological oxygen demand and chemical oxygen demand by various levels of geranular activated carbon- and genetic algorithm-based simulation

Municipal wastewater treatment in Mashhad, Iran, became increasingly concerned with removing hazardous organic matter. Granular activated carbon (GAC) units downstream are necessary to minimize chemical oxygen demand (COD) and biological oxygen demand (BOD) concentrations by 80–94% to meet effluent treatment; secondary treatment from municipal wastewater only reduces 47% of residual COD and BOD. This study analyzes different types of GAC for COD and BOD adsorption at different contact times and dosages. The dosage of GACs is 0.15, 0.2, and 0.25, with a surface area of 644.5 m2/g and a suitable size of 14.89 nm. Using and genetic algorithms-artificial neural networks (GA-ANNs), sustainable and optimization values are determined for municipal wastewater. Despite that, it can find solutions to difficult or impossible problems using traditional methods. Another advantage is that GA-ANN can be used to solve problems that have multiple objectives or constraints. They can be used either in conjunction with the biological process or as a tertiary stage after the advanced wastewater treatment process. GAC = 0.25 also confirmed the effectiveness of COD and BOD removal, removing 91% and 93%, respectively.

Sodium hydroxide or tetramethylammonium hydroxide modified corncob combined with biodegradable polymers to prepare slow-release carbon source for wastewater denitrification

This study proposed a method to improve the bioavailability of artificially prepared carbon sources for the purpose of wastewater denitrification. This carbon source (named SPC) was prepared by mixing corncobs with poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHBV), where the corncobs were pretreated by NaOH or TMAOH. The results of compositional analysis and FTIR showed that both NaOH and TMAOH degraded lignin, hemicellulose and their connection bonds in corncob, thus increased the cellulose content from 39% to 53% and 55%, respectively. The cumulative carbon release from SPC was about 9.3 mg/g and was consistent with both the first-order kinetic and Ritger-Peppas equation. The released organic matters contained low concentration of refractory components. Correspondingly, it showed excellent denitrification performance in simulated wastewater, and the total nitrogen (TN) removal rate was above 95% (influent NO3−-N was 40 mg/L) and effluent residual chemical oxygen demand (COD) was less than 50 mg/L.

Feasibility of Bio-Coagulation Dewatering Followed by Bio-Oxidation Process for Treating Swine Wastewater.

The unsatisfactory performance of the conventional swine wastewater treatment is drawing increasing attention due to the large amount of refractory chemical oxygen demand (COD), nitrogen, and phosphorus attached to the suspended solids (SS). In this study, for the first time, a novel process based on bio-coagulation dewatering followed by a bio-oxidation (BDBO) system was developed to treat swine wastewater containing high-strength SS, COD, TN, and TP. Firstly, after the bio-coagulation process, the removal efficiencies of SS, COD, NH3-N, and TP reached as high as 99.94%, 98.09%, 61.19%, and 99.92%, respectively. Secondly, the filtrate of the bio-coagulation dewatering process was introduced into the subsequent bio-oxidation process, in which the residual COD and NH3-N were further biodegraded in a sequence batch reactor. In addition, the dewatering performance of the concentrated swine slurry was substantially improved, with the specific resistance to filtration decreasing from 17.0 × 1012 to 0.3 × 1012 m/kg. Moreover, the concentrated swine slurry was pressed and filtered into a semi-dry cake after pilot-scale bio-coagulation dewatering treatment. Finally, the concentrations of COD and NH3-N in the effluent after the BDBO process, ranging between 150-170 mg/L and 75-90 mg/L, met the relevant discharge standard. Compared to traditional treatments, the BDBO system has excellent large-scale potential for improving the treatment efficiency, shortening the operation period, and reducing the processing costs, and is emerging as a cost-effective alternative for the treatment of wastewater containing high concentrations of SS, COD, TN, and TP.

Efficient removal of tannins from anaerobically-treated palm oil mill effluent using protein-tannin complexation in conjunction with electrocoagulation

Despite the significant removal of chemical oxygen demand (COD) by anaerobic digestion, anaerobically-treated palm oil mill effluent (POME) still contains tannins and other phenolic compounds, resulting in residual COD and a brownish color. In this study, we investigated the removal of tannins from anaerobically treated POME using protein-tannin complexation in conjunction with electrocoagulation. The amino acid composition of the protein, aqueous pH, and protein: tannin ratios were found to be important parameters affecting the tannin removal efficiency. Pig blood protein was superior to casein protein in removing tannins, possibly because it had aspartic acid as the major amino acid component. At an optimal condition with a pig blood protein: tannin ratio of 0.33 (w/w), a current density of 30 mA/cm2, pH 5, and an electrolysis time of 10 min, the removals of tannins, COD, and color were 93%, 96%, and 97%, respectively.

