Ammonium Removal from Anaerobically Digested Swine Waste Using Zeolite in a Sequencing Batch Reactor

Increasing meat demand is a worldwide environmental problem due to the need for sustainable technologies for animal waste treatment.  Swine production represents 40% of the world’s meat production, and wastes generated from this industry contain high concentrations of organic matter, nutrients, pathogens, trace metals, and salts. Government agencies are endorsing the use of anaerobic digesters to treat swine waste to produce methane that can be use as an energy source. However, further treatment is required for anaerobically digested swine waste because nutrients, such as nitrogen in the ammonium form are not removed. Ammonium concentrations in anaerobically digested swine waste have been reported in the range of 800 to 4,000mg/L. The importance of nitrogen removal is to avoid eutrophication, which stimulates the growth of algae and aquatic plants in receiving waters leading to water quality degradation and habitat loss. Removal of ammonium can be accomplished by biological nitrification and denitrification. However, concentrations of ammonium greater than 100mg/L are inhibitory to nitrifying bacteria. The objective of this research is to remove ammonium from anaerobically digested swine waste by nitrification and denitrification using zeolite in a bench scale sequencing batch reactor (SBR). Chabazite, which is a natural zeolite with ion exchange properties, will be added to the SBR to adsorb ammonium to prevent inhibition of the nitrification process. The SBR will be operated in 24hrs cycles with the following phases: anoxic-fill (2h), anoxic-reaction (4h), settling and decant (1h), aerobic-reaction (16h), and idle (1h). Results of the experiments will be presented at the conference.