STUDIES ON BIODEGRADATION OF PHENOL

Abstract

Phenolic compounds are used for various purposes in many areas for example chlorinated phenolic compounds are specifically utilized as preservatives of paints, leather, textile goods and as antimicrobial agents. Because of improper treatment, they widely contaminate soil and groundwater and their toxicity greatly affects living organisms. To treat phenolic compounds, biological methods are preferable because this are economical and there is less possibility of the production of byproducts. The microorganisms used are usually aerobes, including Pseudomonas putida, Pseudomonas flurescence, Azobacter, Achromobacter and Bacillus cereus. In the present study Pseudomonas putida has been used and an attempt has been made for the treatment of three phenolics; phenol, o-cresol and 4-chlorophenol upto a concentration range (0-400 mg/1) using both batch and column reactor. The microorganisms showed initially the lag phase followed by the log or exponential phase. The value of umax for phenol, o-cresol and 4-chlorophneol was found to be 0.290, 0.514 and 0.393 and the value of Ks was found to be 43.77, 75.65 and 57.22. The percentage Chemical oxygen demand (COD) reduction for the concentration 200 mg/1 for phenol, o-cresol, and 4- chlorophenol was found to be 90%, 84%,70% in 24 hrs. The inhibitor cyanide used, showed the inhibition effect as the degradation of all the three phenolics; phenol, o-cresol and 4- chlorophenol showed more degradation time required for the concentration 200 mg/l. In the column study first the phenol degrading microorganism have been adsorbed on the granular activated carbon and then the reactor was used for the degradation of higher phenolic concentration viz. 250 mg/1, 300 mg/1 and 400 mg/1 which were found to be successfully degraded at these concentration.