TREATMENT OF PULP CONDENSATE WASTE LIQUID BY METHANE FERMENTATION

PURPOSE:To efficiently form useful by products by adjusting a waste liquid to properties suitable for methane fermentation, by directly contacting the fermentation gas generated by methane fermentation with the waste liquid before treatment. CONSTITUTION:A pulp condensate waste liquid with pH 10 is supplied to a scrubber 2 from a line 1 and directly contacted with the fermentation gas guided from line 3 and absorbs carbon dioxide in the fermentation gas to be neutralized so as to be adjusted to pH 6-7. The sulfur compound in the waste liquid is transferred to the fermentation gas by methane in said gas and removed from the waste liquid. The fermentation gas receives the removal treatment of carbon dioxide in the scrubber 2 and absorbs the sulfur compound and is subsequently sent to a cooler 4 from the scrubber 2 through a line 15 and resulting steam is removed by condensation. The fermentation gas receives desulfurization treatment, if necessary, and is them effectively utilized as the fuel of a boiler or an incinerator.