Degradation of meta-cresol in waste waters by entrapped bacillus laterosporus cells

ABSTRACT

Degradation of m-cresol in different waste water samples instead of the mineral medium was carried out. Meta-cresol degradation in nonsterile waste water was slower than in sterile. However, the entrapped Bacillus laterosporus cells proved to actively degrade m- cresol in all the tested water samples except in the case of two samples collected from El-Max region near Alexandria Harbor. The growth and rate of degradation in both free and entrapped cell cultures were affected by Pb and Hg salts at concentrations higher than 10 mg/l. The rate of degradation was reduced by 75% when 100 mg/l and salts of these metals were present in the medium. Also, the rate of degradation was reduced in presence of 5 mg/l of zinc or cadmium salts. It was noticed that entrapped cells did not show higher resistance than the free cells in presence of the tested heavy metals. The presence of 4-chlorophenol, 4-bromophenol or p- nitrophenol in the medium delayed the degradation time and the rate of degradation was much lower in presence of these substituted phenols together with m-cresol. However, the degradation activity was not completely lost