An optimal magnetite immobilized Pseudomonas-putida 5-x cellsystem for Cu2+ removal from industrial waste effluent

An optimal magnetite immobilized Pseudomonas putida 5-x cell system was dev eloped to remove Cu2+ from industrial waste affluent. Cu2+ adsorption capac ity of P. putida 5-x cultured in sulphate-limiting medium (SLM) was minimum in early log growth phase, and reached maximum in late stationary growth p hase or early death phase. Pretreated cells by 0.6 N HCl could greatly enha nce the adsorption capacity of biomass up to 85.6 mg/g and had no significa nt effect for the loss of P. putida 5-x cells during the pretreatment. In a semi-continuous biosorption system, the removal efficiency of Cu2+ from wa stewater reached 96%, and recovery efficiency of Cu2+ was 95%, and the conc entration in the recovery solution was 1.4 g/L using 0.6 N HCl as eluant. T he mechanism of Cu2+ adsorption by this type of biomass was studied by usin g the technique of transmission electron microscopy (TEM). Degradation of a peptidoglycan layer on the cell surface was observed after acidic pretreat ment, but no further degradation appeared after the adsorption-desorption c ycle. TEM and X-ray analysis also showed that Cu2+ was mainly accumulated o n the cell surface, so it was effectively desorpted by acidic treatment in the desorption process. The process of adsorption obeyed the Freundlich iso therm.