Eliciting expert judgements to underpin our understanding of faecal indicator organism loss from septic tank systems

Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved..

Septic tank systems (STS) in rural catchments represent a potential source of microbial pollution to watercourses; however, data concerning the risk of faecal indicator organism (FIO) export from STS to surface waters are scarce. In the absence of empirical data, elicitation of expert judgements can provide an alternative approach to aid understanding of FIO pollution risk from STS. Our study employed a structured elicitation process using the Sheffield Elicitation Framework to obtain expert judgements on the proportion of FIOs likely to be delivered from STS to watercourses, based on 36 scenarios combining: (i) septic tank effluent movement risk, driven by soil hydro-morphological characteristics; (ii) distance of septic tank to watercourse; and (iii) degree of slope. Experts used the tertile method to elicit a range of values representing their beliefs of the proportion of FIOs likely to be delivered to a watercourse for each scenario. The experts judged that 93 % of FIOs would likely be delivered from an STS to a watercourse under the highest risk scenario that combined (i) very high STS effluent movement risk, (ii) STS distance to watercourse <10 m, and (iii) a location on a steep slope with gradient >25 %. Under the lowest risk scenario, the proportion of FIOs reaching a watercourse would likely reduce to 5 %. Expert confidence was high for scenarios that represented extremes of risk, while uncertainty increased for scenarios depicting intermediate risk conditions. The behavioural aggregation process employed to obtain a consensus among the experts proved to be useful for highlighting both areas of strong consensus and high uncertainty. The latter therefore represent priorities for future empirical research to further improve our understanding of potential pollution risk from septic tanks and in turn enable better assessments of potential threats to water quality in rural catchments throughout the world where decentralised wastewater systems are common.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:921

Enthalten in:

The Science of the total environment - 921(2024) vom: 15. März, Seite 171074

Sprache:

Englisch

Beteiligte Personen:

Mzyece, Chisha Chongo [VerfasserIn]
Glendell, Miriam [VerfasserIn]
Gagkas, Zisis [VerfasserIn]
Quilliam, Richard S [VerfasserIn]
Jones, Ian [VerfasserIn]
Pagaling, Eulyn [VerfasserIn]
Akoumianaki, Ioanna [VerfasserIn]
Newman, Claire [VerfasserIn]
Oliver, David M [VerfasserIn]

Links:

Volltext

Themen:

E. coli
Environmental pollution
Expert elicitation
Faecal bacteria
Hydrological connectivity
Journal Article
Sheffield Elicitation Framework
Water quality

Anmerkungen:

Date Completed 11.03.2024

Date Revised 11.03.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.scitotenv.2024.171074

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM368680835