A Combined Coagulation/Flocculation and Membrane Filtration Process for the Treatment of Paint Industry Wastewaters

Coagulation/flocculation process is considered as a nonexpensive and effective method to reduce organic and inorganic content of industrial wastewaters. In the present study series of polyelectrolytes were tested to optimize the existing procedure with new chemical reagents that resulted in removal percentages up to 93%. Organic load expressed in terms of chemical oxygen demand, particle size distribution, pH, and zeta potential of suspended particles were among the parameters that were investigated for the best coagulation/flocculation of particles suspended in paint industrial wastewaters. The target was to find the optimum concentration values of polyelectrolytes that neutralize the zeta potential and shrink the particle size distribution. The remaining organic compounds were further treated with a combined ultrafiltration/reverse osmosis system that almost eliminated the organic content, and the final permeate stream is suitable for reuse in the premises of the industry.