Inactivation ofCryptosporidium parvumoocysts and faecal indicator bacteria in cattle slurry by addition of ammonia

Aims To determine inactivation ofCryptosporidium parvumoocysts and reduction ofEscherichia coliand enterococci in cattle slurry added aqueous ammonia. Methods and Results Escherichia coli, enterococci and nonviableC. parvumoocysts (DAPI+PI+) were enumerated every second day for 2 weeks in cattle slurry amended with 60 mmol l(-1)aq. ammonia and compared with untreated slurry at three temperatures. Regardless of temperature, the proportion of nonviableC. parvumoocysts increased significantly faster over time in slurry with added ammonia than raw slurry (P = 0 center dot 021) corresponding to 62 center dot 0% higher inactivation (P = 0 center dot 001) at day 14. Additionally, 91 center dot 8% fewerE. coliand 27 center dot 3% fewer enterococci were observed in slurry added ammonia at day 14 compared to raw slurry. Conclusion The addition of aqueous ammonia to raw slurry significantly reduced the viability ofC. parvumoocysts and numbers of bacterial indicators. Hence, ammonia is usable at lower pathogen concentrations in slurry before application to agricultural land. Significance and Impact of the Study Livestock waste is a valuable source of plant nutrients and organic matter, but may contain high concentrations of pathogens likeE. coliandCryptosporidiumsp. that can be spread in the environment, and cause disease outbreaks. However, die-off rates of pathogens in organic waste can increase following increasing ammonia concentrations.

Automated summary

The study demonstrates that adding aqueous ammonia to cattle slurry significantly increases the inactivation rate of Cryptosporidium parvum and reduces the numbers of bacterial indicators. Therefore, ammonia can effectively lower the pathogen concentration in slurry before application to agricultural land.