Microbiological Factors intheTreatment ofPhenolic Wastes

Aqueous wastes are by-products in the catalytic cracking of petroleum and contain, in addition to phenols, sulfides, volatile hydrocarbons, chlorides, ammonia, and cyanide in various concentrations. Elimination of these undesirable elements prior to their discharge into natural waterways would preserve the natural and most desirable qualities of that water for future recreational, municipal and industrial uses. Extraction, adsorption, catalytic oxidation, and biological processes have been used successfully for the treatment of such wastes. Only the latter can be considered most suitable from an economical standpoint. Harlow et al. (1938) have worked with this process using a full-scale biological treatment plant constructed by the Dow Chemical Company. This plant was placed in operation about 1937 and is in operation at the present time. The work described here was undertaken to determine the nature of the biological treatment involved in phenol destruction and factors influencing the efficiency of such process, with the hope of developing phenol-resistant strains of microorganisms capable of metabolizing this aromatic compound. Phenol has long been used as a disinfectant. Lord Lister was the first to use it in aseptic surgery. Grant and Zobell (1942) stated that phenols in low concentrations are not only nonlethal to certain bacteria, but also can be metabolized. Buddin (1914) and Matthews (1924) found that phenol in certain concentrations encouraged the growth of microorganisms in the soil. Fowler et al. (1911) established that phenols present in sewage or other decomposing matter failed to prevent bacterial growth. Gray and Thornton (1928) used a salt medium containing phenol as the sole source of carbon in a concentration of 1000 ppm to isolate phenol-resistant organisms from the soil. Berger and Wyss (1953) reported that Micrococcus pyogenes var. aureus can be propagated to resist up to 0.2 to 0.3 per cent phenol. The effect of phenol on bacteria was also described in the literature by Fogg and Lodge (1945) and Gale and Taylor (1947).