COMPARISON OF ELECTROCOAGULATION AND CHEMICAL COAGULATION IN THE TREATMENT OF ARTISANAL TANNERY EFFLUENTS

In this study, the treatment of the effluents of an artisanal tannery by electrocoagulation with iron electrodes was carried out. During electrolytic treatment, a current intensity of 0.4 A was used, and the electrolysis time was varied from 0 to 40 minutes. The performance of electrocoagulation was compared with that of chemical coagulation with ferric sulfate. The results obtained showed that highest removals after electrocoagulation were 71.15, 98.26, and 86.59% for the COD, colour and turbidity respectively. Chemical coagulation reduced the COD up to 83.17%, while colour and turbidity removals were 99.81 and 98.62% respectively. Although chemical coagulation leads to highest percentage removals after treatment, electrocoagulation results in near neutral pH values and also decrease conductivity weakly. By contrast, chemical coagulation increases the acidity of the effluent and its conductivity. Hence with close to neutral pH and weak conductivity values obtained for effluents treated by electrocoagulation, it is inferred that such treated effluents can be recycled. http://dx.doi.org/10.4314/njt.v35i1.2

<bold>The efficiency of electrocoagulation using aluminum electrodes</bold>i<bold>n treating wastewater from a dairy industry</bold>

This research deals with the investigation of electrocoagulation (EC) treatment of wastewater from a dairy plant using aluminum electrodes. Electrolysis time, pH, current density and distance between electrodes were considered to assess the removal efficiency of chemical oxygen demand (COD), total solids (TS) and their fractions and turbidity. Samples were collected from the effluent of a dairy plant using a sampling methodology proportional to the flow. The treatments were applied according to design factorial of half fraction with two levels of treatments and 3 repetitions at the central point. The optimization of parameters for treating dairy industry effluent by electrocoagulation using aluminum electrodes showed that electric current application for 21 minutes, an initial sample pH near 5.0 and a current density of 61.6A m-2 resulted in a significant reduction in COD by 57%; removal of turbidity by 99%, removal of total suspended solids by 92% and volatile suspended solids by 97%; and a final treated effluent pH of approximately 10. Optimum operating condition was used for cost calculations show that operating cost is approximately 3.48R$ m-3.</p

Electrocoagulation as an Eco-Friendly River Water Treatment Method

Electrocoagulation (EC) is an effective water and wastewater treatment technology, where the coagulants are produced in situ by electrolytic oxidation of a sacrificial anode. In this technique, pollutant removal is done without adding chemicals; therefore, it remarkably reduces the sludge produced and consequently reduces the cost of sludge handling. This method has been efficiently used to remove, up to 99%, of a wide range of pollutants such as heavy metals, oil, dyes, and fluoride. Therefore, the EC method could be the cost-effective, safe, and reliable option to face the growing water scarcity. However, like any other treatment method, the EC technology still has some drawbacks that could limit its applications. This chapter has been therefore devoted to present the principles, history, applications, limitations, advantages and disadvantages of the electrocoagulation technology, the role of key operating parameters on the performance of the EC reactors, and highlight the differences between the traditional coagulation process and EC technology. More importantly, this chapter will highlight the defects of EC technology that need to be enhanced.</p