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Disinfection of swine wastewater using chlorine, ultraviolet light
and ozone.
Department of Biological Sciences, University of
Missouri-Rolla, 65409, USA.
Veterinary antibiotics are widely used at concentrated
animal feeding operations (CAFOs) to prevent disease and promote growth
of livestock. However, the majority of antibiotics are excreted from
animals in urine, feces, and manure. Consequently, the lagoons used to
store these wastes can act as reservoirs of antibiotics and
antibiotic-resistant bacteria. There is currently no regulation or
control of these systems to prevent the spread of these bacteria and
their genes for antibiotic resistance into other environments. This
study was conducted to determine the disinfection potential of chlorine,
ultraviolet light and ozone against swine lagoon bacteria. Results
indicate that a chlorine dose of 30 mg/L could achieve a 2.2-3.4 log
bacteria reduction in lagoon samples. However, increasing the dose of
chlorine did not significantly enhance the disinfection activity due to
the presence of chlorine-resistant bacteria. The chlorine resistant
bacteria were identified to be closely related to Bacillus subtilis and
Bacillus licheniformis. A significant percentage of lagoon bacteria were
not susceptible to the four selected antibiotics: chlortetracycline,
lincomycin, sulfamethazine and tetracycline (TET). However, the presence
of both chlorine and TET could inactivate all bacteria in one lagoon
sample. The disinfection potential of UV irradiation and ozone was also
examined. Ultraviolet light was an effective bacterial disinfectant, but
was unlikely to be economically viable due to its high energy
requirements. At an ozone dose of 100 mg/L, the bacteria inactivation
efficiency could reach 3.3-3.9 log.
PMID: 16678233 [PubMed - indexed for MEDLINE]
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