Method for the anaerobic degradation of organic material

DETAILED DESCRIPTION The present invention consists in means for the anaerobic bacterial degradation of organic materials present in an aqueous medium, comprising a contact reactor, a fluidized bed reactor having an effective volume not more than 0.
35 times the effective volume of the contact reactor, inlet means to introduce untreated aqueous medium into the contact reactor, pump means to pump aqueous medium from the contact reactor to the bottom of the fluidized bed reactor to fluidized the bed of a finely divided inert solid in the fluidized bed reactor, means to convey treated aqueous medium from the fluidized bed reactor to the contact reactor and an outlet for removing aqueous medium from the degradation means.
In a further aspect the present invention consists in a process for the anaerobic bacterial degradation of organic material present in an aqueous medium, comprising introducing the aqueous medium into a contact reactor pumping the aqueous medium into a fluidized bed reactor which has an effective volume not more than 0.
35 times the effective volume of the contact reactor and which contains a bed of a finely divided inert solid which supports a population of substantially anaerobic bacteria, to maintain the bed of the fluidized bed reactor in a fluidized state, returning the aqueous medium which has passed through the fluidized bed reactor or a part thereof to the contact reactor and continuously or discontinuously withdrawing a treated effluent from the contact reactor or from the fluidized bed reactor.
The present invention still further consists in a method of establishing a population of substantially anaerobic bacteria in a multiple vessel reactor system which includes a fluidized bed reactor and a contact reactor, comprising passing a stream of an aqueous medium containing organic material and nitrate ions into the system to establish a population of substantially anoxic bacteria in the fluidized bed reactor and the contact reactor and gradually reducing the concentration of nitrate ions in the stream until the population of anoxic bacteria is substantially replaced by a population of anaerobic bacteria, the anaerobic microbial population being substantially fixed on the solid median of the fluidized bed reactor and is substantially free floating in the contact reactor