The UNC Water & Health Conference Oct 2022, North Carolina
Olivia Reddy attended this event virtually, the picture below is her poster presentation on greenhouse gas emissions. Right click on the image and open in new tab to see detail.
Olivia’s Abstract on greenhouse gas emission
To view Olivia’s abstract in the Abstract Book, turn to page 133
A total end-to-end approach showcasing national greenhouse gas emission profiles from sanitation
Olivia Reddy, University of Bristol
Additional Authors: Eleanor Waring, James Mock, India Ross, Barbara Evans
This study attempts to improve the accuracy and reliability of the Nationally Determined Contributions (NDCs), regarding sanitation, using Nepal, Senegal, and Ethiopia as examples. Due to decomposing waste, sanitation is a significant source of emissions, the quantity of which depends on technologies and management practices. The current global estimates of greenhouse gas (GHG) emissions gloss over and ignore the intricacies of sanitation management, especially in low- and middle-income countries (LMICs). The limited pathways presented by the Intergovernmental Panel on Climate Change (IPCC) do not capture the mix of on- and off-site technologies, as well as imperfect management. Given the importance of cutting emissions, together with targets for methane reduction, providing better estimates of the contribution from sanitation, considering different management methods and technologies is essential for this sector. These countries were chosen as examples as they are likely to be making big investments in sanitation over the next 20-40 years.
Based on the current IPCC methods, this method carries out national audits to create probable profiles for each of the three selected countries. An end-to-end approach is used to determine contributions by each system type. Each element is assessed in terms of emissions impact from storage and collection through transportation to treatment. Using data from shit flow diagrams (SFD), the Joint Monitoring Programme (JMP), in-country partners, and other national and international sources, the total country emissions profile is determined by calculating the proportion of users for different conditions and types of sanitation systems along the sanitation management chain. Where official figures and data were not available (such as for emptying practices) and where data was limited, assumptions were made using existing literature and SFDs. Throughout the audit, different sanitation service chains at varying levels of urbanization were considered.
Overall, the total emissions for Nepal were 2.42 bn kg CO2e/year, and 1.73 bn kg CO2e/year for Senegal. Containment was shown to be the primary emitter, with figures from Senegal accounting for 1.2 bn kg CO2e/year. The main sources are latrines that are never emptied, and those which are submerged. These findings are mirrored in Nepal where 78% of the population use pour-flush toilets, the moisture resulting in higher CH4 emissions compared to standard pit latrines. Transportation contributes minimal amounts, with CO2 from emptying trucks in Nepal representing <1% of the total. Wastewater treatment in Senegal represents 6% of total emissions but an extra 140 kg CO2e/cap/year, indicating that as treatment plants develop, GHG emissions will increase. Results from Ethiopia are expected soon and are anticipated to support these findings.
This end-to-end approach takes into consideration the whole sanitation management chain. Splitting up sanitation types generates not only clearer information for NDCs but encourages people to truly evaluate every aspect involved. Exploring exactly how management works on multiple levels can act as a springboard for generating intervention pathways. Over the next few months, it is expected that this study will provide more details about potential ways of reducing emissions.
Abstract of Baba Ngom
To view the abstract of Baba Ngom, University Theis in the abstract book turn to page 95.
Investigating Temporal and spatial variability of GHG emissions from on-site sanitation systems in Senegal Baba Ngom, Ecole Polytechnique de Thies
Additional Authors: Mamadou Matar Dramé, Rose Dianga Tine, Olivia Reddy, Nathalie Andre, Guy Howard. Senegal is on the western coastline of Africa, bordering the Atlantic Ocean from 12 to 17 °N. It has a tropical climate with pleasant heat throughout the year with well-defined dry and humid seasons that result from northeast winter winds and southwest summer winds. The country experiences a dry season from November to May dominated by a northeastern wind pattern, and a wet season from June to October with a southwesterly wind pattern. rainfall increases substantially farther south, exceeding 1,500 mm (59.1 in) annually in some areas. As well as being susceptible to the impacts of precipitation and temperature changes caused by climate change, Senegal is vulnerable to sea level rise, groundwater level variability.
All these temporal and spatial changes may have great impact in greenhouse gas emissions from onsite sanitation systems. The proportion of these systems is significantly higher in low– and middle– income countries (LMICS) in comparison to the global average, for instance in Senegal it represents over 80% of used sanitation systems. The widespread use of on-site sanitation system provides one example showing the importance of deepening our understanding on factors influencing GHG productions in such sanitation facilities.
In this work we study impacts of climate (temperature) and geophysical characteristics on GHG emissions. 20 households were selected in two different Senegalese cities (Tivaouane and Kaolack), and an initial survey to collect data related to onsite sanitation system typology, design and management were conducted. After that, direct analysis of containment effluent and gas emissions were operated using flux chamber. These measurements were made in four different seasonal contexts: [1] Middle of the dry season (~ March), [2] end of the dry season (~ June), [3] middle of the rainy season (~ August), and [4] end of the rainy season (~ November). It is planned to choose 10 sanitation facilities located in low land and 10 others in high land.
The preliminary results showed that Senegalese households use almost similar design and management of sanitation systems. Interestingly, a high variability of gases compositions and emissions rate were recorded over time and space. This ongoing study will identify the main factors associated with GHG emissions from on-site sanitation systems. To our knowledge this study design is the first of its kind that is applied in western Africa to investigate the impacts of climate and geophysical characteristics on GHG emissions in on-site sanitation systems. The results of this study will be instrumental to better inform policy makers and program designers to reduce GHG emissions.