Field-based methods for measuring greenhouse gases emissions from on-site sanitation systems: A systematic review of published literature

Prativa Poudel; Anish Ghimire; Guy Howard; Barbara Evans; Miller A Camargo-Valero; Freya Mills; Olivia Reddy; Subodh Sharma; Sarana Tuladhar; Abraham Geremew; Kenan Okurut; Baba Ngom; Manish Baidya; Sheila Dangol

doi:10.1016/j.heliyon.2023.e19947

Field-based methods for measuring greenhouse gases emissions from on-site sanitation systems: A systematic review of published literature

Heliyon. 2023 Sep 7;9(9):e19947. doi: 10.1016/j.heliyon.2023.e19947. eCollection 2023 Sep.

Authors

Prativa Poudel^{1

2}, Anish Ghimire¹, Guy Howard³, Barbara Evans⁴, Miller A Camargo-Valero^{5

6}, Freya Mills⁷, Olivia Reddy³, Subodh Sharma^{1

2}, Sarana Tuladhar^{1

2}, Abraham Geremew⁸, Kenan Okurut⁹, Baba Ngom¹⁰, Manish Baidya², Sheila Dangol²

Affiliations

¹ Department of Environment Science and Engineering, Kathmandu University, Nepal.
² Aquatic Ecology Centre, School of Science, Kathmandu University, Nepal.
³ Department of Civil Engineering and Cabot Institute for the Environment, University of Bristol, Bristol BS8 1TR, UK.
⁴ WASH Research Group, School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK.
⁵ BioResource Systems Research Group, School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK.
⁶ Departamento de Ingeniería Química, Universidad Nacional de Colombia, Campus La Nubia, Manizales, Colombia.
⁷ Institute for Sustainable Futures, University of Technology Sydney, 235 Jones St, Ultimo, NSW, 2007, Australia.
⁸ College of Health and Medical Sciences, Haramaya University, Dire Dawa, Ethiopia.
⁹ Department of Civil and Environmental Engineering, Kyambogo University, Kampala, Uganda.
¹⁰ Laboratoire Sciences et Techniques de l'Eau et de l'Environnement (LASTEE), Ecole Polytechnique de Thies (EPT), Thies, Senegal.

Abstract

On-site sanitation systems (OSS) are a source of greenhouse gas (GHG) emissions. Although efforts have been made recently to measure and quantify emissions from septic tanks using various field-based methods, the vast majority of published literature reporting GHG emissions from OSS units (e.g., pits and tanks) is based on non-empirical evidence. This systematic review presents an overview and limitations of field-based methods used for the quantification of GHG emissions from OSS. Papers published in English were searched in three databases: Google Scholar, PubMed, and Directory of Articles and Journals. Peer-reviewed papers that reported field-based methods applied to containment units in OSS were included in this study. Only eight out of 2085 papers met the inclusion criteria with septic tanks as the sole technology reported and were thus, considered for the review. Most of the studies have been conducted in middle- and high-income countries. Field-based measurements of GHGs are conducted using a flux chamber (FC) and the most commonly used FC methods are (a) the modified simple static FC, (b) automated static FC, and (c) floating FC. Data reported in published studies do not provide sufficient information on the calibration and validation of the results from the FCs used. The complex FC designs, laborious fieldwork operations, and reliance on expensive, specialist equipment, suggest that such methods may not be suitable in Low and Middle-Income countries (LMICs), where resources and access to laboratory facilities are limited. Also, the complexity of pits and tank typology in LMICs (i.e., unstandardised designs and sizes) may be a challenge to the use of FCs with fixed dimensions and set operational conditions. The variation in the quantification methods and resulting emission rates among the studies indicates that gaps prevail in the use of existing methods. Therefore, there is still a need for a simple field-based, easily adaptable FC method with adequate calibration and validation that can help in reliably quantifying the emissions from different OSS in any LMICs.

Keywords: Greenhouse gas emissions; Onsite sanitation; Pit latrines; Septic tanks.

Publication types

Review