A PERFORMANCE STUDY OF SIMULTANEOUS MICROBIAL REMOVAL OF NO AND SO2 IN A BIOTRICKLING-FILTER UNDER ANAEROBIC CONDITION

The behaviors of simultaneous removal of NO and SO2 using the coculture of anaerobic denitrifying bacteria and sulfate reducing bacteria was investigated in a bench-scale biotrickling-filter. When the combined NO/SO2 removal biotrickling-filter was operated at an empty bed residence time of 76 s with NO and SO2 feed concentrations of 2 and 2 g/m(3), respectively, the SO2 removal efficiency was always above 95%, while NO removal exhibited an evident periodicity of 5-6 days for the initial 60 days after the attachment phase. A steady-state NO-removal efficiency of around 90% was obtained after 130 days of continuous operation. Experimental results indicated that the coculture in the combined NO/SO2 removal biotrickling-filter showed a higher resistance to shock NO-loadings and a better tolerance to starvation than the single denitrifying bacteria in the NO removal biotrickling-filter.