Use of carbonate and alkali to eliminate Escherichia coli from dairy cattle manure

A procedure to eliminate Escherichia coli in dairy cattle manure was developed. E. coli persisted in fresh manure and farm storage tanks, and viable counts ranged from 10⁵ to 10⁸/g. If the feces to urine ratio of fresh manure was decreased from 2.2 to 1, E coli did not persist for ≥10 days (<10 viable cells/g), and it appeared that the urine was killing E. coli. Fecal urease contamination produced CO₂, and 16% was trapped as carbonate. When urine pH was decreased, antimicrobial effect was lost, even if the pH was readjusted to 8.5. When E coli K-12 and O157:H7 were treated with Na₂CO₃ (100 mM, pH 8.5, 24 h), viable cells were not detected. The E. coli count of manure (feces to urine ratio of 2.2:1) was decreased by Na₂CO₃ addition (8 g/kg), but pH sometimes declined and carbonate was lost. When NaOH was included (2 g/kg), Na₂CO₃ additions could be decreased (4 g/kg), and treatment time was 5 days. Treatment cost could be <$10 year^-1 (dairy cow)^-1. Water dilution (3-fold) did not diminish the effectiveness of the carbonate/alkali treatment, and viability was <10 cells/g.