Patent ID: 7811455
Filing Date: 2010-10-12
Classification: B01D,C02F,Y02E,Y10S

Abstract:
1. A process for recovering ammonia nitrogen as a solid ammonium carbonate and/or bicarbonate from a liquid effluent stream (digestate) of an anaerobic digester while improving the BTU content of a biogas effluent stream of the digester, comprising the steps of: a. converting ammonium ion (NH b. stripping the ammonia gas from the pH-adjusted digestate within a stripping chamber by reducing the partial pressure of ammonia within said chamber to form a stripped ammonia gas; c. blending the stripped ammonia gas with biogas containing carbon dioxide to precipitate ammonium carbonate and/or bicarbonate, thereby forming a gas deficient in ammonia and carbon dioxide; and d. returning the gas deficient in ammonia and carbon dioxide (stripping gas) to the stripping chamber to maintain a low partial pressure of ammonia within said chamber.