Effect of Green Oxidizing Agent on Inhibition of Escherichia coli Present in Livestock Wastes

The optimisation tests of sodium percarbonate (biocide) with the formula 2Na₂CO₃·3H₂O₂, as a green oxidizing agent for biological deactivation of chicken manure, were carried out. The microbiological analysis of fresh manure which consisted of the enumeration of bacteria, fungi and eggs of intestinal parasites showed that the number of bacteria Enterobacteriaceae, i.e. 8.3 log₁₀CFU/g, and the bacteria E. coli, i.e. 6.96 log₁₀CFU/g, exceeded the required level in organic fertilizers. The Response Surface Methodology for three input parameters (biocide concentration, temperature and time) on the value of E. coli bacteria was applied. The obtained values of the coefficient of the multiple correlation R² and the adjusted coefficient Rₐdⱼ² were 0.90 and 0.75, respectively, which indicate a good fit of the data obtained with the model and the experimental data. It was concluded that a decrease in the count of the analysed microorganisms followed an increase in the sodium percarbonate concentration, an increase in the temperature and a longer time of contact of the manure sample with the biocide. The content of bioavailable macronutrients (P, N, Ca, Mg, K) in water extracts of fresh chicken manure before and after its biological deactivation was determined with the ICP-OES method. The concentration of phosphorous in fresh manure extract was 310 mg/l and decreased after addition of one of the following agents: 7.5 wt.% of sodium percarbonate to 66.9 mg/l or 3.0 wt.% of traditional hygienizing agent, i.e. calcium hydroxide to 5.7 mg/l.. The results of the concentration of N in chicken manure with sodium percarbonate was also higher than in sample with calcium hydroxide, i.e. 1040.0 mg/l and 860.0 mg/l, respectively. While the addition of 2Na₂CO₃·3H₂O₂ decreased the content of Ca, Mg and K in fresh chicken manure.