As shown in Fig. 1a, COD removal was lower than 90% for both
reactors during the initial 10 days, most probably due to low MLSS
in the reactors and some adaptation period was necessary for the
seed sludge (used to treat domestic wastewater) to effectively treat
the synthetic wastewater prepared in this study. From day 12 on,
however, the COD removal efficiencies in Rc and Rs were averagely
96.1% and 95.2%, respectively with effluent COD < 30 mg/L till the
end of experiment, suggesting the granular sludges in both reactors
have good potential for organics removal