The submerged iron contactor process, which have been recently developed, is a new dephosphorization method suitable for small-scale domestic wastewater treatment plants such as rural sewage treatment plants. In this study, we carried out laboratory experiments on the treatment of artificial wastewater by using the aerating submerged iron contactor process, submerged iron contactor process and contact aeration method in combination, and the following findings were obtained. (1) The corrosion

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... e of the submerged iron contactors by sulfate-reducing-bacteria was affected by the changes in BOD loading on the contactors. This indicates that in determining the optimum total surface area of iron contactors to be submerged, consideration has to be given to BOD loading. (2) Close interrelations were found between the T-P removal rate and molar ratio of iron cations dissolved from the iron contactors to T-P loading, and also between the molar ratio and T-P concentration of the treated wastewater. Judging from these interrelations, we concluded that the molar ratio has to be about 2 or more to obtain a phosphorus removal rate which is 90% or higher and that the molar ratio has to be about 1.5 or more to get a T-P concentration of treated wastewater which is 1 mg/l or less. (3) More sludge was produced by this method than by the ordinary contact aeration method.