A dynamic control system for aerobic granular sludge reactors treating high COD/P wastewater, using pH and DO sensors

A dynamically controlled anaerobic/aerobic granular sludge reactor efficiently treats brewery/bottling wastewater

“…Between days 156 and 383, the anaerobic and aerobic steps were controlled dynamically. The control strategy was based on the anaerobic pH profile treating acetate based synthetic wastewater with a COD of 1,250 mg•L À1 and low P content of 5 mg•L À1 , as described earlier (De Vleeschauwer et al 2020). The anaerobic step was terminated when the pH profile stopped increasing and started decreasing.…”

“…Using these data, the pH-based dynamic control was adjusted. The current strategy uses the same 4 calculation variables proposed by De Vleeschauwer et al (2020). CV 1 is the sample interval of the sensor value.…”

“…The pH increase in phase 1 can be related to the uptake of volatile fatty acids (VFA) (Figure 1). The pH has a strong tendency to increase during the anaerobic uptake of acetate by GAO, followed by a pH decrease coinciding with the depletion of the available VFA (Filipe et al 2001;De Vleeschauwer et al 2020). The pH and DOC keep on decreasing during phase 2.…”

“…The dynamic control of the acetate-fed AGS SBR, described by De Vleeschauwer et al (2020), was more straightforward than the brewery-fed AGS SBR. It was programmed to end the anaerobic step when a switch from a positive to a negative pH slope occurred coinciding with acetate depletion.…”

“…Kishida et al (2008) and De Vleeschauwer et al (2019) used a conductivity-based controlled anaerobic step in an enhanced biological phosphorus removal (EBPR) SBR fed with synthetic wastewater with a low COD/P ratio. For an anaerobic/aerobic AGS SBR treating synthetic wastewaters with a high COD/P ratio, De Vleeschauwer et al (2020) developed a dynamic control strategy based on the pH signal. In an AGS SBR system, the anaerobic step was automatically terminated when the pH profile slope changed from positive to negative, leading to near-complete anaerobic COD uptake by GAO.…”