Three-dimensional Electrode Reactor Research Articles

Advanced treatment of biologically pretreated coking wastewater by a bipolar three-dimensional electrode reactor

Electrochemical oxidation is a promising technology for the treatment of bio-refractory wastewater. In this research, advanced treatment of coking wastewater which had previously undergone A/O (anaerobic–aerobic biological) treatment was investigated over Ti/RuO 2·IrO 2 anode, stainless steel cathode and coke powder particle electrodes which were packed into the electrodes in a bipolar three-dimensional electrode reactor (BTDR). The results showed that the removal efficiency of COD and ammonia nitrogen increased with applied current density. The main influencing factors of BTDR were evaluated by an orthogonal test, including reaction time, plate distance, current density, plate amounts and aeration flow rate. With reaction time of 60 min, plate distance of 1.0 cm, current density of 20 mA/cm2 and plate amounts of four pairs, most of the contaminants in coking wastewater can be remediated by BTDR, which can then meet the discharge limit for coking wastewater in China. For organic pollutants, 12 kinds of organic pollutants can be completely removed, and the removal efficiencies of 11 kinds of organic pollutants are between 13.3 and 70.3% by advanced treatment with BTDR. We conclude that there is great potential for BTDR in engineering applications as a final treatment for coking wastewater.

활성탄 충진 3D 복극전기분해조를 이용한 ETA 처리

활성탄 충진 3D 복극전기분해조를 이용한 ETA 처리

Electrolytic degradation of polyacrylamide in aqueous solution using a three-dimensional electrode reactor

ABSTRACT In this study, electrochemical treatment of a synthetic solution containing 2,000 mg/L of polyacrylamide (PAM) was studied using a three-dimensional electrode reactor, which received granular activated carbon (GAC) as particle electrodes. Air and ferrous salt were introduced into the system to electrogenerate hydrogen peroxide and Fenton’s reactions. The effect of operating conditions such as solution pH, current density, ferrous concentration and GAC amount on the efficacy of the process was investigated. The experimental results showed that the effluent with a satisfied chemical oxygen demand removal efficiency (84%) was obtained after 60 min of electrolysis when the initial pH was 3.0, current density was 40 mA/cm2, air flow = 1.5 L/min, pH = 3, [Fe2+] = 1.5 mM, and temperature = 28°C. The analyses of five-day biochemical oxygen demand and Microtox® toxicity indicated that the optimum electrolysis duration was 30 min, at which satisfied biodegradability of wastewater was achieved. The three-dimensional electrode method can be selected as an effective alternative to PAM wastewater pretreatment before subjected to the biological process.

Regeneration of activated carbon adsorbed EDTA by electrochemical method

Activated carbon after saturated adsorption of EDTA was used as particle electrode in a three-dimensional electrode reactor to treat EDTA-containing wastewater. Electrochemical method was used to regenerate activated carbon after many times of electrolysis. Based on the analysis of infrared spectra of activated carbon after adsorption and repeated electrolysis, EDTA was degraded into glycine, and then non-catalytic activated associated complex was formed with N—H bond on the activated carbon. The catalytic ability of the activated carbon vanished and the EDTA degradation efficiency was dropped. Activated carbon could be effectively regenerated by electrochemical method in the three-dimensional reactor. Effects of electric current, conductivity and pH on activated carbon regeneration were investigated, and the optimum conditions were concluded as follows: 100–300 mA of current intensity, 1.39 mS/cm of electric conductivity, 60 min of electrolysis time and pH 6.0-8.0. Under the optimized conditions, the activity of the activated carbon can be recovered and the residual total organic carbon (TOC) was below 10 mg/L (the initial TOC was 200 mg/L) in the three-dimensional electrode reactor.

