Cyclic sequential batch reactor: nitrogen and phosphorus removal from domestic sewage

Treatment of domestic sewage by sequential batch processes has been shown to be quite attractive, mainly because it allows the maintenance of anaerobic, anoxic and aerobic conditions, which are necessary for the removal of nitrogen and phosphorus, in a single reactor. The aim of this study was to evaluate the behavior of a new reactor known as "cyclic sequential batch reactor" on the removal of organic matter, nitrogen and phosphorus from domestic sewage in a tropical climate. The removal of organic matter, nitrogen and phosphorus reached values of 90.6%, 90.5%, and 89.1%, respectively. Effluent quality of less than 8.3 mg N/L total nitrogen, 4.6 mg N/L ammonia nitrogen, and 0.8 mg P/L of total phosphorus were routinely obtained in reactor conditions as following: temperature about 26 degrees C, a solids retention time of 12 d, a hydraulic retention time of 4 h, organic loading rate of 2.1 g COD/L d, nitrogen loading rate of 0.24 g TKN/L d, phosphorus loading rate of 0.03 g P/L d and food-to-mass ratios of 0.76 g COD/g MLVSS d.