DETERMINATION OF CHEMICAL BIODEGRADATION BY DIRECT AND INDIRECT METHODS

Degradation of 10 organic chemicals by pre-acclimated microorganisms in BOD dilution water was determined directly by UV spectrophotometry and indirectly by a modified BOD method. Residual chemical concentrations were periodically measured and pseudo-first-order biodegradation rate constants (k1) were calculated. The k1 spectrophotometry values ranged from 0.006/h to 0.077/h and k1-BOD values from 0.002/h to 0.043/h for 1-methylnaphthalene and indole, respectively. The ratios of k spectrophotometry to K1-BOD were between 1.5 for salicylic acid and 3.0 for 1-methylnaphthalene with a mean of 2.7. A significant (alpha = 0.001) linear correlation (r2 = 0.854, F = 46.630) existed between the two sets of rate constants. Results from this study suggest that the modified BOD method may be used to estimate chemical biodegradation rates in synthetic media.