Optimum operating conditions for a real scale ammonia stripping tower: an experimental case

In recent years, several studies focused on developing processes aimed at recovering nutrients such as nitrogen. In this paper, a real plant for ammonia stripping has been tested on a real aqueous waste in order to optimize the process conditions (air flow rate and pH). The results of a finite element mathematical model were compared with the ones of experimental tests. The results showed that 500 Nm3/h was the minimum flow rate necessary to allow reaching ammonia nitrogen removals close to 80% in 9 hours of stripping (reactor operating in semi-batch mode). Moreover, the tests showed the possibility of increasing the pH value by exploiting the alkalinity that characterizes the digestates without the dosage of reagents for basification (e.g. NaOH).