Electrocoagulation Sludge Research Articles

Zn-Al@LDH infused hydrochar as cathode catalyst for upgrading tetracycline degradation and hospital wastewater treatment: A synergy of Fenton-like and bio-electrochemical systems

The present investigation proposed a “Bio-electro-Fenton like (BEFL)” approach for the treatment of antibiotic (tetracycline, TC) containing wastewater. The system is modified using a uniquely developed cathode catalyst Zn-Al@layered double hydroxide (LDH) supported by low-cost carbonaceous material hydrochar (i.e., Zn-Al@LDH/HC), derived from anaerobic digestate and electrocoagulation sludge (waste materials). The result revealed nearly 96.90 ± 0.25 % removal of 10 mg/L of TC as well as about 89.50 ± 0.45 % abatement of total organic carbon (TOC) during 240 min of treatment time using Zn-Al@LDH/HC based BEFL system. Simultaneously, the chemical oxygen demand (COD) abatement in the anodic chamber (with glucose as substrate having COD of 1000 mg/L) was observed to be 85.16 ± 0.50 %. In-situ hydrogen peroxide (46.2 ± 1.2 mg/L as mean 4 h concentration) generation capability of the Zn-Al@LDH/HC was responsible for the outstanding performance of BEFL system. Additionally, the BEFL was also proficient in generation of bioelectricity (1141 ± 25 mA/m2) via the microbial activity in the anodic chamber. Further, the technology was extended for TC degradation in presence of surfactants and real hospital wastewater to depict the effect of real field conditions on the performance of as-synthesized waste derived catalyst. Intermediate products formed, the mechanism of TC degradation, and the phytotoxicity assessment were also illustrated to confirm the negligible toxicity of the treated effluent. Overall, deriving the catalyst from waste materials would reduce the scale-up cost of the proposed technology, enhance environmental sustainability, and contribute to circular economy.

Unraveling synergistic mechanisms of enhanced electrocoagulation sludge dewatering using modified sludge-based biochar

Electrocoagulation (EC) is an environmentally friendly and efficient method that enhances sludge dewatering. However, EC has limited cracking efficiency for extracellular polymeric substances (EPS) and sludge cells. In this study, sludge-based biochar prepared by KOH impregnation (SB-KOH) was added to the EC process as both conductor and skeleton particles of the EC sludge dewatering system. As a result, the current transmission capacity and the “flocculation” effect of sludge were enhanced by SB-KOH. By optimizing the voltage, carbon dosage, specific resistance to filtration (SRF), and capillary suction time (CST0/CST), using enlarged plate area (EFe-EC + SB-KOH) and anode material replacement (Al-EC + SB-KOH), enhanced sludge dewatering performance was achieved. The results showed that SRF and CST0/CST were reduced by 66.29 % and 75.71 %, respectively, when using SB-KOH with optimal EC voltage of 25 V and 15 % dry solid (DS). In addition, the Zeta potential of the system and the sludge particle size were increased, and the surface roughness of flocs was reduced. Three-dimensional fluorescence (3D-EEM) analysis indicated that EC + SB-KOH greatly decomposed aromatic protein-like substances in EPS and led to internal material transfer or absorption. Scanning electron microscopy (SEM) and particle size analysis showed that EC + SB-KOH was beneficial to achieve stronger flocculation and solid-liquid separation performance. The above findings indicate that the efficiency of sludge dewatering was enhanced using SB-KOH self-circulation technology, which provides a validation basis for green and sustainable development.

