Consumer waste stream

It has been argued that the burning of plastics to recover the calorific value is a form of recycling in which the CO2 produced can then be fixed by plants in the photosynthetic pathway to create new fuels. Unfortunately, the natural recycle time for carbon is of the order of 300-400 years, but this process does recover the energy value of wastes. Although plastics account for only about 7% of the mass disposed of to landfill, they contribute 30% of the calorific value of MSW, so if plastics are removed from the post-consumer waste streams that are currently incinerated, oil or gas would have to be used to allow the material to bum. 

The majority of nonwoven waste material is generated by domestic and personal consumption, and so, consumer waste streams are the primary routes for recycling the greatest volumes of nonwovens. In order to reuse postconsumer nonwovens, it is... 

In 1980, approximately 111,000 t of synthetic organic dyestuffs were produced in the United States alone. In addition, another 13,000 t were imported. The largest consumer of these dyes is the textile industry accounting for two-thirds of the market (246). Recent estimates indicate 12% of the synthetic textile dyes used yearly are lost to waste streams during dyestuff manufacturing and textile processing operations. Approximately 20% of these losses enter the environment through effluents from wastewater treatment plants (3). 

After polymerization, PET is processed to final products, distributed to consumers and eventually ends up in a waste treatment system. Manual sorting or various automated methods can be applied to separate the PET fraction from a waste stream [HI]. 

The vendor states that MRRP may not be cost effective for contaminated water or wastewater as a primary treatment system but could recover mercury from carbon systems used to treat these waste streams. According to the Gas Technology Institute, the mobilization and demobilization of mobile thermal treatment systems can be costly and time consuming. These technologies are often energy intensive. 

The production of ort/ro-toluidine and its use as an intermediate in the production of dyes and pigments, mbber chemicals and other products may result in its release to the environment through various waste streams. The primary routes of potential human exposure to ort/ro-toluidine and its hydrochloride salt are inhalation and dermal contact. Consumer exposure may occur from residues present in commercial dyes and on textiles and via smoking (lARC, 1982 Department of Health and Human Services, 1982 Environmental Protection Agency, 1984, 1997 Department of Health and Human Services, 1999). 

Total oxygen demand (TOD) tells us how much 02 is required for complete combustion of pollutants in a waste stream. A volume of N2 containing a known quantity of 02 is mixed with the sample and complete combustion is carried out. The remaining 02 is measured by a potentiometric sensor (Box 17-1). Different species in the waste stream consume different amounts of O,. For example, urea consumes five times as much 02 as formic acid does. Species such as NH3 and H2S also contribute to TOD. 

While cleaning up previous contamination is a high priority, developing new technologies to prevent future contamination is equally important, if not more so. Without environmentally acceptable industrial processes, power production, and consumer activity, the Earth s environment will continue to be threatened. Development of inherently clean technologies as well as implementation of effective waste stream treatment are viable routes to preventing future environmental contamination. 

Continued research into both fundamentals and applications of chemical treatment technologies will hopefully provide solutions to many current pollution treatment problems, both for waste streams and for contaminated sites. Only through cooperation among scientists, engineers, industry, government, and consumers can we maintain a healthy and productive environment for the future. 

A distinct advantage of plastic pyrolysis into fuels as a means of recycling is its ability to handle mixed and unwashed plastics. Post-consumer plastics are often commingled and contaminated with extraneous materials such as soil, dirt, aluminium foils, paper labels and food remnants. While soil, dirt and glue can be removed from post-consumer plastics by washing, this is a fairly expensive operation and it leads to secondary waste streams... 

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