The influence of magnetic field enhances the growth rate of microbes. The biodegradation of phenolic waste liquors in bubble columns (BCR) and airlift bioreactors (ALR) have shown that the degradation is faster in ALR in comparison to BCR. The influence of magnetic field results in a faster degradation and the maximum reduction has been noted at a field intensity of 220 Oe. The application of super-imposed magnetic field can be extended to processes such as fermentation and production of antibiotics.