Electrocoagulation treatment of paint wastewater from equipment cleaning and conversion of by-product sludge into nano-pigment

This work aims to treat paint wastewater from industrial equipment cleaning by electrocoagulation (EC) using aluminum electrodes and reusing residual sludge as a starting material for synthesizing a blue inorganic nano-pigment. An initial pH of the wastewater without adjustment, a current density of 133.33 A/m2, an electrolysis time of 30 min and an inter-electrode distance (IED) of 2 cm were the best operating conditions for EC. The reduction rate of COD and turbidity was about 92% and 99.6%, respectively. At optimum conditions, specific metal consumption and specific electrical energy consumption are about 0.168 kg/m3 and 15 kWh/m3, respectively. The paint wastewater treatment sludge (PWTS) from EC was first characterized and then mixed with cobalt(II) chloride to synthesize an inorganic blue nano-pigment. The effects of Co/Al molar ratios and temperatures were studied. From colorimetric data, the pigment obtained at 1100 °C is more bluish than those synthesized at a lower temperature. This study will have beneficial effects on the environment as well as on the economy because it makes it possible to transform PWTS into value-added products. Treated wastewater can be reused for paint equipment cleaning and EC sludge can be completely transformed into pigment. The zero-waste principle can therefore be achieved.

An economical electrocoagulation process of a hazardous anionic azo dye wastewater with the combination of recycled electrodes and solar energy.

The energy and electrode costs are the restrictions of applying electrocoagulation (EC) in wastewater treatment and many attempts have been made to decrease these costs. In this study, an economical EC was investigated to treat a hazardous anionic azo dye wastewater (DW) that threatens the environment and human health. Firstly, an electrode for EC process was produced from recycled aluminum cans (RACs) by remelting in an induction melting furnace. The performance of the RAC electrodes in the EC was evaluated for COD, color removal, and the EC operating parameters such as initial pH, current density (CD), and electrolysis time. Response surface methodology which is based on central composite design (RSM-CCD) was used for the optimization of the process parameters which were found to be pH 3.96, CD 15mA/cm2, and electrolysis time 45min. The maximum COD and color removal values were determined as 98.87% and 99.07%, respectively. The characterization of electrodes and the EC sludge was conducted by XRD, SEM, and EDS analyses for the optimum variables. In addition, the corrosion test was conducted to determine the theoretical lifetime of the electrodes. The results showed that the RAC electrodes show an extended lifetime as compared to their counterparts. Secondly, the energy cost required to treat DW in the EC was aimed to decrease by using solar panels (PV), and the optimum number of PV for the EC was determined by the MATLAB/Simulink. Consequently, the EC with low treatment cost was proposed for the treatment of DW. An economical and efficient EC process for waste management and energy policies was investigated in the present study which will be instrumental in the emergence of new understandings.

Use of Fe and Al Containing Electrocoagulation Sludge as an Adsorbent and a Catalyst in Water Treatment

In this study, three different electrocoagulation (EC) sludges were studied as an adsorbent (removal of humic acids) and as a catalyst [catalytic wet peroxide oxidation (CWPO) of bisphenol A (BPA)]. The sludges originated from electrocoagulation process in which aluminum (Al) and iron (Fe) electrodes were used for the treatment of mining industry wastewater. All the materials were used as dried sludge and calcined material. The stability of these materials was studied in neutral and alkaline conditions with analysis of the leached iron content in solution. Based on the EC sludge characterization with X-ray fluorescence (XRF), X-ray diffractometer (XRD), and diffuse-reflectance infrared Fourier transform (DRIFT) spectroscopy different forms of Fe occurring in EC sludges were found. The Brunauer–Emmett–Teller (BET) method showed reduced surface area after calcination process. Stability of the sludges was studied in neutral conditions, and the amount of iron leaching was low (<1.4 ppm). Adsorption experiments showed that the removal of humic acids (measured as total organic carbon) was over 50% in all tested materials in the pH range of 3–9, and over 92% with the S3 calcined material in all studied pH range. The calcined samples were catalytically more active than raw material in CWPO of BPA. The highest removal of BPA was 85% over calcined sludge. Therefore, calcined EC sludges are suitable materials for catalyst and adsorbent use. The main novelty of this paper was the finding of sludge modification in the EC process of water treatment through different electrode material and current density. This modification can be made in EC water treatment process, and it may provide low-cost materials to different utilization of EC sludge.

