Formation of bioavailable disinfection by-products

The formation of biodegradable structures by disinfection of drinking water with chlorine and ozone/chlorine was systematically investigated. The biodegradable structures identified were carboxylic acids, ketoacids, oxalic acid and aldehydes. Between 50 and 80% of the total BDOC could be identified in form of single structures. The common characteristic of these by-products is their instability. That means, they are formed by the oxidation of the organic matter and they are precursors of further disinfection by-products formation in the case of residual disinfectants. Depending on the kinetics of this process the aldehydic and particularly the acitic structures form concentration maxima and minima versus the contact time with residual disinfectants and (or) the dose of disinfection. A model comparable to an oscillating system is developed in order to explain this process in general.