INDIRECT BIOREMEDIATION - BIODEGRADATION OF HYDROCARBONS ON A COMMERCIAL SORBENT

Urea-formaldehyde polymer is currently used as a sorbent for containme nt and clean up of hydrocarbons. The aerobic biodegradability of this polymer and hydrocarbons sorbed to the polymer were tested. Soil micro organisms readily grew on the polymer, and two organisms, a bacterium and a fungus, capable of growth on the polymer were Isolated. However, biodegradation of the polymer was very slow and possibly incomplete. Biodegradation of the polymer was evident as a change in appearance of the polymer, but disappearance of the polymer was not detectable in l iquid cultures incubated for six months or soil cultures incubated for one month. Destruction of the polymer by soil microorganisms at ambie nt temperature does not appear to be practical. Degradation of C-14-la beled hexadecane and phenanthrene mixed with crude oil in liquid cultu res inoculated with soil microorganisms was used as an estimate of gen eral hydrocarbon degradation. When nitrogen was not limiting, the rate s of hexadecane and phenanthrene degradation were the same, whether th ose hydrocarbons were sorbed to the polymer or not sorbed. When nitrog en was limiting, the polymer stimulated the rate of hexadecane degrada tion but not the rate of phenanthrene degradation. The polymer may sti mulate hexadecane degradation by serving as a source of nitrogen. Howe ver, optimal degradation of sorbed hydrocarbons requires nitrogen addi tion. The results suggest that it may be feasible to decontaminate spe nt polymer by biodegradation of sorbed hydrocarbons.