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

Abstract

This study investigated the application of a dynamic control strategy in an aerobic granular sludge (AGS) reactor treating real variable brewery/bottling wastewater. For 482 days, the anaerobic and aerobic reaction steps in a lab-scale AGS system were controlled dynamically. A pH-based control was used for the anaerobic step, and an oxygen uptake rate (OUR) based control for the aerobic step. Additionally, the effect of an elongated aerobic step, and the effect of the removal of the suspended solids from the influent, on AGS formation were also investigated. In comparison to a static operation, the dynamic operation resulted in similar reactor performance, related to effluent quality and the anaerobic dissolved organic carbon (DOC) uptake efficiency, while the organic loading rate was significantly higher. The removal of suspended solids from the influent by chemical coagulation with FeCl3 turned hybrid floccular-granular sludge into fully granular sludge. The granulation coincided with a significant increase in the abundance of the glycogen-accumulating Candidatus Competibacter and an increase in the content of gel-forming EPS to respectively around 14% and 30%. In conclusion, this study showed the successful application of a dynamic control strategy based on common and low-cost sensors for AGS treatment of industrial wastewater.

Granulation strategies applied to industrial wastewater treatment: from lab to full-scale

“…In the presented full-scale study, the sludge loading rate during the feeding phase, and the associated substrate build-up, may be increased by shortening the feeding time, within the practical limitations of the existing pumps, and taking the impact of feeding acidic wastewater into account. Finally, the absence of a hydraulic selection pressure prevents the selective washout of the floccular sludge fraction, resulting in a hybrid sludge consisting of both floccular and granular structures (Stes et al 2020;De Vleeschauwer et al 2021). Further research should explore these hypotheses in more detail, to optimize the granulation in the full-scale treatment plant.…”

“…Previous research shows that the presence of suspended solids, e.g. due to a failing DAF, could prevent or be detrimental for (full) granulation (de Kreuk et al 2010;Martins et al 2011;De Vleeschauwer et al 2021). Also leaking of soluble, potentially rapidly degradable, COD into the aerobic phase likewise hinders granulation, especially if aeration is insufficient (Pronk et al 2015b;Haaksman et al 2020).…”

“…Regarding industrial wastewater treatment by AGS, most lab studies report the application of a pulse feed of wastewater to build up substrate during the first minutes of a cycle, followed by prolonged anaerobic mixing phase to promote PAO/GAO metabolism (e.g. Caluwé et al 2017;Stes et al 2019;De Vleeschauwer et al 2021).…”

“…feeding the influent in a few minutes time, like is often done in lab-scale studies (e.g. De Vleeschauwer et al 2021), is, to the best of our knowledge, not technically feasible at full-scale. Conversion of existing full-scale installations to Nereda ® type reactors with an upflow batch feeding regime, on the other hand, can be done, but at a significant investment cost.…”

Continuous-Flow Aerobic Granular Sludge Treatment of Dairy Wastewater

“…PAO and GAO are fundamental in forming dense and stable granules, and anaerobic feeding encourages their proliferation [31,32]. Thus, when the aim is to develop strong and compact aerobic granules, anaerobic feeding is the most common strategy [18,[33][34][35][36][37][38].…”