2.3.8. Anaerobic digestion systems
While anaerobic digestion has not been used to treat hatchery waste it is the most popular process used to treat human effluent and other livestock waste. It has the advantage of being a high efficiency process and produces biogas [48] for power generation or heating. The Poultry Industry has overlooked using anaerobic digestion as a means of treating hatchery waste. It is by far the most popular process used to treat organic wastes in a number of other organic waste industries. The biosolids remaining after the digester process can be sold as a high quality fertiliser. Kumar [49] demonstrated the use of a two stage anaerobic process for effluent from piggeries and abattoirs will produce methane and the nutrients can be also recovered from the waste to grow algae, zooplankton and fish. The treatment system has clear advantages in cost and environmental benefit due to recycling of waste. The benefits also include income from the sale of electricity generated through biogas and fertiliser to produce bioproducts such as algae, zooplankton and fish as livestock feed. Anaerobic digestion involves the degradation and stabilisation of an organic waste under anaerobic conditions by microbial organisms to produce methane and inorganic products [13] as described in the equation below.