Treatment of organic waste from animal slaughteries

Abstract

Reime Econ's physical -biological plant for treatment of organic waste was examined at Vest­Ro's animal slaughtery in Sandeid, SW Norway. The system comprises 1) an initial separation of the waste into a solid and a liquid phase, and 2) a combined solid settling and aerobic biological treatment of the liquid phase. The solid phase is further processed by composting, while the treated fluid phase is led to the domestic sewer system. The gradual and overall treatment efficiency of the plant was estimated by monitoring of the mass flux through the system. An overall reduction of 91 % through the plant was found for Dry matter. Wilh regard to Chemical oxygen demand, Nitrogen and Phosphorus of the liquid phase, the removal efficiency was 85 %, 67 % and 63 %, respectively.

The overall treatment efficiency of Dry matter increased with increasing waste loading up to 1,300 kg DM/day. The Bioreactor of the plant was overloaded in the test. However, the capacity can been adjusted in order to achieve an improved treatment efficiency of organic mater (COD). The total fixed and variable costs of the plant was estimated to NOK 185,000 annually ($US 20,000). Assuming an annual waste loading of 1,500 cu. m of solids and 3,500 cu. m of liquid waste at Vest-Ro, the total treatment costs corresponded to NOK 37 per cu. m ($US 4/cu. m).