Review on the Progress of Treatment Methods of Heavy Metals in Municipal Solid Waste Incineration Fly Ash

Abstract

Municipal solid waste incineration is an important method of solid waste management, though this method reduces a great portion of the waste volume, it also produces fly ash which is rich in dioxins, heavy metals, soluble salts and other harmful substances that can be detrimental to the environment if not well treated. The disposal of incineration residues especially fly ash has been of great concern, due to the wide range of heavy metals and soluble salt which are harmful to the environment and groundwater This paper aims to evaluate the advantages and disadvantages of the different treatment techniques (land fill, chemical stabilization, acid extraction, cement solidification etc.,) of heavy metals in Municipal Solid Waste Incineration Fly Ash (MSWIFA) which have been used. Over the years scientist have experimented better ways to either eliminate, utilize or consolidate heavy metals in fly ash. Therefore, a systematic and structural review of both ancient and recent treatment methods of heavy metals in MSWIFA for different geographical locations is done following three principal criteria's; (i) treatment efficiency, (ii) cost, and (iii) operability. The study depicts that the cement solidification method was mostly used because it is cheap and easy to operate, whereas vitrification method is expensive due to high energy consumption. On the other hand, methods such as; chemical stabilization, melting process, geopolymer and acid extraction are very costly. This review provides some guidance; on the selection of the best treatment methods of heavy metals in MSWIFA, useful for the application of a zero-waste concept which goes beyond traditional composting and recycling.