The seed sludge was obtained from an anaerobic digester in
Daejeon municipal wastewater treatment plant and heat treated at 901C for 10 min to inhibit the methane-producing
bacteria activity [2,10]. The digester was operated at a
temperature of 351C and a HRT of 25 days by feeding a
mixture (1:52:0% VS) of primary sludge and waste activated
sludge. The pH, alkalinity and volatile suspended solids (VSS)
concentration of the sludge were 7.5, 1150 mg/L as CaCO3 and
13,500 mg/L, respectively.