Sustainable remediation solution for heavy metal contaminated soils of Pakistan: A review

The heavy metals are recognized as major threat to the agricultural land. Most of these heavy metals enter in soil due to anthropogenic sources including rapid urbanization, industrialization, excessive use of pesticides, herbicides and fertilizers, mining and smelting activities and electronic wastes etc. The complexity of soil-heavy metal interaction is also increased due to inefficient sewage systems, use of industrial water for irrigation purposes without proper treatment. The translocation of H.M.s from Soil to the vegetative parts and accumulation in vegetative parts of the plants and humans has become an emerging threat to human health. Several physical, chemical, and biological techniques are being practiced for the remediation of heavy metals contaminated soils in Pakistan. However, in developing countries like Pakistan, high costs of equipment, energy supply, operation and maintenance limits their applicability and sustainability. On the other hand, Phytoremediation is a cost-effective technique which relies on solar energy to boost up the process with minimum technical, operational and maintenance cost. Finally, the disposal of contaminated plants used in Phytoremediation can be achieved through different procedures like incineration, compacting, pyrolysis, leaching depending upon the availability of resources and type of plants. The cost-benefit analysis reveals that cost highly varies depending upon a number of factors and the minimum estimated cost ranging from $10-35. The hyperaccumulator plants provide a reasonable solution for heavy metal contaminated lands with less cost and limitations as compared to the other techniques.