Nutrient removal from membrane bioreactor permeate using microalgae and in a microalgae membrane photoreactor.

Area of Science:

• Environmental Engineering
• Biotechnology
• Water Treatment

Background:

• Conventional wastewater treatment often requires tertiary steps for nutrient removal.
• Membrane bioreactors (MBR) are effective but may leave residual nutrients.
• Microalgae offer a sustainable solution for polishing treated wastewater.

Purpose of the Study:

• To evaluate the efficacy of a novel microalgae membrane photoreactor (mMR) for polishing aerobic MBR effluent.
• To assess the nutrient removal capabilities of four different microalgae species.
• To determine the long-term performance of an integrated MBR-mMR system.

Main Methods:

• Isolation and testing of four microalgae species (Chlorella sp., C. vulgaris, S. quadricauda, S. dimorphus) in batch reactors.
• Nutrient analysis (NH4, NO3, NO2, PO4) in MBR permeate before and after microalgae treatment.
• Operation of a continuous MBR-mMR system for 23 days to assess sustained performance.

Main Results:

• All tested microalgae species achieved complete ammonium (NH4) removal within 3 days in batch tests.
• High removal rates for nitrite (NO2, 83-95%) and phosphate (PO4, 70-92%) were observed.
• The continuous MBR-mMR system demonstrated consistent removal of NH4 (50%), NO2 (75%), NO3 (35%), and PO4 (60%).

Conclusions:

• Microalgae membrane photoreactors are a viable technology for polishing MBR effluent.
• Specific microalgae species show high potential for efficient nutrient removal.
• The integrated MBR-mMR system offers a promising approach for advanced wastewater treatment.