Novel combined method of biosorption and chemical precipitation for recovery of Pb from wastewater.

A novel combined biosorption-precipitation process has been designed and applied to recycle Pb from low concentration lead containing wastewater. Pb was firstly removed selectively from wastewater by pyromellitic dianhydride (PMDA) modified sugarcane bagasse (SB) fixed-bed column, and then, it was desorbed into the concentrated eluate and recycled by adding chemical precipitant. Adsorption performance of the column and optimum desorption and precipitation condition for Pb were investigated in detail. Results showed that the as-prepared column could efficiently remove Pb from aqueous solution and optimum condition for Pb precipitation in eluate was at pH 3.0 and molar ratio of precipitant to Pb of 5:1 by using NaPO as precipitant. Recovery experiment illustrated that Pb was selectively removed from wastewater containing ions of Pb, Zn, Cd, Ca, K, and Na through competitive substitution adsorption on the modified SB, and mass ratio of the five metal ions in eluate was 96.8:0.7:0.7:0.7:0.5:0.5. Pb in this concentrated and purified eluate solution was recycled efficiently by adding NaPO. The combined method had great potential in application of heavy metal recovery from wastewater.