The temperature of slaughterhouse effluent
appears to vary significantly worldwide. In Europe, it
is frequently cool (20°C), in contrast to Australian
effluent, which is routinely 30-35°C, but can be even
hotter in sub-tropical areas. This can be a significant
issue in the choice and economics of wastewater
treatment operations (i.e. high-rate anaerobic systems;
nitrification), since biological systems typically
perform considerably faster at higher temperatures
(37°C); conversely, fat emulsification at the hotter
temperatures causes substantial difficulties,
especially in intensive-treatment systems, such as
activated-sludge plants.
The physical nature of slaughterhouse wastewater
has been studied by Sayed et al. (1987), who have
shown that of COD in screened (1 mm mesh) effluent,
40-50% was present as coarse, suspended
matter, which was insoluble and only slowly biodegradable,
and the remainder as colloidal and
soluble matter. This varies considerably from domestic
wastewater, in which the COD is present mainly
in the colloidal form.
An independent rendering plant will produce
quite different wastewater to that of an integrated
slaughterhouse (Metzner & Temper, 1990; Cooper