The existing drainage around and under the piggery was modified to recover the waste products, and automatic flushing valves were installed and linked to the main pumping station. The valves are solenoid activated and enable remote controlled flushing at various times of the day, working in a similar way to an automatic watering system in a domestic garden. Grit removal is crucial in removing granules of bone that reside in the slurry and can potentially damage internal mechanisms of the pump. The slurry thickening occurs when the finer suspended solids are separated from the water, and the clarified water is recycled as flush water and applied directly to the land. The thickening plant separation process is a combination of an existing screen and a newly developed flotation system.
Flotation allows the separation of water from the smaller suspended particles.
Primary and secondary digestion are the anaerobic processes crucial to biogas production. The digesters provide the ideal conditions for the process to proceed at a faster, more controlled rate, by excluding air, thoroughly mixing the contents and maintaining optimum temperatures. Biogas purification occurs when it is purged of potentially damaging sulfur by scrubbers, traps and a dehumidifier, before being pumped to the co-generation thermic plant where it is converted into thermic heat and electricity. The solid and colloidal parts of the digested slurry are separated from the water by centrifuge. The end result is composted humus - a valuable fertilizer, currently under development trials for the domestic potting mix market.