Mineralization of the Pharmaceutical β-Blocker Atenolol by Means of Indirect Electrochemical Advanced Oxidation Process: Parametric and Kinetic Study

Atenolol is a β-blocker that can be found in urban wastewaters and which is not removed efficiently by conventional wastewater treatments. In the present study, electro-Fenton (EF) process was used to assess the degradation and mineralization of pharmaceutical atenolol in aqueous solutions. Electrolyses of 250 mL of atenolol solution (0.17 mM), at initial pH 3, were carried out in an undivided electrolytic cell in galvanostatic mode. Influence of material cathode (graphite, stainless steel, and platinized titanium), applied current (100–500 mA), sulfate dosage (0.01–0.5 M), and catalyst ferrous ions concentration (1–10 mM), on the oxidation efficiency was studied. Atenolol mineralization was monitored by COD dosage. Kinetic analysis indicated that atenolol mineralization followed a pseudo-first order model and the rate constant increased with rising current, ferrous ions concentration (up to 5 mM) and electrolyte concentration. Results showed that graphite cathode, 0.5 M Na₂SO₄ electrolyte, 0.3 A and 5 mM FeSO₄ catalyst were the best conditions for atenolol mineralization. In these optimal conditions, after 240 min more than 87% of the initial COD was removed. The corresponding current efficiency (CE) and specific energy consumption (SEC) were 22.33% and 0.194 kWh/kg COD, respectively. This latter corresponds to 0.078 kWh/m³ of treated wastewater.     

Electrochemical oxidation of tannery wastewater

Tannery wastewater was treated by an electrochemical oxidation method using Ti/Pt, Ti/PbO₂ and Ti/MnO₂ anodes and a Ti cathode in a two‐electrode stirred batch reactor. The changes in colour concentration, chemical oxygen demand (COD), ammonia (NH₄⁺), sulfide and total chromium have been determined as a function of treatment time and applied current density. Gas chromatography–mass spectrometry (GC–MS) analysis, performed on the wastewater samples before and after treatment, as well as on foam samples, is reported. Anode efficiency, rate constants and energy consumption were estimated and discussed. The efficiency of Ti/Pt was 0.802 kgCOD h^?1 A^?1m^?2 and 0.270 kgNH₄⁺ h^?1 A^?1m^?2, and the energy consumption was 5.77 kWh kg^?1 COD and 16.63 kWh kg^?1 of NH₄⁺. The order of efficiency of anodes was found to be Ti/Pt ? Ti/PbO₂ > Ti/MnO₂. The results indicate that the electro‐oxidation method could be used for effective oxidation of tannery wastewater and a final effluent with substantially reduced pollution load can be obtained. © 2001 Society of Chemical Industry     

Pre-Treatment of Pistachio Processing Industry Wastewaters (PPIW) by Electrocoagulation using Al Plate Electrode

The objective of the present study is to assess the efficiency of electro-coagulation treatment of pistachio processing industry wastewaters (PPIW) using an aluminum plate electrode. The effect of some of the parameters was examined on the removal of chemical oxygen demand (COD), total organic carbon (TOC), and total phenols (TP) removal efficiency. The treatment was carried out in a batch system. The influences of current density (from 1 to 6 mA cm^?2), initial pH of wastewater (from 2 to 8), constant pH of wastewater (from 3 to 7), stirring speed (from 100 to 500 rpm), and supporting electrolyte concentration (from 10 to 50 mg L^?1 NaCl) on removal efficiency were investigated to determine the best experimental conditions. The evaluation of the physico-chemical parameters during the treatment by electrocoagulation showed that the best removal efficiency was obtained under the conditions of 180 min electrolysis time, wastewater with constant pH of 6, and 6 – mA cm^?2 current density. Under such experimental conditions, COD, TOC, and TP removal efficiency were found to be 60.1%, 50.2%, and 77.3%, respectively, while energy consumption was 39.6 kW-h m^?3. The results of the study show that the electrocoagulation can be applied to PPIW pre-treatment.     

