Abstract
In this study, an expanded granular sludge bed (EGSB) reactor was applied to the low strength (about 1, 000 mg-COD/L) beverage industrial wastewater treatment at low-temperature (17-19°C) in order to evaluate process performance. As a result, the EGSB reactor achieved 15 kg-COD/(m3 ·d) at the day 65. The COD removal and the methane gas conversion rate were 88 - 93%, and 60 - 69% respectively. At this time, COD sludge loading was 0.63 kg-COD/(kg-MLSS · d). The EGSB reactor operated at low-temperature achieved the good treatment efficiency as with a mesophilic EGSB process. Distribution of particle diameter of retained granular sludge tended to increase during operation, on the other hand the sludge possessed the stable settleability. As results of methanogenic activity measurement of the retained sludge, the methanogenic activity at low-temperature (20°C) reached the same level as mesophilic (35°C) activity of seed sludge by proliferation of methanogens with low-temperature tolerability. This microbial acclimation of the retained sludge contributed for stable operation of the EGSB in an unheated condition.
