| The novel way of advanced treatment of municipal wastewater was proposed and characterized by purifying wastewater by Spirogyra. The characteristics of nitrogen and phosphorus removal by Spirogyra were studied aiming at nitrogen and phosphorus removal in advanced treatment of sewage. Under natural light, when Spirogyra's dosage (gross mass) was more than 3.05 g/L, total phosphorus concentration, NH+4-Ｎ concentration, TN concentration and permanganate index decreased to less than 0.09, 2.82, 4.31 and 16.86 mg/L respectively, with removal efficiencies of more than 96.84%, 88.60%, 85.49% and 24.56 %. During the treatment of sewage, pH value increased, while both calcium cation and magnesium cation concentration decreased, and conductivity decreased. During the growth of Spirogyra, increasing pH value induced saline minerals precipitation, and the precipitated minerals adsorbed phosphate, which were considered as the main mechanisms of phosphorus removal. Furthermore, phosphorus removal by Spirogyra followed Langmuir adsorption isotherm model, and the saturated adsorption of Spirogyra (gross mass) for phosphorus was 3.159 mg/g under this test condition. The increasing pH value made ammonia evaporate during Spirogyra growth, which might be the main mechanism of nitrogen removal. Under suitable Spirogyra's dosage and hydraulic retention time, the treated sewage might meet the demands of water supply for landscape impoundments on nitrogen and phosphorus concentrations. The better performance of Spirogyra removing nitrogen and phosphorus might provide a novel alternative way for advanced treatment of sewage. |
