Performance optimization of coagulation/flocculation in the treatment of wastewater from polyvinyl chloride plant

This study is conducted & thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science in Chemical Engineering, College of Engineering, King Saud University, Riyadh, Kingdom of Saud Arabia, January 2008GThe emulsion polymerization of vinyl chloride generates contaminated waste water. Before the wastewater can be returned to the sea or reused, the contaminates must be removed. The EPVC (Emulsion Poly Vinyl Chloride) particles are removed from wastewater by a treatment plant. The objective of this work is to study the coagulation and flocculation of EPVC contaminated water in order to optimize the treatment process. The experiments were carried out on a model wastewater which is chemically identical to actual plant wastewater but is more consistent. Inorganic ions and water soluble polyelectrolytes were added to the wastewater. Coagulation/flocculation efficiency was determined by measuring supernatant turbidity and by measuring the relative settlement of the flocs in the Jar Test. The experimental results showed that aluminum sulphate (0.5% Al2(SO4)3) combined with polyelectrolyte (PE1) at pH in the range of 7 to 8, and agitation speed of 600 rpm give the best results. Ferric chloride (2.5% FeCl3) combined with polyelectrolyte (PE3) is slightly less effective. As for calcium chloride (2.5% CaCl2) combined with PE3 it is the least effective since 0.7 gm of the coagulant (=19 times that of Al3+ ions) are needed to obtain the same coagulation as aluminum sulphate.King Saud Universit