The purpose of the work was to evaluate the feasibility of a biological treatment process for herbicide-containing solid waste material from a fertilizer-manufacturing plant. The waste contained approximately 1.5% (w/w) 2,4-dichlorophenoxyacetate (2,4-D) and 1.4% (w/w) 2-(2-methyl-4-chlorophenoxy)propionate (MCPP, mecoprop). Both herbicides could be dissolved from the bulk matrix (vermiculite) within 3 days of chemical leaching in aqueous solution. Upon subsequent inoculation of herbicide-degrading bacterial consortia derived from soil samples adjacent to the plant, 2,4-D was completely degraded in the presence of up to 5% (w/v) pulp densities. The biodegradation of MCPP was concurrent but incomplete. The degradation process was acid-producing, and pH control enhanced the rates of herbicide degradation.