BACKGROUNDBiological nutrient removal methods typically use separate anaerobic/anoxic and aerobic processes for the removal of nitrogen, phosphorus, or other nutrients from wastewaters. These processes require high operational and material costs. In this work, photosynthetic biofilm in a single photorotating biological contactor (PRBC) reactor was used to simultaneously remove carbon, nitrogen, phosphorus, and sulfur from high-chroma-dye wastewater. RESULTSSupplementary illumination of 12 h d(-1) in PRBC readily enhanced photosynthetic bacterial activity, leading to 90.3% color removal, 93.9% chemical oxygen demand (COD) removal, and 94% 1-2-7-triamino-8-hydroxy-3-6-naphthalinedisulfate removal. Moreover, the removal efficiency of total nitrogen, phosphate, and sulfide at an illumination time of 12 h d(-1) and a hydraulic retention time of 10 h was maintained at 69%, 72%, and 67%, respectively. Component analysis revealed that the protein, phosphorus, and sulfur in the photosynthetic biofilm were 67.5%, 2.4%, and 1.8%, respectively. CONCLUSIONCultivating photosynthetic biofilm in a single PRBC can achieve better efficiency of removal of carbon, nitrogen, phosphorus, and sulfur compared with biofilm in a rotating biological contactor. A feasible technology for removing nutrients and recycling useful elements from wastewater using photosynthetic biofilm in a single PRBC is proposed. (c) 2013 Society of Chemical Industry