Sequential Electrocoagulation Research Articles

Sequential electro-coagulation and electro-Fenton processes for the treatment of textile wastewater.

Textile wastewater, laden with persistent dyes and non-biodegradable organics, poses a challenge for treatment in common effluent treatment plants (CETPs) using conventional methods. Pre-treatment of textile effluents is essential to ensure compatibility with CETPs. The present study employed three-dimensional (3D) aluminum and graphite electrodes for a sequential electro-coagulation and electro-Fenton (EC + EF) process. An experimental plan of 25 experiments was constructed using Taguchi method. The combination resulted in high removal efficiencies: 99.91% for color, 93.20% for chemical oxygen demand (COD), and 91.75% for total organic carbon (TOC) for the operating parameters; for EC, current density (J): 20 mA/cm2, time (t): 45 min, speed of rotation (N): 55 rpm; and for EF, current density (J): 25 mA/cm2, time (t): 50 min, iron concentration: 40 mg/L. Post-treatment, the wastewater exhibited an enhanced biodegradability index of 0.875, rendering it suitable for CETPs. There was an increase of 11% in the total energy consumption when energy spent during rotation and aeration at the time of EC and EF, respectively, were considered. This energy increases the cost and is not accounted for, in previous research. The energy consumption in kWh per g of COD removed at optimum condition for the hybrid treatment was 0.0314, which is lower than the energy consumption by other electrochemical processes employing plate electrodes. This indicates that 3D electrodes are more energy efficient than plate electrodes. PRACTITIONER POINTS: Hybrid electrochemical processes can be used as pre-treatment method for textile effluents. Three-dimensional electrodes improve removal rates with lower energy consumption. Significant color, COD, and TOC abatement were noted post-hybrid treatment of textile wastewater. Biodegradability of the textile effluent improves after the hybrid treatment.

Electrocoagulation-photocatalysis sequential combined method for the removal of anticancer drugs from pharmaceutical wastewater using NH2-MIL-125(Ti)/cobalt ferrite nanorods composite photocatalyst

This research reports that the novel NH2-MIL-125(Ti)/cobalt ferrite nanorods composite photocatalyst based on metal-organic framework (MOF) has been synthesized by the microwave heating method. Herein, the sequential electrocoagulation (EC)-photocatalysis combination method was used to remove the chemical oxygen demand (COD), doxorubicin hydrochloride (DOX), and 5-Fluorouracil (5-FU) antineoplastic drugs from wastewater by the composite photocatalyst under a simulated sunlight irradiation. The synthesized photocatalysts were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Brauner-Emmet-Teller surface area analyzer, vibrating sample magnetometer, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, transient photocurrent response, and electrochemical impedance spectroscopy. In the EC process, three-level, three-factor Box-Behnken design was used to investigate the interaction effects of pH (3−8), time (10–60 min), and current density (100–200 A/m2) on the removal of contaminants. The maximum experimental removal efficiencies of COD, DOX, and 5-FU were 68.2 %, 21.1 %, and 24.5 %, respectively, under EC time of 60 min, pH of 5.98, and current density of 176.77 A/m2. About 99.2 % COD, 93.8 % DOX, and 97.0 % 5-FU were removed from pharmaceutical wastewater using NH2-MIL-125(Ti)/ cobalt ferrite nanorods photocatalyst under cobalt ferrite content of 0.288 g, reaction time of 58.48 min, pH of 7.54, and catalyst dosage of 0.5 g/L. The obtained results demonstrated that the combined process of EC and photocatalysis in the presence of MOFs-based photocatalysts is an effective treat strategy for the pharmaceutical wastewater.

Integration of sequential electrocoagulation and adsorption for effective removal of colour and total organic carbon in textile effluents and its utilization for seed germination and irrigation.

