DEGRADATION OF PENTACHLOROPHENOL BY FIXED FILMS OF WHITE-ROT FUNGI INROTATING TUBE BIOREACTORS

A rotating tube bioreactor (RTB) was developed to examine chemical deg radation by fungal biofilms under controlled laboratory conditions. Ea ch RTB consists of a sealed tube containing mycelia growing on a piece of steel mesh on the inside wall of the tube. Tubes are mounted horiz ontally in a tube rotator and slowly rotated to expose the fungal biof ilm to a wetting-aeration cycle typical of fixed film reactors such as trickling filters and rotating biological contactors. The extent of p entachlorophenol (PCP) dehalogenation by three different species of fu ngal biofilms was evaluated by measuring concentrations of PCP (using HPLC) and the total concentrations of organic and inorganic halides (u sing a TOX analyzer). The three species of fungi removed PCP from solu tion at similar rates, but they differed in ability to completely deha logenate PCP. Nitrogen-deficient growth media only slightly increased the extent of PCP mineralization, All species of fungi (grown on nitro gen-sufficient media) removed PCP to <0.1 mg l(-1) (> 99% removal) wit hin 1 d. Within 8 d, the greatest percent of dehalogenation, measured by the appearance of chloride ion in solution, was achieved by Tramete s versicolor (62%), followed by Phanerochaete chrysosporium (38%) and Inonotus dryophilus (21%). These removals based on chloride ion concen trations are comparable to claims by others of complete mineralization for recoveries of 10-50% of (CO2)-C-14 from C-14-labeled PCP in stati c flask cultures.