Dissolved organic matter from the effluent of a nitrifying reactor was characterized with fluorescence spectroscopy of the excitation-emission matrix in 3D.

Only two fluorescence peaks were identified at the effluent of the nitrifying reactor and they were attributed to humic acids from soluble microbial products.

The EEM-3D from the effluent of an aerobic autotrophic nitrifying reactor showed that the nitrifying bacteria did not produced aminoacid-like microbial products.