Inhibition of phenol biodegradation by thiocyanate

Abstract

Based on long-term continuous culture experiments, the following conclusions may be drawn. Thiocyanate inhibits the biological oxidation of phenol. This inhibition becomes significant to operation and design when low phenol discharge levels are required. The relationship of sludge age (theta, days), effluent phenol level (P, mg/l), thiocyanate level (SCN, mg/l), and temperature (/sup 0/K) is given. The yield coefficient (Y) is 1.2 kg ss produced/kg phenol degraded, and the decay coefficient was 0.24/d. These values were not influenced by the presence of thiocyanate. As the ability to measure sub-milligram per liter levels of phenol improves and becomes routine, it is expected that difficulties in maintaining pipeline discharge standards for phenol in thiocyanate-laden waters will become more apparent. Design equations and families of curves developed herein should assist in the rational design and operation of biological treatment facilities for such discharge limits. 11 figures, 13 tables.