FORMATION AND REMOVAL OF ALDEHYDES IN PLANTS THAT USE OZONATION

Recently developed analytical techniques allow for the quantification of C1-C-10) straight-chain aliphatic aldehydes, benzaldehyde, and the dialdehydes glyoxal and methylglyoxal down to 1 mug/L. These compounds are formed as the partial oxidation production of the reaction betwee n disinfectants (particularly ozone) and naturally occurring organic m atter. Various full-scale and pilot treatment plants in North America that employ ozonation were surveyed using these techniques, which show ed a trend toward both monoaldehyde and dialdehyde formation. Once for med, aldehydes can persist in the water and their concentrations may e ven increase following postdisinfection. An effective means of aldehyd e removal appears to be the use of biologically active granular activa ted carbon filters, whose filtration mode determines the actual degree of removal. Dialdehydes require a slower filtration rate for their re moval than formaldehyde and acetaldehyde.