The Use of Straw for Removal of Heavy Metals from Waste Water

The efficiency of barley straw (Hordeum vulgare L.) in removing heavy metals from solutions was investigated in capacity and in column experiments. In the capacity experiments the efficiency of the straw was compared to that of activated carbon, pine sawdust, and CaCO3. It was found that 1 g of straw was able to adsorb amounts of Zn, Cu, Pb, Ni, and Cd ranging from 4.3 to 15.2 mg. One gram of activated carbon removed from 6.2 to 19.5 mg and pine sawdust from 1.3 to 5.0 mg. From 1.6 to 19.8 mg of the different metals were precipitated by CaCO3. The efficiency of the straw was not reduced in column experiments where flow rates of 167 to 370 ml/min were used. The efficiency of the straw was improved by 10–90% when being mixed with CaCO3. A column packed of barley straw and saturated with Cu was regenerated with 1 liter of acid (±1.0N HCl) and could be reused at least five times.