Hybrid Life-Cycle Environmental and Cost Inventory of Sewage Sludge Treatment and End-Use Scenarios: A Case Study from China

Abstract

Sewage sludge management poses environmental, economic, and political challenges for wastewater treatment plants and municipalities around the globe. To facilitate more informed and sustainable decision making, this study used life-cycle inventory (LCI) to expand upon previous process-based LCIs of sewage sludge treatment technologies. Additionally, the study evaluated an array of productive end-use options for treated sewage sludge, such as fertilizer and as an input into construction materials, to determine how the sustainability of traditional manufacturing processes changes with sludge as a replacement for other raw inputs. The inclusion of the life-cycle of necessary inputs (such as lime) used in sludge treatment significantly impacts the sustainability profiles of different treatment and enduse schemes. Overall, anaerobic digestion is generally the optimal treatment technology whereas incineration, particularly if coal-fired, is the most environmentally and economically costly. With respect to sludge end use, offsets are greatest for the use of sludge as fertilizer, but all of the productive uses of sludge can improve the sustainability of conventional manufacturing practices. The results are intended to help inform and guide decisions about sludge handling for existing wastewater treatment plants and those that are still in the planning phase in cities around the world. Although additional factors must be considered when selecting a sludge treatment and end-use scheme, this study highlights how a systems approach to planning can contribute significantly to improving overall environmental sustainability.

Environmental implications of increasingly stringent sewage discharge standards in municipal wastewater treatment plants: case study of a cool area of China

“…Rather than anaerobic digestion, the common means of sludge disposal in China is dewatering followed by landfill. According to a previous literature, landfill represents a worse sewage sludge treatment and end-use scenario than anaerobic digestion or reuse for fertilizer and cement manufacture (Murray et al, 2008). In Scenario 1A, sludge contributes 28% to global warming potential, 21% to photochemical oxidant formation, and 2e6% to other aspects when calculated on the basis of appropriate management.…”

Bacterial communities and their association with the bio-drying of sewage sludge

“…Thus, the moisture content should be reduced to an appropriate level for the subsequent disposal, and this should become a principal part of SS treatment (Huang et al, 2014). SS management in which dewatering plays a significant part accounts for between 49 and 53% of the total operating costs (Murray et al, 2008;Hospido et al, 2010), and improper treatment may lead to repollution because of the large amounts of pollutants in SS (VerBerkmoes et al, 2009;Poulsen and Bester, 2010). Consequently, drying SS poses economic and environmental challenges for WWTPs and municipalities around the globe (Raynaud et al, 2012;Jin et al, 2014).…”

Holistic sludge management through ozonation: A critical review

“…Using the life-cycle inventory of sludge treatment and disposal reported by Murray et al, (2008), it can be inferred that the annual ozonation cost in the study of Romero et al, (2015) could be easily offset by savings in sludge dewatering alone. Further savings can be attained through reductions in sludge drying, digestion, transportation, and other downstream processes.…”