Binary sacrificial anodes using transition metals (M + Fe, M = Ni, Cu, Zn) for electrocoagulation of boron and recovery of magnetic spinel oxides

Electrocoagulation (EC) using metals Fe, Cu, Ni, Zn, and Al as sacrificial anodes was performed for boron removal. Boron (B) was efficiently swept by the EC sludge that could be recovered as spinel oxides when combined the two anodes, Cu + Fe, Ni + Fe, Zn + Fe, and Ni + Al, and Al cathode. Effects of EC conditions, such as applied current, pH, initial concentration, on the faradaic efficiency, energy consumption, and B removal were investigated. A consecutive kinetic model was proposed to evaluate the rates of coagulation and metal dissolution as affected by the metal type and current density. The coagulant generated during EC was magnetic ferrites, including CuFe2O4 (20.23 emu g−1), NiFe2O4 (51 emu g−1), and ZnFe2O4 (6.54 emu g−1) (emu = electromagnetic unit), depending on the type of two anodes. The dissolution potential (i.e., open circuit potential) of metals influenced the sludge formation under constant current, while the electrostatic interactions between the sludge and B were the determining factor in the EC efficacy. EC was optimized at pH where the positively charged coagulants tended to trap boron oxyanions (B(OH)4−). Among combined metals, EC sludge of Ni + Fe and Ni + Al had relatively high coagulation capacity due to the high pHpzc, which obtained higher than 90% removal ([B]0 = 100 mg L−1) at 12.5 mA cm−2 in one hour.

Sulphate Removal in Industrial Effluents Using Electrocoagulation Sludge as an Adsorbent

The high concentration of sulphates is detrimental to the infrastructure of wastewater treatment plants. Hence in this study, we present the application of electrocoagulation sludge as an adsorbent to remove sulphates from industrial effluents before they are released back to the environment. The sludge contains iron and aluminium cations and cationic complexes that precipitate sulphates in water. Corrugated iron sheet was used as a sacrificial electrode during electrocoagulation (EC) to generate sludge. FTIR, XRD, SEM, TEM, and Zeta Potential were used to characterize the sludge. The following parameters: contact time, pH, initial concentration, and adsorbent dosage were optimized to 120 min, 2, 100 mg/L and 150 mg, respectively. For the synthetic water, the sulphate removal was 99.1%, whereas for the real water it was found to be 98.7%. The adsorption capacity of the EC sludge was 66.76% for 2 h under acidic conditions. The Langmuir isotherm fitted better than the Freundlich isotherm. This confirmed the homogenous distribution of the active sites on the EC sludge. At different EC’s sludge, the pseudo-second order kinetic model produced the best fitting experimental results which confirmed the removal of sulphate ions by chemisorption. This approach (method) is useful for purifying industrial effluents before they are discharged into the environment.

Post-tanning wastewater treatment using electrocoagulation: Optimization, kinetics, and settlement analysis

Post-tanning process in the tannery industry generates complex wastewater. Continuous electrocoagulation (EC) with carbon-steel electrodes was used to treat synthetic/post-tanning wastewater. Research surface methodology, based on central composite design (RSM-CCD), was used for variables optimization and analysis of variance (ANOVA) to relate all parameters. Optimal variables were identified as initial pH 3.0, current density 6.4 mA m−2, initial dye concentration 125 mg L−1, NaCl concentration 1000 mg L−1, and inlet flow rate 176 mL min−1 to produce 71% dye removal, operational costs (OC) 0.05 US$ m−3, power consumption 1.3 kWh m−3, iron consumption 0.05 kg m−3, dye removal capacity per dissolved mg iron (qe) 4.3 mg Dye L−1 C−1 and total dissolved solids (TDS) removal 43.5%. Best process conditions were used to treat real post-tanning wastewater and resulted in carbon oxygen demand (COD) and TDS abatement (23% and 76%, respectively), as well as low OC (0.84 US$ m−3) and energy consumption (20.6 kWh m−3). Pseudo-first-order kinetic model was found fitting experimental results, having electrical energy per order (EEO) of 1 kW h m−1 order−1 with a higher k = 1.14 min−1. Scanning electron microscopy analysis suggested the presence of iron nanoparticles within the sludge. All input and output parameters resulted in statistically significant where TDS and qe were the most valued for effective pollutant removal optimization and prevention of TDS increase in treated water. The outcomes of this study suggest EC as a suitable treatment for post-tanning wastewater and further knowledge of steel-carbon EC reactor design and sludge reusing purposes.

