Post-primary treatment of slaughterhouse wastewater
depends on the location. In Europe, most
slaughterhouses and rendering plants deliver their
wastewater to municipal systems after preliminary
primary treatment (Sayed et al., 1987). Where this is
not feasible, some plants have installed activatedsludge
plants with biological nutrient removal. In the
US, the situation is unclear, although there seems to
have been a trend towards activated-sludge plants.
In the majority of Australian slaughterhouses, wastewater
has passed through anaerobic treatment ponds
then into aerobic-pond systems. In a few, direct
aerobic treatment (i.e. activated sludge) has been
used. The goal of the former has been to achieve
BOD reduction, whereas the goal of the latter has
often also included nitrification. In contrast, New
Zealand slaughterhouses often irrigate primarytreated
or anaerobic-treated wastewater directly to
land.