Submitted to: Proceedings of American Society of Agricultural Engineers
Publication Type: Abstract Only
Publication Acceptance Date: 7/17/2005
Publication Date: 7/17/2005
Citation: Vanotti, M.B., Furukawa, K., Garcia-Gonzalez, M.C., Szogi, A.A. 2005. Nitrogen removal with the anaerobic ammonia oxidation (Anammox) process using polymer gel biomass carrier seeded with swine effluent sludge [abstract]. Proceedings of the American Society of Agricultural Engineers Annual International Meeting, July 17-20, 2005, Tampa, Florida. 2005 CDROM.
Technical Abstract: Research was conducted to develop process applications for the slow-growing anaerobic ammonium oxidation (Anammox) bacteria using continuous flow treatment and microbial immobilization techniques. In the Anammox process, the ammonia (NH4+) is converted to harmless dinitrogen gas (N2) under anaerobic conditions with nitrite (NO2-) as the electron acceptor. It is more energy-efficient than traditional biological N removal systems because only part of the ammonium needs to be nitrified and there is no need for carbon addition for denitrification. The Anammox microorganisms were discovered in the sludge of a pilot plant providing nitrification treatment to anaerobic lagoon effluent in a swine farm in North Carolina. Laboratory bioreactors were seeded with the sludge isolated from the pilot reactor after acclimation with nitrate solution to remove endogenous carbon. The bioreactors were operated in continuous flow and contained polyvinyl alcohol (PVA) hydrogel biomass carrier beads for immobilization and enrichment of the slow growth microorganisms. A distinct red biomass growth, which is typical of the Anammox planctomycete, developed in the reactors after 6 months of continuous flow operation. Fluorescent in situ hybridization (FISH) analysis of the biofilm using 16S rDNA oligonucleotides Ana-1 and Amx 820 confirmed Anammox bacteria; imaging revealed a high density of cells growing in clusters. Removal of NO2- and NH4+ was simultaneous at a stoichiometric ratio of 1.3:1 that is characteristic of the Anammox reaction: NH4+ + 1.32 NO2- + 0.066 HCO3- + 0.13 H+ = 1.02 N2 + 0.26 NO3- + 0.066 CH2O0.5N0.15 + 2.03 H2O Hydraulic retention time was gradually decreased from 24 to 12 h over a 16 month period to increase N load. Nitrogen removal rate obtained was 0.5 kg N/m**3/day, which is in the range of industrial bio-treatment applications. This finding may lead to development of more economical treatment systems for livestock wastewater and other effluents containing high ammonia concentration.