A novel method for sewage and wastewater treatment using microorganisms immobilized with magnetic particles was developed with a proposal of the treatment process. This process has the characteristic of having microorganisms in effluent recovered magnetically. Batch and continuous experiments for phenol removal were carried out using microorganisms immobilized with ferromagnetic particles after cultivation in the presence of phenol. In the continuous experiment, almost 100% of phenol in feed water was removed for at least 4.0 days, during which a developed apparatus, mainly consisting of a reactor and a separator with magnet, was operated without difficulty. In the mixed system of the immobilized microorganisms and activated sludge, phenol and easily biodegradable substance were removed simultaneously and efficiently. Thus the addition of the immobilized microorganisms to a reactor with activated sludge was considered to be able to endow the reactor system with further capability for treatment. Furthermore, it became apparent that a mixture of three kinds of microorganisms, immobilized with ferromagnetic particles and feeble magnetic particles respectively and without magnetic particles, could remove the objective substrate, and that the microorganisms immobilized with magnetic particles could be recovered using a magnet and a High Gradient Magnetic Filtration (HGMF) equipment.
These results show that a new process, in which the microorganisms in a reactor would become controllable and be maintained in high concentration, could be developed.