METHANE FERMENTATION TREATMENT OF SULFATE ION-CONTAINING WASTE WATER

摘要

PURPOSE:To perform methane fermentation in the presence of a high concn. sulfate ion in such a state that sulfate reducing reaction is suppressed to a low level, by adjusting the pH of waste water containing a sulfate ion at a high concn. to 6-7 and subsequently allowing the waste water to flow to a methane fermentation bioreactor to perform methane fermentation. CONSTITUTION:The pH of waste water containing a sulfate ion at a high concn. is held to about 6-7, desirably, to about 6.5-6.8. The waste water after pH adjustment is allowed to flow in a methane fermentation bioreactor to perform the treatment of the waste water and the production of methane gas. When methane fermentation is performed under this condition, hydrogen sulfide being an acidic substance rapidly moves to a gaseous phase and the hydrogen sulfide held in the liquid is almost eliminated. Further, sulfate reducing reaction causing the formation of hydrogen sulfide is suppressed to an extremely low level and methane fermentation can be performed even in waste water containing the sulfate ion at a high concn. without hindrance.