Development of Anammox Process for Animal Waste Treatment: Experiences in the USA

Research was conducted to develop process applications for anaerobic ammonium oxidation (anammox) bacteria acclimated to animal wastewater conditions using microbial immobilization techniques. In the anammox reaction, under anaerobic and autotrophic conditions, ammonium (NH4) serves as the electron donor using nitrite (NO2) as the electron acceptor resulting in production of harmless di-nitrogen (N2) gas. Compared to conventional nitrification-denitrification, this combined pathway saves more than 50% of the oxygen supply for nitrification and 100% of the external organic source for denitrification. This leads to a significant reduction in energy needs of treatment, and a decrease in operational costs. In addition, by-products do not include greenhouse gases. The isolation of anammox adapted to animal wastewater environments can be of significant importance to farming systems because excess ammonia in modern, industrial-type livestock production is a global problem and the use of conventional biological N removal methods is usually hindered by cost. Thus, we think that the more economical anammox based treatment can greatly facilitate adoption of advanced wastewater treatment technologies by farmers. The anammox cultures were successfully established using continuous-flow unit processes and biomass carriers seeded with sludges of manure origin. Anammox removal rates obtained were in the range of industrial N removal applications.These findings overall may lead to development of more economical treatment systems for livestock wastewater and other effluents containing high ammonia concentration.