Textile effluent discharge can negatively impact the environment and living organisms due to its potential toxicity, higher percentages of total organic carbon (TOC) contents, and so on. The study investigates the extraordinary performance of the electrocoagulation process (ECP) combined with powdered activated carbon (PAC) as a highly effective and environmental friendly method of treating textile effluents. This scientific work mainly includes the focus on removing toxic components in textile effluents, such as high concentrations of colour and TOC using synthesized PAC derived from coconut shells coupled with the ECP (ECP-PAC). Initially, PAC was characterized by using XRD, Raman, BET, FTIR, and TGA studies. Subsequently, the pilot-scale ECP-PAC batch reactor was constructed with iron (Fe) as an anode and copper (Cu) as a cathode. The pilot-scale ECP-PAC batch reactor has achieved higher treatment efficiency in a shorter reaction time with low energy consumption compared to a stand-alone ECP. Further, the optimum conditions for effective ECP-PAC have been optimized, such as pH 7.5, applied current density (0-50mA/cm2), reaction time (0-30min), electrode combinations (Fe-Cu) with electrode distances of 5cm apart, and an optimum dose of 5g/L of PAC. Specifically, 98% of the colour and 96% of the TOC contents present in the industrial textile effluent were treated in 15 and 30min, respectively. In quantitative perspectives, the developed batch reactor has sharply decreased TOC (324.1mg/L), IC (1410mg/L) and TC (1019mg/L) to 13.55mg/L (96%), 31.49mg/L (97%), and 48.05mg/L (95%), respectively, in 30min demonstrating its sensitivity and selectivity with the utmost care. Moreover, the physicochemical properties of the treated water were convincingly assessed. That is, it remains suitable for the seed germination of mung bean and chlorophyll content study. Thus, the developed methodology could effectively reduce freshwater consumption in the agricultural sector, increase freshwater availability in water-scarce regions, and facilitate the increase of the recharging capacity of groundwater tables.

Sequential electrocoagulation and Fenton/Photo-Fenton processes for the treatment of membrane bioreactor effluent of landfill leachate

Membrane Bioreactor (MBR) effluents can be characterized by high concentrations of resistant organic compounds and suspended solids. To improve the performance of advanced oxidation processes such as the Fenton and Photo-Fenton processes applied for resistant organic matter degradation, electrocoagulation (EC) was applied for effective suspended solids removal from leachate MBR effluent. In the EC process, the Al anode was combined with alternative cathodes (Al, Stainless Steel (SS), Gr, Ti), and the Al-SS anode-cathode combination was selected since it was the most effective combination based on chemical oxygen demand (COD) removal efficiency and specific energy consumption (SEC). The EC process parameters were optimized by Box-Behnken Design and 72.5% COD, 82.5% TSS, 71.1% UV254, and 92.5% color removal was obtained with the SEC value of 2.01 kWh/kg COD under optimum conditions (pH 6.87, current density 120 A/m2, and reaction time 17.3 min). Following the EC process, the Fenton and Photo-Fenton processes were conducted separately. Under the optimum conditions determined by conventional optimization; 71.9% COD, 90.3% color, 79.5% TSS, and 87.8% UV254 removal efficiencies were obtained by the Fenton process whereas 75.1% COD, 93.3% color, 82.0%, TSS and 89.8% UV254 removal efficiencies were obtained by the Photo-Fenton process. Total %92.3 and %93.1 COD removal efficiency were achieved by sequential EC-Fenton and EC-Photo-Fenton processes, respectively, and the final COD concentrations were 381 mg/L and 340 mg/L. Sequential separation-degradation processes showed good performance in the treatment of leachate MBR effluent and could be applied to the treatment of similarly characterized wastewater.

Evaluation of Using Sequential Electrocoagulation and Chemical Coagulation for Urea Removal from Synthetic and Domestic Wastewater

The presence of urea in wastewater can give rise to many issues, including the proliferation of algae as a consequence of eutrophication as well as the discharge of ammonia, which exerts a detrimental impact on aquatic organisms. To assess the efficacy of several treatment strategies for lowering urea concentrations, this study compared the removing performances of electrocoagulation (EC) with those of conducting electrocoagulation and chemical coagulation in sequence (EC-CC) or vice versa (CC-EC). Many effective parameters of electrocoagulation have been studied, such as current density, spacing between electrodes, electrolyte type, and electrolysis time. A scanning electron microscope was used to investigate the electrode morphology, and a Fourier transform infrared was conducted to analyze the formed sludge. The electrocoagulation was carried out at its optimum conditions at 30 A/m2, and the chemical coagulation was conducted using three types of iron coagulants: FeSO4, Fe2(SO4)3, and FeCl3. The results showed insufficient improvement in urea removal for synthetic and domestic wastewater via EC-CC, regardless of the coagulant type. The urea removal efficiency via EC-CC improved by less than 0.5% and 5.5% for synthetic and domestic wastewater, respectively. In contrast, CC-EC proved a better improvement for urea removal for both synthetic and domestic wastewater, but only for FeCl3. Treatment by CC-EC at 30 A/m2 for 60 min using iron electrodes and 0.5 g/L of FeCl3 resulted in an improvement in the removal efficiency of urea by about 3.4% and 10.40% for synthetic and domestic wastewater, respectively. CC-EC achieved better removal of COD from domestic wastewater than that achieved by EC-CC by 6%. The results obtained from the study indicate that the CC-EC process is a cost-effective method for removing urea from both synthetic and domestic wastewater.

