Synthetic Phenolic Wastewater Research Articles

Using red mud to prepare the iron-bearing catalyst for the efficient degradation of phenol in the Fenton-like process

Phenol pollution is widely environmental and health problems that require new insights and urgent attention. A iron-bearing catalyst (FRM/2%A) was prepared with red mud by HCl dissolution, ascorbic acid reducing and precipitation of filter liquor, and activated H2O2 to degrade the phenol in synthetic wastewater. Results show that FRM/2%A had the highest degradation efficiency (99.3 %) in the reaction time of 5 min among investigative samples, due to the production of ferrous polymetallic oxides on the catalyst and the formation of mesoscopic particles and microcellular structures. The optimal conditions were 1 g/L of catalyst dosage, 5 mM of H2O2 concentration, 3–6 of initial pH and 100 mg/L of initial concentration of phenol in the FRM/2%A/H2O2 system. The degradation data fit into the pseudo-first-order kinetics model and the reaction rate constant (k) of FRM/2%A was 0.865 min−1. The removal efficiency (77 %) of COD below the value (99.3 %) of phenol degradation implied the intermediates generating during the phenol degradation. The possible degradation pathway was proposed as phenol → catechol → benzoquinone → muconic acid → small molecular organic acids → CO2 and H2O. The findings suggested a new way for the synthesis of the efficient catalyst with RM and optimal operating strategies for the treatment of phenol wastewater.

Automated microextraction by packed sorbent of endocrine disruptors in wastewater using a high-throughput robotic platform followed by liquid chromatography-tandem mass spectrometry.

An automated microextraction by packed sorbent followed by liquid chromatography-tandem mass spectrometry (MEPS-LC-MS/MS) method was developed for the determination of four endocrine disruptors-parabens, benzophenones, and synthetic phenolic antioxidants-in wastewater samples. The method utilizes a lab-made repackable MEPS device and a multi-syringe robotic platform that provides flexibility to test small quantities (2mg) of multiple extraction phases and enables high-throughput capabilities for efficient method development. The overall performance of the MEPS procedure, including the investigation of influencing variables and the optimization of operational parameters for the robotic platform, was comprehensively studied through univariate and multivariate experiments. Under optimized conditions, the target analytes were effectively extracted from a small sample volume of 1.5mL, with competitive detectability and analytical confidence. The limits of detection ranged from 0.15 to 0.30ng L-1, and the intra-day and inter-day relative standard deviations were between 3 and 21%. The method's applicability was successfully demonstrated by determining methylparaben, propylparaben, butylated hydroxyanisole, and oxybenzone in wastewater samples collected from the São Carlos (SP, Brazil) river. Overall, the developed method proved to be a fast, sensitive, reliable, and environmentally friendly analytical tool for water quality monitoring.

Synthesis and Evaluation of HSOD/PSF and SSOD/PSF Membranes for Removal of Phenol from Industrial Wastewater.

Phenol is regarded as a major pollutant, as the toxicity levels are in the range of 9–25 mg/L for aquatic life and humans. This study embedded silica sodalite (SSOD) and hydroxy sodalite (HSOD) nanoparticles into polysulfone (PSF) for enhancement of its physicochemical properties for treatment of phenol-containing wastewater. The pure polysulfone membranes and sodalite-infused membranes were synthesized via phase inversion. To check the surface morphology, surface hydrophilicity, surface functionality, surface roughness and measure the mechanical properties of the membranes, characterization techniques such as Scanning Electron Microscope (SEM), contact angle measurements, Fourier Transform Infrared, Atomic Force Microscopy (AFM) nanotensile tests were used, respectively. The morphology of the composite membranes showed incorporation of the sodalite crystals decreased the membrane porosity. The results obtained showed the highest contact angle of 83.81° for pure PSF as compared to that of the composite membranes. The composite membranes with 10 wt.% HSOD/PSF and 10 wt.% SSOD/PSF showed mechanical enhancement as indicated by a 20.96% and 19.69% increase in ultimate tensile strength, respectively compared to pure PSF. The performance evaluation of the membranes was done using a dead-end filtration cell at varied feed pressure. Synthetic phenol-containing wastewater was prepared by dissolving one gram of phenol crystals in 1 L of deionized water and used in this study. Results showed higher flux for sodalite infused membranes than pure PSF for both pure and phenol-containing water. However, pure PSF showed the highest phenol rejection of 93.55% as compared to 63.65% and 64.75% achieved by 10 wt.% HSOD/PSF and 10 wt.% SSOD/PSF, respectively. The two sodalite infused membranes have shown enhanced mechanical properties and permeability during treatment of phenol in synthetic wastewater.