Biological treatment of saline wastewaters from marine‐products processing factories by a fixed‐bed reactor

Wastewaters generated by a factory processing marine products are characterized by high concentrations of organic compounds and salt constituents (>30 g dm^?3). Biological treatment of these saline wastewaters in conventional systems usually results in low chemical oxygen demand (COD) removal efficiency, because of the plasmolysis of the organisms. In order to overcome this problem a specific flora was adapted to the wastewater from the fish‐processing industry by a gradual increase in salt concentrations. Biological treatment of this effluent was then studied in a continuous fixed biofilm reactor. Experiments were conducted at different organic loading rates (OLR), varying from 250 to 1000 mg COD dm^?3 day^?1. Under low OLR (250 mg COD dm^?3 day^?1), COD and total organic carbon (TOC) removal efficiencies were 92.5 and 95.4%, respectively. Thereafter, fluctuations in COD and TOC were observed during the experiment, provoked by the progressive increase of OLR and the nature of the wastewater introduced. High COD (87%) and TOC (99%) removal efficiencies were obtained at 1000 mg COD dm^?3 day^?1. © 2002 Society of Chemical Industry     

Supercritical water oxidation of flammable industrial wastewaters: economic perspectives of an industrial plant

BACKGROUND: Supercritical water oxidation (SCWO) is a promising technology that respects the environment, destroys wastes and allows energy recovery. This process has been applied to many model compounds and real wastewaters at laboratory scale. However, SCWO treatments at pilot plant scale of real wastewaters are scarce. The application of this technology to industrial wastewaters has drawbacks such as corrosion, salt deposition and high cost, so industrial scale‐up has been delayed. RESULTS: In a first stage, for safety reasons the feasibility of SCWO applied to flammable industrial wastewaters was evaluated at laboratory scale in an isothermal plug flow reactor with low concentrations (3–10 g COD L^?1), at a constant pressure of 250 bar and at different temperatures in the range 350–500 °C. In a second stage, experiments were conducted with much higher concentrations (20–90 g COD L^?1) in a SCWO reactor at pilot plant scale. Experiments at pilot plant scale demonstrated the possibility of working under autothermal conditions and the results were used to estimate the treatment costs for a SCWO plant with a capacity of 1 m³ h^?1. CONCLUSION: Results demonstrated the technical feasibility of using a SCWO process to treat flammable industrial wastewater at pilot plant scale due to the absence of operational drawbacks related to the flammability of this wastewater, such as plugging, pressurization or preheating problems and uncontrolled reactions (explosion, etc.). The economic feasibility was demonstrated, especially bearing in mind the energy recovery optimization. Copyright © 2011 Society of Chemical Industry     

Electrochemical conversion of phenolic wastewater on carbon electrodes in the presence of NaCl

The electrochemical conversion of highly concentrated synthetic phenolic wastewater was studied on carbon electrodes in a batch electrochemical reactor. The effects of reaction temperature, electrolyte concentration, current density and initial phenol concentration on phenol conversion were elucidated. The wastewater was synthetically prepared and used in reactions carried out generally at 25 °C with an initial phenol concentration of 3500 mg dm^?3. Although current density increased, phenol conversion% and initial phenol conversion rate did not increase correspondingly above 35 °C and an electrolyte concentration of 90 g dm^?3. As the voltage values applied were increased, the increasing current density resulted in fast phenol conversion. Kinetic investigations denoted that overall phenol destruction kinetics was of zero order with an activation energy of 10.9 kJ mol^?1. Under appropriate conditions, phenol was completely converted within 15 min for an initial phenol concentration of 98 mg dm^?3 while 8 h was required to gain 95% conversion using 4698 mg dm^?3. Solid polymeric materials were produced at initial phenol concentrations above 500 mg dm^?3 using the appropriate current density. In the reaction medium, only mono‐, di‐ and tri‐substituted chlorophenols were formed and 100% of all species were either oxidised or contributed to the formation of a polymeric structure. Almost all of the phenol loaded to the reactor was converted into non‐passivating polymeric products, denoting a safe and easy method for the separation of phenol. © 2001 Society of Chemical Industry     

Use of various processes for pilot plant treatment of wastewater from a wood‐processing factory

