Biosorption of Heavy Metals

Abstract

Feasibility of five different non-conventional biosorbents of microbial and plant origin were tested for removal of priority metal ions such as Pb, Cr, Zn, Ni and Fe from synthetic effluents in single metal state and multi-metallic state. The objective was to develop inexpensive and effective metal ion adsorbents that are available in large quantity as an alternative to existing commercial adsorbents. Five biowastes such as waste carrot juice pulp, waste tea leaves, wood powder (saw dust), paper mill sludge and mycelial waste were tested for biosorption efficiency and compared with that of activated charcoal. The effect of biomass concentration, pH and metal concentration on the ability of dried biomass to remove metal from solution was investigated. Dried powder of waste carrot juice pulp can remove 74 % Zn, tea leaves 25 % lead, wood powder 36 % lead and 35 % Zinc, whereas mycelial waste could remove 74 % Pb and 46 % Fe and paper mill sludge could remove 66 % lead and 46 % Fe from 50 ppm of synthetic metal solution in 30 min. of contact time at pH 4.0 at room temperature with continuous stirring at 80 rpm. The adsorption of metal ion on paper mill sludge reached equilibrium in 30 min. and by mycelial waste in 60 min. Maximum uptake of metal ion occurred in the range of pH 4-5 by paper mill sludge and at pH 3 by mycelial waste by a biomass concentration of 2 %. For the same metal ion different adsorbents had different removal rate. A combination of biosorbents was effective in simultaneous removal of Pb, Zn and Ni from multimetal metallic solution. There is a plenty of scope for large scale application of non living biomass from fermentation industries for removal of metal ions. Paper mill sludge and mycelial waste biomass can be used in the wastewater treatment for the removal of metal ions which are available in large quantities can have tremendous usage as an alternative to existing commercial adsorbents.