SURVIVAL OF SALMONELLA-TYPHIMURIUM IN THE SOLID FRACTION FROM A PIG FARM WASTE-WATER TREATMENT-PLANT

Survival of Salmonella typhimurium pathogens was followed in the slurr y solid fraction from a pig farm waste water treatment plant. The test ed S. typhimurium pathogens have survived for 117 days. The solid frac tion was kept in the laboratory at 20-23 degrees C. Indicatory microor ganisms at the beginning of the experiment numbered 10(8)-10(9) CFU in 1 ml sample. This number decreased by 4-5 series throughout the exper iment, except for faecal coliform bacteria, which were not detected af ter 43 days of cultivation. Enterobacteria showed a decreasing tendenc y until day 83, however, on the final sampling (day 117) their count w as almost double. Of physico-chemical parameters, pH showed the most s triking variations. Its' initial value of 6.9 increased to 8.1 at day 30, then decreased to 7.2 at day 43, and increased to 7.7 at the end o f the experiment. Ammoniacal nitrogen in solid fraction was almost twi ce as high as the initial level. Other physico-chemical parameters wer e not changed significantly throughout the experiment. On the results of this experiment, decimal reduction times T-90 were determined for i ndicatory microorganisms during the storage of solid fraction under co nstant conditions: psychrophilic bacteria 31.25; mesophilic bacteria 3 8.12; coliform bacteria 27.49; faecal streptococci 24.57 and enterobac teria 30.46 days., These data suggest a relatively long time of surviv al for indicatory microorganisms in the solid fraction from agricultur al waste water treatment plants.