Electrical stimulation on biodegradation of phenolics in a novel anaerobic–aerobic-coupled upflow bioelectrochemical reactor

• An anaerobic–aerobic-coupled upflow bioelectrochemical reactor was constructed. • Intermittent electrical stimulation mode promoted phenolics degradation. • Aerobic cathodic chamber showed high contribution to the phenolics removal. • Specific microbes were enriched in the cathodic and anodic chambers of the system. Phenolics were widespread in the effluents of coal gasification plants and oil refineries processes, while the impact of electrical stimulation on phenolics degradation in the combined biological processes remained unclear. Here, a novel anaerobic–aerobic–coupled upflow bioelectrochemical reactor (AO-UBER) was used to treat phenol-containing synthetic wastewater and simulated phenolic wastewater. The AO-UBER could treat phenolic compounds effectively via electrical stimulation. Phenol and total phenol removal efficiencies in the intermittently electrically stimulated system with a hydraulic retention time of 6 h were about 22.6% and 31.1%, respectively, higher than that in the biological system not exposed to voltage. The contribution of the aerobic cathodic chamber to the removal of phenolic compounds was higher than that of the anaerobic anodic chamber under the intermittent voltage application mode. High-throughput sequencing analysis indicated that electrical stimulation selectively enriched Acinetobacter , Cloacibacterium , Acidovorax, and Zoogloea in the phenol-containing synthetic wastewater treatment process, and Rhodococcus , Achromobacter , Chryseobacterium, and PSB-M-3 in the simulated phenolic wastewater treatment process. These results demonstrate that the AO-UBER under intermittent voltage application mode holds good potential for efficient phenolic wastewater treatment.

Ternary Ag/AgCl/BiOCl Synthesis and the Effects of its Constituents on Phenol Degradation

Mineralisation of organic constituents in wastewaters emanating from petrochemical processing plants, coal powered energy generation, nuclear power and processing of algal infested waters could render the waste streams reusable for the purpose of reduction of water consumption and protection of the environment from harmful pollutants. Semiconductor photocatalysis, a particle physics based class of advanced oxidation processes (AOPs) has been tried as greener technology for removal of organic pollutants in gaseous phases (e.g. air and steam) and in aquatic phases. Pioneering investigators utilised titanium as a photocatalyst using UV light as the energy source resulting in an electron band-gap of 3.2 mV. The UV lamps consumed a lot of electricity which makes the technology operationally non-feasible. This study focussed on the synthesis and evaluation of an alternative photocalyst comprised of Ag/AgCl/BiOCl with the potential of achieving photocatalysis of organic compounds under solar irradiation. All degradation tests were carried out on synthetic phenol wastewater. The effect of the components that make up the composite was also investigated. The catalysts were characterised using X-ray diffraction (XRD) and Fourier-transform infrared (FTIR). The degradation efficiency of Ag/AgCl/BiOCl, AgCl/BiOCl and BiOCl under UV light were 60 %, 56 % and 55 %. The visible light irradiation achieved degradation of 52 %, 51 % and 15 % for the same catalysts after 4.5 h of irradiation. These results suggest a more practical and realistic application of photocatalysis in the industry through the development of a visible-light responsive catalysts.

