Studying the efficiency of using aluminium oxychlorides of different trademarks

Summary

With each passing year, the task of centralized provision of the population with drinking water has becoming increasingly important. Because of increased technogenic and anthropogenic pollution of surface water sources, traditional water treatment schemes have become insufficient. Purification of natural water using chemicals in most cases is currently the only possible method of providing for the sustained water quality in domestic water supply systems. The paper considers the effectiveness of coagulants – highly basic aluminum oxychlorides supplied by various manufacturers depending on the initial turbidity and color of the water. The experiments were based on the use of model water with the parameters close to natural water in different periods of the year. It was shown that in terms of permanganate index, a water quality indicator, the efficiency of the chemicals was quite high and sustainable. As to such parameters as turbidity and color, the chemicals demonstrated extremely low efficiency in their respect. The trademarks of oxychlorides that showed the best results in relation to turbidity and color of clarified water in the process of low turbid and colored water purification were identified. In the water treatment practice a well-known method for increasing the efficiency of low turbid natural water clarification is the use of opacifiers. As a rule, finely dispersed clay or powdered activated carbon is used as a opacifier. During the study the efficiency of aluminium oxychlorides with preliminary addition of activated carbon slurry into the model water was investigated; and the most efficient trademarks of highly basic aluminum oxychlorides were determined.

Key words

turbidity , chromaticity , coagulant , permanganate oxidizability , natural water treatment , low turbid water , opacifiers of natural water

Selection of efficient chemicals for low turbid water purification from surface water sources

Summary

The results of laboratory study of selecting chemicals and optimal dosage for the purification of low turbid water of the Saratov water reservoir are presented. The laboratory tests of aluminium polyoxychlorides (14 kinds) and aluminium sulfate (16 kinds) were carried out. Coagulants manufactured by domestic and foreign manufacturers were studied. The optimal dosages of coagulants and flocculants were determined. Two of the coagulants studied were selected that could ensure the maximum degree of water clarification at the minimum concentration of residual aluminium and permanganate value in drinking water. It was stated that water treatment exclusively with coagulants with subsequent sedimentation and filtration ensured meeting the state drinking water standard. The results of the experimental studies of coagulation of low turbid water of the Saratov water reservoir showed that the maximum water clarification was achieved by sedimentation at the optimal coagulant dosage of 9.6 mg/dm³ for Al₂O₃ and 0.2 mg/dm³ flocculant dosage. At that the pollution loading on filters is reduced and the filter run increases.

Key words

turbidity , chromaticity , coagulant , flocculant , residual aluminium , permanganate oxidizability , low turbid water