Utilization of biowaste for mine spoil rehabilitation

Globally, around 0.4\ua0×\ua010 km area of land is estimated to be disturbed by mining activities, thereby contributing to severe environmental consequences including the generation of large amounts of mine spoils. The shortfall in topsoil due to poor striping practices and low levels of organic matter have been identified as common problems in rehabilitation of mining spoil. High heavy metal concentrations in mine spoil can adversely impact microbial activity and subsequent revegetation succession. The release of acids associated with mine spoils (ie, acid mine drainage through oxidation of pyrite) can also create adverse effects on the surrounding vegetation. Large quantities of biowaste, such as manure compost, biosolids, and municipal solid waste (MSW) that are low in contaminants [including metal(loid)s] can be used to rehabilitate mine spoils. These biowastes provide a source of nutrients and improve the fertility of spoils. These biowastes also act as a sink for metal(loid)s in mine tailings reducing their bioavailability through adsorption, complexation, reduction, and volatilization of metal(loid)s. This review provides an overview of the sources of biowastes and the current regulations for utilization; describes their benefits in terms of improving the physical, chemical, and biological properties of mine spoils; and elaborates on the role of the utilization of biowastes on mine spoil rehabilitation through several case studies. Finally, future research needs and strategies are identified in terms of sustainable biowaste utilization in mine spoil rehabilitation