High-rate algal pond coupled with a matrix of Spirogyra sp. for treatment of rural streams with nutrient pollution

This study evaluated the unique features of a filamentous algae matrix (FAM) that can be applied to high rate algal ponds (HRAPs) as a promising way to remove nutrient from polluted rural streams. The results show that the HRAPs, coupled with the FAM, effectively removed nitrogen and phosphorus (79.8% and 81.2%, respectively), and achieved high production of DO, with a maximum of 11.0 g O2 g FAM−1 d−1. The FAM functioned wells as a screen to prevent excessive algae loss from the system and obtained relatively high biomass growth rate (0.032 mg L−1 d−1 for nitrogen and 0.344 mg L−1 d−1 for phosphorus). The harvested FAM was a useful fertilizer and the rate of addition of FAM were 1.52 kg d−1 ha−1 of nitrogen and 0.44 kg d−1 ha−1 of phosphorus. Thus, combining the HRAP with the FAM was an effective nutrient removal and resource utilization system for rural streams. •A filamentous algae matrix (FAM) was applied to high rate algal ponds (HRAPs).•Algae in the FAM of HRAPs were dominated by the genus Spirogyra.•The HRAPs effectively removed nutrient without an artificial carbon source.•FAM can act as a screen to prevent excessive algae loss in the treatment system.•FAM produced oxygen with a maximum 11.0 g O2/g FAM/d in HRAPs.