Concentrated microalgae cultivation in treated sewage by membrane photobioreactor operated in batch flow mode

This study investigated the microalgae biomass production and nutrients removal efficiency from treated sewage by newly developed membrane photobioreactor in which Chlorella vulgaris was cultured in batch flow mode. Its performance was compared with conventional photobioreactor. The results show that the volumetric microalgae productivity was 39.93 and 10.36 mg L−1 d−1 in membrane photobioreactor and conventional photobioreactor, respectively. The nutrients removal rate in membrane photobioreactor was 4.13 mg N L−1 d−1 and 0.43 mg P L−1 d−1, which was obviously higher than that in conventional photobioreactor (0.59 mg N L−1 d−1 and 0.08 mg P L−1 d−1). The better performance of membrane photobioreactor was due to the submerged membrane module in the reactor which acted as a solid–liquid separator and thereby enabled the reactor to operate with higher supply flow rate of cultivation medium. Moreover, in the outflow stage of the membrane photobioreactor, the microalgae culture liquor in the reactor could be further concentrated.