Geneviève Gésan-Guiziou
INRA, France
Title: Regeneration of cleaning solutions in the dairy industry
Biography
Biography: Geneviève Gésan-Guiziou
Abstract
Current European regulations relating to landfill management, land spreading and purified water quality along with social pressure, press on the dairy industry to significantly reduce its production of effluents. However, in most cases, cleaning operations for food production equipment are still carried out in empirical modes and the frequency of cleaning solutions discharge is based on subjective criteria (colour, odour). Several works have recently been performed to regenerate caustic soda solutions, most commonly used as chemical cleaning detergent. We demonstrated the added value of using crossflow microfiltration to regenerate re-used caustic soda solutions. This process preserves the surface tension characteristics of the solution while retaining suspended solids, rendering the regenerated solutions more efficient than a fresh solution. Among the different purification operations (micro-, ultra- or nanofiltration, decantation, centrifugation), microfiltration has proved to be the most appropriate operation: suspended solids are removed, surfactants are only slightly retained; pay-back time is short. However, microfiltration generates high levels of soluble chemical Oxygen demand, COD in regenerated solutions, the impact of which still needs to be quantified. These results offer a prospect for major economic savings regarding cleaning of stainless steel industrial equipments. The limits of the recycling of caustic soda solutions over several weeks (effect of the COD,.) still need to be determined on an industrial scale, so the savings in product quantity, water and energy can be evaluated. These works also open the way to a general debate on the cleaning of equipment containing membranes, and the formulation of new detergent solutions.