Influence of nitrogen loading rate on nutrient removal and algal biomass production using revolving algae biofilm reactor

Background: Microalgae-based technologies show promise due to their efficient absorption of nutrients and biomass production. Method: The study focuses on a Revolving Algae Biofilm Reactor (RABR), a novel technology with a large sunlight-exposed surface area within a comparatively smaller footprint. This study aimed to determine the optimal nitrogen loading rate (NLR) for maximizing biomass growth and nutrient removal efficiency in a RABR system, employing both synthetic wastewater (first stage) and actual wastewater (second stage). Significant findings: The first stage using synthetic wastewater achieved a biomass productivity peak of 16.6 g/m².d at the highest NLR (0.03 kg N/m³.d). Chlorophyll-a concentrations correlated positively with nitrogen loading, peaking at 12.6 mg/L at NLR of 0.02 kg N/m³.d, indicating enhanced photosynthetic activity. The second stage, utilizing real wastewater from post-anaerobic treatment, showed lower biomass productivity (2.8 g/m².d) with notable Chemical Oxygen Demand (COD) removal efficiencies (70.2 %). NH₄⁺-N removal dynamics varied, with an initial boost at NLR of 0.02 kg N/m³.d and followed by a decrement at NLR of 0.03 kg N/m³.d.