A mathematical model for the vacuum evaporation process was developed and validated to remove ammonia from anaerobically digested sludge under different pH and temperature conditions. Six combined process scenarios were tested using Anaerobic Digestion Model 1. The most effective options were vacuum evaporation as a post-treatment at pH 9 and as an intensification step at pH 9, both recovering over 76% of the influent nitrogen without reducing methane production. Economic analysis showed that the pH-9 intensification scenario was cost-neutral, performing significantly better than the control scenario, which had a net present value of –22 million dollars.
Vacuum-evaporation-coupled-with-anaerobic-digestion-for-process-intensification-and-ammonia.pdf
Paper