River water treatment by continuous electrocoagulation: insights into removal of acetaminophen, and natural organic matter

Abstract River water was treated by continuous electrocoagulation (EC) for acetaminophen (AP), natural organic matter (NOM measured as UV254), and removal of elements. HRT at 40 min with 0.5 mg/L AP exhibited the best removal efficiency for NOM (55.9%) and AP (53.4%) removal. Except for aluminium, other elements in river water were removed completely. The EC sludge (floating and settled) XRD spectrum showed peaks from AP were reduced, and the few peaks left were from aluminium hydroxide formed by EC. Several bonds in functional groups of AP and NOM were significantly deformed. FESEM images revealed that the sludge was highly porous material as needed for adsorption. EDAX showed that floating sludge had slightly higher carbon compared with settled sludge whereas nitrogen was higher in settled sludge. Other element concentrations in both sludges were similar, proving that water treatment was due to electro-floatation, adsorption, and sweep flocs. Single-factor ANOVA showed significant variance at HRT for NOM (F4.066 = 92.67, p = &amp;lt;0.05) and AP (F4.066 = 20.59, p = &amp;lt;0.05) removal. Variance was significant between treatments at different drug concentrations for NOM (F3.478 = 88.53, p = &amp;lt;0.05) and AP (F3.478 = 529.85, p = &amp;lt;0.05) removal. NOM removal correlated well with AP removal during continuous electrocoagulation.

Efficiency of the heterogeneous catalyst from electrocoagulation sludge for the removal of methylene blue in the presence of persulfate

Persulfate activation by heterogeneous catalysts based on transition metals is of interest in textile effluent treatment processes. Thus, iron-rich electrocoagulation sludge has been thermally treated to obtain new catalysts. The characterization of this catalyst by X-ray diffraction revealed the presence of FeAl2O4 nanoparticles active in the decomposition of persulfate into sulfate radicals (SO4 •−). The efficiency of catalyst/persulfate was monitored during the methylene blue (MB) solution discoloration. The effects of temperature, pH, initial MB concentration, catalyst dose and persulfate dose were also studied. MB removal catalytic activity showed around 94% discoloration and 45.7% TOC reduction after 180 minutes batch reaction at pH = 4.0 (catalyst dose: 0.5 g/L, persulfate dose: 1 g/L; initial MB concentration: 20 mg/L). This catalyst reuse further confirmed its catalytic potential as a discoloration rate of about 82.45% was obtained after five cycles. The biodegradability monitoring measured by the carbon oxidation state (COS) has revealed a remarkable and continuous degradation of organic compounds. The EPR tests revealed that this catalytic reaction generates the radical species responsible for the degradation of MB. Finally, these results show that this catalyst from the thermal activation of electrocoagulation sludge is capable of decomposing persulfate to degrade bioresistant compounds such as textile dyes.

Electrocoagulation Sludge Valorization—A Review

In the field of electrocoagulation (EC), various studies on pollutant removal and on the use of different EC technologies have already been made. An EC process generates sludge, which is considered waste, resulting in increased operational costs that come from waste disposal. Sludge contains valuable materials, such as the nutrients or metals removed during water purification, along with metals, such as aluminum or iron, which come from the electrodes used in an EC system. Based on the principles of circular economy or based on existing legislations, reducing the production of valuable wastes, and increasing the valorization rate of as many materials as possible are important endeavors. This study is mainly a review of the existing sludge valorization studies. This review highlights the valorization of sludge as a fertilizer (mainly as struvite), pigment, construction material (mainly as blocks), adsorbent, and catalyst. While it has already been found that EC sludge is valorizable, more studies on EC sludge valorization and on the quality of sludge produced from the effluent of EC processes are warranted.

