Start-Up and Operation of Anammox Process in a Granular Sludge Membrane Bioreactor (Gsmbr)

A new-type granular sludge membrane bioreactor (GSMBR) was developed to achieve Anammox rapid start-up and stable operation. Anammox start-up period was shortened to 43 days. After 115 days of operation, the maximum nitrogen removing rate and efficiency reached 0.83 kg N·m -3 ·d -1 and 96.59% respectively. The mature Anammox granules was cultivated and displayed brownish-red color. Most of these granules sized at 0.5~1.0 mm. Candidatus Kuenenia was identified as the dominant Anammox species in these granules, accounting for 82.93% of Anammox bacteria. The population shift from Candidatus Brocadia to Candidatus Kuenenia was found. During the experiment, the maximum transmembrane pressure (TMP) only reached 0.032 Mpa that was lower than the threshold value for cleaning and replacement of the membrane module. Scanning electron microscope (SEM) observation showed that there were still several visible micropores and channels on the fouled membrane surface even after 115 days operation of the GSMBR. TMP monitoring combined with SEM observation indicated that the membrane fouling is relatively light. In the novel reactor, combination of sludge granulation with membrane filtration not only significantly improved the biomass retention of Anammox bacteria, but also largely alleviated and effectively controlled the membrane fouling.