Recovery of Ammonia From Digestate As Fertilizer

High levels of nitrogen give rise to two problems for anaerobic digestion (AD) operators. Firstly, ammonia inhibition can be a major problem during digestion of municipal and industrial sludge. Higher NH3-N concentrations are inhibiting or even toxic for methanogen bacteria which can cause a decrease in biogas production. Secondly, because of the reduction of COD in anaerobic digestion the effluent of the anaerobic treatment often results in a COD/Nitrogen ratio which is too low resulting in the need for additional dosing of a carbon source in the biological nitrogen removal process. The Nijhuis Ammonia Recovery system (NAR) is an innovative process which can solve these issues by removing ammonium from digestate or other substrate for digestion and recover ammonium as ammonium sulphate, an agricultural fertilizer. NAR is a robust technology for digestate treatment with a stable ammonia removal efficiency of 75-90% and competitive to current state of the art ammonia removal technologies.