SURVEY OF CAMPYLOBACTER SPP IN SEWAGE PLANTS IN THE NETHERLANDS

The prevalence of Campylobacter spp. in two trickling filters and one activated sludge system in The Netherlands was monitored. The waste of two poultry abattoirs, which are located in the drainage area of the investigated sewage plants, was sampled also, in order to reveal possible contamination sources of culturable Campylobacter spp. The numbers of Campylobacter isolated from the different plants could be related to the presence of poultry abattoirs in the drainage areas. There appeared to be a seasonal variation in the numbers observed in the sewage of the activated sludge system; during the end of the summer the numbers were on average 1 log10 unit smaller than during the rest of the year. This variation was not correlated to water temperature, oxygen pressure, pH, intensity of rainfall or sunlight. Purification in an activated sludge tank reduced the Campylobacter counts by 1 log10 unit and in a trickling filter system the decline was 0·6 log10 unit. The reduction in the investigated sewage plants was shown to be influenced by several factors. Since the elimination of Campylobacter is far from complete, disinfection of sewage plant effluxes should be considered in order to obstruct the environmental cycles if Campylobacter. © 1994 Academic Press Limited.