Treatment of artificial pharmaceutical wastewater containing amoxicillin by a sequential electrocoagulation with calcium salt followed by nanofiltration

The present study deals with the treatment of an artificial pharmaceutical waste which contained amoxicillin (AMX) by using successively an electrocoagulation (EC) with Ca(NO3)2 as an electrolyte and a nanofiltration (NF) with a Nanomax-50 membrane. The effect of the current intensity and of the operating pressure was investigated for separately EC and NF, respectively. The AMX removal as a function of pH and initial AMX concentration was also investigated for the separately conducted EC and NF processes. The best percentage removal of AMX by EC and NF was recorded to be 52.7 % and 99.0 %, respectively. In the case of the sequential processes EC followed by NF, the removal of AMX was 98.2 % and 97.5 % at pH 2.5 and 10, respectively. The contribution of both EC and NF towards the AMX removal efficiency in the case of the sequential process was very much significant. It is remarkable that the EC pre-treated feed into NF was explored with several benefits such as high removal efficiency, calcium involved in EC process, prolonged membrane life and reduced power consumption. The electrogenerated solids (the sediment and the cathode deposit) were characterized using Fourier Transform Infra-red spectroscopy (FTIR), Energy Dispersive Spectroscopy (EDS) coupled to Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and Thermo Gravimetry Analysis (TGA). It appeared that calcium was involved in the electrogenerated solids. It gave a cathode deposit of Ca(OH)2 in which some AMX was embedded.

Efficient and sustainable treatment of tannery wastewater by a sequential electrocoagulation-UV photolytic process

Tannery wastewater contains large amounts of pollutants that, if directly discharged into ecosystems, can generate an environmental hazard. The present investigation has focused the attention to the remediation of wastewater originated from tanned leather in Tunisia. The analysis revealed wastewater with a high level of chemical oxygen demand (COD) of 7376 mgO2/L. The performance in reduction of COD, via electrocoagulation (EC) or UV photolysis or, finally, operating electrocoagulation and photolysis in sequence was examined. The effect of voltage and reaction time on COD reduction, as well as the phytotoxicity were determined. Treated effluents were analysed by UV spectroscopy, extracting the organic components with solvents differing in polarity. A sequential EC and UV treatment of the tannery wastewater has been proven effective in the reduction of COD. These treatments combined afforded 94.1 % of COD reduction, whereas the single EC and UV treatments afforded respectively 85.7 and 55.9 %. The final COD value of 428.7 mg/L was found largely below the limit of 1000 mg/L for admission of wastewater in public sewerage network. Germination tests of Hordeum Vulgare seeds indicated reduced toxicity for the remediated water. Energy consumptions of 33.33 kW h/m3 and 314.28 kW h/m3 were determined for the EC process and for the same followed by UV treatment. Both those technologies are yet available and ready for scale-up.

Removal of Intracellular and Extracellular Antibiotic Resistance Genes from Swine Wastewater by Sequential Electrocoagulation and Electro-Fenton Processes

Antibiotics are often used excessively in the livestock industry, and the effluent from livestock wastewater treatment is one of the main sources of antibiotic resistance genes (ARGs) in the enviro...

