Input Materials

Source control investigations should focus on changes to input materials, process technology, and the human aspect of production. Input material changes can be classified into three elements: purification, substitution, and dilution.

Purification of input materials prevents inert or impure materials from entering the production process. Such impurities cause waste because the process must be purged to prevent undesirable accumulation. Examples of purified input materials include diionized water in electroplating and oxygen instead of air in oxychlorination reactors for ethylene dichloride production.

Substitution involves replacing a toxic material with a less toxic or more environmentally desirable material. Industrial applications of substitution include: using phosphates instead of dichromates as cooling water corrosion inhibitors; using alkaline cleaners instead of chlorinated solvents for degreasing; using solvent-based inks instead of water-based inks; and replacing cyanide cadmium plating bath with noncyanide bath.

Dilution is a minor component of input material changes. An example of dilution is the use of a more dilute solution to minimize dragouts in metal parts cleaning.

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