Formation of the haloacetic acids during ozonation and chlorination of water in warsaw waterworks (Poland)

The results of the study of the HAAs formation in Water Works in Warsaw, Poland are presented. Water taken from Zegrzy skie Lake is characterized by elevated content of humic substances and algae bloom in hot seasons. The water is ozonated and chlorinated. The study was performed from October 1995 to November 1996. The water was analyzed on various stages of treatment and the following parameters were determined: HAAs, THMs, DOC, COD, humic substances, UV absorbance, color and temperature. The big increase of HAAs concentrations occurred after water chlorination, up to 120 μg/l. In 44% it was DCAA and in 40% TCAA. The highest concentration of HAAs was noticed in May and June, when water temperature was the highest and concentration of organic matter the biggest. The changes of HAAs concentrations with time were similar to those in THMs concentrations. The laboratory experiments on the water ozonation and chlorination indicated that ozonation has small influence on the HAAs formation. The study of the HAAs volatization during water boiling showed that removal of HAAs is rather small.