The reject water produced in the organic waste anaerobic digestion is not only has high content of COD, NH4-N and SS, but also contains organic matter that is difficult to biodegrade such as oil, and needs complex treatment process to meet the discharge requirements. After years of exploration and practice, PURAC has developed the SDN-N process on the basis of the SBR process, which realizes the functions of synchronous nitrification (N) and denitrification (DN), and combines with the MTS jet aeration system to ensure good treatment effect. After SDN-N treatment process combined with different advanced treatment technologies such as clarification, ultrafiltration, or nanofiltration, the effluent can meet the wastewater quality standards for discharge to municipal sewers, or other stricter discharge standards. The advantages of SDN-N process are simple system, less maintenance and low operation costs, which is especially suitable for the treatment of reject water from organic waste anaerobic digestion, and wastewater with high COD and high nitrogen.