Improvement of Treatment Technique of High Colour and Low Turbidity Water

Summary

Humic substances are governing natural pollutants of high color and middle color river water. NII VODGEO has conducted the studies of effects of non-organic and organic coagulants in combination with high molecular flocculants. In the course of studies the efficiency of water treatment with aluminium oxychloride and Polysept has been compared. To improve efficiency of treatment flocculants Praestol have been used. Molecular-mass distribution of humic acids in influent water and water treated with reagents has been investigated. Results of the experiments with natural water have been confirmed with the use of model solutions prepared on the basis of sodium humate and also humic substances extracted from soil, turf and river water.

Key words

coagulant , flocculant , reagent treatment , high color water , humic acids , fulvic acids , molecular-mass distribution , aluminum oxychloride , organic coagulant Polysept

The efficiency of using aluminium polyoxychlorides in natural water purification

Summary

SUE «Vodokanal of St. Petersburg» has been continuously upgrading water treatment technologies with the aim of improving the quality of water services. The results of laboratory, pilot and industrial approbations provided for the data on the use of more than 160 samples of coagulants based on the salts of different polyvalent metals. Among them are aluminium-, iron-, and titanium-based coagulants and also their composite compounds. Investigating more than 50 samples of aluminium oxychloride produced both by local and foreign manufacturers showed that for such special water source as the Neva River the use of chemicals of low and medium base strength in the processes proceeding in contact clarifiers is most preferable. The use of aliminium oxychloride did not result in sharp decrease of alkalinity or pH at the increased coagulant dosages. The residual alkaline reserve in water allows introducing higher chemical dosages which results in improving the efficiency of the first water treatment stage at low temperatures of the water source (less than 4 °С) and reducing filter cycle. SUE «Vodokanal of St. Petersburg» has adopted the concept of using the range of coagulants during different year seasons.

Key words

coagulant , aluminum oxychloride , aluminium sulphate , pilot tests