Greenhouse gas emissions and acceptance of container-based sanitation system in East African cities: a case of Nairobi and Kampala

Abstract

The release of methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) from sanitation systems contributes about 3% of the global greenhouse gases (GHGs). This is a very significant value looking at the direct influence of the GHGs on climate change. These emissions cause conflicts between the sustainable development goals (SDGs) of SDG 13 and SDG 6.2. Container-based sanitation (CBS) systems are considered to emit fewer GHGs than other on-site sanitation systems. This study quantified on-site, the GHGs emitted from the containment of the CBS system in Nairobi, Kenya. The resulting GHGs emitted were then compared to the quantity estimated using the Intergovernmental Panel on Climate Change (IPCC) methodology. Given the anticipated low emission and other opportunities like resource recovery, and less water usage of this new CBS system, the level of acceptability of the system was determined in Kampala, Uganda since it has never been operated in Uganda. Measurements of GHGs (CH4, CO2 and N2O) at the containment of the CBS system in 10 days revealed a total of 44.59 kg CO2 eq/capita/year was being generated from faecal matter. This study did not include emissions from urine and did not characterize the faecal matter. In a comparison of the GHGs obtained from on-site measurement (15.72 kg CO2 eq/capita/year) excluding CO2 with IPCC estimated, it was found that the IPCC methodology (37.3 kg CO2 eq/capita/year) overestimated the quantity of GHGs by over two times. The result from the survey on acceptability administered using Google questionnaires to key informants and household questionnaires in Bwaise II, Kampala revealed a high level of acceptability of 84%. Generally, more field measurements should be carried out to achieve a more accurate estimation of the GHGs from the CBS system. Setting a pilot scheme of the CBS system before promoting the CBS system to scale in Kampala, Uganda may improve the level of acceptability.