Disposability, biodegradable

Monsanto Disposes Biodegradable Plastics, Chemical Week Executive Edition, December 4, 1998, available online at www.chemweek.com. 

Natural Waters. Many water systems have a natural tendency to produce foam upon agitation. The presence of poUutants exacerbates this problem. This was particularly severe when detergents contained surfactants that were resistant to biodegradation. Then, water near industrial sites or sewage disposal plants could be covered with a blanket of stable, standing foam (52,59). However, surfactant use has switched to biodegradable molecules, which has gready reduced the incidence of these problems. 

When antifreeze becomes unsuitable for use, either because of depletion of inhibitors, presence of corrosion products or corrosive ions, or degradation of the fluid, recycling and reuse of the antifreeze, rather than disposal, may be considered. Although ethylene glycol is readily biodegraded in typical municipal waste treatment faciHties, antifreeze disposal becomes problematic because the coolant may contain hazardous quantities of heavy metals picked up from the cooling system. Recycling may be economically preferred over coolant disposal and reduces the concern for environmental impact. 

Poly(3-hydroxybutyrate—3-hydroxyvalerate) [80181 -31 -3] resin, produced from a bacterium during a sugar fermentation process, has been reported to be biodegradable, and its target markets include "flushables" such as feminine hygiene products and disposable diapers (99). 

Landfarming Landfarming is a waste-disposal method in which the biological, chemical, and physical processes that occur in the surface of the soil are used to treat biodegradable industrial wastes. Wastes to be treated are either apphed on top of the laud which has... 

Residuals Produced. The residuals produced from suspended growth systems are the excess biomass produced as the result of biodegradation. In general, this biomass can be disposed without further treatment. However, site-specific conditions may require stabilization prior to disposal. 

The high specifity of biocatalysts also has the advantage of reducing disposal costs (pollution control costs) because relatively few useless and potential harmful byproducts are generated. In addition, waste products that might be produced are, by their very nature, likely to be biodegradable and, therefore, less environmentally damaging compared to those produced in purely chemical synthetic processes. 

Soil burial is widely used as the method of testing susceptibility to degradation. It closely mimics the conditions of waste disposal used for plastics but it is often difficult to reproduce results obtained because of absence of control over either the climate at the test site or the variety of micro-organisms involved in the degradation. Soil burial is thus used to provide qualitative indications of biodegradability, with more controlled laboratory work with cultured micro-organisms being used to obtain more quantitative detail. 

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