The wastewater from a wood‐processing factory is characterized by a high COD, chlorides and nitrogen content. Various treatment processes were applied to treat this wastewater in pilot‐scale units. By applying one‐stage denitrification–activated sludge biological treatment it was not possible to remove nitrogen. Nitrification was inhibited by wastewater compounds. By applying a second stage of a nitrification biofilter it was possible to have a high degree of nitrification. The denitrification was complete. With biological methods the reduction of COD, and ‐N and ‐N concentrations to acceptable values was not achievable. Physical–Chemical methods as H₂O₂/UV, electrolysis and ozonation were used as post‐treatment of effluents from the biological system. Radical degradation, initiated by the powerful hydroxyl radicals which are generated from H₂O₂ by UV activation, is used for wastewater post‐treatment. The combination of H₂O₂/UV was not suitable for post‐treatment of this wastewater. With electrolysis, ‐N and COD removal can be complete. The total amount of ammonia and organic nitrogen converted to nitrate nitrogen for current density of 1.15 Adm^?2 and energy consumption of 71.6 kWhm^?3 was 0.35 gdm^?3. Further biological denitrification is required for ‐N removal to permitted values. Energy consumption for the elimination of 1 kg COD was 40.4 kWh and 35.8 kWh for current densities of 0.7 Adm^?2 and 1.15 Adm^?2 respectively. The energy required to reach the limit value of COD equal to 150 mgdm^?3 for current density of 1.15 Adm^?2 was 71.6 kWhm^?3. With ozonation, the COD removal can be complete. Further biological nitrification–denitrification is required to remove ‐N and ‐N to permitted values. At pH 7.0, in order to reach the limit value of COD equal to 150 mgdm^?3, specific ozone dose was 6.0 g per g of COD removed and the total amount of ammonia and organic nitrogen converted to nitrate nitrogen was 0.25 gdm^?3. The total equivalent energy required is estimated to be 75.0 kWhm^?3. © 2001 Society of Chemical Industry     

Veratric acid treatment by anodic oxidation with BDD anode

BACKGROUND: Veratric acid (VA, 3,4‐dimethoxy‐benzoic acid) is representative of the polyphenolic type compounds present in olive mill wastewater (OMW). Given the bactericide factor, the inhibitor character and the anti bacteriological activity of this compound, traditional biological digestion cannot be applied and therefore new technologies, such as electrochemical oxidation using a boron‐doped diamond (BDD) anode have to be considered to avoid its accumulation in the environment. RESULTS: The electrochemical oxidation of aqueous solutions containing 1 mmol L^?1 VA has been investigated using a filter‐press reactor with a BDD anode during galvanostatic electrolysis. The influence of several operating parameters, such as applied current density, temperature, flow‐rate and supporting electrolyte concentration and type has been investigated. The experimental results showed that under the experimental conditions used the oxidation of VA was under mass‐transfer control and VA was completely degraded by the reaction with hydroxyl radicals electrogenerated at the BDD surface. The chemical oxygen demand (COD) decay kinetic followed a pseudo‐first‐order reaction and the apparent rate constant increased with flow rate and temperature. Under optimal experimental conditions of flow‐rate (300 L h^?1), temperature (35 °C) and current density (10 mA cm^?2), 99.5% of COD was removed during 2 h electrolysis, with 16.4 kWh m^?3 energy consumption. CONCLUSIONS: This study suggests that anodic oxidation with a BDD electrode is an excellent method for the treatment of effluents contaminated with VA and related polyphenols. Copyright © 2011 Society of Chemical Industry     

Treatment of dairy industry wastewater by EC and EF processes using hybrid Fe?Al plate electrodes

BACKGROUND: In this study electrochemical treatment of dairy industry wastewater (DW) was investigated using a combined electrode system consisting of iron and aluminum as sacrificial electrodes. The dairy industry generates strong wastewaters characterized by high biological oxygen demand and chemical oxygen demand concentrations. Dairy industry waste effluents are concentrated in nature, and the main contributors of organic load to these effluents are carbohydrates, proteins and fats originating from the milk. Since dairy waste streams contain high concentrations of organic matter, these effluents may cause serious environmental problems. RESULTS: A pole changer device was employed to change polarization in given time intervals to generate iron and aluminum based coagulants respectively. The effects of current density, initial pH, sodium sulfate (Na₂SO₄) and H₂O₂ concentrations on the removal efficiency were investigated. The best experimental conditions obtained in electrochemical studies were as follows: current density = 15 mA cm^?2, natural pH, without supporting electrolyte addition, H₂O₂ concentration = 3 × 1000 mg L^?1. Under these conditions, 79.2% COD removal from DW was achieved. CONCLUSION: According to the results, 20 min electrolysis is enough, since insignificant variations in COD removal were observed after this time. These methods were found to be successful for the treatment of DW. Copyright © 2011 Society of Chemical Industry     

Electrochemical treatment of cotton textile-based dyeing effluent

The electrochemical treatment (ECT) of textile wastewater was carried out in a 1.5 dm³ electrolyte batch reactor using iron electrodes. With the four plate configurations, a current density (CD) of 89.2 A/m² and a pH value of 8.5 were found to be optimal, at which maximum reduction in chemical oxygen demand (COD) and colour achieved were 86% and 79%, respectively. Loss of 0.0666 kg/m³ iron electrode and 18.44 kWh/m³ power consumption was observed during ECT with a maximum COD reduction of 79%. The settling characteristics of electrochemically treated effluents as well as the characteristics of foam and residue were also analysed.     

