Removal Of Mixed Heavy Metal Cations In Waste Water By Biosorption Method

In this paper,we used beer yeast embedded in sodium alginate and polyvinyl alcohol which mix by 1:2 as embedding medium adsorbed heave metal cations in waste water,the results were the following. The optimal conditions of the beer yeast adsorbed Zn²⁺ showed that: beer yeast was pretreated by the 0.1mol/LHCl,pH value was 6.0, adsorption time was 40min, 4% of mass concentration of CaCl₂ solution, the initial concentration of Zn²⁺ was 50mg/L, adsorption rate was 65.72%. when the strippant was 1.0mol/L HCl,desorption rate was 96.50%.The optimal conditions of the beer yeast adsorbed Cd²⁺ showed that: pH value was 6.3,the initial concentration of Cd²⁺ was 50mg/L,the cell concentration was 6.3g/L, adsorption time was 120min,when adsorption temperature was 24.5℃,adsorption rate was 79.44%.The optimal conditions of the beer yeast adsorbed mixed heavy metal cations Pb²⁺,Cu²⁺,Zn²⁺,Cd²⁺ showed that: pH value was 5.0, the initial concentration of Pb²⁺,Cu²⁺,Zn²⁺,Cd²⁺ were 100mg/L, the cell concentration was 20g/L, adsorption time was 2h, when adsorption temperature was 36℃, adsorption rate were respectively 95.80%,90.20%,68.04%,87.04%;The optimal conditions of desorption showed that: when the strippant was 0.5mol/LHCl,desorption temperature was 36℃, desorption time was half an hour, desorption rate for Pb²⁺,Cu²⁺, Zn²⁺,Cd²⁺ were respectively 82.45%,69.87%,64.99%,75.57%;adsorbed and desorbed again,adsorption rate for Pb²⁺,Cu²⁺,Zn²⁺,Cd²⁺ were respectively 93.55%,69.58%,45.67%,46.18%;desorption rate were respectively 56.08%,66.30%,49.64%,63.45%. The immobilized ball would getting smaller by twice adsorption and desorption. If it continues,the effects was sharply decreased.