PURPOSE: To perform an anaerobic digesting treatment efficiently, by a method wherein an organic waste liquid containing sulfate ions is treated by an electrolyzer, and then it is introduced into an anaerogic digesting treatment device to convert sulfur contained in the liquid into a soluble difficult iron-sulfur compound.
CONSTITUTION: The liquid to be treated is introduced into an electrolyzing treatment tank 2 provided with an iron electrode 3 and a carbon electrode 4 through an introducing pipe 12, and an electric current is passed through the liquid to dissolve iron ions in an amount of 1W2 times of the equivalent required for the reaction with the sulfate ions generated by the anaerobic digsting treatment. The liquid with the iron ions dissolved therein is introduced into an anaerobic digesting treatment tank 1 in which anaerobic bacteria are cultivated, and is decomposed into gaseous methane and gaseous carbon dioxide by the anaerobic digesting treatment. On the other hand, the sulfate ions are converted into sulfide ions by the function of sulfuric acid reducing bacteria. The sulfide ions react with the iron ions dissolved in the liquid, and iron sulfide is precipitated in the tank.
ICHIKAWA HIROYUKI
KURODA JIYUNZOU
