This study is aimed at determining the occurrence of campylobacters in waste water, sewage sludge and in a river system. The selective medium for the isolation of campylobacter consists of blood agar supplemented with the antibiotics vancomycin (10 µg/ml), cephalexin (15 µg/ml), trimethoprim (5 µg/ml), polymycin B (2.5 µg/ml) and rifampicin (5 µg/ml). Raw sewage samples contained about 103 Campylobacter/100 ml while the effluent showed an average concentration of 1.3 × 102/100 ml. Raw sewage from an oxidation pond treatment plant contained an average of 51 Campylobacter/100 ml while none were found in the effluent. No Campylobacter could be found in digested, conditioned sludge. The organism could be detected in 82.1% of river waters examined with the majority showing <10/100 ml. The presence of waterfowl and the faecal contamination from a poultry farm resulted in higher Campylobacter levels. About 50 % of the isolates typed as C. coli were really confirmed as C. jejuni by electrophoretic pattern (whole cell protein profiles).

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Bquatic ecosystems have the ability t o compensate for oscillations of the inputs (substrate concentration, dilution rate, temperature). The mechanisms of this buffering capacity are studied in this paper (see fig. 7). The inputs exert an influence on the biomass and the activity of the organisms (activity = specific rate of RNA-synthesis or specific P-removal rate [pg/mg biomass * day]). The activity is regulated either directly by the inputs and/or indirectly by t h e biomass. The activity decreases with an increase of the biomass (see fig. 5 and 6). The product of biomass and activity determines the transient response (= effective performance) of the system which is better buffered than biomass or activity alone.Considering the theory developed in this paper the effect of shock loadings on t h e phosphate removal in preimpoundment basins of drinking water reservoirs is discussed. Inhaltsverzeichnis

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