Efficient treatment for textile wastewater through sequential electrocoagulation, electrochemical oxidation and adsorption processes: Optimization and toxicity assessment

In this work, the sequential Electrocoagulation + Electro-oxidation + Activated carbon adsorption (EC + EO + AC) process was studied as an alternative for the treatment of an industrial textile wastewater (TWW) issuing from a manufacturing company located in Medellín (Colombia). The EC's and EO's operational conditions were optimized using a Box-Behnken experimental design, the Response Surface Methodology and a constrained nonlinear optimization algorithm in terms of organic matter degradation efficiency. The best performance for EC (i. e., dye removal = 94%, COD and TOC degradation of 45 and 40%, respectively) was obtained using Fe anode and Boron Doped Diamond (BDD) cathode, with current density, j EC , equals to 5 mA/cm 2 , pH = 9.3, 60 RPM and 10 min of electrolysis. After EC treatment, the effluent biodegradability (evaluated as the BOD 5 /COD ratio) increases from 0.14 to 0.23. Regrettably, EC was not effective for the removal of acute toxicity to Artemia salina since the treated effluent remained very toxic (100%). The treatment of EC's effluent by EO enhanced organic pollutant removal. For EC + EO sequential process, EO optimal operational conditions ( j EO = 10 mA/cm 2 , pH = 3, 240 RPM , BDD as anode and Fe as cathode) allowed reduction of 100% of color, 88% of COD and 79% of TOC after 30 min of electrolysis. Moreover, the BOD 5 /COD ratio increased from 0.23 to 0.58; however, the treated effluent remained very toxic to the Artemia salina . Consequently, an activated carbon adsorption step was included to complete the treatment process. Thus, by coupling the EC + EO + AC process, effluent's acute toxicity decreased completely. From molecular weight distribution analysis, it was concluded that EC + EO was efficient in eliminating low molecular weight (< 5 kDa) compounds. Finally, the operation cost, which includes chemical reagents, electrodes, energy consumption, and sludge disposal, for the EC + EO + AC sequential process was estimated in 3.83 USD /m 3 . Graphical abstract

Efficient treatment for landfill leachate through sequential electrocoagulation, electrooxidation and PMS/UV/CuFe2O4 process

Landfill leachate is well known as one of the most serious environmental problems due to the high concentrations of organic and inorganic compounds. Several methods have been reported for the treatment and detoxification of landfill leachate. However, high organic load and the presence of refractory organic pollutants resulted in inefficiency of those methods when at least applied alone. The present work recommended a sequence of processes: electrocoagulation (EC), electrooxidation (EO) and peroxymonosulfate (PMS)/UV/CuFe2O4 (sulfate radical-based advanced oxidation process, SR-AOP) for treatment of landfill leachate. A parametric evaluation was conducted for each process including pH, current densities, electrode type, catalyst loading, PMS dosage and reaction time. Al and Fe electrodes for the EC process and Pt, PbO2 and graphite for the EO process were investigated. The results showed that Fe and PbO2 were more efficient than other electrodes for EC and EO respectively. COD removal efficiencies were up to 60.0, 50.0 and 77.9% for EC, EO and SR-AOP, respectively. Removal efficiencies for the sequential process were 95.6, 90.5, 91.6 and 99.8% for COD, TOC, BOD and ammonia (NH4-N) respectively. Biodegradability was significantly enhanced according to the BOD/COD ratio and the average oxidation state of carbon (AOSC). Biodegradation test indicated that the organic matter was completely degraded by activated sludge in seven days. Phytotoxicity experiments also demonstrated a considerable reduction in phytotoxicity after each process. The results confirmed that the proposed sequence is efficient for COD removal, phytotoxicity reduction and biodegradability improvement being an acceptable treatment for landfill leachates.

Enhanced cork-boiling wastewater treatment by electro-assisted processes

In the cork processing industry, a large amount of highly polluted wastewater is generated during the cork-boiling step. In this work, we propose two novel approaches for the treatment of cork-boiling wastewater (CBW): (i) a sequential electro-coagulation coupled to Fenton oxidation process (EC + Fenton) and (ii) the electro-Fenton process (EF). Both technologies were tested at 80 °C with the stoichiometric dose of H2O2 required for complete mineralization of the organic matter. Both treatments resulted in a high TOC conversion, around 87%, with complete phenolic compounds removal. The resulting effluents were biodegradable (BOD5/COD > 0.65), containing non-toxic carboxylic acids as formic, acetic, oxalic and malonic acids. Regarding the economy of the process, the main cost is related to H2O2 consumption. In this sense, an initial physic-chemical pretreatment diminished the oxidant requirements and thus, the operational costs can be reduced by 40% in the EC + Fenton process.