Coupling the phenolic oxidation capacities of a bacterial consortium and in situ-generated manganese oxides in a moving bed biofilm reactor (MBBR)

Phenolic wastewater containing phenol and 4-chlorophenol pose a risk to the environment and to human health. Treating them using chemical-biological coupling method is challenging. In this study, manganese oxidizing bacteria (MnOB) were enriched in moving bed biofilm reactor (MBBR) using synthetic phenol wastewater (800 mg L−1) to facilitate in situ production of biogenic manganese oxides (BioMnOx) after 90 days of operation. Then, 4-chlorophenol (4-CP) was added to the MBBR to simulate mixed phenolic wastewater. Comparing the MBBR (R1) without feeding Mn(II) and the MBBR with BioMnOx (R2) production, R2 exhibited robust phenol and 4-CP removal performance. 16S rRNA gene sequencing was employed to determine the microbial community. Subsequently, a batch experiment demonstrated that partly purified BioMnOx does not exhibits a capacity for phenol removal, but can efficiently remove 4-CP. Interestingly, 5-chloro-2-hydroxymuconic semialdehyde was found in the products of 4-CP degradation, which was the unique product of 4-CP degradation by catechol 2,3-dioxygenase (C23O). In both reactors, only catechol 1,2-dioxygenase (C12O) activity from microbes can be detected, indicating that the existence of BioMnOx provide an alternative pathway in addition to microbe driven 4-CP degradation. Overall, MBBR based MnOB enrichment under high phenol concentration was achieved, and 4-CP/phenol removal can be accelerated by in situ-formed BioMnOx. Considering the C23O-like activity of BioMnOx, our results suggest a new coupling strategy that involves nanomaterials and a microbial consortium.

A comparative study on growth and degradation behavior of C. pyrenoidosa on synthetic phenol and phenolic wastewater of a coal gasification plant

Phenol and its derivatives are highly hazardous chemicals profoundly dangerous even at low levels. Hence the management of phenol polluted wastewater represents major environmental challenges. This study investigates the growth and the phenol utilization behavior of microalga DEE 01 isolated from coal gasification effluent treatment plant and identified as Chlorella pyrenoidosa based on 18SrRNA sequence analysis (KX686118). The average % reduction of phenol concentration of the four samples (0.2, 0.4, 0.6 and 0.8 g/L) by C. pyrenoidosa is 97.4% under local ambient conditions at pH-8. It could also degrade phenol in the coal gasification effluent. Haldane inhibitory growth kinetics was used to fit the experimental data and the kinetic parameters obtained were: μmax = 0.7123 day−1, Ks = 0.1899 gL−1; Ki = 0.6898 gL−1 with R2 = 0.9916. In addition to the phenol reduction C. pyrenoidosa was found to reduce the metal ions present in the effluent. The kinetic study of C. pyrenoidosa is observed to possess maximum specific growth and degradation rate, tolerance to toxicity (Ki) and high phenol affinity (Ks).

Photocatalytic degradation of phenol by LaFeO3 nanocrystalline synthesized by gel combustion method via citric acid route

Focusing on the photocatalytic degradation of phenol under visible light, the synthesized lanthanum orthoferrites (LaFeO3) by gel combustion method using citric acid as sacrificial agent were investigated. With the highest reaction temperature of 200 °C, the physicochemical properties of synthesized samples were characterized by X-Ray diffraction (XRD) analysis, Brunauer–Emmet–Teller (BET), and Energy Dispersive X-Ray spectroscopy (EDS). On the other hand, UV–Vis spectroscopy analysis was carried out to determine the phenol photodegradation activities and mechanism. The results suggested the well-defined LaFeO3 nanocrystals with specific area of 28 m2 g−1 were successfully synthesized. Besides that, variations in operating parameters such as pH, catalyst dosage and initial concentration of phenol in synthetic wastewater were also examined. In conclusion, LaFeO3 nanocrystalline exhibited an exceptional photocatalytic activity for phenol degradation, thus providing a perfect alternative for pharmaceutical wastewater treatment.

