I want to stipulate once more that heavy metals can not be broken down to harmless constituents.  This would require real magic to occur.

There are - in my opinion- two ways to do something about it.

One is to convert it into a very insoluble form such as a sulfide, which is considered to be less harmful than a soluble form like acetate.

The second route is growing plants or trees that accumulate the metal in the parts above the ground and those can be removed and disposed of in another way.

For me second way proposed by Dr. Kan is better. You can select bacteria or yeasts that improve the absorption by plants for improve the process. Careful about where the plants accumulate metals. obviously during growth the plants should not be food for animals.

good luck

For enhance ability of plant to accumulation of heavy metals, you can use Phosphate fertilizers because these fertilizers can enhance the precipitation of heavy metals in plant. 

Best regards 

Thank you all for your brilliant answers. however, can you suggest a journal or give an attach? thanks

Barea, J.-M., Pozo, M.J., Azcón, R., and Azcón-Aguilar, C. (2005) Microbial co-operation in the rhizosphere. J Exp Bot 56: 1761–1778.

Chaudhry T. M., Hayes W.J. , Khan A.G., Khoo C.S. (1998) Phytoremediation—focusing on hyperaccumulator plants that remediate metal-contaminated soils. Australasian Journal of Ecotoxicology 4, 37–51.

Qin S., Xing K., Jiang J.-H., Xu L.-H., Li W.-J. (2010) Biodiversity, bioactive natural products and biotechnological potential of plant-associated endophytic Actinobacteria. Appl Microbiol Biotechnol 89: 457–473

http://link.springer.com/chapter/10.1007/978-1-4614-5577-6_2

http://link.springer.com/article/10.1631/jzus.2007.B0192#page-1

A generic term such as heavy metals does nit give the information needed to properly answer your question.  Phytoremediation has not been shown to work except in specialized situations and that is dependent on the metals as well as the length of time that you have to complete the cleanup,  Arsenic, for example might be better left undisturbed as often it is sorbed to substances in the soil and is not bioavailable.   Lead too is often immobile.  Other metals are more problematic for plants as often they are multiple metals and so the contamination is complex.  Many metals are toxic at high dosage to plants and even to be taken up the metals have to pass through the symplastic membrane system of the plant that exists in the root to keep toxic substances out of the plant itself.  Bacterial mediation of metal removal to produce sulphides is far more efficient since the sulphides, are generally insoluble except at low pH such as exists in stomachs.  There are methids that have been developed that utilize a collection system to collect the contaminated water then pass the water through a biochemical reactor.  This method has shown demonstrable success in many environments. 

Before answering further it would be good to know the metals that you refer to as well as the type of soil and the nature of the contaminated area - i.e. is it a brownfield site, are there organic contaminants present as well, is there vegetation currently present?

Thank you Mr Allan, in response to your mail, i would like to inform you about the site. The polluted area in question is an abandoned gold mine soil and we discovered great number of metals like; Pb,Cr, Zn etc. the pollutants here is purely inorganic in sandyloamy soil. we look forward for your prompt assistance and attach. Regards

If high polluted soil from heavy metals, recommend to assigns as red or restrict zone. First, do not plant any food crop follow with appropriate technique selection for remidiate the heavy metals. Because soil characteristic are different so shoud study site by site for select suitable methods.

 Dear Aransiola

According to my experience , special plants can rescue the soil, but first of all we should know the type of soil and then finding appropriate plants .Phosphate fertilizers could be good due to   enhance the precipitation of heavy metals in plant. 

You say that the soil is contaminated with a variety of heavy metals including Pb, Cr Zn.  Are there others.  At what concentration are the metals found.  Have you done an analysis that can pinpoint the concentration. There is a site that you should go to, IRTC which presents a decision tree that can be used to make the decision regarding treatment options.  It is weighted towards biochemical reactors but a similar decision tree can be used for other treatment modalities.  In my opinion unless the concentrations are very low - in which case you might want to do nothing but plant non-food crops the idea of phytoremediation is not a viable one.  To my knowledge there has not been a site that was cleaned up to acceptable standards using this technology except for a few using very specialized planting techniques such as long tubes in which the roots of phreatophytes are placed so that the roots are forced to go down to the source of contaminants - in this case a form of hydrocarbon.  You need to provide the complete description of the contaminants, the concentration of the contaminants, and the type of soil before making any decision.