Environmental life cycle analysis of pipe materials for sewer systems

Abstract

Wastewater system performance continues to be a matter of utmost importance to the development of sustainable communities today. Over the past few decades, we have seen dramatic increases in urbanization that has substantially added to an already-enhanced need for improvement of wastewater infrastructure systems. Traditionally studies on sewer system design have been focusing on maximizing the economic advantages, while limited work has been done on the analysis of environmental impacts of sewer systems made of different piping materials. In this paper, a comparative life cycle analysis (LCA) is performed for six different types of wastewater pipe materials: composite fiber reinforced polymer (FRP), PVC, high density polyethylene (HDPE), ductile iron, vitrified clay, and reinforced concrete. The functional unit is defined as one kilometer sewer infrastructure needed for a small city with population of 25,000 people for a period of 50 years. Considering various life cycle stages, environmental impacts were quantified and compared for all pipe materials in two types of sewer systems i.e. pure gravity sewer and sewer with lifting stations. The results indicate that the manufacturing stage in pure gravity sewer systems has the maximum impact, while for sewer systems with lifting use phase can have comparable or even higher impacts than manufacturing phase. Among the six pipe materials, ductile iron seems to be the worst option while reinforced concrete seems to be the best option. Results from the analysis may help current and future wastewater infrastructure designers and material manufacturers to understand and develop more sustainable sewer systems.