Back To Basics: Revisiting Blood Collection
Technological advances in waste minimization, waste stream analysis and wastewater treatment have focused the environmental efforts of many poultry processing plant personnel on the minutia of pollution prevention. However it is often a good idea to periodically step back from the small details and revisit the basics. One of these pollution prevention basics is blood collection. The potential impact of blood on poultry processing wastewater streams is significant. Research shows that blood volume in chickens varies with body weight, with smaller birds having a greater percentage of blood versus larger birds. However, once chickens reach about 4.5 lbs of body weight and above, the percent blood in their bodies is about 7.5%. Once a chicken is electrically stunned unconscious during processing and the throat cut is made, research shows that approximately 50% of the blood in the carcass will drain out. This represents about 3-4% of total body weight (Barbut, 2002; Raj, 2004; Sams, 2001). Table 1 shows the potential impact that unrecovered blood has on wastewater based on weight (lbs) and volume (gallons) of blood that is typically bled-out during the slaughter process. The table shows that a 250,000 small-bird/day processing plant must handle 42,200 lbs or about 4,800 gallons of blood a day, while a 250,000 large-bird/day plant must be prepared to recover 70,300 lbs or about 7,900 gallons of blood a day.