The WMAC team at Colorado State University inspected a plant blending and mixing raw materials into paints, coatings, stains, and surface- treating products. For water-based paints, water, latex, resins, extenders, and pigments are mixed and blended. For oil-based paints, solvents replace water and latex, and plasticizers, tints, and thinners are also added. These batches are then transferred to let-down tanks where additional ingredients are incorporated. After testing, the paints meeting specifications are filtered, canned, labeled, and packaged for shipping.
Hazardous wastes result when the mixing vessels, let-down tanks, and lines are cleaned.
This waste is hazardous because it contains mercury used as the bactericide. Although the plant reuses rinse water, recovers solvent, and has adopted other measures to reduce waste, the team report, detailing findings and recommendations, suggested that additional savings could result from installing a pipe cleaning system, using a solvent-recovery system based on distillation, and substituting an organic material for the mercury bactericide. This Research Brief was developed by the principal investigators and EPA's Risk Reduction Engineering Laboratory, Cincinnati, OH, to announce key findings of an ongoing research project that is fully documented in a separate report of the same title available from the authors. The amount of hazardous waste generated by industrial plants has become an increasingly costly problem for manufacturers and an additional stress on the environment. One solution to the problem of hazardous waste is to reduce or eliminate the waste at its source.