Determination of the biodegradable fraction of dissolved organic matter in waters

Abstract

Two bioassay procédures are proposed for determining biodégradable dissolved organic carbon (BDOC) in waters. Both involves stérile filtration of the sample, reinoculation with a natural assemblage of bacteria from the same origin as the sample, and incubation for at least 10 days in the dark at 20°C. In the first procédure, dissolved organic carbon (DOC) is followed, until a plateau is reached and the différence between initial and final DOC is taken as a measure of BDOC. In the second procédure, bacterial biomass and mortality rate are followed and the integrated flux of mortality during the incubation period is calculated and divided by the growth yield to give an estimate of BDOC. Both procédures provide closely concordant results. An example of application to the study of ozonation and biological activated carbon filtration in drinking water treatment is presented.

Modélisation de la biomasse et de l'activité bactérienne dans la Meuse belge

“…2.1 Principe et équation du modèle général de dégradation bactérienne de la matière organique Sur base des connaissances microbiologiques actuelles et de diverses études menées sur le sujet dans notre laboratoire (BILLEN et al, 1980 ;SOMVILLE et BILLEN, 1983 ;SERVAIS et al, 1985SERVAIS et al, , 1987, nous avons proposé un schéma conceptuel des interactions matière organiquebactéries (figure 3) (BILLEN et SERVAIS, 1988) appelé modèle H3SB et dont les grandes lignes peuvent être résumées de la manière suivanteOn peut distinguer deux sources principales d'apport de matières organiques au réseau hydrographique : la production primaire endogène et les apports extérieurs (allochtones).…”

Hyporheic biofilm development on artificial substrata, as a tool for assessing trophic status of aquatic systems : first results

“…These variables should be complemented by the determination of BDOC and RDOC concentrations (measured by the Servais et al 1987Servais et al , 1989, and the identifica tion of the proportion of the bacterial population that is actively respiring (measured with the CTC method). This set of parameters provides useful information on relationships between biofilm development and orga nic nutrients ; ii) total bacteria and ETS-active bacteria abundances that develop on artificial substrata during short exposure times could be simple, global parame ters that provide information on functional linkages between biofilms and biodegradable and refractory fractions of DOC.…”

“…DOC was measured with a Dohrman DC80 'Total Carbon Analyser' based on UV-promoted potassium persulfate oxidation (pre cision ±1%) after removing mineral carbon using orthophosphoric acid (lul/ml) and C02 stripping under a 10 min oxygen flow. Biodegradable (BDOC), the part of DOC assi milated by autochtonous heterotrophic bacteria during a short incubation time (< 4 weeks), and refractory (RDOC) fractions of dissolved organic carbon were assessed accor ding to the method of Servais et al (1987Servais et al ( ,1989. A 0.2 urn cellulose acetate membrane was washed 3 times with 20 ml of organic-C free distilled water and then used to filter 130 ml of the sample.…”

AOC removal and accumulation of bacteria in experimental sand filters

“…To date, several methods are availabie for this purpose ( VAN DER KOOU et al, 1982 ;WERNER, 1985 ;JORET and LEVI, 1986 ;SERVAIS et al, 1987 ;STANFIELD and JAGO, 19.88). The so-called AOC détermination, introduced by VAN DER KOOU étal.…”