OxyFile #482

Effect of Remineralization on Ozonation and Biodegradation of 
Surface Water

R. Desjardins, C. J. Zoungrana, M. Provost.

Polytechnic of Montreal, Canada.

Surface water with low mineralization is often high in natural 
organic matter. These characteristics make treatments designed to 
produce drinking water difficult. In order to improve the 
treatment, some water distributors have introduced a 
remineralization stage in the treatment line that consist in 
increasing alkalinity and the hardness of the water by adding 
calcium ions and bicarbonates ions. The position of the 
remineralization in the line varies, depending upon the desired 
objective (buffer effect at the coagulation stage, correction of 
aggressivity, direct oxidation by ozone, etc.). Tests were carried 
out in order to show the effects of remineralization on the 
evaluation of biodegradability of natural organic matter and on 
some disinfection of by-products during ozonation and 
biodegradation. These treatment steps are preceded by coagulation-
flocculation-decantation and sand-anthracite filtration. Results 
have shown that remineralization increase the reduction of UV 
absorbance by ozonation. Remineralization also increases the 
production of oxalate and biodegradable dissolved organic carbon 
(BDOC). Results have also shown that remineralization increase 
removal of chlorine demand, chloropicrine and haloacetic acids by 
biological treatment (ozonation and biodegradation).

Source: 2nd International Symposium on Ozone Applications
        Havana, Cuba - Mach 24-26, 1997.