Electrochemical oxidation of Basic Blue 3 dye using a diamond anode: evaluation of colour,COD and toxicity removal

BACKGROUND: Textile industries generate considerable amounts of waste‐water, which may contain strong colour, suspended particles, salts, high pH and high chemical oxygen demand (COD) concentration. The disposal of these coloured wastewaters poses a major problem for the industry as well as a threat to the environment. In this study, electrochemical oxidation of Basic Blue 3 (BB3) dye was studied in a bipolar trickle tower (BTT) reactor using Raschig ring shaped boron‐doped diamond (BDD) electrodes in recirculated batch mode. The effects of current density, temperature, flow rate, sodium sulfate concentration (Na₂SO₄) as supporting electrolyte, and initial dye concentration were investigated. RESULTS: The best experimental conditions obtained were as follows: current density 0.875 mA cm^?2, temperature 30 °C, flow rate 109.5 mL min^?1, Na₂SO₄ concentration 0.01 mol L^?1. Under these conditions, 99% colour and 86.7% COD removal were achieved. Toxicity tests were also performed on BB3 solutions under the best experimental conditions. CONCLUSION: Based on these results, the BDD anode was found to be very successful for the simultaneous degradation of BB3 and removal of COD. Additional toxicity test results also showed that electrochemical treatment using a BDD Raschig ring anode in a BTT reactor is an effective way of reducing toxicity as well as removing colour and COD. Copyright © 2010 Society of Chemical Industry     

A new electrochemical technique for bleaching cellulose pulp

A study of electrochemical bleaching of cellulose pulp was carried out in an electrolyte cell composed of a horizontal graphite anode and a parallel stainless screen steel cathode, using NaCl as electrolyte. Variables studied were: current density, sodium chloride concentration, pulp concentration, pH and temperature. The rate of bleaching was found to increase with increasing current density, salt concentration and temperature. The rate of bleaching was found to decrease with increasing pH and pulp concentration. Energy consumption ranged from 0.1 kWh kg^?1 (pulp) to 1.75 kWh kg^?1 (pulp), depending on current density and degree of bleaching. The quality of electrochemically bleached pulp was found to compare favourably with that of chemically bleached pulp.     

Influence of various parameters on the electrochemical treatment of landfill leachates

The influence of some basic parameters of an electrolytic system on the effectiveness of the treatment of landfill leachates is investigated. The controlling parameters of the system examined were: (i) the leachate input rate, (ii) pH and temperature, (iii) the amount of electrolyte (NaCl) added, (iv) the voltage applied and (v) the concentration of Fe²⁺ (added as FeSO₄ · 7H₂O). The performance of the system was assessed in terms of the COD, BOD₅ and NH₄ ⁺ reduction in the leachate samples as well as in terms of the energy consumption of the system (i.e., kWh consumed per kg of COD removed). These two parameters are referred to as the optimization parameters of the system. By implementing a 2⁶ factorial experiment, linear models, which interrelate each optimization parameter with the controlling parameters of the system, were generated. Using these models, effective treatment of landfill leachates by electrochemical oxidation can be designed.     

Control of the Fenton process for textile wastewater treatment using artificial neural networks