Integrated electrochemical processes for textile industry wastewater treatment: system performances and sludge settling characteristics

Textile wastewater containing toxic dyes needs efficient treatment before being released into the environment. Certain dyes are known or presumed to have carcinogenic potential for humans. In this work, hybrid electrochemical processes including electrocoagulation (EC) alone and combined with electro Fenton (EF), anodic oxidation (AO) and peroxi-coagulation (PC) were tested to treat real textile wastewater using a batch reactor. A sequential EC and EF (EC-EF) process was found to be more effective. The experimental results indicated that the effectiveness of the treatment decreases in the following order: EC-EF > EC-AO > EC-PC > EC. EC-EF results showed a decrease in chemical oxygen demand (COD, 97%), total organic carbon (98%), total suspended solids (98%), and the concentration of metal species; showing that the treatment of such wastewater type can be achieved by combined EC-EF process in a one-pot bench-scale reactor. The electrical energy consumption, the iron dissolution, and the biological oxygen demand/COD ratios of EC and EC-EF processes were evaluated. Characterization of the sludge generated during EC treatment at current density of 20 mA cm− 2 was carried out. Precipitation, adsorption, and electrochemical oxidation/reduction of organic dyes and metallic ions occurred during the treatment. This investigation shows the efficiency of combined EC-EF to treat textile wastewater.

Enhanced Removal of Phosphorus from Wastewater Using Sequential Electrocoagulation and Chemical Coagulation

An electrokinetic batch treatment scheme was investigated combining sequential electrocoagulation (EC) and chemical coagulation treatment (CC) processes. Synthetic and microbrewery wastewaters were tested in this investigation. The generated results demonstrated the capacity for the integration of EC-CC to effectively remove phosphorus contamination from wastewater under varying operating conditions. The effect of several operational parameters such as current density, conductivity, nutrient loading, and electrolysis time were investigated. The results showed that increased salinity can significantly accelerate the removal of phosphorous during EC treatment with 84.2% and 92.4% removal found for the applied power of 5 and 10 W, respectively. The addition of a sequential chemical coagulant stage following treatment by EC demonstrated the potential for an integrated EC-CC system to lower energy consumption while maintaining effective nutrient removal capabilities. Removal of phosphorous at 95% and 98% was achieved in just 10 min of EC treatment coupled with the addition of 15 mg/L aluminum sulfate. The estimated power consumption over a 10-min period was found to be 0.28 Kwh/m3 with a dissolution rate of 0.28 g/cm2 min held at a constant current density. The experimental anode dissolution rate for the synthetic wastewater ranged between 0.13 and 0.24 g/cm2 min encompassing all salinity levels. The anode dissolution rate increased during treatment of microbrewery wastewater with 0.67 g/cm2 min for 10 W EC treatment. This was attributed to the increase in current density and nutrient loading resulting in increased energy consumption and electrode passivation.

Sequential treatment of crude drug effluent for the elimination of API by combined electro-assisted coagulation-photocatalytic oxidation

This work reports the elimination of the emerging contaminant cefixime, an active pharmaceutical ingredient (API) from Indian based drug effluent. A sequential two step electrocoagulation (EC) and photocatalytic oxidation treatment is proposed to eliminate the API below its minimum inhibitory concentration (MIC). This study is prominent due to the treatment of high strength crude drug effluent, with total organic carbon (TOC) of 7395 mg/l, in order to reduce the organic load with complete elimination of pre-existing microbial population. Treatment processes were conducted in batch reactors, in which, EC was carried out by two electrodes viz. Aluminum and Iron. On optimization, at 10 V and 24 V for aluminum and iron electrode, TOC was found to reduce by 14% and 22% respectively. By Fenton’s reaction with iron electrode, 41% TOC removal was observed, with reduction of cefixime to 0.01 mg/l. On step two EC with H2O2, a further 2% TOC removal facilitated in reduction of cefixime to 0.001 mg/l, determined by HPLC-MS (High Performance Liquid Chromatography-Mass Spectrometry). The sequential EC treated-diluted effluent, subjected to TiO2 and H2O2 assisted photocatalytic oxidation by natural sunlight and UV source, separately, resulted in further TOC reduction of 30% and 33% respectively. EC treatment effectively reduced the API below MIC (6 mg/l), determined by antimicrobial activity and EC-Fenton’s reaction allowed elimination of pre-existing bacteria in effluent, below the lower limit of detection (LOD) i.e., 0.5 colony forming units (CFU)/ml. Thus, this work highlights the significance of non-biological treatments of drug effluents to prevent microbial drug resistance in environment.

