Methane fugitive emissions from domestic wastewater storage tanks | |
| Author | Bayasgalan, Ariunzul |
| Call Number | AIT Thesis no.EV-25-19 |
| Subject(s) | Climate change Sewage disposal |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Emissions of methane (CH₄) and nitrous oxide (N₂O) from domestic wastewater are increasing in response to growing urbanization and population pressures. These greenhouse gases (GHGs) are generated through various biological processes, particularly methanogenesis and fermentation, and can be released at multiple stages throughout the collection, transport, and treatment of wastewater within a sewer system contributing to the climate change. The study investigated passive fugitive methane (CH₄) emissions from domestic wastewater storage tanks at the Asian Institute of Technology (AIT), focusing on emissions from wet wells and their relationship with wastewater quality parameters from two sites called primary wastewater storage tank and a secondary wastewater storage tank located near ST6,7 & 8 wet well and near the Physical Plant called the Main sump pump respectively. Primary and Secondary storage tank provided a stable carbon input scenario of a total methane flux of 0.964 g CH4/m2.day and 0.4482 g CH4/m2.day and yielded a first-rate estimate of annual methane flux of 351.86 g CH4/m2.year (9.5 kgCO2eq./m2 .year) and 175.93 g CH4/m2.year (4.75 kg CO2eq./m2.year) respectively. Fugitive methane emissions were monitored over 24-hour intervals within 216 hours resulting in a CH4 emission mean of 127.6 ± 11.4 ppm from primary tank and 63.7 6 ± 75.6 ppm. The primary wastewater storage tank presented a significantly strong negative correlation of CH4 with both Total Suspended Solids (TSS) and Total Phosphorous (TP) giving speculation of advanced anaerobic decomposition present. Secondary wastewater storage tanks showed CH4 to have significant positive correlation between Total Solids (TS) and TP in addition to a negative moderate correlation with pH. The study concludes that although methane emissions from the storage tanks are not explosive, they represent a noteworthy contribution to greenhouse gas outputs. Recommendations to manage GHG emission include physical and chemical interventions such as urine separation to chemically dose later, promote active mixing to prevent stratification by placing baffles strategically using the fluid dynamic and pumps vortices, and improve tank hatch/vent to reduce emissions. Further microbiological and infrastructural research studies are suggested to identify methanogenic hotspots and explore methane mitigation strategies, including nitrate and ammonia dosing under controlled pH and redox conditions. |
| Year | 2025 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Water Resources and Environmental Engineering (DWREE) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Cruz, Simon Guerrero; |
| Examination Committee(s) | Xue, Wenchao;Ekbordin Winijkul; |
| Scholarship Donor(s) | Thai Pipe Scholarship;AIT Scholarship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2025 |