Sources of nutrients in wastewater from integrated cattle slaughterhouses Available to Purchase

The generation of the nutrients, nitrogen and phosphorus, by various process areas of two large, integrated cattle slaughterhouses was studied to assist the better management of wastewater production and treatment. The Dinmore slaughterhouse, located near Ipswich, processes predominantly grass-fed cattle, while the Beef City slaughterhouse west of Toowoomba processes grain-fed cattle. Nitrogen in the wastewater streams largely originated from the rendering plant (50% of the total daily generation at Dinmore and 62% at Beef City), the decreased cattle bone process at Dinmore (22%) and the cattle holding yards at Beef City (32%). Phosphorus was generated primarily in the offal, paunch and tripe processing area at Dinmore (49%) and the holding yards at Beef City (57%). Nitrogen was present mostly as organic or ammonium nitrogen, whereas ortho-phosphate was the main form of phosphorus present in wastewater streams. Significant differences were found in nutrient generation between the two slaughterhouses, with the Dinmore plant releasing almost twice the quantity of nitrogen, and four times more phosphorus, per animal processed compared to the Beef City plant. These results will assist management in allocating resources aimed at cleaner production by minimising and removing nutrients in the wastewater.