Toxic metal removal by Biosorption

Toxicity of Flouride and Chromate ions is well known,causing Fluorosis and Cancer respectively.  Arsenic , mercury, lead and cadmium  are highly toxic even at low levels. Zn( ll) is substituted in metallo enzymes by cadmium. Toxic As ( lll) inhibits enzyme action. Mercury is  responsible for Minimata disease   while lead poisoning occurs due to its presence at high levels in food and water.Developing country like. India needs cheap water treatment methods which are sludge free and adsorption has an edge over all other techniques Like  .Biosorption and  Low cost adsorbents prepared from waste organic matter , Tree leaves, Bark,  Sawdust ,Rice husk , coal ,Flyash have been tested for removal of  these toxic anions and cations from water It  has  long been  known  that   many   biological  materials  will  accumulate  metals     This   phenomenon   tends  to exacerberate  the   environmental    impact  of  various  metals   that   are  released  in    the  environment  because  they   become  concentrated in the flora  and \or fauna   and   ultimately get  into  the  food chain .   How ever , the  same  phenomena   potentially can be   used   in   a  controlled  environment   to  remove  dissolved  metal  from     processing   streams   either  for  recovery  of  valuable  resources  or  to   remove  pollutants .This  paper explores  Toxic  metal removal by  Biosorption