Removal of phosphorous cpds. from water - by addn. of alkaline alkali metal-aluminate lyes precipitating transition metal-aluminium complexes under alkaline conditions

摘要

Process for the removal of phosphorous cpds. from water by adding alkaline alkali metal-aluminate lyes (A) that ppte. transition metal-aluminium complexes under alkaline conditions. (A) Pref. have an alkali metal oxide-aluminium oxide mol. ratio of 1.1-6.5:1 and an Al2O3 content of 3.5-25 wt.%. The pH for the process is pref. 3-10. The aluminate soln. pref. contains polycarboxylic acids. Pref. polymeric flocking additives are added during the process, which is pref. for water contg. 0.1-500 mg/l phosphate. The mol. ratio of aluminium to phosphorous cpd. (calculated as phosphate) pref. corresponds to a beta value of 0.5-2.5. USE/ADVANTAGE - Useful for the purificn. of drinking water, effluent or sewage effluent. The pptn. of phosphates increases with pH, making it suitable for acid-producing biological processes, e.g. nitrification. (A) Show good stability during storage and freezing. The obtd. phosphate slurry has a smaller vol. than that obtd. by prior art methods, and smaller amts. of pptg. agent are required.