Russell et al. (1993) reported that the rate of N20
release from pasture and forest irrigated with effluent
rose markedly immediately following irrigation,
but fell back to base emission rates within 24 h of
irrigation ceasing. Emission was affected by the type
of wastewater and temperature. Both N20 emission
and denitrification were minimal at temperatures
below 12°C (Russell et al., 1993).
A further concern for the management of slaughterhouse-
wastewater irrigation systems is human
exposure to potentially pathogen-contaminated
aerosols. Sprinkler irrigation systems lead to the
aerosolisation of 0.1-1% of the sprayed water.
Shuval et al. (1984) found that irrigation workers
exposed to aerosol-forming (sprinkler) irrigation
were three times more likely to be carrying antibodies
to Legionella pneumophila, the causative
agent of Legionnaires disease, than the normal
population, regardless of whether the water was
clean or treated-wastewater. Oxidation-pond water,
in particular, may be a natural habitat of this bacterium
and aerosol irrigation of such water may pose
an occupational risk to exposed workers. It must be
noted, however, that this finding was only preliminary
and the authors suggest a more detailed study
is required. Clearly, irrigation with slaughterhouse
wastewater should preferably be by non-aerosolforming
techniques.
Russell et al. (1993) reported that the rate of N20release from pasture and forest irrigated with effluentrose markedly immediately following irrigation,but fell back to base emission rates within 24 h ofirrigation ceasing. Emission was affected by the typeof wastewater and temperature. Both N20 emissionand denitrification were minimal at temperaturesbelow 12°C (Russell et al., 1993).A further concern for the management of slaughterhouse-wastewater irrigation systems is humanexposure to potentially pathogen-contaminatedaerosols. Sprinkler irrigation systems lead to theaerosolisation of 0.1-1% of the sprayed water.Shuval et al. (1984) found that irrigation workersexposed to aerosol-forming (sprinkler) irrigationwere three times more likely to be carrying antibodiesto Legionella pneumophila, the causativeagent of Legionnaires disease, than the normalpopulation, regardless of whether the water wasclean or treated-wastewater. Oxidation-pond water,in particular, may be a natural habitat of this bacteriumand aerosol irrigation of such water may posean occupational risk to exposed workers. It must benoted, however, that this finding was only preliminaryand the authors suggest a more detailed studyis required. Clearly, irrigation with slaughterhousewastewater should preferably be by non-aerosolformingtechniques.
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