Concurrent removal of hardness and fluoride in water by monopolar electrocoagulation

Water treatment based on electrocoagulation (EC) is attractive since required chemicals and colloids are produced in-situ. However, optimisation of EC operation parameters is necessary to enhance its efficiency. We optimised EC cell parameters by the response surface method (RSM). The optimal removal efficiencies of hardness (63%) and fluoride (97%) were achieved at 1.98 kW h/m3. With the removal of divalent cations, some anionic species concurrently remove via an energetically feasible route to adjust the charge balance. When simulated water is used (450 mg/L TDS, 580 mg/L CaCO3, 10 mg/L fluorides and pH 6.50), 83% hardness and 99% fluoride are removed with 0.69 kW h/m2 energy consumption. The chemical species in the solution matrix, particularly SO42, significantly affect the hardness and fluoride removal efficiencies. The contaminated EC sludge resulted from feed water is characterised by spectroscopic methods to probe hardness and fluoride removal mechanisms. In the presence of Mg2+, F- interacts with Al-sludge sites forming≡MgF−OH. When Ca2+ and F- are present, both ≡CaF−OH and ≡CaF are formed. In Ca2+, Mg2+ and F- treated Al-sludge dominates CaF−OH and ≡CaF over ≡MgF−OH.

Recycling electro-coagulated sludge from textile wastewater treatment plants as an adsorbent for the adsorptions of fluoride in an aqueous solution

This research investigated the high content of iron-based materials from recycled electro-coagulated (EC) sludge for the adsorptive removal of fluoride, and the properties of the material were characterized. The thermal activation of EC sludge in which the unwanted impurity was removed by beneficiation and thermally activated at 500 °C, and was used for fluoride removal. Basic operating parameters (mixing time, adsorbent dosage, adsorbate concentration, solution pH, and temperature) were examined to evaluate the optimum de-fluoridation capacity (DC). The functional groups, the crystalline structure, and surface morphology of thermally treated and raw EC sludge were analyzed using FTIR, XRD, and SEM, respectively, and demonstrates that thermally activated EC sludge contains significant content of magnetite and hematite. The optimum DC was recorded as 5.12 mg of F−/gm with experimental conditions: mixing time = 20 min, adsorbent dosage = 0.3 gm/100 ml, initial fluoride concentration = 1 mg/L, and pH = 5 at the temperature of 353 K. The Langmuir isotherm model was fitted, and the capacity is calculated as 6.43 mg/g. The adsorption process follows the Pseudo-Second-order kinetic models. It can be concluded that the prepared adsorbents have excellent fluoride removal capacity, and EC sludge can be used as an alternative adsorbent for de-fluoridation.

Use of alumina sludge arising from an electrocoagulation process as functional mesoporous microcapsules for active corrosion protection of aluminum

The process of fluoride removal from underground water using the electrocoagulation technique with aluminum electrodes results in the generation of large amounts of drinking-water treatment sludge (DWTS) corresponding to electrocoagulated metal hydroxide sludge (EMHS). EMHS, hazardous for the environment, must be adequately managed from the water treatment plant, causing an additional cost to the process and an environmental impact from its disposal. In this study, the revaluation of the EMHS produced using a laboratory scale electrocoagulation reactor with aluminum electrodes was investigated for the manufacture of mesoporous alumina microcapsules (MAMs). The obtained microcapsules have been characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), zeta-potential measurement, thermal gravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) techniques, allowing them to be classified as mesoporous particles of micro and nanometer dimensions. These particles were used as microcapsules to contain corrosion inhibitors (namely, 8-hydroxyquinoline and benzotriazole), and they were subsequently dispersed in a commercial polymer matrix employed to protect aluminum from the corrosive attack of the environment. The corrosion resistance of the resulting functionalized coatings has been characterized by electrochemical impedance spectroscopy (EIS) in the case of artificially-defective coatings, demonstrating that these MAM’s released locally the corrosion inhibitor to effectively heal the damaged area of the metal. The overall study demonstrates that the electrocoagulation sludge can be employed to produce microcapsules for efficient anticorrosion protection of engineering metals.

