Continuous flow reactors for cultivating aerobic granular sludge: configuration innovation, principle and research prospect

Abstract

Efficient start‐up, cultivation and maintenance of aerobic granular sludge (AGS) in continuous flow reactors (CFRs) is critical for its full‐scale application in wastewater treatment plants (WWTPs). The successful implementation of AGS under continuous flow condition depends on the configuration of CFR that provides the selective pressures and hydraulic shear force (HSF) to sludge required for rapid granulation. Important progress has been witnessed with respect to CFR configurations in recent decades for in‐situ granulation of aerobic sludge. This review summarized the difficulties of granulation during continuous flow, as well as the reactor configuration, granulation mechanism and the AGS characteristics, along with the future research prospects. It is of significance to promote the innovation of continuous flow configuration in order to realize the AGS application in mainstream WWTPs in the future. © 2021 Society of Chemical Industry (SCI).

Aerobic Granular Sludge: Perspectives for Excess Sludge Management and Resource Recovery

“…Kent et al [14], e.g., emphasized that the stable cultivation of compacted granules is critical for operating an AGS-CFR unit; although it was also highlighted that the granulation process is still unstable under long-term operation in both SBR and CFR regimes [14]. Yan et al [12] pointed out that the risk of instability is higher in CFR mode. Current literature reports several factors that influence the granulation process in AGS system, known as ''selective pressures''.…”

“…The authors clarified that the longer SRT, the lower biomass yield rate. Yan et al [12] reported that the AGS systems work usually with a SRT two times longer than that in the CAS. This clarification meets the perspective of Bengtsson et al [8].…”

“…The CFR system has a higher capability to deal with changes in influent quality and shockloading conditions [14]. Therefore, the engineering community is paying more effort to establish the AGS technology in CFR systems, which is then referred to AGS-CFR [12,15]. Rosa-Masegosa et al [6] and Guo et al [16] reported that none of the documented lab-scale experiments has yet succeeded in upscaling the AGS-CFR system to fullscale conditions.…”

“…Rosa-Masegosa et al [6] and Guo et al [16] reported that none of the documented lab-scale experiments has yet succeeded in upscaling the AGS-CFR system to fullscale conditions. In the same sense, Yan et al [12] summarized that at least 70 % of AGS-CFR experiments utilized synthetic wastewater instead of real municipal wastewater influents. Guo et al [16] emphasized that the synthetic inflow has lower complex compounds and suspended solids than real municipal wastewater.…”

“…Additionally, running of the AGS concept at continuous flow mode (CFR) is a crucial application dilemma. Further to that, potential bio‐energy recovery and excess sludge management are still not clearly formulated at the AGS scope 11, 12. Świątczak and Cydzik‐Kwiatkowska 13 emphasized that uncovering of these aspects can lead to significant problems on the long‐term, which could threaten the technology sustainability consequently.…”