Estimation of greenhouse gas emissions from sewer pipeline system

• Published in: The international journal of life cycle assessment 2017-12, Vol.22 (12), p.1901-1911
• Main Authors: Kyung, Daeseung, Kim, Dongwook, Yi, Sora, Choi, Wonyong, Lee, Woojin
• Format: Article
• Language: English
• Subjects: Biofilms; Carbon Footprinting; Case studies; Cast iron; Concrete pipes; Earth and Environmental Science; Emissions; Environment; Environmental Chemistry; Environmental Economics; Environmental Engineering/Biotechnology; Estimating techniques; Greenhouse effect; Greenhouse gases; Hydraulic retention time; Life cycle analysis; Life cycle assessment; Life cycle engineering; Life cycles; Methane; Mitigation; Natural gas; Pipelines; Pipes; Polyethylene; Polyethylenes; Polyvinyl chloride; Rehabilitation; Retention time; Sensitivity analysis; Sewer gas
• ISSN: 0948-3349; 1614-7502
• DOI: 10.1007/s11367-017-1288-9

Purpose The aim of this study was to estimate the total greenhouse gas (GHG) emissions generated from whole life cycle stages of a sewer pipeline system and suggest the strategies to mitigate GHG emissions from the system. Methods The process-based life cycle assessment (LCA) with a city-scale inventory database of a sewer pipeline system was conducted. The GHG emissions (direct, indirect, and embodied) generated from a sewer pipeline system in Daejeon Metropolitan City (DMC), South Korea, were estimated for a case study. The potential improvement actions which can mitigate GHG emissions were evaluated through a scenario analysis based on a sensitivity analysis. Results and discussion The amount of GHG emissions varied with the size (150, 300, 450, 700, and 900 mm) and materials (polyvinyl chloride (PVC), polyethylene (PE), concrete, and cast iron) of the pipeline. Pipes with smaller diameter emitted less GHG, and the concrete pipe generated lower amount of GHG than pipes made from other materials. The case study demonstrated that the operation (OP) stage (3.67 × 10 4  t CO 2 eq year −1 , 64.9%) is the most significant for total GHG emissions (5.65 × 10 4  t CO 2 eq year −1 ) because a huge amount of CH 4 (3.51 × 10 4  t CO 2 eq year −1 ) can be generated at the stage due to biofilm reaction in the inner surface of pipeline. Mitigation of CH 4 emissions by reducing hydraulic retention time (HRT), optimizing surface area-to-volume (A/V) ratio of pipes, and lowering biofilm reaction during the OP stage could be effective ways to reduce total GHG emissions from the sewer pipeline system. For the rehabilitation of sewer pipeline system in DMC, the use of small diameter pipe, combination of pipe materials, and periodic maintenance activities are suggested as suitable strategies that could mitigate GHG emissions. Conclusions This study demonstrated the usability and appropriateness of the process-based LCA providing effective GHG mitigation strategies at a city-scale sewer pipeline system. The results obtained from this study could be applied to the development of comprehensive models which can precisely estimate all GHG emissions generated from sewer pipeline and other urban environmental systems.