Catalytic Ozonation using Iron-Doped Water Treatment Sludge as a Catalyst for Treatment of Phenol in Synthetic Wastewater

In this study, iron (Fe)-doped water treatment sludge, designated as Fe/WTS, was prepared by a hydrothermal method using phosphoric acid and impregnation with ferric nitrate. The results from X-ray diffraction (XRD) confirmed the presence of Fe loaded on the WTS support, while Brunauer-Emmett-Teller (BET) analysis indicated an increase of specific surface area of the WTS from 37.37 m2/g to 118.51 m2/g after acid modification. The Fe/WTS was successfully used as a catalyst in catalytic ozonation for degradation of phenol in synthetic wastewater. Factors affecting phenol removal efficiency including reaction time, pH, catalyst dosage, and Fe content were investigated. At the optimum condition, i.e., reaction time of 120 min, pH of 11, catalyst dosage of 1 g/L, and Fe content of 2% (w/w), the removal efficiency of phenol was 99.16% which was higher than that of sole ozonation (44.61%). The results of kinetic analyses indicated that the reactions of catalytic ozonation in the presence of Fe/WTS and WTS catalysts followed pseudo-first order kinetic model with rate constants of 0.0362 and 0.0065 min-1, respectively, while that of sole ozone was 0.0046 min-1. This finding presented the potential use of Fe/WTS as a novel catalyst for catalytic ozonation.

Optimal design and evaluation of electrocatalytic reactors with nano-MnOx/Ti membrane electrode for wastewater treatment

Nano-MnOx loaded porous Ti membrane was employed as anode to constitute electrocatalytic reactor (ECR), electrocatalytic membrane reactor (ECMR), fixed-bed electrocatalytic reactor (FBER) for synthetic phenolic wastewater treatment. The effects of operating voltage, residence time and reaction stage were investigated. Results showed that FBER under the voltage of 2.0 V and residence time of 10.5 min displayed the better electrochemical degradation performance. When the concentration of phenolic wastewater was 188 mg/L, the remove rate of phenol and COD obtained from FBER were up to 73.6% and 66.0% for one-stage FBER, 96.0% and 89.3% for eight-stage FBER, respectively. The apparent reaction rate constant of FBER raised from 0.167 min−1 to 0.389 min−1 with the increase of FBER stages from one to eights. Further, the energy consumption of FBER with one stage and eight stages were 0.25 and 0.75 kWh/kg COD, respectively. ECMR and FBER with a high electrocatalytic reaction efficiency were ascribed to the synergy effect of electrocatalytic oxidation and enhance mass diffusion. Moreover, the uniformity of fluid distribution in FBER leaded to a high diffusion coefficient. Furthermore, a pilot-scale membrane bioreactor (MBR)-FBER plant was developed to the treatment of landfill leachate (COD 22,500 mg/L and NH4+-N 207 mg/L). The total COD and NH4+-N removal rate reached 95.6% and 84.5%, respectively. The pilot-scale MBR-FBER plant exhibits a great application potential in the industrial wastewater treatment.

Biotransformation of phenol in synthetic wastewater using the functionalized magnetic nano-biocatalyst particles carrying tyrosinase.

