Biodegradable in the environment

As a result of our increasing knowledge of the effect of pollutant structure on biodegradation in the environment, efforts are being focused on developing and... 

A biodegradation accelerant increases or accelerates the rate of biodegradation in the environment. For example, calcium carbonate, calcium hydroxide, calcium oxide, barium oxide, barium hydroxide, sodium silicate, calcium phosphate, magnesium oxide, may accelerate the biodegradation process. These compounds may also act as processing aids. A commonly used compound is calcium carbonate (20). 

As reviewed by Alexander (1985) and Morris Pritchard (1994), many studies suggest that bioavailability represents one of the most important factors influencing PAH biodegradability in the environment. This is because PAHs, especially the HMW, hydrophobic compounds, possess intrinsically low water solubilities and therefore tend to partition onto soil mineral surfaces and to sorb tightly to available organic materials (Hites et al., 1977 Means et al., 1980 Weber etal., 1993). When PAHs are adsorbed in this way they become physically unavailable to resident microorganisms and are therefore protected from microbial catalysis. 

Pure culture studies are helpful in identifying possible pathways of degradation, but organism(s) isolated by enrichment are not necessarily active in the environment. The organism isolated under high nutrient conditions with the chemical as the only carbon source may not be the organism(s) responsible for the chemical s biodegradation in the environment. 

Therefore, mixed microbial cultures from natural samples should be used as an inoculum or as the whole test sample for determining biodegradability in the environment. 

Stable complexes with EDTA and its related compounds are formed with most polyvalent metal ions, hence their wide use in chelation therapy. Pure EDTA is a white crystalline solid with a relative molar mass of 292.1. It is a weak, tetrabasic acid which is sparingly soluble in water. EDTA is not metabolized in the human body and is effectively non-biodegradable in the environment. 

Abramowicz DA. 1995. Aerobic and anaerobic PCB biodegradation in the environment. Environ Health Perspect Suppl 103(5) 97-99. 

Surfactants are performance chemicals that is, they are used to perform a particular function in some process or product, in contrast to other organic chemicals that may be used to produce another chemical or product. Since they are used in products or processes that impact on the environment, there are concerns regarding their effect, particularly their biodegradability in the environment and their toxicity to marine organisms. 

The above views, which are based on experimental evidence (pages 53-55), are often in conflict with the beliefs of environmental campaigners. The popular view is that all synthetic polymers are non-biodegradable in the environment. The following excerpts from a controversial report sponsored by Greenpeace in 1990 entitled Breaking down the degradable plastics scam epitomise popular misconceptions ... 

While naturally occurring polymers are readily biodegradable in the environment, most synthetic high polymers biodegrade only very slowly under comparable exposure conditicMis. There are, however, exceptions to this observation, and several classes of synthetic polymers that undergo ready enviromnental biodegradation are... 

Poly(Hydroxyalkanoates) Unlike bio-based PE, PET, and PEA, the poly(hydroxyalkanoates) (PHA) are bioplastics synthesized by bacteria. It was the first bacterial polymer to be harvested commercially. PHAs are deposited within the bacterial cells of many species as a lipoic material (Bnrdon, 1946). It is also unusual in that PHAs though hydrophobic still rapidly biodegrade in the environment. All bacterial polymers are not necessarily biodegradable (Steinbuchel, 2005) PHAs biodegradability is attributed to its saturated polyester chemical structure. 

Tertiary-butyl alcohol is commonly used as a co-solvent in gasoline/ methanol blends and as an oxygenate and octane booster by itself. It is predominantly produced from isobutene, but may also be a product of fermentation reactions [15], It is biodegradable in the environment, and is infinitely soluble in water. 

Ready Biodegradability Aerobic degradation of concentrated solution measured by change in dissolved organic carbon, biochemical oxygen demand, or carbon dioxide. "Pass/fail" test if substance meets criteria for success, it is expected to undergo rapid and ultimate biodegradation in the environment. 

Needless to say, a wide variety of composting plants and cycles, home composting procedures and environments exist. Hence, it has been necessary to establish and fix some parameters (temperature, substrate, pH, microbial population, moisture and so on), in order to obtain reproducible standard laboratory conditions which verify the ability and the potential of different materials to undergo safe biodegradation in the environment where they are allocated for treatment. 

Besides being readily biodegradable in the environment, starch-based foams offer superior antistatic properties. However, they are brittle and their densities are higher than expanded polystyrene (EPS) [14]. 

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