Fractionation of beef cattle waste after methane fermentation: Chemical studies on the fractions

• Published in: Energy in agriculture 1986-04, Vol.5 (1), p.73-79
• Main Authors: Nielsen, H.C., Wall, J.S.
• Format: Article
• Language: English
• ISSN: 0167-5826
• DOI: 10.1016/0167-5826(86)90007-0

Anaerobic fermentation can convert 40% of the organic solids in beef cattle waste to carbon dioxide and methane. After such fermentation, 56% of the solids in the effluent could be isolated by filtration on a 60-mesh screen. On a dry basis this fibrous material contained 3.17% nitrogen and 13.2% ash. Centrifugation of the remaining filtrate at 1500 g yielded a further 25% solids, which contained 5.15% nitrogen and 26.1% ash. The two solid fractions were quite similar to fiber and cell fractions previously isolated from unfermented cattle waste. The remaining clear, dark brown supernatant represented one-fifth of the original system solids but contained only 2% total solids. On a dry basis the supernatant contained 5.55% nitrogen and 28.6% ash. Attempts to isolate solids from this supernatant by heat coagulation, dialysis, and ultrafiltration were not successful. All of the fractions had similar amino acid compositions with good amounts of essential amino acids. From 23 to 38% of the nitrogen in all fractions was ammonia.