Life cycle assessment of prospective sewage sludge treatment paths in Germany

Life cycle assessment (LCA) on total sewage sludge treatment systems including thickening, anaerobic digestion, dewatering, and incineration/melting was performed to estimate a global warming impact as carbon dioxide (CO2) emission. As representative processes for the assessment, the most typical and widely used processes were selected. Generally, the life cycle of actual treatment facilities consists of three stages: construction, operation and dismantlement. In this study, the amount of CO2 produced from the life cycle steps of existing unit sludge treatment processes, was calculated by inventory analysis of input materials. In addition, for all processes investigated, individual CO2 emission units (CEUs), i.e. the amount of emitted CO2 for treating a unit weight of sludge, were also calculated. Byusing the obtained CEU matrix, it was possible to simulate the CO2 production from various types of complex treatment systems as well as to trace the dominant cause of CO2 production in individual treatment processes.

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LIFE CYCLE ASSESSMENT OF GREENHOUSE GAS EMISSIONS REDUCTION BY TECHNOLOGY CHOICE AND PLANT REPLACEMENT IN SEWAGE SLUDGE TREATMENT PROCESS

Journal of Japan Society of Civil Engineers Ser G (Environmental Research) ◽

10.2208/jscejer.68.i_137 ◽

2012 ◽

Vol 68 (5) ◽

pp. I_137-I_146

Author(s):

Yugo YAMAMOTO ◽

Satoru KONOMA ◽

Noboru YOSHIDA ◽

Tohru MORIOKA

Keyword(s):

Life Cycle Assessment ◽

Life Cycle ◽

Sewage Sludge ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Treatment Process ◽

Emissions Reduction ◽

Technology Choice ◽

Sludge Treatment ◽

Sewage Sludge Treatment

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An environmental LCA of alternative scenarios of urban sewage sludge treatment and disposal

Thermal Science ◽

10.2298/tsci0703153t ◽

2007 ◽

Vol 11 (3) ◽

pp. 153-164 ◽

Cited By ~ 27

Author(s):

Mario Tarantini ◽

Patrizia Buttol ◽

Lorenzo Maiorino

Keyword(s):

Life Cycle Assessment ◽

Life Cycle ◽

Anaerobic Digestion ◽

Sewage Sludge ◽

Sludge Management ◽

Sludge Treatment ◽

Urban Sewage ◽

Sewage Sludge Treatment ◽

Urban Sewage Sludge ◽

Treatment And Disposal

The majority of pollutants that affect wastewater are concentrated by treatment processes in sludge; it is therefore critical to have a suitable evaluation methodology of sludge management options to analyze if pollution is redirected from water to other media, such as air and soil. Life cycle assessment is one of the most widely known and internationally accepted methodologies to compare environmental impacts of processes and systems and to evaluate their sustainability in the entire life cycle. In this study the methodology was applied to assess and compare three scenarios of urban sewage sludge treatment and disposal: sludge anaerobic digestion followed by dedicated incineration, sludge incineration without previous digestion, and sludge anaerobic digestion followed by composting. The potential benefits of spreading the compost to soil were not included in the system boundaries even if, due to its nutrients contents and soil improving features, compost could partially replace the use of commercial products. The study was aimed at finding out the environmental critical points of the treatment alternatives selected and at providing a technical and scientific contribution for further debates with national and local authorities on the environmental optimization of sewage sludge management. Life cycle assessment results confirmed the major contribution of electricity and methane consumption on several environmental impact categories. Incineration contributes more than sludge composting to almost all categories, although the heavy metals content of urban wastewater sludge raises substantial concerns when composted sludge is spread to soil. In this paper the models adopted, the hypotheses assumed and the main findings of the study are presented and discussed. .

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