A Hybrid Immobilized Cells Bioreactor For The Treatment Of Cyanide

Cyanide is deadly toxic, but it is widely used in industrial production because of the strong complexing of CN-, thus produces large amounts of cyanide wastewater. Cyanide is very easily to form hydrogen cyanide under neutral and acidic conditions, hydrogen cyanide is highly volatile for its boiling point is only26℃. Therefore air pollution control in the process of cyanide wastewater treatment is very important. The aim of the present study was to build a hybrid immobilized cell bioreactor, to investigate the feasibility of simultaneous removal of liquid and gaseous cyanide, and offer new method for biological treatment of cyanide contamination.Natural material corncob was selected as immobilization carrier according to previous research in our group, and its properties of cyanide adsorption were investigated here. The result showed that the increasing of cyanide adsorption rate slowed down after2hours, and the final adsorption rate at7h was29.27%. After autoclaved at121℃for20min, it took longer to get adsorption equilibrium. However, the final adsorption rate were nearly the same. Cyanide adsorption rate of the corncobs increased with the increasing of its dosage, but the amount of CN" adsorbed on unit weight of corncobs tended to be closed. The higher the initial cyanide concentration was the greater the amount of adsorbed cyanide was under the same condition. The effect of pH (8,9,10) on the adsorption process were studied, it was found that alkali environment promote the cyanide adsorption, the final adsorption rate for pH8,9,10after8h were29.6%,43.8%and56.1%respectively.A4.5L cylindrical hybrid bioreactor composed of a packed bed column and a biofilter was designed. The traditional packed bed column maintained removal efficiencies about99%with volumetric loading of200mg/L-d, but the treatment effect was not satisfactory when the cyanide load increased, continuously volatilization of cyanide in aqueous phase was found when the packed bed column was operated with aeration. When handling with high cyanide load of450mg/L and650mg/L, the cyanide removal efficiencies reched98%. In long-term operation, removal efficiencies for200mg/L cyanide were ranging from95%to98%most of the time. Even when cyanide concentration was increased to627mg/L, a removal efficiency of92.3%was achieved, a short shock loading did not influence the performance significantly.