Influence of nitrogen sources on wastewater treatment performance by filamentous algae in constructed wetland system

Although filamentous algae have the characteristics of high nutrient assimilation ability, and adaptation to different conditions, studies on their role in water purification of constructed wetlands (CWs) are limited. In this study, the wastewater treatment capacity under different nitrogen sources was explored by constructing a filamentous algal CW (FACW) system. Results confirmed the fast and stable operation efficiency of the FACW system. Ammonia nitrogen was preferred in Cladophora sp. absorption and assimilation. The nutrient consumption rate (NCR) for total nitrogen (TN) of AG was 2.65 mg g^-1 d^-1, much higher than that of nitrate nitrogen (NG) (0.89 mg g^-1 d^-1). The symbiosis of bacteria and Cladophora sp. Contributed to pollutant removal. A stable and diverse community of microorganisms was found on Cladophora sp. Surface, which revealed different phylogenetic relationships and functional bacterial proportions with those attached on sediment surface. In addition, temperature and light intensity have great influence on the purification ability of plants, and low hydraulic retention time is beneficial to the cost-effective operation of the system. This study provides a method to expand the utilization of wetland plants and apply large filamentous algae to the purification of wetland water quality.