Screening Of A Copper-nickel-chromium Tolerant Bacterial Strain And Analysis Of Its Removal Efficiency Against Electroplating Wastewater

Bioremediation is a technology that uses microorganisms to treat heavy metals,which is favoured because of is favored for low cost and greenwash.A bacterium strain resistant to copper-nickel-chromium,named Bacillus cereus ZW1,was isolated from electroplating waste water with hexavalent chromium,and the removal efficiency for these three heavy metals was preliminarily studied.The minimal inhibitory concentrations of this strain for copper,chromium and nickel was 350 mg/L,250 mg/L and 400 mg/L respectively in LB liquid medium.The Rice washing water of Guilin Rice Noodle(RWW)and waste liquor of alcohol(WLA)are wastewaters of starch industry and sugar industry,respectively,which are used as the carbon sources of microorganisms to treat electroplating waste water with certain effects of energy saving and environmental protection.A central composite design was applied to optimize the content of the carbon source(RWW,WLA),p H and culture time to obtain a better removal efficiency for heavy metals under the conditions of 36? and 160 rpm.min-1.Based on the above results,the second-order polynomial regression model was established,and the reliability of the model was verified.In addtion,the foctors were optimized using response surface methods.The optimal removal efficiency for copper is 71.80% when the strain ZW1 was grown in the electroplating waste water without extra carbon source.The optimal removal efficiency for copper is 69.85% when the strain ZW1 was grown in the electroplating waste water with 1 m L RWW under the conditons of p H 9 and culture time 95.98 h.Meantime,the optimal removal efficiency for copper is 74.79% when the strain ZW1 was grown in the electroplating waste water with 10 m L WLA under the conditons of p H 6 and culture time 12 h.We inferred that the WLA was more appropriate as carbon source compared with RWW because of the shorter cycles and the higher removal efficiency.The optimal removal efficiency for nickel is 45.72% when the strain ZW1 was grown in the electroplating waste water without extra carbon source.The optimal removal efficiency for copper is 20.32% when the strain ZW1 was grown in the electroplating waste water with 1 m LRWW under the conditons of p H 6 and culture time 88.95 h.Meantime,the optimal removal efficiency for nickel is 62.86% when the strain ZW1 was grown in the electroplating waste water with 1 m L WLA under the conditons of p H 6 and culture time 96 h.We inferred that the WLA was more appropriate as carbon source compared with RWW because of the higher removal efficiency.The optimal removal efficiency for chromium is 29.29% when the strain ZW1 was grown in the electroplating waste water without extra carbon source.The optimal removal efficiency for copper is 92.58% when the strain ZW1 was grown in the electroplating waste water with 10 m L RWW under the conditons of p H 9 and culture time 96 h.Meantime,the optimal removal efficiency for chromium is 73.09% when the strain ZW1 was grown in the electroplating waste water with 10 m L WLA under the conditons of p H 9 and culture time 96 h.We inferred that the RWW was more appropriate as carbon source compared with the WLA because of the higher removal efficiency.