Abstract
Summary: Three strains of bacteria responsible for the destruction of the major constituents of carbonization waste liquor were isolated from a laboratory scale, activated sludge plant successfully treating such a liquor. Of the 3 strains one was able to grow on thiocyanate; the other 2 strains grew well on phenol. Behaviour of these organisms in pure and mixed culture showed marked differences: in pure culture, growth of the thiocyanate‐degrading strain was unaffected by the presence of 100 mg of phenol/l, but in mixed culture, active growth of another organism on the phenol completely inhibited growth on the thiocyanate. Batch and continuous culture experiments were made with 2 organisms competing for phenol. Both stimulation and inhibition of growth were found, dependent on the ratio between the concentrations of organisms present.