Electrocoagulation of an Industrial Wastewater Using Copper Electrodes

The electrochemical method of electrocoagulation allows to effective elimination of the organic contamination present in the residual wastewaters. The electrocoagulation is an operation that employs electric energy as promoter of electrochemical reactions in which there are dissolution of the sacrifice anodes, they allow the production in situ of coagulants agents, which destabilize an emulsion and they allow percent high chemical demand removal of oxygen (DQO), biochemical oxygen demand (DBO), total solids, fecal coliforms and turbidity (1-3).

This project perform a study of an electrocoagulation process using copper (Cu), as sacrifice electrode for industrial wastewater with the objective of improving the water quality, the evaluation and optimization of key variables like pH and the  current density are presented and discussed.

A batch cylindrical electrochemical reactor containing a pair of Cu electrodes  was used for electrochemical tests. Each electrode was 20.0 cm by 2.5 cm with a surface area of 50 cm². Batch volumes of 0.3 L were treated in a 1.0 L glass reactor. A direct-current power source supplied the system with 0.5, 1.0 and 2.0 amperes, corresponding to current densities of 10, 20, and 30 mA/cm². COD, turbidity and Color were used as indicators for obtaining the improving waster quality

Figure 1 shows the results of the COD removal as a function of treatment time at different initial pH values. As observed the best removal takes place at an acidic pH value reaching a 70 % removal. This can be explained since the Cu ions are present in wastewater as a free ion when the pH is low. However, when the pH of the solution is increases the formation of Cu(OH)₂(s) takes place and the removal of all colloidal mater occurs. 

 References

1. Grandon, Rodrigo; Hansen, Henrik and Nuñez, Patricio. (2006). Electrocoagulation as a remediation tool for wastewaters containing arsenic. Minerals Engineering. Vol. 19, No. 5; p. 521-524
2. Muttucumaru, S. (2009). Review of pollutants removed by electrocoagulation and electrocoagulation/flotation processes.
3. Rajashwar, K. and Ibañez, J. Environmental electrochemistry: (1997). Fundamentals and Applications in pollution abatement. San Diego, California: Academic Press limited. P. 776