Synthesis and characterization of α-Fe2O3/γ-Fe2O3-nanoparticles from recyclable electro-coagulated sludge: insights and predictions for different application

This research work reports on the synthesis and characterization of iron oxide nanoparticles from sludge. Precipitates generated from the electro-coagulation process were collected, size reduced, beneficiated, and thermally treated in an inert atmosphere to form iron oxide nanoparticles. Structural, surface, and optical properties of raw and thermally treated sludge were examined using XRD, SEM, FTIR, UV/Vis, TGA/DTA, and Zeta Potential. The X-ray diffraction pattern confirmed that as the sludge is annealed at a temperature of 100, 300, 500, and 800 °C, the phase transformed to goethite, magnetite, maghemite, and hematite respectively. Pure hematite weere formed at the highest temperature. The crystallite size of hematite nanoparticle was calculated using the two most intense diffraction peaks and found to be about 30.4 nm at 800 °C and 28.3 nm at 500 °C. The SEM micrograph for heat-treated powered has an irregular shape with rough and porous surfaces leading to the best adsorptive feature. The optical band gap was found to be 2.06, 1.98, and 2.00 eV for 300 °C, 500 °C, and 800 °C heat-treated samples respectively. These findings can be an input to the industrialists and environmentalists that controlled sludge recycling mechanisms during wastewater treatment is beneficial in terms of cost and sustainability. Furthermore, an integrated wastewater treatment system with resource recycling technology at the initial stage of the installation could be made.

Recovery of iron hydroxides from electro-coagulated sludge for adsorption removals of dye wastewater: Adsorption capacity and adsorbent characteristics

The aims of this research work was to investigate the potentials of raw and calcined iron hydroxides/oxides sludge adsorption for DR28 dye removal. The adsorbent is prepared from electro-coagulated (EC) sludge in industrial wastewater treatment plant, as a Nobel adsorbent for decolorizing direct red 28 dye (DR28). The EC sludge adsorbent were prepared with soaking processes and calcination in a range of temperature. The surface properties of raw and calcined EC sludge adsorbent were examined using Zeta Potential, XRD and FTIR. Basic (effect of solution pH, temperature, initial dye concentration) operation parameters were examined for raw and calcined EC sludge adsorbent. The diffraction patter suggests that the crystalline hematite are produced during calcination and increases its intensity as temperature increases. Langmuir and Freundlich Equation were used to model the adsorption equilibrium; and pseudo first and second order Equation were used to model the adsorption kinetics. The results suggested that the adsorption of DR28 dye is chemisorption, the interaction between the adsorbent surfaces with dye is strong. The Langmuir adsorption capacity of DR28 dye with raw and calcined EC sludge adsorbent was calculated as 1.262 mg/g and 1.252 mg/g respectively with experimental conditions: mixing time=20 min, adsorbent dosage=0.5 grams, initial dye concentration= 20 mg/L and solution pH =2 at ambient temperature. The adsorption kinetics model data were consistent with the pseudo-second-order. The removal efficiency of 97% was recorded at pH 2, ambient temperature 20 mg/l concentration and 1 g/100 ml for 1 hour. High direct red 28 dye uptake capability and cost-effectiveness of sludge utilization from textile wastewater treatment plant make it potentially attractive for dye removal.

