**5. Industrial application**

The mesophilic tank leaching is the most common bioleaching process in the world; thermophilc tank is favored while the temperature is high, among such tanks BioCop™ well known, In order to have effective thermophilc tank the following are basic requirements, microbial catalyzed reaction which is needed to facilitate metal dissolution by microbial oxidizing of ferrous iron to ferric iron, initial solublization of ferrous ion takes place using acid solution, oxidation of mineral sulfide takes place by the combination effects of ferric iron and acid solution followed by oxidization of reduced sulfur to sulfate by microorganisms. Reactor configuration is the other factor where the six equal size continuous reactor, three arranged in parallel considered as primary reactors, and the other three arranged in series considered as secondary reactors, in this case reactors are considers as a large continues stirred tank supplied with aeration and agitation. The other factors are oxygen, carbon dioxide, pulp density and finally even though the operational cost is much less plant location, construction material, blower or compressor to supply oxygen to the microbes, high power agitator in case of oxygen plant for oxygen dispersal in the reactor. Growth of industries results the demand of metals in very high quantity and likely go further in the years to come. This brings diminution of high grade ore with effluents and solid wastes that needs to be treated to recover the important elements and protect the environment.

Regarding to environment biohydrometallurgy is vital process, the fact that bioprocess is conducted without the presence of toxic chemical and relatively required low cost makes it most needed. The direct implication of microorganisms in the reduction of uranium is of considerable interest because of its potential application in bio remediating of contaminated sites, in pretreating radioactive wastes, bioleaching is becoming a promising technology.

*Heavy Metals - Their Environmental Impacts and Mitigation*
