Influence of effluent-recirculation condition on the process performance of expanded granular sludge bed reactor for treating low strength wastewater.
A 2.0 L volume of EGSB reactor was operated at 20 degrees C for more than 500 days with 0.3-0.4 g COD/L of sucrose base wastewater to investigate the influence of effluent-recirculation on the process performance. At the start up period, the reactor was operated in EGSB mode with 5 m/h upflow velocity by continuous effluent recirculation. The COD loading was set to 7.2-9.6 kg COD/m(3) day with HRT of 1 hour. However, in this mode, EGSB reactor exhibited insufficient COD removal efficiency, i.e., 50-60%. Therefore, UASB mode (without recirculation, 0.7 m/h upflow velocity) was used for 30 minutes in every 40 minutes cycle to increase the COD concentration in the sludge bed. As a result, an excellent process performance was shown. The COD removal efficiency increased from 65% to 91% and the reactor could maintain a good physical property of retained sludge (sludge concentration: 33.4 g VSS/L and SVI: 25 mL/g VSS). Furthermore, retained sludge possessed sufficient level of methanogenic activity at 20 degrees C.
Yoochatchaval
W
W
Department of Environmental Systems Engineering, Nagaoka University of Technology, Niigata, Japan. wilasinee.y@nies.go.jp
Nishiyama
K
K
Okawara
M
M
Ohashi
A
A
Harada
H
H
Syutsubo
K
K
D000693:Anaerobiosis; D019149:Bioreactors; D008697:Methane / Q000378:metabolism; D017020:Methanosarcina; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods*
D012722:Sewage; D008697:Methane