Mixed culture biological activity in water containing low concentrations of cyanide, phenol and BOD

A laboratory-scale study was performed to determine the biodegradability of glucose in the presence of cyanide and phenol. The concentration of chemicals was maintained at a low level which would normally be experienced in natural streams receiving industrial wastes. A continuously fed, complete-mix reactor was utilised. The system was totally closed and included traps to separate volatilised cyanide from the products resulting from hydrolysis. For several steady-state conditions the influent and effluent water quality with respect to micro-organism, glucose, cyanide, phenol, ammonia, and total nitrogen concentration was determined. Influent waste quality varied (i.e., different concentrations of feed chemicals) for different steady-states.

Biological degradation kinetics for total organic carbon, cyanide, and phenol were developed. The rates were found to be related to temperature and the concentration of the different chemicals in the solution. The system sensitivity with respect to cyanide, phenol, and organic carbon levels was discussed. The results indicated that statistically developed relationships for the biodegradation of glucose, cyanide and phenol can adequately represent the degradation rates at low concentrations of cyanide and phenol (cyanide < 4·00 mg litre⁻¹ and phenol < 1·40 mg litre⁻¹).