BIOTECHNOLOGY - V. H. Herasymenko - 2006

Part II. Special Biotechnologies

Chapter 22. BIOTECHNOLOGIES FOR WASTE UTILIZATION AND BIOCONVERSION IN THE AGRO-INDUSTRIAL COMPLEX

22.3. NON-CONVENTIONAL METHODS. BIOTECHNOLOGY FOR BIOGAS PRODUCTION VIA ANAEROBIC WASTE DIGESTION

22.3.4. Fractions Generated during Biomethanogenesis

22.3.4.3. Liquid Fraction: Composition and Utilization

Following anaerobic manure Processing, the liquid fraction complies with environmental protection standards established for wastewater quality. Like sludge, it is free of specific odors and contains 80% less organic matter, while its biological oxygen demand is 80% lower than prior to anaerobic Fermentation. The Sanitary and hygienic parameters of the supernatant liquid allow it to be discharged into sewage systems or Water bodies. However, this is inefficient, as it contains a significant amount of nutrients and can be utilized as a liquid organic fertilizer. On average, the liquid fraction of manure contains (%): dry matter - 1.0-5.0; organic matter - 0.25-4.2; nitrogen - 0.3-1.1; phosphorus - 0.05-0.7; pH - 6.5-8.3.

Furthermore, the liquid fraction can serve as a substrate for cultivating microalgae (such as Chlorella and Spirulina, a blue-green alga). Their biomass serves as a valuable protein, vitamin, and trace mineral feed Supplement for livestock diets, while Spirulina also acts as a raw material for the pharmaceutical industry. Hydrobiont biomass can additionally be used for biogas production.

When evaluating the economic efficiency of methane fermentation biotechnology, it is essential to consider not only The Role of biogas in addressing energy challenges, particularly in rural areas, but also the benefits of manure disinfection, high-quality fertilizer production, and environmental protection. Calculations indicate that despite significant capital investments, the payback period for an industrial biogas plant is approximately three years (Dubrovin et al., 2004).



Last update: 11/08/2026

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