The study of phenol biodegradation has been performed using calcium alginate entrapped activated sludge in a recirculation reactor. An effective recirculation reactor system may be used on the laboratory scale to produce phenol oxidase, Phenol oxidase was isolated and concentrated from the degradation solution of phenol by ultrafiltration and freeze-drying respectively,

The effects of various concentrations of phenol, pH, temperature, ionic strength, cations, anions and 2- chlorophenol were studied on the oxidation reaction of enzyme. The optimal conditions of activated sludge phenol oxidase are [phenol] = 100 ppm; pH = 6.0; temperature 37°C; ionic strength equivalent to 0.1 M Na₂HPO₄-NaH₂PO₄ ; The enzyme activity was increased by Cu²⁺, inhibited by Ag⁺, Cl^-, and unsignificantly changed by Zn²⁺, Fe²⁺, NO₃ , and SO₄^2-; other substrates such as 2-chlorophenol, styrene, and methylene chloride, have also been shown to be oxidized by this enzyme; the enzyme activity was inhibited by beta-hydroxybutyric acid as a substract.

Preliminary studies indicate that phenol stimulates the activated sludge to release phenol oxidase at low concentrations of phenol and inhibit at high concentrations of phenol.