ELECTROCOAGULATION

Akshat Singhal2011CH70143Mr. Anil K. Saroha

DEPARTMENT OF CHEMICAL ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY DELHIUnder the guidance ofby*

Contents

IntroductionLiterature reviewResultsEffects of AC vs. DCRole of Sacrificial ElectrodesIndustrial waste water characteristicsFuture workReferences**

IntroductionElectrocoagulation electro meaning to apply an electrical charge to water and coagulation is the process by which suspended matter forms an agglomeration. It works primarily by reduction of the net surface charge to a point where colloidal particles, originally stabilized by electrostatic repulsion in solution, can approach close enough for van der wall forces to hold them together and allow aggregation.

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Process and BenefitsEC requires simple equipment and is easy to operate with sufficient operational latitude to handle most problems encountered on running. Wastewater treated by EC gives palatable, clear, colourless and odourless water.Sludge formed by EC tends to be readily settable and easy to de-water.The EC process has the advantage of removing the smallest colloidal particles, because the applied electric field neutralises any residual charge, thereby facilitating the coagulation.

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The EC process generally avoids excessive use of chemicals and so there is reduced requirement to neutralize excess chemicals and less possibility of secondary pollution caused by chemical substances added at high concentration as when chemical coagulation of wastewater is used.The electrolytic processes in the EC cell are controlled electrically and with no moving parts, thus requiring less maintenance.

**Process and Benefits

Literature Review**

AuthorObjectiveAbstract / ResultsGuohua Chen(2003)Electrochemical technologies in wastewater treatmentReviews the development, design and applications of electrochemical technologies in water and wastewater treatment. Factors affecting electrocoagulation current density, pH effect, temperature, power supply

Literature Review**

AuthorObjectiveAbstract / ResultsV. Khandegar, Anil K. Saroha(2013)Electrocoagulation for the treatment of textile industry effluent Review the potential of electrocoagulation for the treatment of industrial effluents, mainly removal of dyes from textile effluent. Attractive method for treatment of various kinds of wastewater due to benefits such as environmental capability, safety, cost effectiveness and energy efficiency.

Literature Review**

AuthorObjectiveAbstract / ResultsO. T. Can, M. Kobya, E. Demirbas, M. Bayramoglu(2005)Treatment of textile wastewater by combined electrocoagulationInvestigate the effect of initial addition of a chemical coagulant such as PAC or alum on the COD removal efficiency of EC treatment of textile wastewaters.

Literature Review**

AuthorObjectiveAbstract / ResultsR. Mahajan, V. Khandegar, Anil K. Saroha(2013)Treatment of hospital operation theatre effluent by electrocoagulationRemoval efficiency determined by the reduction in chemical oxygen demand (COD) of the effluent. The effect of operational parameters on the COD removal efficiency was investigated.

Diagram**

ResultsElectrocoagulation depends on a number of parameters EC time: Increase in EC time provide better results and a thick floc. After sufficient time the separation downs to nearly zero.Current density: Increase in current density provides better results faster. After long residence time, they nearly converge to the same results. Conductivity: It increases the electrochemical activity in the system, and hence increase in the separation process and gas formation.

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Initial pH: If the pH is away from the neutral (7), increase in foam and sediments is observed.Inter-electrode distance: Increase in the distance increases the EC efficiency. As the distance provides greater probabilities to generate global flocks.In-flow rates, material of the electrodes, and impurity concentrations also affect the process.

**Results

Effects of AC vs DCIn practice, direct current (DC) is used in an electrocoagulation processes. In this case, an impermeable oxide layer may form on the cathode as well as corrosion formation on the anode due to oxidation. This prevents the effective current transfer between the anode and cathode, so the efficiency of electrocoagulation processes declines. These disadvantages of DC have been diminished by adopting alternating current (AC) in electrocoagulation processes.**

Sacrificial ElectrodesSacrificial Anodes are highly active metals that are used to prevent a less active material surface from corroding. Sacrificial Anodes are created from a metal alloy with a more negative electrochemical potential than the other metal it will be used to protect. The sacrificial anode will be consumed in place of the metal it is protecting, which is why it is referred to as a "sacrificial" anode.**

INDUSTRIAL WASTE WATER CHARACTERISITICS: Physical characteristics: Total Solids Colour Odour Temperature

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INDUSTRIAL WASTE WATER CHARACTERISITICS: Chemical characteristics: Inorganic chemicals Organic chemicals (BOD, COD)Volatile organic carbons (VOC) Heavy metals and inorganic species

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Future Work Effect of AC vs. DC on electrocoagulation.

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References[1] Chen, G.,Electrochemical Technologies in Wastewater Treatment, Separation & Purification Technology, 38(1) 11-41 (2004)[2] Khandegar, V. and Saroha, A. K., "Electrocoagulation for the treatment of textile industry effluent A review."Journal of Environmental Management, 949-963 (2013).[3] O. T. Can, M. Kobya, E. Demirbas, and M. Bayramoglu, Treatment of the textile wastewater by combined electrocoagulation,Chemosphere, vol. 62, no. 2, pp. 181187 (2006).[4] Mahajan R.; Khandegar V.; Saroha A. K., Treatment of hospital operation theatre effluent by electrocoagulation. International Journal of Chemical and Environamental Engineering, 104 107 (2013)[5] Wang & Howard. "Handbook of Industrial and Hazardous Wastes Treatment". USA 2004. [6] WBG, World Bank Group. "Pollution Prevention and Abatement Handbook",1998. **

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