Increased industrial activities have resulted in the generation of large amounts of wastewater polluted with heavy metals.
Adsorption is recognized as an effective and economic method for low concentration heavy metal wastewater treatment.
Activated carbon is the commonly used adsorbent, the major drawback being the high cost. Low cost adsorbents from waste
materials have been tried by different researchers. The current research is focussed on the need to find an economical
adsorbent for the removal of heavy metals from aqueous solutions. Both fly ash and sludge are produced in large scale and
cause major disposal problems. This paper reviews the use of sludge and fly ash as an adsorbent for the removal of heavy
metals from aqueous solutions which meets the dual goals of disposal and treatment. It is evident from the existing literature
that both fly ash and sludge can be effectively used as an adsorbent for heavy metal removal. Different modes of operation and
activation methods to improve the adsorption capacity are the future scope for the research.