Implementation of FeSO4·H2O as an Eco-Friendly Coagulant for the Elimination of Organic Pollutants from Tertiary Palm Oil Mill Effluent: Process Optimization, Kinetics, and Thermodynamics Studies

The biologically treated palm oil mill effluent (POME) urges further treatment to minimize the residual pollutant concentration for safe discharge in the nearest watercourse. In the present study, the post-treatment of biologically treated POME was conducted using ferrous sulfate monohydrate (FeSO4·H2O) as a coagulant. The influence of the FeSO4·H2O coagulation of POME was determined on the elimination of biochemical oxygen demand (BOD), suspended solids (SS), and chemical oxygen demand (COD) with varying flocculation time (min), slow mixing speed (rpm), coagulant doses (g/L) and pH. The FeSO4·H2O coagulation–flocculation experimental conditions were designed following the central composite design (CCD) of experiments and optimized by employing response surface methodology (RSM) based on the optimal SS, COD, and BOD elimination from POME. The maximum BOD, SS, and COD elimination achieved were about 96%, 97%, and 98%, respectively, at the optimized experimental condition. The surface morphology and elemental composition analyses of raw FeSO4·H2O and sludge generated after coagulation revealed that the FeSO4·H2O effectively removed the colloidal and suspended particles from POME. The well-fitted kinetic model equation was the pseudo-second-order kinetic equation to describe the FeSO4·H2O coagulation–flocculation behavior. The thermodynamics properties analyses revealed that the FeSO4·H2O coagulation of POME was non-spontaneous and endothermic. The residual SS, COD, and BOD in treated POME were determined to be 28.27 ± 5 mg/L, 147 ± 3 mg/L, and 6.36 ± 0.5 mg/L, respectively, lower the recommended discharged limits as reported by the Department of Environment (DoE), Malaysia.

Integration of coagulation-flocculation process for improved solid–liquid separation of anaerobically treated textile effluent

ABSTRACT Anaerobic process is a promising technique for textile effluent treatment. However, poor solid–liquid separation and residual chemical oxygen demand (COD) in the treated effluent limit its scope for industrial applications. The study analyzed the nature of suspended microbial biomass in the anaerobically treated effluent and further targeted its feasible separation process. The size of the majority of suspended biomass (82%) particles ranged from 500 to 1000 nm. The suspended biomass showed 37.13% hydrophobicity and −15.4 mV zeta potential. The optimization of the coagulation-flocculation (CF) process showed 93% turbidity removal at 400 mg/L of alum, 8 mg/L of a cationic polymer and acidic pH 4, through one variable at a time approach. The optimized results using Central Composite Design (CCD) were experimentally validated, and 97% turbidity removal was recorded at 400 mg/L alum concentration, 12 mg/L of the cationic polymer, and pH 3.2. The results obtained were statistically significant, with a high regression coefficient (R2 = 0.97) at 95% confidence limits. The final treated effluent after CF showed 67% COD removal (from 862 ± 40 to 280 ± 14 mg/L) with 83% color removal (from 740 to 124 Hazen). Hence, the integration of the CF process with the anaerobic process could be a promising approach for textile effluent treatment.

Fenton process for the treatment of wastewater effluent from the edible oil industry.

The present study intends to investigate the performance of the Fenton reaction as one of the most efficient (AOPs) in a batch mode for treating wastewater effluent from the edible oil industry, as well as the parameters that influence the reaction, such as pH, hydrogen peroxide (H2O2), and ferrous sulfate heptahydrate (FeSO4.7H2O) doses at various reaction times. The response surface methodology (RSM) was applied with a central composite design (CCD) for optimizing the responses of pollutant removals. The obtained results indicated that the authenticated response to the chemical oxygen demand (COD) removal was 93.52%, at optimum values of pH, FeSO4.7H2O dose, H2O2 dose, and reaction time of 3, 1 g/L, 8.38 g/L, and 50 min, respectively. Furthermore, the authenticated response to oil and grease (O&G) removal was 99.8%, at optimum values of pH, FeSO4.7H2O dose, H2O2 dose, and reaction time of 3, 0.71 g/L, 8.7 g/L, and 37.4 min, respectively. Under these conditions, the residual COD and O&G after Fenton oxidation become 155.4 mg/L and 10 mg/L, respectively.