Treatment of Reverse Osmosis Concentrates Using a Three-dimensional Electrode Reactor

Treatment of Reverse Osmosis Concentrates Using a Three-dimensional Electrode Reactor

Continuous Electrochemical Oxidation of Phenol Using a Three-Dimensional Electrode Reactor

The removal of phenol wastewater was experimentally investigated using a three-dimensional electrode reactor with granular activated carbon and titanium filter electrode arrays. The effects of the electric current, the residence time and the initial concentration on the phenol removal were evaluated. For the initial concentration of 490 mg/L, the phenol removal was obtained as 90% under the conditions of electric current 2 A, residence time 40 min. The effluent path of the electrochemical cell was optimized, using the anode effluent instead of the top effluent, where the phenol and COD removal was both increased to 95% and the corresponding energy consumption was decreased from 9.66 to 7.63 kWh/kg COD.

Continuous electrochemical oxidation of methyl orange waste water using a three-dimensional electrode reactor

The removal of methyl orange wastewater was experimentally investigated using a three-dimensional electrode reactor with granular activated carbon and titanium filter electrodes arrays. The effects of the electric current, the residence time and the initial dye concentration on the methyl orange removal were evaluated. For the initial concentration of 1150 mg/L, the COD removal was obtained as 90% under the conditions of electric current 2 A, residence time 40 min. The effluent path of the electrochemical cell was optimized, using the anode effluent instead of the top effluent, where the COD removal was increased to 93% and the corresponding energy consumption was decreased from 15.5 to 14.6 kW-hr/kg COD.

Electrochemical pretreatment of heavy oil refinery wastewater using a three-dimensional electrode reactor

The pretreatment of heavy oil refinery wastewater (HORW) was experimentally investigated using a three-dimensional electrode reactor (TDER) with granular activated carbon (GAC) and porous ceramsite particle (PCP) as the combination particle electrode and DSA ® type anodes as the anode. The results showed that higher chemical oxygen demand (COD) removal was obtained in TDER comparing with the two-dimensional electrode reactor (without particle electrodes packed), and combination particle electrode was favorable to improve the COD removal efficiency and reduce the energy consumption. The treated HORW under the optimal experimental condition (GAC percentage = 75%, current density = 30 mA/cm 2, pH not adjusted and treatment time = 100 min) presented that the removal efficiencies of COD, total organic carbon and toxicity units were 45.5%, 43.3% and 67.2%, respectively, and the ratio of 5-day biochemical oxygen demand to COD was increased from 0.10 to 0.29, which is beneficial for further biological treatment. Furthermore, the application of electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry to characterize polar compounds in HORW and their oxidation products was well demonstrated to reveal the composition variation.

Removal of Acid Orange 7 in simulated wastewater using a three-dimensional electrode reactor: Removal mechanisms and dye degradation pathway

The removal of Acid Orange 7 (AO7) in simulated wastewater was experimentally investigated using a three-dimensional electrode reactor with granular activated carbon as the particle electrode, ACF (activated carbon fiber)/Fe as the anode, and ACF/Ti as the cathode. Particular attention was paid to the reaction mechanisms and the dye degradation pathway in the system. The removal of AO7 in the system was mainly dependent on the oxidation by the produced active substances ( OH, etc.) and the coagulation by Fe(II) or Fe(III) dissolved from the anode. The former mechanism was predominant. A possible pathway for AO7 degradation was proposed by monitoring the temporal evolution of intermediates in the solution, with the use of some techniques including GC/MS, FTIR and HPLC. The AO7 molecule was observed to be firstly decomposed to aromatic intermediates, further degraded to ring opening products and finally mineralized to CO 2, H 2O and inorganic salts. The intermediates increased the biodegradability of the wastewater, which was proved by the increase of the BOD/COD value after electrolysis treatment. The three-dimensional electrode method can be considered an effective alternative to dye wastewater pretreatment prior to the biological process.

3차원 전극을 사용한 Rhodamine B의 전기분해에 미치는 운전인자의 영향

A simulated wastewater containing the dye Rhodamine B (RhB) was electrolytically treated using a three-dimensional electrode reactor equipped with granular activated carbon (GAC) as particle electrode. The effect of type of packing material (GAC, ACF, Nonwoven fabric fiber coated with activated carbon), amounts of GAC packing (25-100 g), current (0.5-3 A) and electrolyte concentration (0.5-3 g/l) was evaluated. Experimental results showed that performance for RhB decolorization of the 3 three-dimensional electrodes lie in: GAC > Nonwoven fabric fiber > ACF. When considered RhB decolorization, oxidants concentration and electric power, optimum GAC dosage was 50 g. Generated concentration of 3 oxidants (, free Cl, ) was increased with increase of applied current, however optimum current for RhB degradation was 2.5 A. The oxidants concentration was increased with increase of NaCl concentration and optimum NaCl dosage for RhB degradation was 1.5 g/l.

