A novel algal biofilm membrane photobioreactor for attached microalgae growth and nutrients removal from secondary effluent

• A novel algal biofilm membrane photobioreactor was developed to culture C. vulgaris.
• Biomass production of the reactor was enhanced with the addition of solid carriers.
• Most of the produced biomass was immobilized as algal biofilm in BMPBR.
• Higher biomass production in BMPBR enabled the reactor to remove more nutrients.
• Algae were completely isolated from the effluent in this attached culture system.

In this study, a novel algal biofilm membrane photobioreactor (BMPBR) equipped with solid carriers and submerged membrane module was developed for attached growth of Chlorella vulgaris and secondary effluent treatment. The volumetric microalgae production achieved in BMPBR was 0.072 g L−1 d−1, which was 1.44-fold larger than that in suspended growth membrane photobioreactor (MPBR). Furthermore, 72.4% of the total produced algal biomass was immobilized as algal biofilm in BMPBR. Advanced nutrients removal from secondary effluent was achieved both in BMPBR and MPBR, with average reduction of about 85% for PO43−-P in the stable stage. Additionally, BMPBR showed better nitrogen removal performance than MPBR due to its higher algal biomass productivity. Moreover, with the filtration effect of the submerged membrane module in the reactor, suspended microalgae could be completely isolated from the effluent and a low average SS concentration of 0.28 mg L−1 was achieved in the effluent of BMPBR.