Biological breakdown

The biological breakdown is the Décomposition /d egradation of organic matters by micro-organisms (Bactérie S, Champignon S and/or Algue S).

The materials known as biodegradable (except Pigment S minerals and possible load) are converted into Carbon dioxide (or carbonic gas) and/or methane, water and in biomass (because the micro-organisms use material like a source of carbon to develop).
Le process of biological breakdown is often used for the natural waste processing.

A material is known as biodegradable when it can undergo a total biological breakdown. For example, the majority of the plastic bags are not biodegradable, but the paper bags are it. That can make an important difference in becoming to it waste, because the plastic bags will remain a long time intact so abandoned in nature, whereas the paper bags break up rather quickly.

However, in an anaerobic medium, i.e. without air, the biodegrability is compromised: the materials generally do not deteriorate because of the absence of oxygen necessary to the aerobic micro-organisms. If a biological breakdown takes place nevertheless, it is by an anaerobic process which produces methane, which is a gas with Greenhouse effect. However, this methane, if it is collected is an energy source. Its combustion will release from the Carbon dioxide, him also gas with greenhouse effect, but as this carbon comes originally from the atmosphere (fixed in a plant by Photosynthèse), one considers that this energy source is neutral with respect to the greenhouse effect.

Techniques like the Compost or the Biogaz make it possible to domesticate the degradation of the organic matters; they require specific equipment for crushing, the compaction, ventilation, the reversal then the sifting. Above all, the matters to be perforated must be carefully sorted nonbiodegradable matters, it is a exercise to which each consumer must be formed.

There exist now plastics hydro-dégradables. In the actual position of the technique, they cannot agree for the conservation of food because they are sensitive to the moulds and micro-organisms of which they should protect food.

It is advisable to be attentive with the terminology of the biodeterioration. A product biodégrade that if it is in contact with a favorable environment in micro-organism. There can be confusion with Photodégradable: degradation under the effect of the Ultraviolet rays; or with the materials Hydrosolubles which disaggregate under the effect of moisture. Certain materials are known as oxo-biodegradable: by oxidation of the connections carbon hydrogenates, the molecular mass of materials decreases and around 5000 let us daltons certain micro-organisms could then degrade them. However this mode of degradation is not in conformity with the requirements of the current standard INTO 13432 (a sheet of tree either besides). The polylactic Acide (PLA) is an example of biodegradable material.

Behavior of the consumer

It is necessary to draw the attention of the consumer: a biodegradable article should not be anywhere abandoned. Droppings of dog are perfectly biodegradable, but on a pavement it is not its place. In the same way, a biodegradable bag which floats with the wind will be a visual pollution during several months because the requirements with its composting are not met: 60° minimum and a sufficient moisture. This is different for thebiodegradable ones which will be oxidized by UV and Heat. The visual disappearance of the product will be activated quickly; The study of their biological breakdown and their ecotoxicity was undertaken by several universities moreover one study is published on the site of the ADEME.

In addition, it should not systematically be considered that a biodegradable material is ecological. Some result from the starch of the plants, which are sometimes very greedy corn out of water or transgenic varieties like the American PLA (PolyLactic Acid), this product is compostable but nonbiodegradable in lower part of 55°C. Thus although normalized it does not regulate any problem environmental. There exist even biodegradable materials resulting from oil, resource nonrenewable.

The principal industrial applications of biodegradable plastics and compostables are the bags distributed in the supermarkets (38% of the total intake), the sector of packing (food goblets and containers, films, nets, foams) as well as the producing sector of the plastic bags for the collection and the composting of natural waste.

The key actors of the market of the biodegradable plastics are: BASF (Germany), NatureWorks LLC (the United States), BIOTEC (Germany which uses potato starch), Novamont (Italy), Rodenburg Biopolymers (Netherlands), Vegeplast (France), SYMPHONY ENVIRONMENTAL (England), EAR (Canada) for thebiodegradable ones. Alone, these companies add up more than 90% of the European market of the biodegradable plastics and their share on the worldwide market reached of the proportions of the same order. The international association of biodegradable polymers (International Biodegradable Polymers Association & Working Groups, IBAW) gathers the matter manufacturers at vegetable bases. See also Biodegradable Products Institute.

Time of degradation of current products

See too

There exist now several biodegradable plastics as the PLA (polyacid lactic) which is perfectly ready to contain food. Several are thus already marketed. But nonbiodegradable in lower part of 55°C, they are difficult has to recycle and damage the dies. They must thus be the subject of a recycling.

Organic chemistry
carbonic Chain

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