STUDY ON POSSIBILITIES FOR APPLYING OF FORMALIN FOR DECONTAMINATION OF CATTLE MANURE

Teodora P. Popova, Baiko D. Baikov

Abstract: Comparative studies of the use of formaldehyde in concentrations of 0.5%, 1%, 2% and 4% for processing of fresh manure from dairy cows with a view to decontamination were performed. Test-strains of Proteus vulgaris, Pseudomonas aeruginosa and Staphylococcus epidermidis, multiresistant to gentamicin and tetracyclines, were used. TS were added in the manure each in concentration at 105 CFU/g from its content and the changes in their quantities were traced. Also determination of minimum inhibitory and bactericidal concentrations of formaldehyde for 18 strains of microorganisms from different groups was performed, respectively by 3 strains of Salmonella entericа, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes, Paenibacillus alvei and Candida albicans. It was found that treatment with formalin ensures inactivation of pathogenic test microorganisms and of Clostridium perfringens in the manure even after 24 h using 2 and 4%, and in lower concentrations of 0.5 and 1% - within 48 h. Inactivation of E. coli was achieved within 24 h after administration of 4%
formaldehyde, with 1 and 2% - for 2 days and with 0.5% - for 3 days. Minimum inhibitory concentrations of formaldehyde for the investigated Gram-positive and Gram-negative organisms ranged from 21.3 ± 9.2 to 32.0 ± 0.0. The values of minimum bactericidal concentrations were twice as high and ranged from 53.3 ± 18.5 to 64.0 ± 0.0. When processing fresh cow manure with formaldehyde in final concentrations 0.5 and 1% was achieved rapid and effective decontamination for a period of 24-48 h for bacteria that do not form spores and for 7-8 days for spore-forming. At higher concentrations tested of 2 and 4% the results were similar
for non spore-forming microorganisms - killing for 24-48 h, and the rest - for double shorter time (4-5 days). The use of formaldehyde in final concentrations 2 and 4% did not give better results than the smaller concentrations of 1 and 0.5%, which are recommended for use.

Keywords: cattle manure; decontamination; formaldehyde; test bacteria

Date published: 2023-01-31