Researchers investigated methods to renovate reactive dyebaths biologically and reuse the high salt containing mixture in the dyeing process. Bath assays used an anaerobic methanogenic culture enriched from municipal sewage sludge to evaluate the potential toxicity of nine commercial reactive dyes to anaerobic microorganisms. Researchers also determined the anaerobic biodegradability of these dyes and examined the kinetics of color removal of a wide range of dye concentrations. Results confirmed color removal of commercial reactive dyes under methanogenic conditions. With the exception of Blue 4 and Blue 7, color removal at an initial dye concentration of 2,000 milligrams per liter exceeded 83 percent. Breakdown products of Blue 19, Blue 4, and (to a lesser degree) Black 5 inhibited anaerobic culture. Despite severe inhibitiory conditions, however, the low redox potential of the methoanogenic culture achieved a high degree of color removal. Current studies are evaluating the effect of high salt concentration on culture activity nd kinetics of color removal. 5 refs.