Cyanide bioremediation

Three cyanide-degrading nitrilases were recently cloned and purified and their kinetic profiles were evaluated in order to better understand their applicability to cyanide bioremediation. CynD from Bacilluspumilus Cl and DyngD from Pseudomonas stutzeri exhibit fairly broad pH profiles with >50% activity retained across pH 5.2 to pH 8.0 while the CHT (NHase) from Gloeocercospora sorghi exhibited a more alkaline pH activity profile with almost all of its activity retained at pH 8.5, slightly lower thermal tolerance, and quite different metal tolerance compared with the two bacterial enzymes [46]. 

Bioremediation is not effective in the removal of metals, cyanides, and some chlorinated compounds. High levels of some contaminants may inhibit biological activity in the treatment system. A treatability study is typically performed prior to initiation of a full-scale treatment system to determine the applicability of slnrry-phase bioremediation. If ambient temperatures are low, heating of the bioreactor may be required. 

Pintail Systems, Inc. s, spent-ore bioremediation technology includes two main treatment processes. The first process involves the biological treatment of cyanide wastes using indigenous bacteria, which are isolated from contaminated sites and cultured in large quantities for full-scale applications. The second process involves metal biomineralization in which biological processes are adapted to immobilize soluble and leachable metals. 

Full-scale demonstrations of Pintail Systems, Inc. s, spent-ore bioremediation process have been conducted at a number of mine sites in the United States. The first full-scale demonstration of the process for cyanide detoxification in a spent-ore heap was performed at the Yellow Pine Mine near Yellow Pine, Idaho, in 1992. In addition, the technology has been used at sites in Mexico and Canada. This technology and several similar bioremediation processes are commercially available through the vendor. Pintail Systems, Inc., is also working with Sub-Surface Waste Management, Inc. (a subsidiary of U.S. Microbes, Inc.), to further apply its bioremediation technologies in the United States, as well as in Europe and Asia. 

Chapatwala, K.D., Babu, G.R.V., Armstead, E.R., White, E.M., and Wolfram, J.H. 1995. A kinetic study on the bioremediation of sodium cyanide and acetonitrile by free and immobilized cells of Pseudomonas putida. Applied Biochemistry and Biotechnology, 51/52 717-26. 

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