Nutrient removal performance of novel Filamentous Algae Nutrient Scrubber (FANS) configurations

Filamentous algae nutrient scrubbers (FANS) can recover nutrients from wastewater, producing harvestable algae biomass that repurposes nutrients and removes them from water. This study evaluates the performance of three FANS modes (standard FANS, shallow suspended FANS, and deep suspended FANS) by comparing biomass productivity, nutrient removal rates, algae photosynthetic efficiency, nutrient composition in algae biomass, and diurnal nitrate concentration reduction. FANS modes differed by algae attachment medium, water depth, algae contact time or hydraulic retention time, and horizontal water velocity. Shallow suspended FANS emerged as the most effective configuration, with highest nitrate reduction efficiency and nutrient recovery rates for nitrogen and phosphorus in algae biomass. Shallow suspended FANS exhibited at least 30 % higher biomass productivity in summer (2.8 f 1.2 g VS m- 2 & sdot;d- 1) and 40 % higher productivity in winter (1.4 f 0.4 g VS m- 2 & sdot;d- 1) compared to other modes. Nutrient assimilation rates for shallow suspended FANS were at least 10 % higher in summer (0.165 f 0.072 g N m- 2 & sdot;d- 1, 0.022 f 0.010 g P m- 2 & sdot;d- 1 and 39 % higher in winter (0.085 f 0.028 g N m- 2 & sdot;d- 1, 0.013 f 0.004 g P m- 2 & sdot;d- 1). These results demonstrate that optimized FANS can enhance algae photosynthetic efficiency, growth, nutrient assimilation, and nutrient recovery year-round.