Resumo

ARANGO RUIZ, Álvaro. Effects of the pH and the conductivity on the electrocoagulation of waste water from dairy industries. Rev. P+L [online]. 2012, vol.7, n.1, pp.59-67. ISSN 1909-0455.

Introduction. In recent years, and given the necessity to investigate, adapt and implement efficient technologies to remove pollutants from diverse kinds of waste waters, electrocoagulation has been considered as a feasible alternative to treat liquid effluents, so it has acquired an important scientific and industrial interest. Objective. To study the effects of pH and the conductivity on the electrocoagulation process performed to waste waters from dairy industries. Materials and methods. Waste waters from dairy industries were treated with electrocoagulation. To do so, a 3x2x3 factorial experimental design was tested. It had the following factors: pH, current density and time of treatment. The variable response was the COD removal percentage. Additionally, a monitoring to the pH and to the conductivity of the process was performed. Results. The highest COD removal percentages were those for the pH 5, current density of 43,23 A/m3 and 15 minutes of treatment. During the process, a pH increase up to two units was observed, and so was a conductivity reduction for the acid pH. Conclusion. The treatment with electrocoagulation for waste water from dairy industries es more effective for an initial pH value of 5 in the water, a density of electric fow of 43,23 A/m3 and a 15 minutes time. Under these conditions, 93,99 % COD is removed. During this electrocoagulation process there is a pH increase in the aqueous solution, from 1.5 to 2 units. Additionally, the conductivity of the aqueous médium has a reduction during the whole treatment to these conditions.

Palavras-chave : electrocoagulation; iron and aluminum electrode; electrochemistry.

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