The exact approach will depend on the specific metal(s) and concentration. Some bacteria treat metals by precipitating them out of solution.  For instance F. thioxidans will remove Fe from solutions by such a mechanism.  Another approach would be biosorption, where fungi or bacteria sorb the metals to biomass.  Without know the target metals/levels it is difficult to suggest a specific bioremediation technique.

Thanks Teresa Cut right, for your reply. Here I want to know that whether F.thioxidans is being removed commercially some where. I also know many bacteria's for various metals but there commercial use is not known. Is some consortium of becterias or fungi is in use for the purpose. Thanks.

A company called Casino Mining in Canada is looking at using microorganisms for metals removal from wastewaters. You can follow their progress on the attached website. They have also written a comprehensive review paper, see the attached link.

http://www.casinomining.com/community/sharing_stories/wetlands/

http://www.casinomining.com/_resources/Passive_treatments_review_-_Cold_Climate_-_YRC2014.pdf

Hi Rafael Mattos Dos Santos; Thanks for such an interesting answers and useful links. I appreciate your help. Though the links are related to cold climates but a ray of light is there for such works in other climates also. Regards Dr. Dubey

Microorganisms can be used to remove heavy metals, there are two processes: adsorption (biosorption) or bioaccumulation. In general, bacteria can be used, microalgae, macroalgae and fungi. However to bioaccumulate algae but are studied, however the design level have some difficulties to control growth, biomass and amount of variation in the degree of accumulation. There are many works in ELSEVIER base mentioning various types of biomass, especially in adsorptive processes.

Thanks Carlos Eduardo De Farias Silva  for your answer. We also used algae etc as bioaccumulation. We also identified the bacteria which reduced BOD, COD and declaration of the waste waters in isolation very efficiently. But in real life in sewage water where consortium of other bacteria are present the isolated becterias do not work so efficiently. Thanks

There are some strategies to provide optimal conditions for microalgae to remove nutrients and heavy metals from wastewater. I would like to suggest you to read a review I wrote on Phycoremediation hoping that you could find some useful information:

Olguín, E.J. 2003. Phycoremediation: key issues for cost-effective nutrient removal processes. Biotech. Adv. 22: 81-91.(F.I.= 9.646)

Any microbial method used should be assessed against other methods of removing heavy metals from wastewater. Depending on the type of treatment (e.g. lagoons or ponds), a large proportion of the heavy metals are likely to be present in the sludge collected at the bottom of the treatment ponds. Perhaps the most efficient way of removing heavy metals in the supernatant wastewater is to aid processes (e.g. reducing acidity of the wastewater which will reduce dissolution of heavy metals, use of fine and high cation exchange minerals such as zeolites, enhanced flocculation) that could remove free heavy metals from the wastewater.

Having stated the above, our healthy discussion on microbial removal of heavy metals should continue.

Thanks Selva Selvarajah; That's true we all know the chemical process but here as you said the our healthy discussion on microbial power of heavy metal removing should continue. Thanks for your interesting answer. Regards

We have used a calcium phosphate gel (fine particles suspended in water), in the form of hydroxyapatite, a biocompatible substance, and added it to a waste water treatment plant, and found that somehow, it helps the biological digestion process by removing part of the toxic metals and part of the BOD also. Probably the cells adsorb to the particles and the metals also surface exchange with calicum ions to fix the toxic metals in insoluble phosphate form. All this helps in reducing the load on the waste treatment plant. The new process has been patented by Solvay Co.

Hi Prof. Patrick J. Sharrock ; Thanks for giving such an important information and shared your experiences. Thanks

Dear friends I would like to know that though the microbes eat away the havey metals but they themselves remain in the system, do how we should consider the removal. Your comments please.