BACKGROUND: The Fenton process is a popular advanced oxidation process (AOP) for treating textile wastewater. However, high consumption of chemical reagents and high production of sludge are typical problems when using this process and in addition, textile wastewater has wide‐ranging characteristics. Therefore, dynamically regulating the Fenton process is critical to reducing operation costs and enhancing process performance. The artificial neural network (ANN) model has been adopted extensively to optimize wastewater treatment. This study presents a novel Fenton process control strategy using ANN models and oxygen reduction potential (ORP) monitoring to treat two synthetic textile wastewaters containing two common dyes. RESULTS: Experimental results indicated that the ANN models can predict precisely the colour and chemical oxygen demand (COD) removal efficiencies for synthetic textile wastewaters with correlation coefficients (R²) of 0.91–0.99. The proposed control strategy based on these ANN models effectively controls the Fenton process for various effluent colour targets. For treating the RB49 synthetic wastewater to meet the effluent colour targets of 550 and 1500 ADMI units, the required Fe⁺² doses were 13.0–84.3 and 5.5–34.6 mg L^?1 (Fe⁺²/H₂O₂ = 3.0), resulting in average effluent colour values of 520 and 1494 units. On the other hand, an effluent colour target of 550 ADMI units was achieved for RBB synthetic wastewater. The required Fe⁺² doses were 14.6–128.0 mg L^?1; the average effluent colour values were 520 units. CONCLUSION: The Fenton process for textile wastewater treatment was effectively controlled using a control strategy applying the ANN models and ORP monitoring, giving the benefit of chemical cost savings. Copyright © 2009 Society of Chemical Industry     

Electrochemical treatment of olive mill wastewater

Background Olive mill wastewater (OMW) constitutes a very strong agro‐industrial wastewater posing severe environmental threats in olive oil producing countries. The main objective of this study was to treat olive mill wastewater by electrochemical oxidation. The variables studied included the type and concentration of electrolyte solutions, voltage and time applied. Results: The electrolyte type and concentration significantly affected the degradation efficiency of the electrochemical oxidation. Optimal conditions for NaCl concentration were 3% (w/v) and 16 V. At these conditions chemical oxygen demand (COD) removal reached 70.8% after 8 h of electrochemical treatment, while color and turbidity were completely removed after short periods of treatment. However, bio‐assays indicated that the ecotoxicity of the treated wastewater remained unchanged, possibly due to the formation of chlorinated by‐products. Na₂SO₄ did not demonstrate sufficient efficiency. The simultaneous use of FeCl₃ and NaCl contributed to electro‐coagulation of OMW. After settlement, two separate phases were formed: the supernatant phase and the settled solids. Under optimal conditions (2% Na₂SO₄ + 1% FeCl₃; 24 V), the removal efficiency of COD reached 85.5% at the supernatant phase. Conclusion: NaCl was an effective electrolyte for OMW treatment. The electro‐coagulation process was also a successful process, but as in the case of NaCl the remaining acute toxicity of treated OMW was high. Copyright © 2007 Society of Chemical Industry     

Batch treatment of saline wastewater by Halanaerobium lacusrosei in an anaerobic packed bed reactor

BACKGROUND: This study considers batch treatment of saline wastewater in an upflow anaerobic packed bed reactor by salt tolerant anaerobic organisms Halanaerobium lacusrosei . RESULTS: The effects of initial chemical oxygen demand (COD) concentration (COD₀ = 1880–9570 mg L^?1), salt concentration ([NaCl] = 30–100 g L^?1) and liquid upflow velocity (V_up = 1.0–8.5 m h^?1) on COD removal from salt (NaCl)‐containing synthetic wastewater were investigated. The results indicated that initial COD concentration significantly affects the effluent COD concentration and removal efficiency. COD removal was around 87% at about COD₀ = 1880 mg L^?1, and efficiency decreased to 43% on increasing COD₀ to 9570 mg L^?1 at 20 g L^?1 salt concentration. COD removal was in the range 50–60% for [NaCl] = 30–60 g L^?1 at COD₀ = 5200 ± .100 mg L^?1. However, removal efficiency dropped to 10% when salt concentration was increased to 100 g L^?1. Increasing liquid upflow velocity from V_up = 1.0 m h^?1 to 8.5 m h^?1 provided a substantial improvement in COD removal. COD concentration decreased from 4343 mg L^?1 to 321 mg L^?1 at V_up = 8.5 m h^?1, resulting in over 92% COD removal at 30 g L^?1 salt‐containing synthetic wastewater. CONCLUSION: The experimental results showed that anaerobic treatment of saline wastewater is possible and could result in efficient COD removal by the utilization of halophilic anaerobic bacteria. Copyright © 2008 Society of Chemical Industry     

Characterization of biomass from a pilot plant digester treating saline wastewater

