Organic Waste Recycling

Biofuels production 147

4.1 OBJECTIVES, BENEFITS AND LIMITATIONS OF

BIOGAS TECHNOLOGY

The main purposes and benefits of biogas technology are classified as follows:
Original uses:

Addition of methane generation:

Figure 4.1 Impact of anaerobic fermentation on use of organic wastes (NAS 1977)

Animal wastes Crop residues

Burned as fuel

Heat

Applied directly to the land

as fertilizer

Ploughed under to increase

soil organic matter and

return nutrients to soil

Animal wastes

Night soil

Crop residues

Domestic wastes

Methane

generator

Original nitrogen and other

nutrients returned to soil

as fertilizer; sludge

improves soil structure

and increases organic

matter

Electrical energy

Heat and light

Mechanical energy

Fuel

Sludge

residue