Study On Screening And Culture Conditions Of The Cyanide-degrading-better Strains

The 16 cyanide-degrading strains were isolated and screened from the active sludge neighbor the campus laboratory sewage discharging-mouth in the experiment. They can live in KCN concentration of 100~1100 mg/L, 8 strains of them can live in above 500mg/L, among the latter 16~# strain can live in KCN concentration of 1100mg/L, it was the highest density. Through carriying on the experiment of cyanide-degrading after those 8 strains being cultured 36h, we found that all these 8 strains had good tolerance and degradation to cyanide, five of them can remove cyanide at a rate of over 80%, particularly, 16 strain can reduce KCN by 94.50%. Through microe-xamination and Gram stain , it was initially identified that 16# strain was Penicillium.sp according to the culture shape of it and the result of Gram stain showing that it was Gram-positive. At the same time, the influence of initial temperature ,pH value, rotational speed of the table, culture time ,inoculating amount and density of cyanide was studied. The result showed that the strain's optimum cyanide-degrading pH value was 6.0, the optimum range oftemperature was 25℃~30℃, and the optimum culture time was 48 h, inoculating amount ,rotational speed of the table and density of cyanide have some influence to cyanide-degrading. In the optimum cyanide-degrading conditions, the CN" concentration was reduced to 0.5mg/L at intitial CN" concentration of 50mg/L after 48 h degradation by 16# strain, meets 1st grade of discharge stand of GB8978-1996.