Photoelectro-Fenton as post-treatment for electrocoagulated benzophenone-3-loaded synthetic and urban wastewater

The removal of benzophenone-3 (BP-3), a ubiquitous pollutant in municipal wastewater treatment facilities, was optimal by means of a sequential electrocoagulation (EC)/UVA photoelectro-Fenton (PEF) treatment. Overall mineralization was attained upon combination of EC (Fe/Fe cell, 15 mA cm−2, 20 min) with PEF (boron-doped diamond/air-diffusion cell, 33.3 mA cm−2, 720 min), being superior to EC/electro-Fenton (EF) and requiring shorter time than single PEF. In EC, an Al/Al cell yielded the largest removal of BP-3 in a simulated matrix at pH 11.0 due to precipitation of its neutral form caused by a substantial pH drop, with optimum current density of 15 mA cm−2. EC of BP-3-loaded urban wastewater at natural pH was quite effective also with a Fe/Fe cell, being preferred since it provided the required metal catalyst for subsequent treatment. Among the electrochemical advanced oxidation processes tested, PEF was superior to electrochemical oxidation with electrogenerated H2O2 (EO-H2O2) and EF, especially when using the boron-doped diamond instead of a RuO2-based anode, due to the oxidation of generated active chlorine and hydroxyl radicals, along with the photolytic action of UVA irradiation. GC-MS revealed the formation of 14 cyclic products in PEF treatment, two of them being also formed during EC.

Optimization and toxicity assessment of a combined electrocoagulation, H2O2/Fe2+/UV and activated carbon adsorption for textile wastewater treatment

In this study, the potential application of sequential Electrocoagulation + Fenton (F) or Photo-Fenton (PF) + Active carbon adsorption (EC + F/PF + AC) processes were analyzed as alternatives for the treatment of an industrial textile wastewater resulting from an industrial facility located in Medellín (Colombia). In order to maximize the organic matter degradation, each step of the treatment was optimized using the Response Surface Methodology. At first, the optimal performance of EC was achieved with Fe electrodes operating at pH = 7, jEC = 10 mA/cm2 and 60 rpm, during 10 min of electrolysis. At these conditions, EC let to remove 94% of the dye's color, 56% of the COD and 54% of the TOC. Next, sequentially applied Fenton or photo-Fenton process (i.e., EC + F/PF), operating at the optimized conditions (pH = 4.3, [Fe2+] = 1.1 mM, [H2O2] = 9.7 mM, stirring velocity = 100 rpm and reaction time = 60 min.), improved the quality of the treated effluent. The EC + F let to achieve total color reduction, as well as COD and TOC removals of 72 and 75%, respectively. The EC + PF reached 100% of color, 76% of COD and 78% of TOC reductions. The EC + F/PF processes were more efficient than EC in elimination of low molecular weight (<5 kDa) compounds from wastewater. Moreover, the BOD5/COD ratio increased from 0.21 to 0.42 and from 0.21 to 0.46 using EC + F and EC + PF processes, respectively. However, EC + F/PF were not fully effective for the removal of acute toxicity to Artemia salina: 20% and 60% of reduction in toxicity using EC + F and EC + PF, respectively, comparing to very toxic (100%) raw textile wastewater. Thus, activated carbon adsorption was applied as an additional step to complete the treatment. After AC adsorption, the acute toxicity decreased to 10% and 0% using EC + F and EC + PF, respectively. The total operational costs, including chemical reagents, electrodes, energy consumption and sludge disposal, were of 1.65 USD/m3 and 2.3 USD/m3 for EC + F and EC + PF, respectively.

Inactivation of microbiota from urban wastewater by single and sequential electrocoagulation and electro-Fenton treatments

