Measurements of BDOC Kinetics in Humic-Rich Drinking Water

In Boreal regions the raw waters contain high concentrations of natural organic matter (NOM), thus their removal in biofilters is not always effective due to the slow degradation rate of biodegradable organic carbon (BDOC). The aim of this study was to estimate the BDOC degradation rate after ozonation of humic rich dissolved organic carbon (DOC=4-8 mg/L) drinking water. To measure BDOC removal kinetics a simple method was developed for this study. The organic carbon in synthetic water solution in which the only organic substance was acetate was completely removed during the first 120 minutes. During the same period only 9% of the DOC was removed from ozonated drinking water sample (O3 mgL-1/DOC mgL-1 = 1-1.5). In the following 105 minutes another 7% of DOC was degraded by the columns. After that no changes of DOC occurred. These results allow concluding that even at high ozone doses the BDOC produced from humic-rich water is slowly biodegradable and therefore is not effectively removed by biofiltration applying the contact time (20-30 min) currently used by ozonation-biofiltration plants