Kinetics of electrooxidation of landfill leachate in a three-dimensional carbon bed electrochemical reactor

The electrooxidation of high strength leachate from an industrial solid waste landfill site was carried out in a three-dimensional carbon bed electrode reactor (TDR). This paper discusses the kinetics and mechanism of electrooxidation on the basis of time course variation of COD, TOC and TKN (total Kjeldahl nitrogen) from the raw leachate. The batch experiments were run at different applied currents (1–3 A) for a period of 6 h. A two-stage pseudo-first order reaction kinetics model was developed based on the initial rapid removal of pollutants (Phase I) followed by slow oxidation kinetics (Phase II). About 60–64% COD was removed within 1 h with a rate constant 5.83 × 10 −3 min −1 in Phase I, which was near 5–7 times greater than that of Phase II (0.81–1.03 × 10 −3 min −1). The mineralization efficiency was found to be significant in the range 0.83–0.84. The apparent faradic efficiency and specific energy consumption for COD removal were also estimated. The mechanism of electrooxidation was discussed with the help of adsorption, kinetic and SEM results.

Performance of carbon aerogels particle electrodes for the aqueous phase electro-catalytic oxidation of simulated phenol wastewaters

In this paper, the feasibility of using carbon aerogels (CAs) as bed electrodes in a three-dimensional electrode reactor for the electrochemical treatment was studied. It was found that the removal efficiency depended on the airflow, the feed phenol concentration, pH, the ratio of aerogels mass to solution volume, and repeated times. Compared with commercial carbon particle electrodes, the CAs prepared exhibited stronger and longer-term activity to remove phenol simulated wastewater. For 250 mg L −1 of phenol solution, 98% of the initial phenol chemical oxygen demand (COD) can be removed after treatment for 20 min. Moreover, high removal efficiency can be kept basically after being reused many times (e.g. 93% and 82% after 20 times and 50 times, respectively).

Study of Treating Lead-Containing Wastewater by Three-Dimensional Electrode Reactor

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Feasibility study of using carbon aerogel as particle electrodes for decoloration of RBRX dye solution in a three-dimensional electrode reactor

The decoloration of RBRX from simulated dye wastewater in three-dimensional electrode reactor using granular carbon aerogels (CAs) as particle electrodes was experimentally investigated. Decolorization ratio can keep as high as 95% in the 100th run of treatment. Particular attention was paid to probe the function of the CAs through comparing the decolorization ratio of three-dimensional electrode reactor with single adsorption and two-dimensional electrode reactor. Conditional experiments were conducted to evaluate the effect of various parameters such as cell voltage, air flowrate, particle electrode dose, initial dye concentration and pH of the dye solution. The results showed that the decolorization rate increased with increasing cell voltage and particle electrode dose, but decreased with increasing the initial dye concentration. The decolorization rate increased firstly and then kept almost unchanged with the increase of airflow. In addition, the decolorization rate can be also controlled by the pH of the dye solution. The decolorization of RBRX was based on the break of the azo double bonds and the destruction of the other unsaturated bonds.

Electrolytic treatment of C.I. Acid Orange 7 in aqueous solution using a three-dimensional electrode reactor

A simulated wastewater containing the monoazo dye C.I. Acid Orange 7 was electrolytically treated using a three-dimensional electrode reactor equipped with granular activated carbon as particle electrode. The activated carbon fiber cathode was more effective than either a graphite or a stainless steel cathode due to its larger surface area which was beneficial to the electrogeneration of H 2O 2. Under the reaction conditions of 20 V and 3.0 g L −1 Na 2SO 4 at pH 3.0, decrease in the COD of up to 80%, and in the TOC by up to 72% were achieved and almost the complete decolorization of the dye was secured after 180 min electrolysis. Furthermore, decay of the dye followed a pseudo-first-order reaction in the first 60 min treatment. The three-dimensional electrode system generated more hydroxyl radicals than a two-dimensional system due to the formation of microelectrodes under applied high potential.

