A benchmark study of controlled emptying of equalization basins

In English Storm tanks, or equalization basins, have been used for many years in sewer or wastewater treatment systems to reduce the amount of combined sewer overflows. In this paper, a systematic control of an equalization basin is used not only to dampen or reduce the hydraulic load, but also to systematically improve the effluent quality in a nitrogen removal plant. It is demonstrated that the effluent ammonia concentration is the key component. The Benchmark Simulation Model 1, implemented in MATLAB/Simulink, has been used to perform the evaluations. It has been extended with systematic rainfall generations. Intuitively, it is apparent that the equalization basin should be emptied before a rainfall. This requires a prediction capacity. It is shown that the choice of prediction time is by no means trivial and it is not true that a long prediction horizon is a,ways advantageous.