Use of Chabazite to Overcome Ammonia Inhibition During Nitrification of High Strength Wastewater

Treatment of high ammonia (NH4+) strength wastewaters, such as centrate from anaerobic digestion of livestock waste, using biological nitrogen removal processes is a challenge due to nitrification inhibition. The goal of this study was to remove NH4+ from anaerobicically digested (AD) swine waste centrate using a hybrid process that combines cation exchange onto chabazite with bioregeneration by nitrification. Chabazite is a natural ion exchanger that can be used to temporarily adsorb NH4+ to prevent nitrification inhibition. Regeneration of the chabazite is then accomplished through nitrification, allowing reuse of the material. Ion exchange studies were carried out at varying chabazite doses and contact time. The results indicated that a chabazite dose of 150g/L and a contact time of 4 hr are sufficient to reduce the NH4+ concentration by 80%. This will maintain the NH4+ concentration below 350 mg-N/L, which was found to be inhibitory to nitrifying bacteria in nitrification inhibition studies. Nitrification test were carried out with synthetic anaerobically digested swine waste centrate with a NH4+-N concentration of 1,000 mg/L, with and without chabazite addition. Chabazite was found to improve the nitrification rate 0.157 from to 0.363 mg-N/g-VVSS·h.