The present report reviews the potential and applicability of industrial microbe side streams produced in Finnish bioprocess industries for biosorption of heavy metals from waste waters. Microbial side stream biomasses are formed worldwide in e.g. food, brewing, biofuel, pharmaceuticals, wood processing and enzyme manufacturing industries. Although these streams are typically used for low-valued animal feed or biogas production, they would also have potential for biosorbent materials to be used in in situ water treatment. Since major challenges have been recognized, especially regarding the availability of biomass, and to logistic and processing cost, biosorption is not the most economically attractive option for the use of these biomasses at the moment. However, in the future the situation may change due to new incentives or more cost-efficient biosorbent preparation technologies. This report will provide a knowledge basis for the consideration of biosorption applications for industrial microbe side streams.