Synthesis of coagulants to intensify processes of water clarification

Abstract

The problem of highly effective reagent production (aluminuim hydroxchlorides) for water purification is quite urgent nowadays. Even more urgent is the necessity to create the technology of synthesis of aluminium coagulants from aluminuim hydroxchloride manufactured intermediate product and aluminium processing wastes. This article suggests the ways of obtaining aluminium hydroxchloride from amorphous aluminium hydroxid and hydrochloric acid applying positive pressure on the first stage and vacuum on the second stage of the whole process. The reagents relation is established in such a way for the process to progress in production of 1/3 of aluminium hydroxchloride. During the solvent vacuum evaporation on the second stage at different temperatures, solid hydroxchlorides of various basicity were obtained. At t˚ 80 0С 1/3 of aluminium hydroxchloride was obtained, at t˚80-100 0С – 2/3 of aluminium hydroxchloride, at t˚ 120-140 0С – 5/6 of aluminium hydroxchloride. Easier method of increase of aluminium hydroxchloride basicity is the interaction of 1/3 aluminium hydroxchloride with the basis reagents, such as calcium and magnesium oxide, calcium carbonate. The efficiency of obtained coagulants was examined on the Dnieper water, model suspensions of betonite and sodium humate in the Dnieper water. As one can see from the results, during clarification of natural water and model suspensions on its base, the synthesized aluminium hydroxchlorides prevailed over aluminium sulphate. The efficiency of processes increases due to the increase of coagulant dose and change from aluminium sulphate to aluminium hydroxchlorides. The best results were obtained while using 1/3 and 5/6 of aluminium hydroxchlorides.