An Aerobic Piggery Slurry Treatment System with Integrated Heat Recovery and High-Rate Algal Ponds

A piggery with an integrated slurry removal and treatment system with heat recovery and two algal raceways for a secondary treatment of settled treated slurry has been built. Piggery slurry from about 250 fattening pigs and 100 weaners has been aerobically treated in a continuous culture reactor at 36°C. Metabolic heat and heat from the aerator after upgrading by a heat pump was utilized for space heating in a weaner house and in one of the algal raceways. Intermittent heating had little effect upon algal productivity and effluent treatment since the system was essentially light limited. Characteristics of treated slurry and quantity of heat evolved are in good agreement with predicted values by a mathematical model.