AWWA JAW54590

The batch recycle attached growth reactor (BRAGR) was found to be a convenient technique to determine simultaneously the biodegradable dissolved organic carbon (BDOC) concentrations and the biokinetic rate constants for BDOC and aldehyde removal. The rate of biodegradation was first-order with respect to the BDOC remaining. A second-order, intrinsic rate constant was obtained by dividing the first-order rate constant by the attached biomass concentration in the biofilter. The intrinsic rate constant did not increase with an increasing ozone-to-DOC ratio and averaged 8.5 x 10-5 mg/L cells-1 min-1. The biokinetic rate constants for aldehydes were first-order with respect to remaining substrate concentration. The second-order, intrinsic rate constants (mg/L cells-1 min-1) for the aldehydes were much larger than those for BDOC, with the order being: methyl glyoxal (5.93 x 10-4) > glyoxal (4.42 > x 10-4) > formaldehyde (2.23 x 10-4) >> BDOC (8.5 x 10-5). Removal of aldehydes in a laboratory-scale, continuous-flow biofilter packed with anthracite and exhausted granular activated carbon (GAC) was predicted fairly well with rate constants derived from the BRAGR. BDOC removal was significantly under predicted on GAC biofilters, possibly because of residual adsorption capacity. An empty bed contact time that achieves good natural organic matter (NOM) removal will also yield very high removal of aldehydes because aldehydes are degraded much faster than NOM, regardless of the ozonation level. Biokinetic modeling could possibly be improved by accounting for differences in the biodegradability of NOM fractions and by better techniques to measure the concentration and activity of attached biomass in calculation of the intrinsic rate constant. Includes 37 references, tables, figures.