A review of anaerobic treatment of wastewater in fixed film reactors is presented. The biochemistry and microbiology is discussed, with emphasis laid on kinetic parameters like growth constants, substrate removal rates and growth yields. The influence of temperature, toxic substances, nutrients and pH upon process performance is evaluated. The kinetics of anaerobic biofilms is discussed. The effect of diffusional limitation and methane generation within the biofilm are important factors not studied yet. The various reactor types and process configurations are commented upon. Most studies of anaerobic processes until now have been with fixed bed reactors, and with soluble substrates.
The design of reactors should be based upon biofilm area or biomass in the reactors. At present biofilm area can not be used for design due to lack of investigations on anaerobic biofilm kinetics.
Anaerobic fixed film processes can be used for almost all types of industrial wastes containing organic matter at reasonable concentrations. Treatment of municipal wastewater is at present not regarded feasible, but the development of new effective types of reactors is believed to change this in the near future.