ABSTRACT
Consideration of the Effects of Transient Loadings. The basic design given above considered a system that used equalization to dampen transient loadings. Quite frequently, however, facilities are designed without equalization, and consideration must be given to the impacts of typical diurnal loadings or other transients on the system. As discussed in Section 10.3.2, diurnal loadings have little impact on the mass of MLSS in the system because of the dampening effect of the SRT relative to the HRT. Consequently, the main consideration during design is on the oxygen requirement and the feasible bioreactor volumes while meeting the mixing energy and oxygen transfer constraints. Generally, the peak loading is most important because of its impact on the size of the oxygen transfer system and the potential for
floe shear. Little consideration is given to the minimum daily loading because of its short duration. If aeration rates are turned down to the lower limit on mixing energy during that period, and that provides more oxygen than is needed, the penalty in power costs will be small.
