The impact of hydraulic retention time on the performance of two configurations of anaerobic pond for municipal sewage treatment

Cruddas, P.H., Asproulis, N., Antoniadis, A., Best, D., Collins, G., Porca, E., Jefferson, B., Cartmell, E. and McAdam, E.J. (2022) The impact of hydraulic retention time on the performance of two configurations of anaerobic pond for municipal sewage treatment. Environmental Technology, 43(25), pp. 3905-3918. (doi: 10.1080/09593330.2021.1937331) (PMID:34057403)

Abstract

Anaerobic ponds have the potential to contribute to low carbon wastewater treatment, however are currently restricted by long hydraulic residence time (HRT) which leads to large land requirements. A two-stage anaerobic pond (SAP) design was trialled against a single-stage control (CAP) over four HRTs down to 0.5 days, to determine the lowest HRT at which the ponds could operate effectively. No statistical differences were observed in particulate removal between the ponds over all four HRTs, suggesting solids loading is not a critical factor in AP design. Significantly higher biogas production rates were observed in the SAP than the CAP at 1.5 d and 1.0 d HRT, and microbial community profiling suggests the two-stage design may be facilitating spatial separation of the anaerobic digestion process along reactor length. Hydrogenotrophic methanogensis dominated over aceticlastic, with acetate oxidisation a likely degradation pathway. Experimental tracer studies were compared to CFD simulations, with the SAP showing greater hydraulic efficiency, and differences more pronounced at shorter HRTs. Greater flow recirculation between baffles was observed in CFD velocity profiles, demonstrating baffles can dissipate preferential flow patterns and increase effective pond volume, especially at high flow rates. The study demonstrates the potential of APs to be operated at shorter HRTs in psychrophilic conditions, presenting an opportunity for use as pre-treatments (in place of septic tanks) and primary treatment for full wastewater flows. Two-stage designs should be investigated to separate the stages of the anaerobic digestion process by creating preferential conditions along the pond length.

• Item Type: Articles
• Additional Information: This work was supported by European Research Council Starting Grant [3C-BIOTECH 261330].
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Collins, Dr Gavin
• Authors: Cruddas, P.H., Asproulis, N., Antoniadis, A., Best, D., Collins, G., Porca, E., Jefferson, B., Cartmell, E., and McAdam, E.J.
• College/School: College of Science and Engineering > School of Engineering
• Journal Name: Environmental Technology
• Publisher: Taylor & Francis
• ISSN: 0959-3330
• ISSN (Online): 1479-487X
• Published Online: 31 May 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Environmental Technology 43(25): 3905-3918
• Publisher Policy: Reproduced under a Creative Commons License