H. Zhao et al., A NOVEL CONTROL STRATEGY FOR IMPROVED NITROGEN REMOVAL IN AN ALTERNATING ACTIVATED-SLUDGE PROCESS .2. CONTROL DEVELOPMENT, Water research, 28(3), 1994, pp. 535-542
The first part of this two part contribution dealt with an analysis of
nitrification and denitrification in an alternating activated sludge
nutrient removal process for the case of constant process conditions.
The existence of an optimal cycle length, which is a function of the p
rocess conditions, was demonstrated and discussed. Based on these find
ings, this paper examines a control strategy by which the cycle length
of an alternating activated sludge nutrient removal process is automa
tically adjusted in order to compensate for changing process condition
s. Two control algorithms are proposed. One involves proportional-inte
gral-derivative (PID) control which requires minimal process informati
on and computational effort. The second is a model based predictive co
ntrol (MBPC) technique, which introduces a feedforward element into th
e control strategy. The MBPC technique is examined using a relatively
simple process model. The results of experimental demonstrations of th
ese two algorithms in a pilot plant facility indicate their potential
towards improving nitrogen removal in the alternating process.