Screening of aerobic denitrifying bacteria and determination of the culture conditions

Seven strains denitrifying bacteria were isolated by beef extract peptone medium mixed with the coked waste water(DM100),from Huaibei Coking plant 's activated sludge of the A2/O sewage treatment station.After gradient increase of coking waste water's plate domestication and liquid domestication,four strains aerobic denitrifying bacteria with high denitrification capacity and resistance to coking wastewater were isolated in aerobic condition.(DO=2.5 mg/L),named F4,F8,F9,F10.The contrast experiment showed that four mixed aerobic denitrification bacteria had higher denitrification capacity and grew faster than single strain.Under the same condition,four mixed aerobic denitrification bacteria 48 h NO-3-N removal rate is 98.75 percent.And the most suitable culture conditions of them are: 35 ℃,pH=8.0,C/N=5,inoculate quantity is 25 percent(bacteria density is 2×107~3×107/mL).After conditions optimization,the time of four mixed aerobic denitrification bacteria NO-3-N removal rate when attaining 90 percent reduced form 96 h to 18 h.