Separation of the chromium(III) present in a tanning wastewater by means of precipitation, reverse osmosis and adsorption

B.H. HINTERMEYER, N.A. LACOUR, A. PÉREZ PADILLA, E.L. TAVANI

LATIN AMERICAN APPLIED RESEARCH

Universidad Nacional del Sur

Año: 2008 vol. 38 p. 63 - 71

0327-0793

The separation of the chromium(III) dissolved in a tanning wastewater was studied by means of precipitation with calcium carbonate, reverse osmosis with polyamide membrane and adsorption on activated carbon. All tests were carried out at laboratory scale with a wastewater obtained from a unique typical tannage process. In a first stage, the original effluent was treated by sieving and ultrafiltration to perform a partial removal of fats and denaturalized proteins. The separation of chromium(III) by precipitation, reverse osmosis and adsorption was performed with the tanning wastewater so treated. The precipitation efficiency was determined by taking into account the chromium(III) content of the supernatant with the reaction time and with the alkali amount added. The polyamide membrane behavior used was established by the permeate flux and by the rejection of each species. The adsorption valuation involved the determination of the adsorbed amounts of chromium(III), sodium, chloride and sulfate. Under optimum conditions established for each process, the following results were obtained: a supernatant with less than 3.0 mg L-1 of chromium(III) by precipitation, a permeate with less than 2.0 mg L-1 of chromium(III) by reverse osmosis and an equilibrium solution with less than 6.0 mg L-1 of chromium(III) by adsorption. To conclude, the main physicochemical characteristics of the three processes used to remove chromium(III) dissolved in the industrial effluent were analyzed.