Integrated emissions management for automotive painting operations

An integrated scheme has been studied to reduce gaseous (volatile organic compounds [VOCs]), liquid (scrubber water), and solid (paint sludge) emissions from automotive painting operations by converting an existing spray-booth scrubber system to a bioreactor to capture and degrade VOCs and pyrolyzing paint sludge to produce an adsorbent. This paper describes the experimental results of 1) a pilot-scale study conducted at an assembly plant to evaluate the biological VOC removal using activated-sludge bioreactors and 2) a bench-scale study on VOC adsorption on paint-sludge adsorbents. The results indicate that the biological VOC removal is technically feasible (comparable VOC removal and less energy usage as compared to the widely used, vapor phase-activated carbon adsorption/thermal oxidation process) and economically feasible (one order of magnitude cheaper) and that paint-sludge adsorbents exhibited appreciable adsorption capacity. Implementation of the scheme requires more than technical and economical feasibility. The issues to be overcome include the inertia of past practices, overall systemic thinking, and moving targets (processes and regulations).