Abstract: The present invention provides a method of treating wastewater containing phosphorus and/or nitrogen for removing phosphorus and/or nitrogen from the wastewater, including following steps of: (a) introducing wastewater containing phosphorus and/or nitrogen into a an anaerobic reactor, treating the introduced wastewater with anaerobic microorganisms, to produce biogas from organic matters in the wastewater, and then discharging the treated wastewater saturated with carbon dioxide under carbon dioxide partial pressure of 0.2 to 0.5 atm; and (b) injecting the treated wastewater of step (a) into a carbon dioxide stripping apparatus wherein the wastewater is free-fallen to expose the wastewater to ambient condition with carbon dioxide partial pressure of less than 0.001 atm so that carbon dioxide stripping takes place and increase in pH occurs without addition of alkaline substance, and then providing proper pH of 8.4 to 9.6 to form struvite.

Abstract: The present invention provides a method of treating wastewater containing phosphorus and/or nitrogen for removing phosphorus and/or nitrogen from the wastewater, including following steps of: (a) introducing wastewater containing phosphorus and/or nitrogen into a an anaerobic reactor, treating the introduced wastewater with anaerobic microorganisms, to produce biogas from organic matters in the wastewater, and then discharging the treated wastewater saturated with carbon dioxide under carbon dioxide partial pressure of 0.2 to 0.5 atm; and (b) injecting the treated wastewater of step (a) into a carbon dioxide stripping apparatus wherein the wastewater is free-fallen to expose the wastewater to ambient condition with carbon dioxide partial pressure of less than 0.001 atm so that carbon dioxide stripping takes place and increase in pH occurs without addition of alkaline substance, and then providing proper pH of 8.4 to 9.6 to form struvite.