REMOVAL OF LEAD FROM MINE WASTEWATER BY LOW COST BIOSORBENT 'RICE POLISH'

摘要

During mining process groundwater as well as surface water is required at several stages diromg the mining and mineral processing, wet drilling, water spraying, froth floatation etc. Ground water gets contaminated while coming out of coal seams and surface water from the result of acid mine drainage. Heavy metals such as Zn, Cd, Pb etc., which are always found in this contaminated water, adversely affecting the quality of water because their toxicity. Lead is one of them and its permissible limit in drinking water is 0.05 mg/l. The presence of lead above its permissible level has already been proven to be detrimental and causes so many diseases. The major biochemical effect of lead is its interference with haem synthesis, which leads to haematological damage. The adsorption process, in comparison to other physico-chemical processes for the treatment of polluted aqueous effluents allows flexibility in design and operation. In addition to this, adsorption is sometimes reversible and the regeneration of the sorbent is possible. In the present research work low cost biosorbent "Rice Polish" has been utilized to remove lead from synthetic mine waste water. It has been found to be very effective for the removal of lead from aqueous solutions and as much as 97.5% of leads were removed at pH 6.5 and 30 ℃ from wastewater. The effect of various parameters such as contact time, adsorbate concentration, pH of the medium and temperature have been studied. The adsorption follows first order kinetics. A Langmuir isotherm model fits the equilibrium data well. The thermodynamics of this adsorbate -adsorbent system shows spontaneous and exothermic nature of the process. Various thermodynamic parameters have been evaluated and critically discussed.