Low conversion efficiency and long-processing time are some of the major problems associated with the use of biocatalysts in industrial processes. In this study, modified magnetic iron oxide nanoparticles bearing tyrosinase (tyrosinase-MNPs) were employed as a magnetic nano-biocatalyst to treat phenol-containing wastewater. Different factors affecting the phenol removal efficiency of the fabricated nano-biocatalyst such as catalyst dosage, pH, temperature, initial phenol concentration, and reusability were investigated. The results proved that the precise dosage of nano-biocatalyst was able to degrade phenol at the wide range of pHs and temperatures. The immobilized tyrosinase showed proper phenol degradation more than 70%, where the substrate with a high concentration of 2500mg/L was subjected to phenol removal. The nano-biocatalyst was highly efficient and reusable, since it displayed phenol degradation yields of 100% after the third reuse cycle and about 58% after the seventh cycle. Moreover, the immobilized tyrosinase was able to degrade phenol dissolved in real water samples up to 78% after incubation for 60min. It was also reusable at least seven cycles in the real water sample. The results proved the effectiveness and applicability of the fabricated nano-biocatalyst to treat phenol-containing wastewaters in a shorter time and higher efficiency even at high phenol concentration. The developed nano-biocatalyst can be promising for the micropollutants removal and an alternative for the catalysts used in traditional treatment processes.

Temperature susceptibility of a mesophilic anaerobic membrane bioreactor treating saline phenol-containing wastewater

This study examined the temperature susceptibility of a continuous-flow lab-scale anaerobic membrane bioreactor (AnMBR) to temperature shifts from 35 °C to 55 °C and its bioconversion robustness treating synthetic phenolic wastewater at 16 gNa+.L−1. During the experiment, the mesophilic reactor was subjected to stepwise temperature increases by 5 °C. The phenol conversion rates of the AnMBR decreased from 3.16 at 35 °C to 2.10 mgPh.gVSS−1.d−1 at 45 °C, and further decreased to 1.63 mgPh.gVSS−1.d−1 at 50 °C. At 55 °C, phenol conversion rate stabilized at 1.53 mgPh.gVSS−1.d−1 whereas COD removal efficiency was 38% compared to 95.5% at 45 °C and 99.8% at 35 °C. Interestingly, it was found that the phenol degradation process was less susceptible for the upward temperature shifts than the methanogenic process. The temperature increase implied twenty-one operational taxonomic units from the reactor's microbial community with significant differential abundance between mesophilic and thermophilic operation, and eleven of them are known to be involved in aromatic compounds degradation. Reaching the upper-temperature limits for mesophilic operation was associated with the decrease in microbial abundance of the phyla Firmicutes and Proteobacteria, which are linked to syntrophic phenol degradation. It was also found that the particle size decreased from 89.4 μm at 35 °C to 21.0 μm at 55 °C. The accumulation of small particles and higher content of soluble microbial protein-like substances led to increased transmembrane pressure which negatively affected the filtration performance. Our findings indicated that at high salinity a mesophilic AnMBR can tolerate a temperature up to 45 °C without being limited in the phenol conversion capacity.

Modeling and optimizing of electrocoagulation process in treating phenolic wastewater by response surface methodology: precise evaluation of significant variables

The present work reports treatment of synthetic phenolic wastewater by electrocoagulation process. Aluminum flat sheets were utilized as electrodes. Central composite design combined with response surface methodology has been applied for optimizing the process parameters. The interaction effects of phenol concentration, electrode distance, pH, voltage, and electrolysis time (ET) were analyzed and correlated to assess the efficiency of phenol removal as process response. The ANOVA outcomes declared that the initial phenol concentration (relevant coefficient = −3.44) and ET (relevant coefficient = 1.42), respectively, are the most and the least effective parameters on the efficiency of phenol removal. Furthermore, optimal factors were obtained as follows: influent phenol concentration = 14.23 mg/L, electrode distance = 2.20 cm, pH = 6.37, voltage = 16.46 V, and electrolysis time = 44.66 min, in which the percentage of phenol removal at this condition was about 90.6%.

