High rate bacterial catalyzed processes can serve to improve hydrometallurgical operations. These solutions are not only economical but also environmental sustainable. With references around the globe, the value of this new approach is recognized by industry worldwide. For instance, metals can safely and economically be separated from process and waste streams using biotechnologically produced sulfide, recovering a valuable metal sulfide product instead of a waste gypsum stream for disposal.
Both the natural biological sulfur and nitrogen cycles offer bioconversions that are applied on industrial scale. The shared advantage of these processes is that waste compounds are converted in either a reusable raw material or in a harmless product. This way, natural product cycles can be closed. Applications based upon bioconversions are for example:
Sulfur based: Bioleaching, reduction of oxidized sulfur compounds to elemental sulfur, metal recovery with biogenic produced H 2 S, SO 2 removal from gas streams, etc.
Nitrogen based: Ammonia removal using the anammox-process, biological removal of NOx from gas streams, nitrate removal from water streams, etc.
Metals: Bacterial processes for the reduction of metals such as uranium, selenium. And manganese have proven to offer great potential for clean-up of groundwater streams.
This paper contains a description of the above applications. Further, a short introduction on engineered high rate bioreactor systems and a description of industrial biotechnological applications will be provided.