Steady-state operation of bench-scale activated sludge process using phenol and 2-chlorophenol as substrates

Experiments were conducted to determine whether a continuous process similar to the common activated sludge process could be operated at a relative steady state with phenol and 2-chlorophenol as the sole carbon sources. After a number of unsuccessful trials, process conditions were developed which allowed for operation at a relative steady state with respect to the concentration of microorganisms in the reactor and the concentration of phenol and 2-chlorophenol in the effluent. Phenol and 2-chlorophenol were removed at better than 99 percent efficiency on a continuous basis. The mixed liquor grown under the conditions of the experiment was highly filamentous and exhibited poor settling characteristics. However, reasonably good clarification was achieved by providing a long enough residence time in the clarifier