Recently, as environmental regulation for the removal of nutrients and excess sludge produced through wastewater treatment has become more restricted, many wastewater treatment plants face serious challenges in terms of waste production. Nowadays, the issue of excess sludge production has received considerable critical attention. Recent developments in sludge treatment technologies have heightened the need for more promising strategies to reduce sludge levels in a cost-effective and environmentally friendly manner. The purpose of this paper is to review recent research into the oxic-settling-anaerobic/anoxic (OSA) technology for sludge minimization. The OSA process is a modification of a conventional activated sludge system with the addition of interchange bioreactor parallel to recycled activated sludge line. The OSA process seems to be a revolutionary and cost-effective alternative for sludge reduction approach in the future. It is hoped that this research will contribute to a deeper understanding of the OSA process in terms of sludge reduction efficiency, carbon and nutrient removal, operational parameters, possible reduction mechanisms and microbial community changes after the implementation of the OSA system and applied in the treatment of real wastewater at full-scale.