[Performance and microbial characteristics of an EGSB reactor treating brewery wastewater under 20 degrees C]

A lab-scale EGSB reactor fed by artificial brewery wastewater was operated under 20 degrees C continuously, and its process performance, characteristics of granular sludge, microbial community structure were investigated. The results indicated that: 1) after 184 days' operation, the organic loading rate of EGSB reactor could reach 10 kg/(m3 x d) at HRT of about 18 h, the COD removal efficiencies were above 85%, and the specific biogas production was about 0.58 m3 per kilogram COD removed. 2) As the organic loading rate increased, the average diameter of the granule increased, and the settling velocity increased too, but when the loading rate reached about 10 kg/(m3 x d), the granular average diameter decreased slightly. Compared with the granular sludge operated at mesophilic condition, the ECP contents especially the protein contents in the granular sludge operated at 20 degrees C increased obviously. 3) Compared with the seed sludge, the main Archaea (methanogenes) species in the sludge samples operated at different loading rates under 20 degrees C did not change greatly, but the dominant methanogenes in the sludge operated under 15 degrees C for 6 months seeded with the same mesophilic sludge changed obviously.