ORGANIC WASTEWATER TREATMENT METHOD AND ORGANIC WASTEWATER TREATMENT APPARATUS

摘要

PROBLEM TO BE SOLVED: To reduce the usage amount of an alkali component while suppressing the deterioration in yield of methane.

SOLUTION: The organic wastewater treatment method includes: a biological treatment process of carrying out biological treatment of water to be treated containing an organic substance by methanogen; a mixing process of recirculating a part of the treated water to the biological treatment process or to a process preceding the biological treatment process to mix it with the water to be treated so that the water to be treated is subjected to the biological treatment with the part of the treated water after the biological treatment being mixed with the water to be treated; and a decarbonation process of discharging carbon dioxide contained in the treated water to be recirculated from the treated water before the mixing process. In the decarbonation process, showering with the treated water is performed to discharge carbon dioxide from the treated water, and the treated water with which showering has been performed in the decarbonation process is introduced into a sedimentation tank 50, a granule sludge contained in the treated water introduced in the sedimentation tank 50 is precipitated and separated and the supernatant liquid is recirculated.

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