High-rate anaerobic treatment of wastewater at low temperatures.
Anaerobic treatment of a volatile fatty acid (VFA) mixture was investigated under psychrophilic (3 to 8 degrees C) conditions in two laboratory-scale expanded granular sludge bed reactor stages in series. The reactor system was seeded with mesophilic methanogenic granular sludge and fed with a mixture of VFAs. Good removal of fatty acids was achieved in the two-stage system. Relative high levels of propionate were present in the effluent of the first stage, but propionate was efficiently removed in the second stage, where a low hydrogen partial pressure and a low acetate concentration were advantageous for propionate oxidation. The specific VFA-degrading activities of the sludge in each of the modules doubled during system operation for 150 days, indicating a good enrichment of methanogens and proton-reducing acetogenic bacteria at such low temperatures. The specific degradation rates of butyrate, propionate, and the VFA mixture amounted to 0.139, 0.110, and 0.214 g of chemical oxygen demand g of volatile suspended solids-1 day-1, respectively. The biomass which was obtained after 1.5 years still had a temperature optimum of between 30 and 40 degrees C.
Lettinga
G
G
Sub-Department Environmental Technology, Wageningen Agricultural University, 6703 HD Wageningen, The Netherlands. Gatze.Lettinga@Algemeen.mt.wau.nl
Rebac
S
S
Parshina
S
S
Nozhevnikova
A
A
van Lier
J B
JB
Stams
A J
AJ
D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors; D003470:Culture Media; D019605:Euryarchaeota / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D007220:Industrial Waste; D011422:Propionates / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D014871:Water Microbiology
D003470:Culture Media; D005227:Fatty Acids; D007220:Industrial Waste; D011422:Propionates; D012722:Sewage