Biodegradability and change of physical characteristics of particles during anaerobic digestion of domestic sewage.
At the high-rate anaerobic treatment of domestic sewage, both biological and physical processes play an important role. Therefore, the anaerobic biodegradability of raw, paper-filtered and membrane-filtered sewage and black water has been investigated in batch experiments. Additionally, the effect of anaerobic digestion on physical characteristics, like particle size, surface tension and zeta-potential, of the present particles is studied. The biodegradability of domestic sewage and black water at 30 degrees C is almost similar (71-74%). Moreover, a high methanogenesis of the colloidal fraction in domestic sewage (86 +/- 3%) is achieved, showing that the low removal of colloidal particles in continuous high-rate anaerobic reactors is due to low physical removal rather than biodegradability. The lowest biodegradability is demonstrated for the dissolved fraction (62%). The results show that after anaerobic digestion the average radius of particles with diameter < 4.4 and < 0.45 microns increased for domestic sewage, while it decreased for black water. Part of the surface-active components in domestic sewage is not biodegraded during anaerobic batch digestion, as indicated by the development of the surface tension. The negative zeta-potential of all particles hardly changes during digestion, showing that colloidal interactions were not affected by anaerobic digestion.
Elmitwalli
T A
TA
Department of Agricultural, Environmental and System Technology, Sub-department of Environmental Technology, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Soellner
J
J
De Keizer
A
A
Bruning
H
H
Zeeman
G
G
Lettinga
G
G
D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D003102:Colloids; D007700:Kinetics; D009426:Netherlands; D012722:Sewage; D013500:Surface Tension; D013501:Surface-Active Agents; D018508:Water Purification / Q000379:methods*
D003102:Colloids; D012722:Sewage; D013501:Surface-Active Agents