Global Methane Emissions from Pit Latrines

Abstract

Pit latrines are an important form of decentralized wastewater management, providing hygienic and low-cost sanitation for approximately one-quarter of the global population. Latrines are also major sources of the greenhouse gas methane (CH4) from the anaerobic decomposition of organic matter in pits. In this study, we develop a spatially explicit approach to account for local hydrological control over the anaerobic condition of latrines and use this analysis to derive a set of country-specific emissions factors and to estimate global pit latrine CH4 emissions. Between 2000 and 2015 we project global emissions to fall from 5.2 to 3.8 Tg y(-1), or from ∼ 2% to ∼ 1% of global anthropogenic CH4 emissions, due largely to urbanization in China. Two and a half billion people still lack improved sanitation services, however, and progress toward universal access to improved sanitation will likely drive future growth in pit latrine emissions. We discuss modeling results in the context of sustainable water, sanitation, and hygiene development and consider appropriate technologies to ensure hygienic sanitation while limiting CH4 emissions. We show that low-CH4 on-site alternatives like composting toilets may be price competitive with other CH4 mitigation measures in organic waste sectors, with marginal abatement costs ranging from 57 to 944 $/ton carbon dioxide equivalents (CO2e) in Africa and 46 to 97 $/ton CO2e in Asia.

Taking Container-Based Sanitation to Scale: Opportunities and Challenges

“…Sanitation is a significant contributor of greenhouse gas emissions (GHG), producing ∼2-6% of global anthropogenic methane (Saunois et al, 2016). As urban populations grow, the use of rudimentary sanitation systems like pit latrines, septic tanks, and waste settling ponds will increase sanitation-related GHG emissions, potentially undermining efforts to slow climate change (Reid et al, 2014;Ryals et al, 2019). Thus, increased access to sanitation could be linked to increased GHG emissions, unless the prevailing sanitation paradigm shifts to climatepositive sanitation solutions.…”

Short-lived climate pollutant mitigation and the Sustainable Development Goals

“…For example, in areas where sewerage and waste water treatment infrastructure is already in place, upgrading secondary/tertiary sewerage and waste treatment to collect and utilize methane can support Target 6.3 to halve the proportion of untreated wastewater. Using composting toilets may produce much lower methane emissions than pit latrines and can be economically competitive with other methane measures in organic waste sectors 24 .…”

Sustainable sanitation, improved use of composting latrines through mixing and moisturizing: case study in Paraguay

“…There are issues related to the use (Clasen et al 2012), acceptance (Nayono et al 2010), and diffusion (Jenkins and Cairncross 2010) of latrines in developing countries, influence of latrines on water quality in sandy aquifers (Knappett et al 2012), degree of improvement realized (Exley et al 2015), methane (Reid et al 2014), and volatile compound (Lin et al 2013) emissions, microbial fuel cells for latrines (Castro et al 2014), and the spread of fecal matter from latrine floors (Pickering et al 2012) that are also important, but beyond the scope of this work.…”