Recycling methods contamination problem, solution

The continually increasing demand for environmentally friendly industrial processes has also led to the development of techniques for recycling of the remaining 5-30% sulfate contained in the acidic wash water [2.55]. In modern processes, up to 99 % of sulfuric acid can be recovered and reused in production. In the chloride process, wastewater problems arise if the raw material contains < 90% Ti02. The metal chloride by products are sometimes disposed of in solution by the deep well method (e.g., at Du Pont). The metal chloride solutions are pumped via deep boreholes into porous geological strata. Special geological formations are necessary to avoid contamination of the groundwater by impurities. 

One of the problems faced by recyclers of foamed PS, the kind most commonly used, is the very low bulk density of the materials. Compaction and baling are commonly employed to increase the bulk density, but the material is still expensive to ship for long distances. Recently, several companies have focused their efforts on transforming the PS foam into a gel, with a much higher density, to improve the transport economics. This method also can allow removal of contaminants by filtering the liquid material. One such company is International Foam Solutions, Inc., of Delray, Fla., which has developed STYRO SOLVE, a citrus-based biodegradable solvent for EPS foam and other PS products. The gel is diluted after it is received at... 

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