performance and kinectics aspects of nitrogen removal in a biofilm sequencing batch reactor

a biofilm sequencing batch reactor with a volume of 1.42 m3, nylon nets providing a 4,140 m2/m3 support area for biofilms and an automated operation with 8 hour cycles was studied. the duration of the experiment was 135 days. removal efficiencies e≥ 80% were obtained for carbonaceous matter, producing an effluent with 31±26.8 mg/l of filtered cod, 7±3.6 mg/l of bod5 and 12±3.2 mg/l of toc. the average removal efficiency of ammonium was 77 ± 16.6%, with a mean concentration in the effluent of 14 ± 10.2 mg nh4-n/l. the denitrification efficiency was 80±14.7%. the effluent characteristics met the requirements of brazilian environmental standard for discharge to receiving water bodies. a kinetic study of nitrification and denitrification showed that during the aerobic phase the specific rate of ammonium consumption was 0.057 g nh4-n/g vss.d and the production of nox-n was 0.074 g nox-n/g vss.d, while the specific rate of nox-n consumption was 0.05 g nox-n/g vss.d during the anoxic phase. the suspended and fixed biomass was composed of 50% ammonium-oxidizing bacteria (aob).