4. Conclusions
The main objectives of this study are to study treatment of soybean
protein wastewater using the integrated two-phase anaerobic
reactor and elucidate the microbial phase in the reactor
during the experiments. Based on the data from the experiments,
the following conclusions are drawn:
The soybean protein wastewater could be successfully processed
around 30 days when running under the situation of
dosing seed sludge with the influent approximately 2000 mg/
L and an HRT of 40 h. When the start-up finished, the
removal rate of COD by the reactor was about 80%. In
the zone I, biogas mainly revealed carbon dioxide (CO2)
and hydrogen (H2). Methane was the main component in
the zone 2 which ranged from 53% to 59% with an average
of 55%. The methane content in biogas increased from the
zone I to II. It indicated that the methane-producing capacity
of the anaerobic sludge increased.
There were some differences between the activities of the
sludge in the two reaction zones of the integrated two-phase
anaerobic reactor. The activity of protease was higher in the
reaction zone I and the coenzyme F420 in the reaction zone
II was twice than that in the reaction zone I, which indicated
that the activity of the methanogens was stronger in the reaction
zone II. The integrated two-phase anaerobic reactor in
this study was simple in structure avoiding several equipments
of the traditional two-phase anaerobic system. It was observed
to be an efficient reactor configuration for the treatment of the
soybean protein wastewater.