A new concept for the development of microbial consortia for the degradation of persistent soil pollutants and for pollutant treatment is proposed. The concept defined as "soil immobilization" is based on the entrapment of soil particles, showing microbial activity in degrading the target pollutant, into a solid membrane with a large pore size distribution. The particular hydrodynamic and mass transfer properties of this system result in a very efficient process. A new type of bioreactor is proposed for carrying out the immobilized soil process. The performance of the system was tested by developing a microbial system for the mineralization of pentachlorophenol (PCP). The results show that the volumetric efficiency of the process for PCP mineralization in the immobilized soil bioreactor is 1-3 orders of magnitude higher than reported literature values. Chlorine and carbon atoms of PCP are both nearly completely (99%) mineralized.