This work aims at comparing the ability of two kinds of electrochemical technologies, namely electrocoagulation (EC) and electro-Fenton (EF), to disinfect primary and secondary effluents from municipal wastewater treatment plants. Heterotrophic bacteria, Escherichia coli, enterococci, Clostridium perfringens spores, somatic coliphages and eukaryotes (amoebae, flagellates, ciliates and metazoa) were tested as indicator microorganisms. EC with an Fe/Fe cell at 200 A m−2 and natural pH allowed >5 log unit removal of E. coli and final concentration below 1 bacteria mL−1 of coliphages and eukaryotes from both effluents in ca. 60 min, whereas heterotrophic bacteria, enterococci and spores were more resistant. A larger removal was obtained for the primary effluent, probably because the flocs remove higher amount of total organic carbon (TOC), entrapping more easily the microbiota. EF with a boron-doped diamond (BDD) anode and an air-diffusion cathode that produces H2O2 on site was first performed at pH 3.0, with large or even total inactivation of microorganisms within 30 min. A more effective microorganism removal was attained as compared to EC thanks to •OH formed from Fenton's reaction. A quicker disinfection was observed for the secondary effluent owing to its lower TOC content, allowing the attack of greater quantities of electrogenerated oxidants on microorganisms. Wastewater disinfection by EF was also feasible at natural pH (∼7), showing similar abatement of active microorganisms as a result of the synergistic action of generated oxidants like active chlorine and coagulation with iron hydroxides. A sequential EC/EF treatment (30 min each) was more effective for a combined decontamination and disinfection of urban wastewater.

Moody mares – ovariectomy in the horse

ABSTRACT:Ovariectomy is a treatment employed in the mare for removal of granulosa theca cell tumours (GCT), and for behaviour modification in mares that become aggressive during oestrus. The most common technique is laparoscopic ovariectomy under standing sedation, using sequential electrocoagulation and transection of the mesovarium. In the treatment of GCT the prognosis for resolution of behaviour and return to normal fertility is excellent. When treating mares exhibiting aggressive behaviour during oestrus, approximately 75 per cent of mares will show a significant improvement in their behaviour, over a course of up to 18 months.

Optimisation of reactive dye removal by sequential electrocoagulation–flocculation method: comparing ANN and RSM prediction

The removal of Reactive Black 5 dye in an aqueous solution by electrocoagulation (EC) as well as addition of flocculant was investigated. The effect of operational parameters, i.e. current density, treatment time, solution conductivity and polymer dosage, was investigated. Two models, namely the artificial neural network (ANN) and the response surface method (RSM), were used to model the effect of independent variables on percentage of dye removal. The findings of this work showed that current density, treatment time and dosage of polymer had the most significant effect on percentage of dye removal (p<0.001). In addition, interaction between time and current density, time and dosage of polymer, current density and dosage of polymer also significantly affected the percentage of dye removal (p=0.034, 0.003 and 0.024, respectively). It was shown that both the ANN and RSM models were able to predict well the experimental results (R(2)>0.8).

Laparoscopic ovariectomy using sequential electrocoagulation and sharp transection of the equine mesovarium.

To describe in horses and ponies a laparoscopic ovariectomy technique facilitated by electrosurgical instrumentation. Elective ovariectomy was performed in 23 mares using laparoscopic electrosurgical instrumentation. Twenty-three mares (13 horses, 10 ponies), aged from 2 to 21 years and weighing 90 to 545 kg. Food was withheld for a minimum of 12 hours. Mares were sedated with detomidine hydrochloride (0.02 to 0.03 mg/kg) or xylazine hydrochloride (0.5 to 1.0 mg/kg). Excluding the pony mares, all other mares were restrained in stocks. Portal sites in the paralumbar fossa region were desensitized with 2% mepivacaine. Abdominal insufflation was achieved through a teat cannula positioned in the ventral abdomen or a Verres-type needle placed through the paralumbar fossa. After trocar and laparoscope insertion, the ipsilateral ovary and mesovarium were identified, and the mesovarium, tubal membrane, and proper ligament were infiltrated with 2% mepivacaine. The mesovarium was coagulated using bipolar or monopolar electrosurgical forceps and transected sequentially from cranial to caudal until the ovary was completely freed and then removed. The contralateral ovary was removed in a similar fashion through the opposite paralumbar fossa. Bipolar and monopolar electrosurgical forceps were easy to use and provided adequate coagulation of vessels within the mesovarium. Two mares were euthanatized after the procedure for unrelated reasons. One mare had mild signs of colic 24 hours after ovariectomy. In 1 pony mare, the incision used to remove one ovary dehisced on the 5th postoperative day and was allowed to heal by second-intention. No long-term complications had occurred in 11 horses and 10 ponies, 6 to 24 months after surgery. Laparoscopic ovariectomy and hemostasis of the mesovarium can be easily accomplished using electrosurgical instrumentation. Standing laparoscopic ovariectomy, using electrosurgical instrumentation, is an effective and safe technique to provide hemostasis of the mesovarium in mares.