All around us there are many things which we have thrown as "waste" but which can be used to "treat waste". *Poultry waste , specifically hen eggshells has recently be explored for its utilization as heavy metal adsorbent. *It has been found that after a little chemical modification , these waste eggshells can be used as a tool to treat heavy metal contaminated industrial effluent. Hence , provide a low cost, eco-friendly water treatment technology . It is environmentally safe as it decontaminate water (reduces water pollution) and utilizes solid waste( reduces solid land pollution ) * This book enhance the interest of researchers to find more eco-friendly methodologies to reduce pollution in our planet.