Investigations of metabolic uncouplers in growth systems such as activated sludge treatment are increasing because of their ability to decrease biomass growth. As of 2011, more than 10 metabolic uncouplers were reported to significantly decrease biomass yield by between 21% and 87%. In this paper, we present a detailed review of metabolic uncoupling, different metabolic uncouplers, current applications in waste water treatment systems and their possible use in biological air pollution control systems such as biofiltration in order to improve the substrate degradation rate. This paper will be useful for those who are interested in using metabolic uncouplers to improve the performance of growth or non-growth systems.