Ángel Cambiella

Design and construction of a modular pilot plant for the treatment of oil-containing wastewaters☆

A modular pilot size plant involving coagulation/flocculation, centrifugation, ultrafiltration and sorption processes has been designed and constructed. The pilot plant can be used for the treatment of different water-based coolants and oily wastewaters, generated in metalworking processes and steel cold rolling operations. Different treatments are considered depending on the nature of the oily waste emulsion. The main advantage of the plant is its versatility, allowing the combination of several of the aforementioned treatments. It is a feasible waste management alternative with potential savings as a result of a better control of the elimination of oily wastes and water reuse, with the result of environmental and economic benefits.

Influence of Coagulant Salt Addition on the Treatment of Oil‐in‐Water Emulsions by Centrifugation, Ultrafiltration, and Vacuum Evaporation

Abstract Droplet size is a key factor in the treatment of oil‐in‐water (O/W) emulsions, because of its influence on emulsion properties. The addition of a coagulant salt generally causes emulsion destabilization, increasing the droplet size, and enhancing coalescence between oil droplets, which helps its further treatment. The influence of CaCl2 addition on droplet size distribution of a commercial O/W emulsion used in machining processes was studied in order to facilitate oil removal and to improve its further treatment by centrifugation, ultrafiltration (UF) and vacuum evaporation. The critical coagulation concentration (CCC) was observed at a CaCl2 concentration of 0.05 M. The quality of the final aqueous effluent, expressed as its chemical oxygen demand (COD) value, was compared for all treatments. The highest COD values were obtained for centrifugation, while the COD of the UF permeate was approximately constant for all UF trials. The best effluent quality was obtained by vacuum evaporation. A combination of these techniques should be appropriate for most industrial treatments of O/W emulsions, depending on the subsequent use of the resulting aqueous effluent.