The effects of ammonia concentration on the performance and stability of mono-fermentation of chicken
manure were investigated in a lab-scale continuous stirred tank reactor at 40 C. Technical stripping was
performed to remove ammonia from the liquid fraction of digestate, and the entire product was recycled
to the fermenter to control ammonia concentration in the fermenter. Organic loading rate (OLR) of
5.3 gVS/(L d) was achieved with an average free ammonia nitrogen (FAN) concentration of 0.77 g/L and
a specific gas yield of 0.39 L/gVS. When OLR was increased to 6.0 gVS/(L d), stable operation could be
obtained with an average FAN concentration of 0.86 g/L and a specific gas yield of 0.27 L/gVS. Monofermentation
of chicken manure was successfully carried out at high ammonia concentrations. Controlled
recirculation of treated liquid fraction of digestate could be a solution in large-scale application for both:
to avoid ammonia inhibition and minimize digestate.