Photoelectrocatalytic degradation of oxalic acid in aqueous phase with a novel three-dimensional electrode-hollow quartz tube photoelectrocatalytic reactor

Taking oxalic acid as an index, we investigated photoelectrocatalytic degradation of organic pollutants by using a newly designed photoelectrocatalytic reactor coupled by a three-dimensional electrode reactor with a packed-bed hollow quartz tube photocatalytic reactor. The efficiency of the photoelectrocatalytic degradation was determined with COD removal from the tested wastewater; the COD removal efficiencies were considerably dependent on the cell voltage and the concentration of the supporting electrolyte. The experimental results showed that oxalic acid could be degraded more efficiently by photoelectrocatalytic process than individually by photocatalytic or electrochemical oxidation in the photoelectrocatalytic reactor. The introduction of hollow quartz tubes into the three-dimensional electrode – packed-bed photoelectrocatalytic reactor could provide a solution to the earlier drawbacks: the inability to treat the high concentration and low-transmittance wastewater by photocatalytic technology.

Removal of formic acid from wastewater using three-phase three-dimensional electrode reactor

A new electrochemical reactor, three-phase three-dimensional electrode reactor, was designed and used to investigate theremoval of formic acid from simulated wastewater. The experimental results were assessed in term of Chemical OxygenDemand (COD) removal efficiency. The results showed that the three-phase three-dimensional electrodes could effectively removeformic acid. Its COD removal efficiency was much higher than those of two-dimensional electrodes and common three-dimensionalelectrodes, respectively. The COD removal efficiency of the three-phase three-dimensional electrodes using air as a spargegas increased 13.5% relative to that using nitrogen as a spargegas. The observation indicated that the sparged air in the three-phase three-dimensional electrodes not only participated insome physical processes but also played an important role in electrochemical reactions to assist COD removal.

Performance of three-phase three-dimensional electrode reactor for the reduction of COD in simulated wastewater-containing phenol

The removal of chemical oxygen demand (COD) from wastewater-containing phenol was investigated using three-phase three-dimensional electrode reactor. Special attention was paid to experimentally probe the performance of the reactor in COD removal in the process of repeated batch runs. The experimental results showed that the reactor could remove COD from phenol-containing wastewater much more efficiently than both granulated activated carbon (GAC) adsorption bed and conventional three-dimensional electrode. For 200th batch run, the three-phase three-dimensional electrode reactor with an airflow of 5 l min(-1) and a cell voltage of 30 V could remove 1350 ppm COD from the wastewater in 30 min while conventional three-dimensional electrode reactor with a same cell voltage and GAC adsorption bed with a same airflow only could remove 610 and 1000 ppm, respectively, at the same reaction duration. Although it was found that COD removal decreased with increasing repeated batch runs in our experimental range, due to adsorption saturation of GAC and electrode passivation, the extent of decrease for the three-phase three-dimensional electrode is much less than those for conventional three-dimensional electrodes and GAC adsorption beds. The passivated reactor could be partly re-activated by electrolysis in the presence of MnO2.

An experimental investigation of chemical oxygen demand removal from the wastewater containing oxalic acid using three-phase three-dimensional electrode reactor

The removal of chemical oxygen demand (COD) from wastewater containing oxalic acid was experimentally investigated using a three-phase three-dimensional electrode reactor. The experimental results show that the removal efficiency depends on the applied cell voltage, airflow, electrolysis time and the number of repeated runs. The former four factors all had a positive effect while the last factor generally had a negative effect on the COD removal in the experimental range. However, for electrolyses under the conditions of 30.0 V cell voltage, 7.0 l min −1 airflow and 60.0 min, the negative effect was negligible. After 50 runs, the electrochemical reactor could maintain a COD removal efficiency of more than 90%.

Electrochemical Degradation of Organic Wastewater by Three-Dimensional Electrode Reactor

Electrochemical Degradation of Organic Wastewater by Three-Dimensional Electrode Reactor