Abstract: Swine wastewater treatment by microalgae is the biotechnology for the resource utilization of wastewater. The microalgae Porphyridium cruentum, which is rich in exopolysaccharide is selected as the object in this study. The effect of NH₃-N, Cu²⁺, and antibiotic sulfadiazine from swine wastewater on the growth of Porphyridium cruentum was investigated. The study aims to investigate the effects of different conditions of pollutants on the growth of Porphyridium cruentum and determine the enrichment effects of the strain on NH₃-N, Cu²⁺, and antibiotics sulfadiazine. The results show that the biomass of Porphyridium cruentum was 1.74, 0.85 and 0.68 g·L^-1, respectively in the culture with NH₃-N concentration of 50, 500 and 2 000 mg·L^-1; with Cu²⁺ concentration of 0.5, 1.0 and 2.0 mg·L^-1, the biomass of Porphyridium cruentum was 1.81, 1.83 and 1.58 g·L^-1, respectively; and with antibiotic sulfadiazine concentration of 5, 10, 20, 100 and 200 mg·L^-1, the biomass of Porphyridium cruentum was 1.18, 1.42, 1.30, 0.98 and 0.88 g·L^-1, respectively. Moreover, the removal rates of NH₃-N, Cu²⁺, and sulfamethazine by Porphyridium cruentum were 73.2%, 54.3% and 56.9%, respectively under the optimal concentrations of the mentioned pollutants. The results indicate that ammonia nitrogen could provide nutrition for the microalgae Porphyridium cruentum and promote growth of the microalgae. However, Cu²⁺ and high concentrations of antibiotic sulfadiazine could inhibit the growth of Porphyridium cruentum. The abundant exopolysaccharide from Porphyridium cruentum has provided a new idea for the bioconcentration and removal of refractory pollutant metal Cu²⁺ or antibiotics in swine wastewater.

Key words: Porphyridium cruentum, swine wastewater, ammonia nitrogen, copper, antibiotics, sulfadiazine