An innovative process combining electrocoagulation and photoelectro-Fenton-like methods during the abatement of Acid Blue 113 dye

This paper focuses on the implementation of a smart hybrid water treatment process that combines electrocoagulation (EC) and active chlorine-based photoelectro-Fenton-like (PEF-like) methods to remove Acid Blue 113 (AB 113) dye, used as a model persistent organic pollutant (POP), from synthetic solutions containing chlorides. The composition of AB 113 solutions expressed in terms of chemical oxygen demand (COD) was 250–1000 mg L-1 in 2000 mg L-1 NaCl at neutral pH. EC is conceived as a dye removal process, where iron flocs partially remove the dye in high concentrations. The residual dye in the solution (after EC) is oxidized to CO2 in the PEF-like treatment. An up-flow EC reactor was used for EC with two Fe plates as anode and cathode. A filter-press cell with a Ti|Ir-Sn-Sb-oxides anode and a stainless-steel cathode was employed for the PEF-like process. During PEF-like, the chloride is oxidized to HClO, reacting with residual Fe2+ from the EC to yield •OH. In EC, the influence of the electrolyte flow velocity (0.69 ≤ u ≤ 3.47 cm s−1), applied current density (6 ≤ j ≤ 18 mA cm−2), and initial AB 113 dye on the COD and color removal were systematically examined. The solution after EC was handled by PEF-like at u = 24.2 cm s-1, j = 15 mA cm-2, adjusting 0.4 mM Fe2+. The best conditions of EC were j = 18 mA cm-2 and u = 0.69 cm s-1, reaching COD removals from 67%. After EC, the residual COD was treated by PEF-like, reaching the complete abatement of organic matter. The total operating costs of the treatment (EC + PEF-like) ranged between 1.36 and 1.39 USD m-3. SEM-EDS, XRD, FTIR, and organic elemental analysis (OEA) of the dry flocs confirmed the adsorption of AB 113 on iron aggregates. HPLC analysis during the PEF-like process allowed to identify traces of carboxylic acids at the end of the treatment.

Continuous Cultivation of Microalgae in Cattle Slaughterhouse Wastewater Treated with Hydrodynamic Cavitation

Cattle slaughtering produce large amounts of wastewater containing high concentrations of organic matter and nutrients and requires significant treatment before disposal or reutilization. However, the nutrients contained can be valued as a medium for microalgal biomass generation. In this work, hydrodynamic cavitation (HC) followed by membrane filtration or biological (microalgae cultivation) treatment in continuous mode were performed. From cattle slaughterhouse wastewater (CSW), by the effect of HC treatment with air injection in batch mode, more than 20% of the chemical oxygen demand (COD) was removed. In a continuous HC process, the COD content in output was 324 mg O2/L, which is 68% lower than the supplied CSW. After that, 76% of residual COD was removed by filtration through a tubular alumina membrane (600 nm). Finally, 85% of residual COD after HC treatment in 24 h in a batch mode was removed by microalgae. On the other hand, the COD concentration in the output was around 59 mg O2/L in continuous mode, which represents 85–93% COD removal. The process involving HC and microalgae growing looks promising since in addition to water treatment, the microalgae produced could be valued in a biorefinery concept.

Chlorine Efficiency in the Reducing Coliforms in the Sanitary Effluent of Septic Tank Treatment Systems with Anaerobic Filter

The lack of basic sanitation is still a problem in Brazil, only about half of all sewage produced undergoes treatment, due to difficulties in introducing sanitary effluent treatment plants considering that most Brazilian cities do not have financial resources for implementation and maintenance of these stations. In this way, many cities have been adopting different methods for treating sewage before discarding into the rain network. Thus, this work aimed to analyze the efficiency of chlorine in the reduction of coliforms in the sanitary effluent of a treatment system with septic tank, anaerobic filter and disinfection. Six sanitary sewage treatment systems were evaluated from different condominiums from august to december 2019. To check its efficiency, the following parameters were analyzed: pH, thermotolerant coliforms, free residual chlorine and chemical oxygen demand (COD). The results showed that of the six stations evaluated, only one (16,78%) presented the amount of thermotolerant coliforms within the permissible standards. Furthermore, of these only three stations (50%) presented the concentrations of free residual chlorine according to the required parameters. In addition, COD was high at four (66,66%) of the analyzed stations. These data allow us to conclude that the efficiency of chlorine in the reduction of coliforms in the sanitary effluent from a septic tank treatment system, anaerobic filter and disinfection unfortunately may not be happening, because this type of system needs to be well operated and inspected frequently, since the operation is mostly done by users.

