Circular Economy

A circular economy keeps materials in productive use and minimizes disposal by treating waste as a resource. For organic materials, it returns nutrients to soil or converts biodegradable waste into energy and bio-based products, thereby closing biological resource loops.

The conversion chain

Organic residues such as animal dung, crop residues, food waste and sewage sludge are first segregated at source, collected and processed to remove contaminants. The chosen biological treatment then converts their carbon and nutrients into usable outputs.

• In anaerobic digestion, microorganisms decompose organic matter without oxygen, producing biogas and nutrient-rich digestate.
• Raw biogas is cleaned and upgraded by removing impurities and carbon dioxide; the biomethane can then be compressed as compressed biogas for transport, industrial or other energy uses.
• Digestate can be processed into organic manure, returning nutrients and organic matter to soil instead of discarding them.

Other resource-recovery pathways

Different organic wastes require different treatment routes, so circularity does not mean converting every residue only into fuel.

• Composting uses aerobic decomposition to produce compost or soil conditioner from suitable biodegradable waste.
• Vermicomposting employs earthworms and microorganisms to convert selected organic waste into nutrient-rich manure.
• Biogas may also generate heat or electricity, allowing local waste streams to support decentralized renewable energy systems.

Benefits and enabling conditions

The model can reduce landfill dependence, capture energy from decomposition and substitute part of the demand for fossil fuels and chemical fertilizers. Its effectiveness depends on maintaining a reliable material loop from waste generators to processing plants and final users.

• Clean feedstock requires source segregation, contamination control and dependable collection.
• Plants need assured feedstock supply, appropriate technology and markets for gas, power, compost and digestate.
• Safe treatment and quality standards are essential because contaminated inputs can reduce product quality and environmental benefits.