Abstract: In an anaerobic treatment method in which contaminated water is introduced into an acidification tank to decompose polymer components in the contaminated water into organic acids, and the effluent from the acidification tank is introduced into a methane production tank containing non-biological fluidized carriers so as to convert the acids into methane, the treatment is carried out stably and continuously by preventing the occurrence of floating of carriers in the methane production tank. The CODCr concentration of polymer components other than organic acids in the acidification tank effluent to be introduced into the methane production tank is controlled to be not more than 300 mg/L. This control prevents the occurrence of acid production reactions in the methane production tank and the consequent proliferation of microorganisms, and thereby suppresses sticking of carriers as well as the occurrence of floating and blockage by the carriers.

Abstract: Anaerobic treatment of water is performed under anaerobic conditions with a biofilm formed on a surface of a fluid non-biological carrier in a reaction vessel. Stable high-load treatment is performed by preventing the blockage of the reaction vessel caused by the flotation and adhesion of the non-biological carrier in the reaction vessel and effectively recovering the settleability of the carrier floating owing to adhering air bubbles by simple means. A reaction vessel is charged with a fluid non-biological carrier having a size in the range of 1.0 to 5.0 mm and a settling velocity in the range of 200 to 500 m/h. Part of the carrier that has floated and flowed out of the reaction vessel is fed downward through a pipe having a vertical height of 50 cm or more so as to remove air bubbles adhering to the carrier and is returned to the reaction vessel.

Abstract: In an anaerobic treatment method in which contaminated water is introduced into an acidification tank to decompose polymer components in the contaminated water into organic acids, and the effluent from the acidification tank is introduced into a methane production tank containing non-biological fluidized carriers so as to convert the acids into methane, the treatment is carried out stably and continuously by preventing the occurrence of floating of carriers in the methane production tank. The CODcr concentration of polymer components other than organic acids in the acidification tank effluent to be introduced into the methane production tank is controlled to be not more than 300 mg/L. This control prevents the occurrence of acid production reactions in the methane production tank and the consequent proliferation of microorganisms, and thereby suppresses sticking of carriers as well as the occurrence of floating and blockage by the carriers.

Abstract: Anaerobic treatment of water is performed under anaerobic conditions with a biofilm formed on a surface of a fluid non-biological carrier in a reaction vessel. Stable high-load treatment is performed by preventing the blockage of the reaction vessel caused by the flotation and adhesion of the non-biological carrier in the reaction vessel and effectively recovering the settleability of the carrier floating owing to adhering air bubbles by simple means. A reaction vessel is charged with a fluid non-biological carrier having a size in the range of 1.0 to 5.0 mm and a settling velocity in the range of 200 to 500 m/h. Part of the carrier that has floated and flowed out of the reaction vessel is fed downward through a pipe having a vertical height of 50 cm or more so as to remove air bubbles adhering to the carrier and is returned to the reaction vessel.