Nutritious medium for fodder yeast mfd. from manure, etc. - by hydrolysing conc. suspension and adding back decanted liq. fraction

The process for converting liq. manure without stable litter into a nutritious medium for the growth of microorganisms esp. yeasts as a source of proteins and vitamins. The manure is sepd., e.g. by centrifuging into a clarified liq. fraction and a conc. suspension. The liq. fraction is sterilised and the conc. suspension is heated and then hydrolysed in the presence of a mineral acid as catalyst, e.g. H2SO4, the hydrolysed prod. then being neutralised. Prod. is treated, e.g. by ultraviolet irradiation to eliminate noxious, volatile, impurities, and is then cooled. Before neutralisation, the sterilized liq. fraction is admixed with the hydrolysed prod. The neutralised prod. is pref. desludged, e.g. via a decanting centrifuge. Used in mfr. of fodder yeast from pig manure, poultry droppings, waste from the futs of slaughtered animals in large abattoirs and similar organic refuse. Adding back the clarified liq. fraction greatly increases the yield of nutritious prod. while reducing mfg. costs. For example, a pig farm raising 108,000 pigs per year can produce 2,000 tonnes p.a. of fodder yeast to make up about 5,200 tonnes of fodder which represents a 10% saving on the fodder bill. The neutralisation process requires 20-80% less alkali when the liq. fraction is added back.