Removal of the low molecular alcohols in the air-dilluted gaseous state by activated sludge was investigated. N-butanol (
n-BA) and isopropanol (
i-PA) were selected for the subjects of this investigation.
When the gaseous alcohol was individually fed into activated sludge aeration tube, each alcohol easily dissolved in the aeration tube liquor before being removed by the acclimated sludge. Accumulation of each alcohol in the aeration tube liquor was not observed.
n-BA and
i-PA were not also detected in the effluent gas.
Uptake rate of
n-BA by the unacclimated sludge increased to 50.4 g/kg-MLSS/day after 8 hours. On the other hand, that of
i-PA gradually enhanced and were 24, 38 and 57 g/kg-MLSSiday at the 1st, 2nd and 3rd day, respectively. Such uptake rate were dependent on the sludge concentration. The maximum uptake rate were 130 g/kg-MLSS/day for
n-BA and 94 g/kg-MLSS/day for
i-PA.
Treating the mixed gas containing n-BA and i-PA, it obtained the same results on the removal efficiency and the acclimation time in comparison with that of single alcohol.
When
i-PA-containing gas was continuously fed without addition of other nutrients during 30 days, removal rate of
i-PA was about 99.5% through this experiment period. Foaming and the sludge defrocing occurred after 7th day.
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