Bio-processing of solid wastes and secondary resources for metal extraction – A review

Metal containing wastes/byproducts of various industries, used consumer goods, and municipal waste
are potential pollutants, if not treated properly. They may also be important secondary resources if processed
in eco-friendly manner for secured supply of contained metals/materials. Bio-extraction of metals
from such resources with microbes such as bacteria, fungi and archaea is being increasingly explored to
meet the twin objectives of resource recycling and pollution mitigation. This review focuses on the bioprocessing
of solid wastes/byproducts of metallurgical and manufacturing industries, chemical/petrochemical
plants, electroplating and tanning units, besides sewage sludge and fly ash of municipal incinerators,
electronic wastes (e-wastes/PCBs), used batteries, etc. An assessment has been made to quantify
the wastes generated and its compositions, microbes used, metal leaching efficiency etc. Processing of
certain effluents and wastewaters comprising of metals is also included in brief. Future directions of
research are highlighted.