Gas generated by the fermentation of waste in landfills. Its main constituent is methane. If captured via underground piping, it can be converted into electricity or thermal energy.

Biological recovery

Organic waste processing technique using composting or methanisation techniques


Product of anaerobic decomposition of organic waste. It is an organic amendment, i.e. it can be used to improve soil quality.


Transformation by micro-organisms (microscopic fungi, bacteria…)or organic waste to a humus-like product in the presence of water and oxygen.

Delegation of utility operation

A recently established legal concept in France, formalised by the French Home Office in August 1987 and the Sapin Act of 29 January 1993. A delegation of utility operation (délégation de service public) contract is an administrative contract drawn up between a public party and a third party (public or private) chosen to run a public utility. The public authority is still responsible for the organisation and overall control of the utility while the third party takes charge of day-to-day operations, at its expense and risk, for a remuneration substantially guaranteed by the results of the operations. The various stages of the process as laid down in the Sapin Act and its implementing decree no. 93-471 of 24 March 1993 are as follows: presentation of a report to municipal council, council vote, election of a commission to open tender bids. This is therefore a procedure originally specific to France, but which is becoming more common elsewhere.

DW (domestic waste)

Waste resulting from household consumption and collected by traditional or selective collection.

Energy-from-waste (EfW)

Recovery of calories contained in incinerated waste, allowing thermal or electrical energy to be generated.

Energy recovery (from waste incineration)

Energy recovery means using the calories contained in a substance to produce energy. When energy is produced during the incineration cycle, this is referred to as energy recovery from waste, or simply energy from waste.


A substance that has the property of flocculating, i.e. aggregating in flake form the particles of colloids in suspension in a solvent.


The treatment by physical or chemical processes to reduce to non-detectable levels the presence of all the pathogenic microorganisms in a medium.


Facility subject to authorisation, designed to incinerate waste. More and more incinerators now rcover waste in the form of electricity or thermal energy. The by-products of incineration (bottom ash and fly ash) are processed with a view to controlling the impacts of this activity both on mankind and on the environment.

Inert waste

Waste which unlikely to evolve physically or chemically (non toxic, non biodegradable, very low solubility in water, non oxidizable), for example, backfill, rubble…


Specialised sites providing high-security storage for hazardous and non-recoverable waste (final residue from household or industrial waste disposal processes).

Material recovery

Waste processing technique, allowing reemployment, reuse and recycling (eg : waste resulting from selective collection which is recycled, bottom ash recovered for use in toadway capping layers).


Colourless flammable gas which is given off from decomposing vegetable matter or the putrescible fraction of household waste.


Methanisation is based on the recovery of gas produced by the degradation of organic matter buried in landfills, a form of biological fermentation caused by bacterial flora. It facilitates the recovery of a gas that otherwise would simply escape into the atmosphere. It also reduces the proportion of final waste in landfills and improves control of the pollution and environmental nuisance caused by the treatment of household waste. Once recovered, biogas can be used to produce electricity or heat, or be used as a clean fuel.

Ordinary industrial waste

Non-hazardous industrial waste that can be assimilated to household waste (paper and cardboard, glass, packaging, etc.).

Organic recovery

Transformation of the putrescible fraction of waste into compost. Organic waste represents on average 65% of household waste tonnage.


Reduction, within controlled conditions, of the initial pollutant potential of waste and/or waste volumes before landfill.


Use of waste for a similar purpose (for example, returnable bottles) or a different purpose from that for which the material was originally intended (for example, using tyres to protect the hull of trawlers).


Generic term encompassing the remployment, reuse, recycling or regeneration of waste.


Direct re-introduction of a waste type into the production cycle from which it originates as a total or partial replacement for a new material. For example, melting down broken bottles to make new ones. Newspapers, magazines and glass can be recycled if they are selectively collected. Textile products and fermentable materials cannot be recycled.

Selective collection

Also known as separate collection: consists of collecting domestic waste which has already been pre-sorted into different categories by householders, so as to enable optimum recovery or specific treatment. Each collection round covers one type of waste.


The end result of treating domestic or industrial waste water; a substance with a high organic matter content. For many years sludge simply drained into sewers before being discharged into the natural environment. Today there is legislation requiring it to be channelled into sewage works. There, any elements which may damage the environment or human health are eliminated.

Sustainable development

Term which designates a type of economic development which takes into account the environment, renewable resources and a rational use thereof, so as to preserve raw materials indefinitely rather than exhausting or destroying them.