Industrial Waste – Water Treatment By Natural Filter Aids

Abstract

Dyes and pigments used by an Iraqi cotton industrial plant in coloring, printing and painting of cotton fabrics result in an alkaline, Na-Cl type waste-water enriched with various concentrations of heavy metals and suspended solids. The efficiency of some natural geological filter aids, including montmorillonite-attapulgite claystones and porcellanite, were tested in this work in the treatment of waste water produced in the cotton fabric industry. Several laboratory experimental tests were carried out to optimize solid: liquid ratio, mixing time, grain size of the filter-aid materials used as well as the efficiency of these filter-aids after activation by HCl and heat in removing or decreasing the pollutant concentration.

The best results were obtained using 15 min. mixing time, and 4 gm/l and 2 gm/l solid: liquid ratio for montmorillonite-attapulgite claystones and porcelanite respectively.  Activation of the natural filter-aid materials by 5% dilute HCl (montmorillonite), heating to 300° C (porcellanite) and 5% HCl + heating at 900° C (porcellanite) generally increased the efficiency of extracting the pollutants from the waste-water. The tests carried out in this work showed that the natural geological filter-aids used in the treatment of industrial waste-water of cotton industry are efficient in reducing the pollutant concentrations to the limits specified by Iraqi environmental authorities. The efficiency of those natural materials was enhanced after activation, where about 95% of the pollutants were removed using optimum conditions.