FLOCCULATION IN PRESENCE OF ORGANIC MACROMOLECULES OF NATURAL-WATER AND SECONDARY EFFLUENTS

Flocculation processes were studied in three types of water representi ng turbid natural surface water, controlled synthetic systems of refer ence clay minerals suspensions in the presence of humates and fulvates at various degrees of interactions, and municipal wastewater treatmen t plant effluents. These systems contain suspended and colloidal dispe rsed solids accompanied by organic substances in dissolved or colloida l form. The presence of organic anionic macromolecules and soluble org anics in water affects flocculation processes by raising the flocculan t demand appreciably and hence affects the final water quality. Extrac tion and elimination of the organics from natural suspended solids, an d removal of soluble organics from effluents reduced the organic conte nt, thus decreasing considerably the flocculant demand. The addition o f the extracted and separated organics to pure clay dispersions increa sed accordingly the cationic polyelectrolyte flocculant demand. (C) 19 97 IAWQ. Published by Elsevier Science Ltd.