Algae-based wastewater treatment is a promising low-cost nutrient polishing process. However, the large footprint, complex biomass composition, and microalgae suspension in the effluent limits the application of microalgae for long-strength wastewater treatment. This work designs an algal-microbial separatory cell (AMSC) system to demonstrate a coupled high-purity microalgae growth during wastewater treatment. The autogenerated bioelectricity from wastewater was effective for nutrient separation, but an additional 0.3 V external voltage enhanced ammonium removal from ~76% to 90%. Due to the sufficient nutrient provision (14.75 ± 2.62 mg L-1 d-1 NH4+-N and 1.27 ± 0.44 mg L-1 d-1 PO43--P) and minimum external disturbance, a daily medium exchange ratio of 30% between the photobioreactor and extracts achieved biomass production of ~0.06 g L-1 d-1. A higher nutrient supply from 10% to 50% volume exchange ratio favored higher protein synthesis from 27.6% to 40.4% of the biomass content. The AMSC achieved removal efficiency of &gt;95% for chemical oxygen demand, 75.5% for NH4+-N, and 75.6% for phosphate without microalgae in the effluent. This study integrates bioelectrochemical mechanisms into algae-based wastewater treatment for reduced residence time (from 2 days to 7.2 hours) and improved microalgae biomass purity, which can potentially turn wastewater treatment process into resource recovery and biorefinery feedstock factories.

Decoupling wastewater treatment and microalgae cultivation in an algal-microbial separatory cell

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.