The main advantage of SBRs is that they can accommodate large fluctuations in the incoming wastewater flow and composition without failing. The same may not be true in conventional activated -sludge processes, in which an increase in the incoming flow rate results in a lower residence time of the wastewater in the aeration tank and of the sludge in the clarifier, with potential failure of one of them or both addition, toxic shocks or significant changes in organic loading may produce alteration in the makeup of microbial populations of conventional activated-sludge processes, with consequent bulking or process failure. Instead, the wastewater residence time in SBRs can be extended until the microbial population has recovered and completed the degradation process. Similarly, the settling time can be varied to allow complete settling before discharging. In other terms, SBR processes, like all batch processes, are more flexible. On the other hand, the use of SBRs to treat a continuous wastewater flow requires the simultaneous use of multiple reactors and/or the presence of holding facilities to store the wastewater until an S becomes available. SBRs have been used also in denitrifying application [23.24