Electrochemical treatment of industrial cooling tower blowdown water using magnesium-rod electrode

Cooling tower blowdown water (CTBW) was treated with simple electrocoagulation (EC) using magnesium-rod electrode. This study examined the effects of the treatment parameters (current density, electrolysis time, electrode distance, initial pH and stirring speed) on the EC ability to remove hardness ions (Ca2+, Mg2+) and dissolved silica from CTBW. Under the optimized condition, magnesium-rod electrode removed 51.80% and 93.70% respectively for total hardness and silica; with an operating cost of 0.88 US$/m3 treated CTBW. EC sludge has been characterized by SVI, SEM-EDX, XRD, and FTIR exploring the ability of sludge to settle, surface morphology, elemental composition, crystalline type, and functional groups. It can be concluded that EC using magnesium-rod electrode can be successfully applied for the treatment of CTBW to facilitate its reuse.

Reduction of chlorophenols and sludge management from paper industry wastewater using electrocoagulation process

ABSTRACT In this study, electrocoagulation (EC) was used to determine the optimum conditions on the basis of maximum chemical oxygen demand (COD) and color removal. At the optimum conditions chlorophenols (CPs), biological oxygen demand and total organic carbon (TOC) were determined. The biodegradability of wastewater was increased significantly with 63% COD, 98% color, 61% TOC and overall 65.51% reductions in CPs. Further, the electro-coagulated sludge was characterized by using different analytical techniques to assist the physicochemical and elemental phases, to find-out better management option, reusability for plant growth and safe disposal. Additionally, aluminum content (70.62%) was successfully recovered from sludge.

Arsenic removal from naturally arsenic contaminated ground water by packed-bed electrocoagulator using Al and Fe scrap anodes

Abstract In this work, feasibility of electrocoagulation (EC) process with Al and Fe scrap anodes for treatment of groundwater contaminated with arsenic (As) was examined as a cheaper treatment alternative for affected remote communities. EC experiments were carried out in a batch packed-bed EC reactor and the effect of applied current (0.010–0.100 A), type of scrap electrode (Fe and Al), packed-bed density (0.1–0.4 kg/m3 for Fe and 0.02–0.08 kg/m3 for Al) and EC time were investigated. Optimum operating conditions to obtain maximum contaminant level (MCL) of 10 μg /L for total As (>93% removal) in groundwater samples were determined as 8 min and 0.05 A for Fe scrap anodes. Whereas for Al scrap anode, 30 min and 0.10 A were the optimums. The operating cost, energy and electrode consumptions at these optimums were calculated as 0.017 US $/m3, 0.070 kW h/m3 and 0.052 kg/m3 for Fe anodes and 0.181 US $/m3, 0.876 kW h/m3 and 0.067 kg/m3 for AL anodes respectively. The As removal slightly decreased with decrease in anode bed density. Moreover, Fe scrap anodes exhibited better As removal than the Al scrap anodes at all tested conditions. The scanning electron microscopy (SEM) of the electro-coagulated sludge revealed irregular and porous particles with amorphous structure. The Fourier-transform infrared spectroscopy (FTIR) showed bonding between Fe(III) - As(V), and As O bond, confirming As removal by co-precipitation and adsorption, respectively in the EC process.

Synthesis and Characterisation of Strontium Hexaferrite Using an Electrocoagulation by-Product

Strontium ferrite (SrFe12O19) was synthesised in a solid phase reaction by applying the conventional ceramic method. The precursor powder, containing magnetic iron species generated by the electrocoagulation technique, was allowed to react with strontium carbonate in the solid phase. The molar ratio of the precursor to strontium carbonate was maintained at 12:1 (Fe:Sr), yielding strontium ferrite (SrFe12O19). The electrocoagulation sludge generated was characterised by X-ray diffraction, scanning electron microscopy and vibrating sample magnetometry. The strontium ferrite obtained was characterised by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis, differential thermal analysis and vibrating sample magnetometry. The combined results of these analyses showed that the strontium ferrite obtained was of excellent quality with excellent magnetic properties.