The effects of variable ammonia concentration on the removal efficiency of organic matter and ammonia nitrogen were examined by conducting sequencing batch experiments. Meanwhile

the soluble microbial products (SMP)

loosely bound extracellular polymers (LB-EPS)

and tightly bound extracellular polymers (TB-EPS) of anaerobic granular sludge were analyzed by using ultraviolet-visible spectroscopy (UV-Vis)

excitation emission matrix fluorescence spectroscopy (EEM)

and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that the removal rate of COD reduced from 94.19% to 93.33% by anaerobic granular sludge

when the influent concentration of ammonia nitrogen reached to 1000 mg·L-1

which indicated that anaerobic granular sludge had an insignificant impact on the removal efficiency of COD. However

at the same time

the removal rate of ammonia nitrogen substantially decreased from 40.6% to 7.9%

due to its influent concentration. UV-Vis spectra analysis showed that a strong absorption band appeared at 205-210 nm scope of the LB-EPS and TB-EPS

and it was demonstrated that the LB-EPS and TB-EPS contained benzene ring and double bond structure. EEM spectra analysis showed that with increase of concentration of ammonia nitrogen

the intensity of aromatic protein adsorption peak decreased in the SMP

and the humic acid adsorption peak at EX/EM=370-390/420-450 nm enhanced. For the LB-EPS

the coenzyme F420 absorption peak disappeared. It was illustrated that high concentration of ammonia nitrogen had an adverse effect on the activity of methanogens. In addition

the protein-like fluorescence peak in the TB-EPS has occurred red shift. At the ammonia nitrogen concentration of 1000 mg·L-1

it was showed the existence of carboxyl in the LB-EPS. By using UV-Vis

FTIR and EEM spectra

the SMP

LB-EPS and TB-EPS of anaerobic granular sludge were analyzed comprehensively

which could provide scientific reference for the operation of anaerobic reactor.