The evolution of biomass contained in a pilot-scale digester treating wastewater from a sea-food processing factory (15–45 g Chemical Oxygen Demand (COD) dm^?3 and high salinity) was studied for 2 years. During this period, different effluents have been treated and several operational conditions were followed. Laboratory-scale experiments were carried out to determine the sludge methanogenic activity and the salinity adaptation of the biomass which developed in the digester. During the different periods, sludge concentration remained between 10 and 12 g Volatile Suspended Solids (VSS) dm^?3, a value that seems to be characteristic for this reactor. A global Organic Loading Rate (OLR) balance showed no significant change of biomass concentration inside the reactor, although a quite important growth of biomass (11·5% of OLR fed) was observed. Methanogenic activity assays indicated a sludge with a good activity (0·5–0·75 g COD g^?1 VSS day^?1) in a saline medium could be obtained from a low activity sludge (0·047 g COD g^?1 VSS day^?1). Toxicity assays showed the importance of antagonistic effects of other cations on the toxicity exerted by sodium.     

Studies on electrochemical treatment of dairy wastewater using aluminum electrode

This study reports results of electrochemical treatment to the synthetic dairy wastewater using aluminum electrode. Response surface methodology with four factors and five level full factorial central composite design has been used to design the experiments. Four operational parameters, namely current density (J): 61.73–308.64 A/m²; dosage of sodium chloride (NaCl) (m): 0–2 g/l; electrolysis time (t): 10–90 min and initial pH (pH_o): 5–11, have been taken as input parameters and percentage chemical oxygen demand (COD) removal (Y₁) and the specific energy consumed (kWh per Kg of COD removed, Y₂) have been taken as responses of the system. Multiresponse optimization technique has been applied to find values of operational parameters which maximize the Y₁ and simultaneously minimize Y₂. The optimum values of operational parameters were found to be J = 123.46 A/m², m = 2.0 g/l, t = 74 min, and pH_o = 6.5. Optimum Y₁ and Y₂ were found to be 70.91% and 1.32 kWh/kg COD removed. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

High power generation with simultaneous COD removal using a circulating column microbial fuel cell

BACKGROUND: A circulating column microbial fuel cell (MFC) with Cu anode and Au? Cu air cathode was used for power generation and chemical oxygen demand (COD) removal from synthetic wastewater. The column was operated in repeated‐fed batch mode using acclimated anaerobic sludge. The contents of the column MFC were circulated while the feed wastewater was fed to the reactor in fed‐batch mode. Effects of feed COD concentration and COD loading rate on voltage difference, power density and percentage COD removal were investigated. RESULTS: The highest voltage difference (650 mV), power density (40 W m^?2) were obtained with a feed COD of 6400 mg L^?1, yielding 45% COD removal with a COD loading rate of nearly 90 mg h^?1. Low COD loadings (<90 mg h^?1) caused substrate limitations, and high loadings (>90 mg h^?1) resulted in inhibition of COD removal and power generation. The highest percentage COD removal (50%) was obtained with feed COD content of 10.35 g L^?1 or a COD loading rate of 145 mg h^?1. CONCLUSION: The power densities obtained with the circulating column MFC were considerably higher than those reported in the literature due to elimination of mass transfer limitations by the high circulation rates, proximity of electrodes and small anode surface area used in this study. Further improvements may be possible with optimization of the operating parameters. Copyright © 2009 Society of Chemical Industry     

COD removal from actual industrial wastewater using a three-dimensional electrochemical apparatus

Chemical oxygen demand (COD) removal was investigated using a three-dimensional electrochemical system. The effects of electrode position, pH value, initial temperature, circulation flow, aeration, and addition of hydrogen peroxide on the removal efficiency of the pollutant were studied. The fillers used in the experiment were centimetre-sized and electrolyte was obtained from an industrial factory with a concentration of COD as high as 25 000–27 500 mg L⁻¹, which was rare in other studies of the past. The degradation of organics was affected by pH and circulation flow, and a decrease in the initial pH value led to the increase in removal efficiency, while a trend of increasing at first and then decreasing was observed with the extension of circulation flow. Aeration and hydrogen peroxide served as enhanced processes for a higher removal rate. Both ultrasound and ultraviolet had effects on the electrolysis system. Oxygen uptake rate measurement and bio-treatment experiments demonstrated a significant increase in biodegradability with this three-dimensional electrochemical system. In addition, a pilot scale test in a pharmaceutical factory showed an economic benefit on energy consumption, which was as low as 10 kWh  kg⁻¹ COD.