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Aluminium hydroxide sludge used as flocculant

The company COMERCIAL E INDUSTRIAL DEL ALUMINIO, SA (COMINAL) is dedicated to the anodizing and electro-coloring of aluminium profiles for the construction industry. The pieces that enter their facilities go through processes of mechanical glazing, chemical degreasing, chemical satin, anodizing, electrocoloring and sealing.

After each of these processes, a water wash is carried out, which generates a large amount of wastewater that must be treated in a physical-chemical treatment plant. The resulting sludge from the process has a composition basically of aluminium hydroxide (20-30%) and water (40-60%).

The high cost of treating this mud, generated the need to find a new way of management. It was recognised, in fact, that this waste had the potential as a flocculating agent. It allows to reduce the use of basic reagents in sewage treatment plants, and it could also be used in the manufacture of cement, since it allowed to replace part of the clays used in the production process. For economic reasons, it was decided to jointly manage the waste generated by all the companies of the ACA (Catalan Anodizers Group).

In all cases it is waste managed under the Catalan by-product administrative framework.