Biodegradation And Structure-biodegradation Relationship Of Substituted Benzenes Using Activated Sludge

In this paper shake-flask tests were taken to determine the biodegradation of 7 kinds of substituted benzenes using acclimated actived sludge. The concentrations of these substrates were determined by gas phase chromatography and liquid phase chromatography during degradation process. According to Monod Kinetic Equation, we calculated the kinetic data of of 7 substrates, and found that 7 kinds of substituted benzenes could be biodegraded in 12 hours, the biodegradability order is that: phenol > benzoic acid > benzene sulfonic acid > toluene > aniline > chlorobenzene > benzene.With the computer software MINITAB, we obtained the best-fit linear correlation model between the constants of biodegradability of substrates and the properties (such as E_HOMO, TVC, Hf) as follows: K=11.5177-21.0×TVC+1.060×E_HOMO-0.192×logp, n=7, R²=0.9957, S=0.0285. From this equition it can be learned that electronic parameters and steric parameters are the dominant parameters governing the biodegradability of substituted benzenes. Besides the effect of the stability of parent compounds on the final biodegradation products shouldn't be ignored.In addition, 19 substituted benzenes from MITI data base were analyzed and classified by factor analysis, the common factors were yielded and their scores were calculated, and then the studied compounds were classified by their properties. A equation was obtained from 8 representative kinds of compounds: BOD=278.23-0.173×Hf+19.5×E_HOMO-2596×TVC, n=8, R²=95.07, S=7.09. The equation shows that biodegradation positive to Heat formation, E_HOMO and TVC. Using this equation 19 substituted benzenes were quantitively predicted with the 79% correct rate.