A model to control intermittent aeration phases

Abstract

Dealing with intermittent aeration as a useful practice to improve nitrogen removal efficiency of activated sludge plants, the possibility to plan optimal temporisation during daytime was investigated. A mathematical model (NIDEN) that allows us to manage different situations, with respect to influent load, environmental conditions and operating strategy, was then developed. The model represents a useful tool especially to plan the aeration cycles in small and medium sized plants, where high costs of automatic control through on-line instrumentation might not be justified. Once the input variables have been defined and the set-point values for tank nutrient concentration have been fixed, NIDEN gives an optimal phase temporisation, to obtain either the maximum energy saving or the best total nitrogen removal.

Intermittent Aeration in a Hybrid Moving Bed Biofilm Reactor for Carbon and Nutrient Biological Removal

“…In Figure 1 the layout of pilot plant is shown. the aerobic phase, and to reduce nitrate concentration during the anoxic phase in order to maximize total nitrogen removal efficiency [4,5]. Although intermittent aeration can guarantee good quality effluent, there are some disadvantages: it is very difficult to manage correctly it on the existing process or to improve it since most processes target the oxidation ditch and need facilities related to selector, final clarifier and return of sludge and treated water [6].…”

“…Among the new strategies, the intermittent aeration can be an optimal solution. More specifically, the intermittent aeration is the reduction of the aeration time of the biological reactor by introducing periods without oxygen supply for the denitrification process [4]. In such a way, aerobic and anoxic phases are periodically alternated simply through the tuning of aeration system (i.e., fixed control of phase duration).…”

“…In such a way, aerobic and anoxic phases are periodically alternated simply through the tuning of aeration system (i.e., fixed control of phase duration). In particular, the control strategy is addressed to complete nitrification in the aerobic phase, and to reduce nitrate concentration during the anoxic phase in order to maximize total nitrogen removal efficiency [4,5].…”