Peanut shells can clean water

peanut shella are an effective tool for cleaning wastewater. The agricultural waste removes poisonous copper ions from industrial wastewater. A new study says the shells perform better than many other waste products such as saw dust. Though the industry uses many chemical processes to remove heavy metals for wastewater, most of them are highly expensive. This new method seems to be cheaper and eco-friendly.

Peanut shell is the first waste product found to be highly efficient in cleaning wastewater. It cleans 95 per cent of the copper ions. Wastewater from electroplating, pulp and paperboard industries contain copper and affects marine and human life. Copper, for example, can damage the human liver.

The study by Duygu zsoy and colleagues in the department of environmental engineering at the Mersin University in Turkey was published in the International Journal of Environment and Pollution (Vol 31, No 1&2). The researchers say peanut husk performs best in a slightly acidic medium. The temperature of the medium does not affect efficiency.

Some other plants and plant products too have been used to clean wastewater. Erythrodontium barteri, a moss, removes 97 per cent of copper from wastewater, says a study done at Olabisi Onabanjo University in Nigeria, published in the International Journal of Physical Sciences (Vol 2, No 11).

How does the biomass act on the heavy metals? "All the ions in the heavy metals are positive. This biomass waste uses its capacity to develop negative ions which can trap the positively charged heavy metal ions," explains Parul Sharma of the Anand Engineering College in Agra. The peanut shell arrests metal ions by forming metal complexes from the water.

Sharma, who has studied the cleaning properties of biomass, says the efficiency of removal of a particular metal from water depends on how well the metal reacts with water. She gives examples -- lead is best absorbed, followed by cadmium, chromium and nickel. Her team has, however, not worked on copper. Some efforts are also on in India to find effective biomass among indigenous plants. Sharma has found that drumstick seeds can remove lead, chromium and cadmium efficiently from water.

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