Characterization of a microbial consortium capable of heterotrophic nitrifying under wide C/N range and its potential application in phenolic and coking wastewater

Nitrogen pollution has been a serious problem in environmental water particularly in industrial wastewater. A microbial consortium named FG-06 was found to exhibit efficient heterotrophic nitrification and aerobic denitrification ability, with the maximum NH4+-N, NO2−-N and NO3−-N removal rate of 7.33, 6.53 and 4.53mg/L/h, respectively. High-throughput sequencing analysis showed that it was mainly made up of Acinetobacter spp. (54.37%) and Pseudomonas spp. (26.52%). The consortium could grow under a wide range of C/N ratio and the NH4+-N removal efficiencies at C/N ratio 4 and 32 were 90.40% and 93.84% separately. Furthermore, simultaneous biodegradation of NH4+-N and COD were achieved by inoculation with enriched consortium in synthetic phenolic wastewater and real coking wastewater samples. Results demonstrated that the consortium had high potential for further practical applications.

Light expanded clay aggregate (LECA) as a support for TiO2, Fe/TiO2, and Cu/TiO2 nanocrystalline photocatalysts: a comparative study on the structure, morphology, and activity

In this work, TiO2 and doped TiO2 photocatalysts (Fe/TiO2 and Cu/TiO2) were synthesized by the sol–gel method. The main objective of this study was to investigate the influence of dopants on the structure, morphology, and activity of the catalysts in powder and immobilized states. XRF, XRD, and SEM methods were used to characterize the catalysts. The structure and phase distribution of the nanocrystalline powders were identified by XRD. Nanoparticles crystallite size and the degree of crystallinity were affected by doping. The anatase contents of catalysts were achieved as follows: TiO2 (5.89 %) < Fe/TiO2 (42.17 %) < Cu/TiO2 (70.28 %). It was indicated that the activity of the catalysts strongly depends on the anatase content. Under the same circumstances, copper-modified TiO2 exhibited a twofold higher photocatalytic activity compared with TiO2. The nanostructured catalysts were immobilized on light expanded clay aggregate (LECA) granules in order to investigate the effect of a novel support on the activity of the catalysts. Morphological changes are recognizable in the SEM images. Activity tests indicated that the best catalytic performance was assigned to Cu/TiO2/LECA. After 120 min of irradiation, 61 % degradation of phenol in synthetic wastewater was achieved. The high photocatalytic activity of Cu/TiO2/LECA confirms that LECA is as an excellent support.

Performance Evaluation of Anaerobic Biodegradation of Synthetic Phenolic Waste Water in Single Stage Fixed Bed Bio- Reactor

Performance Evaluation of Anaerobic Biodegradation of Synthetic Phenolic Waste Water in Single Stage Fixed Bed Bio- Reactor

Performance Characteristics of Anaerobic Biodegradation of Synthetic Phenolic Industrial Wastewater

The treatment of toxic and inhibitory phenolic compounds using biological techniques have been pursued vas a promising and widely accepted treatment process due to its easiness of handling, a greater level of stabilization of waste and properly operated to prevent the production of secondary pollutants. Up-flow Anaerobic Bio-Reactors (UAFB) has been widely applied for the handling of high organic load industrial wastewater. The treatment of synthetic phenolic wastewater by a single stage anaerobic fixed bed bioreactor with granite stones packing at four different temperatures was studied. The effect of hydraulic retention time on COD reduction and other steady state characteristics and kinetic parameters, which form these characteristics, was also studied. A recirculated single stage up-flow anaerobic bioreactor operated at all the above-given temperatures with initial BOD 1462 mg/l and initial COD 5720 mg/l for a digestion period of 25 days with a working volume of 1000 ml. The performance of the reactor was monitored after every five days and analyzed in terms of percentage (COD, BOD, TS, TDS, VS removal and biogas production). The removal efficiency of BOD, COD, TS, TDS and VS reached a maximum value of 63.20%, 61.24%, 44.88%, 47.67% and 53.12% respectively. With the change in HRT, the maximum COD reduction was 66.04% at 24 hrs HRT at 400C with initial COD of 5000 mg/l. Specific biogas yield increased up to 0.0162 ml/mg CODr.