Advanced Treatment of Phosphorus Pesticide Wastewater Using an Integrated Process of Coagulation and Ozone Catalytic Oxidation

Conventional pretreatment and secondary biochemical treatment are ineffective methods for removing phosphorus from phosphorus-containing pesticide wastewater. In this study, coagulation-coupled ozone catalytic oxidation was used to treat secondary biochemical tailwater of phosphorus-containing pesticide wastewater thoroughly. The effects of the coagulant type, coagulant dosage, coagulant concentration, wastewater pH, stirring rate, and stirring time on the removal efficiency of chemical oxygen demand (COD), total phosphorus (TP), and chromaticity were investigated during coagulation. When the dosage of the coagulant PAFS was equal to 100 mg/L, the concentration of the coagulant, pH, stirring rate, and stirring time were 5 wt%, 8, 100 rpm, and 5 min, respectively, and the removal rates of COD, TP, and chroma in wastewater reached the maximum value of 17.6%, 86.8%, and 50.0%, respectively. Effluent after coagulation was treated via ozone catalytic oxidation. When the respective ozone dosage, H2O2 dosage, catalyst dosage, and reaction time were 120 mg/L, 0.1 vt‰, 10 wt%, and 90 min, residual COD and chromaticity of the final effluent were 10.3 mg/L and 8, respectively. The coagulation-coupled ozone catalytic oxidation process has good application prospects in the treatment of secondary biochemical tailwater from phosphorus-containing pesticide wastewater.

Environmental Remediation Potential of Ferrous Sulfate Waste as an Eco-Friendly Coagulant for the Removal of NH3-N and COD from the Rubber Processing Effluent

The present study was conducted to determine the potential of utilizing the FeSO4·7H2O waste from the titanium manufacturing industry as an effective coagulant for treating industrial effluent. In this study, the secondary rubber processing effluent (SRPE) was treated using ferrous sulfate (FeSO4·7H2O) waste from the titanium oxide manufacturing industry. The FeSO4·7H2O waste coagulation efficiency was evaluated on the elimination of ammoniacal nitrogen (NH3-N) and chemical oxygen demand (COD) from SRPE. The central composite design (CCD) of experiments was employed to design the coagulation experiments with varying coagulation time, coagulant doses, and temperature. The coagulation experiments were optimized on the optimal elimination of NH3-N and COD using response surface methodology (RSM). Results showed that coagulant doses and temperature significantly influenced NH3-N and COD elimination from SRPE. The highest NH3-N and COD removal obtained were 98.19% and 93.86%, respectively, at the optimized coagulation experimental conditions of coagulation time 70 min, coagulant doses 900 mg/L, and temperature 62 °C. The residual NH3-N and COD in treated SPRE were found below the specified industrial effluent discharge limits set by DoE, Malaysia. Additionally, the sludge generated after coagulation of SRPE contains essential plant nutrients. The present study’s finding showed that FeSO4·7H2O waste generated as an industrial byproduct in a titanium oxide manufacturing industry could be utilized as an eco-friendly coagulant in treating industrial effluent.

The effect of different types of AOPs supported by hydrogen peroxide on the decolorization of methylene blue and viscose fibers dyeing wastewater.

Wastewater from the textile industry containing a high concentration of organic and inorganic chemicals has strong color and residual chemical oxygen demand (COD). Therefore, advanced oxidation processes (AOPs) are very good candidates to treat textile industry wastewater. In this study, we investigated the effect of different types of AOPs supported with hydrogen peroxide (H2O2) for the treatment of viscose fibers dyeing wastewater. Fenton, photo-Fenton, and Fenton-supported subcritical water oxidation (FSWO) processes were chosen as AOPs to compare the treatment efficiency of viscose fibers dyeing wastewater. The effects of solution pH, Fe2+ concentration, and H2O2 concentration on the treatment of viscose fibers dyeing wastewater were tested. The maximum color and COD removal efficiency was obtained corresponding to pH 2.5 for all oxidation methods when methylene blue (MB) dye solution was used. However, the maximum efficiencies were obtained at pH 3.0 for real textile wastewater decolorization. The MB dye removal efficiency was increased to 97.22, 100, and 100% for Fenton, photo-Fenton, and FSWO processes, respectively, when the addition of H2O2 concentration was adjusted to 125 mg/L. However, the maximum color removal efficiencies of viscose fibers dyeing wastewater were obtained 56.94, 61.26, 64.11% for Fenton, photo-Fenton, FSWO processes, respectively. As a result, the FSWO showed maximum color removal efficiencies.

