Growth and reduction of microorganisms in sediments collected from a greywater treatment system

Aims: To study the effects of competitive microbiota, temperature and nutrient availability on Salmonella, Enterococcus, Campylobacter spores of sulphite reducing anaerobes and bacteriophages MS2 and ΦX174 in sediments from a greywater treatment system. Methods and Results: Standard culture methods were used. Bacteria died off rapidly under normal conditions (20°C, competitive microbiota) but remained stable or grew in the other conditions studied. When the sediments became nutrient depleted after 2 weeks, a log‐linear die‐off was observed for Salmonella, which was higher at 20°C than at 4°C. Bacteriophage decay was shown to be log‐linear from day 0, with T90 values ranging from 9 (ΦX174, 20°C) to 55 days (ΦX174, 4°C). The MS2 phage had a significantly higher decay rate in tyndallized sediments (T90=17 days) than in original sediments (T90=47 days) (P