Kinetics for electro-oxidation of organic pollutants by using a packed-bed electrode reactor (PBER)

According to the intrinsic kinetics of electro-oxidation, a novel three-stage reaction theory (3SRT) involved charge transfer controlled (CTC), mixed-phase controlled (MPC) and mass transport controlled (MTC) regimes is presented to describe the oxidation of organic pollutants by using a packed-bed electrode reactor (PBER). The proposed 3SRT could be universally used for overall oxidation due to the introduction of a parameter, current utilization ratio of γ (∼1.0) related to anode materials. The existence of MPC regime is due to the difference of the applied current density between metallic anode and bipolar activated carbon (AC) particulate anode caused by the difference of the electrode area of the two kinds of anodes. The proposed theory was employed for prediction of chemical oxygen demand (COD) during treatment of synthetic phenolic wastewater, thiophene-2,5-dicarboxylic acid manufacturing wastewater and pyridine wastewater by using IrO2 doped tantalum oxide (IrO2-Ta2O5/Ti) anode. The regression analysis and F-test results illustrate the 3SRT satisfactorily matches the experimental data obtained at different operation conditions such as current density, initial COD values and flow rate. These results confirm the proposed 3SRT could effectively predict the change of concentration of organic pollutants during electro-oxidation by using a PBER.

Effect of presence of chemical species on removal of phenol in electrocoagulation process

Effect of the presence of chemical species, namely, NaHCO3, CaSO4, MgSO4, and MgCl2, on the performance of electrocoagulation (EC) process when treating synthetic phenolic wastewater was investigated. The investigation was performed using individual and combinations of two, three, and four species. Chemical species, under investigation, were added to phenol solution that was prepared using distilled water. Additionally, effects of operational parameters, namely, initial phenol concentration, current density, and supporting electrolyte (NaCl) concentration on the process performance was also studied using phenol solution that was prepared using tap water. The results showed that presence of chemical species such as bicarbonates and sulfates have negative effects on the performance of EC process. Removal efficiency of phenol was found to decrease with respect to time when CaSO4, MgSO4, and NaHCO3 were added to phenol solution. As an example, when only CaSO4 was added to the solution, more than 30% of phenol remained in solution after 10 min of investigation, while complete removal of phenol was achieved after 2 min when chemical species under investigation were not added. The results also showed that addition of more species resulted in more reduction of phenol removal efficiency. When CaSO4 and MgSO4 were added to the solution, 35% of phenol remained in solution after 10 min of treatment period.

Phenolic wastewaters treatment by electrocoagulation process using Zn anode

Electrocoagulation using a Zn anode was applied for the first time to remove the organic load of a liquid effluent. Different operating conditions (pH, current density, distance between electrodes, nature of electrolyte and kind of cathode) were tested with synthetic phenolic wastewater, in order to optimise the process. Both the medium pH and the type of electrolyte that were used greatly affected the efficiency of the system, followed by the influence of the current density and the cathode material, in a lesser extent. The effect of the distance between electrodes was quite negligible. Furthermore, a sequence of fed-batch trials involving the electrodes reuse showed almost constant activity during the operation time. The optimum operating conditions achieved were initial pH of the effluent equal to 3.2, current density of 250A/m2, distance between electrodes of 1.0cm and 1.5g/L of NaCl. Moreover, the Zn anode/stainless steel cathode pair revealed the most interesting results. These parameters led to 84.2% and 40.3% of total phenolic (TPh) content and chemical oxygen demand (COD) removal, respectively. In addition, the depuration of a filtered real olive mill effluent without NaCl addition achieved the abatement of up to 72.3% of TPh and 20.9% of COD. An energy consumption of 40kWh/m3 and 34kWh/m3 was observed for the treatment of the simulated and the real wastewater, respectively. Furthermore, the ecological impact of the treated effluent was detected by bio-luminescence techniques.This study shows the potentiality of the electrocoagulation process as a pre-treatment of other methods, namely the electrochemical oxidation, to ensure the legal limits values of the wastewater to be discharged into the aquatic environment regarding their organic load.