One solution to the problem of handling and treating slurry from a pig fattening house

One competitive solution to the slurry handling problem of some intensive pig houses is described. The system is based on mechanical and chemical separation techniques. The solids produced are easy to store until they can be spread on neighbouring land and their smell is inoffensive. The liquids produced are greatly reduced in bulk, by evaporation, and in polluting potential, thereby reducing the problems of their eventual disposal.

A treatment plant has operated for 3 years in a 500 place finishing piggery in such a way that slurry was flushed from the channels hourly and passed through a mechanical separator to remove the coarse particles. Separation enabled a high rate biological filter to treat the separated liquid reliably without blockages and also increased the pump life tenfold. The treated separated liquid was then flocculated, and the conbined effect of the mechanical separation and the flocculation was to leave up to 40% of the input slurry as a semi-solid at 15% dry matter (DM) together with a clear filtrate liquid, much of which was evaporated by diverting air from the ventilation system around the treatment plant and through an air scrubber/evaporator. Thus, only 30% of the original slurry had to be discharged as liquid. With design modifications to the treatment plant and close control of water wastage this figure 30% can be reduced to zero, i.e. an output of solids only can be attained.