Modified Fe3O4 magnetic nanoparticles for COD removal in oil field produced water and regeneration

There are traces of small-sized oil droplets and anionic polyacrylamide (APAM) in the tertiary oil recovery produced water treated with traditional technology, which causes COD value of the wastewater fail to reach the latest emission limit. In this study, Fe3O4-IDA-Cu2+ magnetic nanoparticles (MNPs) were synthesized and residual chemical oxygen demand (COD) removal in treated oil field produced water was investigated in laboratory scale. Influence of pH, dosage of magnetic nanoparticles, and stirring time was optimized for the COD removal. After 1 h of treatment, about 66.7 % COD removal was achieved with optimized parameters. Magnetic nanoparticles reusability and stability was checked by regeneration treatment. The magnetic separation showed good reusability for six consecutive runs and COD in MNPs treated wastewater was found to be below discharge limit.

Simultaneously upgrading biogas and treating digestate using bioelectrochemical anaerobic trickling filter bed reactor

A bioelectrochemical trickling filter bed reactor (BE-TFBR) was studied as a post-treatment process to upgrade biogas and treat digestate. The trickling filter bed reactor (TFBR) was efficient in upgrading the biogas from 53% to 83%, but it was not effective in removing the chemical oxygen demand (COD) of the digestate (the COD removal efficiency was less than 11%). The BE-TFBR hydraulically induced a high rate of CH4 conversion from the CO2 in the biogas that had injected H2, and it bioelectrochemically improved the removal of residual COD from the digestate. The maximum CH4 content, CH4 production, and COD removal efficiencies in a continuously operated BE-TFBR were 90.5%, 3.52 L/d, and 31.2%, respectively. The BE-TFBR contributed to the further removal of COD (by 0.48 g/d) and to the additional production of CH4 (by 0.31 L). These results are better than those obtained by using a TFBR alone and show that the BE-TFBR could be applied as an effective post-treatment process to remove residual COD in digestate and to qualitatively and quantitatively improve biogas production from wastes.

Novel graphite rod electrode modified with iron-functionalized nanozeolite for efficient wastewater treatment by microbial fuel cells

Microbial fuel cells (MFCs) are a green and efficient approach to treat wastewater and generate energy. According to the present research, a novel MFC fabricate based on graphite rod electrodes (GRE). The surface of this cathode was modified with iron-functionalized ZSM-5 nanozeolite. The characterization of Iron doping in nanozeolite structure and electrode surface modification were obtained by XRD and EDX analyzes, respectively. Chemical analysis of square wave (Sqw) and cyclic voltammetry (CV) determined for all of three graphite electrodes (G, G-Z and G-Z/Fe) with higher efficiency. Morover, the comparison of experimental results from 72-hour fuel cell steering was evaluated and showed that the G-Z/Fe graphite electrodes has maximum efficiency and effectiveness. Thus, the efficiency of fuel cell output current and residual chemical oxygen demand removal with this electrode increased up to 21.8% and 36.9%, respectively. The effiucient recovery for the modification of the graphite electrode was achieved due to increasing of the specific surface area, the active sites of functionalized nanozeolite and the elevation in the electrical conductivity through the presence of iron particles doped in the ZSM-5/Fe nanocatalyst structure. Therefore, the G-Z/Fe cathode can be used as a favorite electrode for the construction of MFCs based on GRE .

Effective removal of organic and inorganic pollutants from stabilized sanitary landfill leachate using a combined Fe2O3 nanoparticles/electroflotation process

The effective removal of organic and inorganic pollutants from landfill leachate is challenging because of their high concentration. In this study, stabilized landfill leachate was treated with the organic and inorganic pollutants, such as color, turbidity, ammonium nitrogen (NH3–N), total dissolved solid (TDS), and chemical oxygen demand (COD) with a combination of Fe2O3 nanoparticles as adsorbents and electroflotation technology. Pollutant removal was achieved with Fe2O3 nanoparticles and electroflotation separately to determine the optimal experimental conditions for adsorption using Fe2O3 nanoparticles (pH, doses, and contact time) and electroflotation (pH, contact time, and current density). Finally, the optimal experimental conditions for both treatment processes were employed to remove COD, color, NH3–N, turbidity, and TDS from the landfill leachate. The combination of adsorption with Fe2O3 nanoparticles and electroflotation technology was effective in removing over 96 % of COD, 99 % of NH3–N, approximately 100 % of color, 99 % of turbidity, and 99 % of TDS from landfill leachate. The residual COD, NH3–N, color, turbidity, and TDS were determined to be approximately 89 mg/L, 4.5 mg/L, 12 ADMI, 5 NTU, and 61 mg/L, respectively, which complies with the standard regulation of leachate discharge limits set by the Department of Environment (DoE), Malaysia in 2009. The finding of this study demonstrates an effective treatment method to remove the organic and inorganic pollutants from stabilized landfill leachate.