Biodegradable bags are bags that are capable of being decomposed by bacteria or other living organisms. Biodegradable bags are so environment-friendly that they can be degraded to co2& water within 20 months. Biodegradable certificate is available applying.
Every year approximately 500 billion to 1 trillion plastic bags are used worldwide.
Distinguishing "biodegradable" from "compostable"
In typical parlance, the word biodegradable is distinct in meaning from compostable. While biodegradable simply means an object is capable of being decomposed by bacteria or other living organisms, "compostable" in the plastic industry is defined as able to decompose in aerobic environments that are maintained under specific controlled temperature and humidity conditions. Compostable means capable of undergoing biological decomposition in a compost site such that the material is not visually distinguishable and breaks down into carbon dioxide, water, inorganic compounds and biomass at a rate consistent with known compostable materials. (ref: ASTM International D 6002)
The inclusion of "inorganic materials" precludes the end product from being considered as compost, or humus, which is purely organic material[opinion]. Indeed, under the ASTM definition, the only criterion needed for a plastic to be called compostable is that it has to appear to go away at the same rate as something else that one already knows is compostable under the traditional definition.
Plastic bags can be made "oxo-biodegradable" by being manufactured from a normal plastic polymer (i.e. polyethylene) or polypropylene incorporating an additive which causes degradation and then biodegradation of the polymer (polyethylene) due to oxidation.
The trade association for the Oxo-biodegradable plastics industry is the Oxo-biodegradable Plastics Association, which will certify products tested according to ASTM D6954 or (as from 1st Jan 2010) UAE 5009:2009
The trade associations for the compostable plastics industry are the Biodegradable Products Institute (BPI), "European Bioplastics," and SPIBioplastics Council. Plastics are certified as compostable for industrial composting conditions in the United States if they comply with ASTM D6400, and in Europe with the EN13432.
Different companies use different kinds of biodegradable bags. Many stores and companies are beginning to use different types of biodegradable bags to comply with environmental benefits. Multinational baking giant Grupo Bimbo SAB de CV of Mexico City claims to have been the first to make "Oxo Biodegradable metalized polypropylene snack bag". In addition to that, a company named "Doo Bandits" has created oxo- biodegradable bags used for picking up dog waste. The Supermarket Chain Aldi Süd in Germany offered until 2013 bio-based ecovio® bags. Those bags are as flexible, tear-resistant, waterproof and suitable for printing, as traditional PE-bags, but are - due to its extra benefit of being certified compostable - a few cents per bag more expensive.
Most bags that are manufactured from plastic made from corn-based materials, like Polylactic acid (PLA)-blends. Biodegradable plastic bags are nowadays as strong and relieable as traditional (mostly PE)-bags. Many bags are also made from paper, organic materials, or polycaprolactone.
"The public looks at biodegradable as something magical," even though the term is broadly used, according to Ramani Narayan, a chemical engineer at Michigan State University in East Lansing, and science consultant to the Biodegradable Plastics Institute. "This is the most used and abused and misused word in our dictionary right now. Simply calling something biodegradable and not defining in what environment it is going to be biodegradable and in what time period it is going to degrade is very misleading and deceptive." In the Great Pacific garbage patch, biodegradable plastics break up into small pieces that can more easily enter the food chain by being consumed."
In- plant scrap can often be recycled but post-consumer sorting and recycling is difficult. Bio-based polymers will contaminate the recycling of other more common polymers. While oxo-biodegradable plastic manufacturers claim that their bags are recyclable, many plastic film recyclers will not accept them, as there have been no long-term studies on the viability of recycled-content products with these additives. Further, the Biodegradable Plastics Institute (BPI) says that the formulation of additives in oxo films varies greatly, which introduces even more variability in the recycling process. SPI Resin identification code 7 is applicable.
Marketing qualification and legal issues
Since many of these plastics require access to sunlight, oxygen, or lengthy periods of time to achieve degradation or biodegradation, the Federal Trade Commission's GUIDES FOR THE USE OF ENVIRONMENTAL MARKETING CLAIM
Advantages and disadvantages
Under proper conditions, some biodegradable plastics can degrade to the point where microorganisms can completely metabolise them to carbon dioxide (and water). For example, starch-based bioplastics produced from sustainable farming methods could be almost carbon neutral.
There are allegations that "Oxo Biodegradable (OBD)" plastic bags may release metals, and may require a great deal of time to degrade in certain circumstances  and that OBD plastics may produce tiny fragments of plastic that do not continue to degrade at any appreciable rate regardless of the environment. The response of the Oxo-biodegradable Plastics Association (www.biodeg.org) is that OBD plastics do not contain metals. They contain salts of metals, which are not prohibited by legislation and are in fact necessary as trace-elements in the human diet. Oxo-biodegradation of polymer material has been studied in depth at the Technical Research Institute of Sweden and the Swedish University of Agricultural Sciences. A peer-reviewed report of the work was published in Vol 96 of the journal of Polymer Degradation & Stability (2011) at page 919-928, which shows 91% biodegradation in a soil environment within 24 months, when tested in accordance with ISO 17556.
There is much debate about the total carbon, fossil fuel and water usage in manufacturing bioplastics from natural materials and whether they are a negative impact to human food supply. To make 1 kg (2.2 lb) of polylactic acid, the most common commercially available compostable plastic, 2.65 kg (5.8 lb) of corn is required. Since 270 million tonnes of plastic are made every year, replacing conventional plastic with corn-derived polylactic acid would remove 715.5 million tonnes from the world's food supply, at a time when global warming is reducing tropical farm productivity. "Although U.S. corn is a highly productive crop, with typical yields between 140 and 160 bushels per acre, the resulting delivery of food by the corn system is far lower. Today’s corn crop is mainly used for biofuels (roughly 40 percent of U.S. corn is used for ethanol) and as animal feed (roughly 36 percent of U.S. corn, plus distillers grains left over from ethanol production, is fed to cattle, pigs and chickens). Much of the rest is exported. Only a tiny fraction of the national corn crop is directly used for food for Americans, much of that for high fructose corn syrup."
Traditional plastics made from non-renewable fossil fuels lock up much of the carbon in the plastic, as opposed to being burned in the processing of the plastic. The carbon is permanently trapped inside the plastic lattice, and is rarely recycled, if one neglects to include the diesel, pesticides, and fertilizers used to grow the food turned into plastic.
There is concern that another greenhouse gas, methane, might be released when any biodegradable material, including truly biodegradable plastics, degrades in an anaerobic landfill environment. Methane production from 594 managed landfill environments is captured and used for energy;some landfills burn this off through a process called flaring to reduce the release of methane into the environment. In the US, most landfilled materials today go into landfills where they capture the methane biogas for use in clean, inexpensive energy. Incinerating non-biodegradable plastics will release carbon dioxide as well. Disposing of non-biodegradable plastics made from natural materials in anaerobic (landfill) environments will result in the plastic lasting for hundreds of years.
Bacteria have developed the ability to degrade plastics. This has already happened with nylon: two types of nylon eating bacteria, Flavobacteria and Pseudomonas, were found in 1975 to possess enzymes (nylonase) capable of breaking down nylon. While not a solution to the disposal problem, it is likely that bacteria have developed the ability to consume hydrocarbons. In 2008, a 16-year-old boy reportedly isolated two plastic-consuming bacteria