The efficiency of electrocoagulation in treating wastewater from a dairy industry, part I: iron electrodes

A critical review of state-of-the-art electrocoagulation technique applied to COD-rich industrial wastewaters

Electrocoagulation (EC) is one of the emerging technologies in groundwater and wastewater treatment as it combines the benefits of coagulation, sedimentation, flotation, and electrochemical oxidation processes. Extensive research efforts implementing EC technology have been executed over the last decade to treat chemical oxygen demand (COD)-rich industrial wastewaters with the aim to protect freshwater streams (e.g., rivers, lakes) from pollution. A comprehensive review of the available recent literature utilizing EC to treat wastewater with high COD levels is presented. In addition, recommendations are provided for future studies to improve the EC technology and broaden its range of application. This review paper introduces some technologies which are often adopted for industrial wastewater treatment. Then, the EC process is compared with those techniques as a treatment for COD-rich wastewater. The EC process is considered as the most privileged technology by different research groups owing to its ability to deal with abundant volumes of wastewater. After, the application of EC as a single and combined treatment for COD-rich wastewaters is thoroughly reviewed. Finally, this review attempts to highlight the potentials and limitations of EC. Related to the EC process in batch operation mode, the best operational conditions are found at 10 V and 60 min of voltage and reaction time, respectively. These last values guarantee high COD removal efficiencies of > 90%. This review also concludes that considerably large operation costs of the EC process appears to be the serious drawback and renders it as an unfeasible approach for handling of COD rich wastewaters. In the end, this review has attempted to highlights the potential and limitation of EC and suggests that vast notably research in the field of continuous flow EC system is essential to introduce this technology as a convincing wastewater technology.

Evaluation of Electrocoagulation and Activated Carbon Adsorption Techniques Used Separately or Coupled to Treat Wastewater from Industrial Dairy

This present study focuses on the evaluation of the effectiveness and the feasibility of a combined treatment between the electrocoagulation (EC) and the adsorption on an activated carbon in grains (GAC) in a continuous mode. The peculiarity of this work is that the experiments are conducted with real wastewater from an industrial dairy. This combined treatment first required an optimization of the EC followed by an adsorption. For each of these techniques, different influential operating parameters such as the current density, the reaction time, the GAC dose, the initial turbidity of water … etc., have been studied. The Turbidity and the COD have been continuously analyzed, while the phosphorus, the BOD5, TSS, nitrogen and the grease have been punctually analyzed, and this happened before and after the water treatment. The EC adsorption coupling results have shown that the addition of an appropriate dose of GAC (2 gL−1) in a separate column, increases the effectiveness of treatment; more than 98 % of reduction for the COD, the BOD5, the turbidity and the greases. A mechanism explaining the phenomena which are involved in this combined treatment is proposed. On the basis of these results of efficiency, speed, low operational cost (~ 3 $m−3 of the treated water), and in comparison with the EC used alone, the EC coupling/the adsorption GAC, could be recommended as a treatment of separation for waters at a high load in organic pollutants.