Techno-Economic and Environmental Assessment of Upgrading Alternatives for Sludge Stabilization in Municipal Wastewater Treatment Plants
Journal article, 2015

In this work we have performed a feasibility study of two upgrading alternatives for sewage sludge stabilization aimed to the reduction of the produced sludge and to the improvement of its qualitative characteristics with respect to its final destination: agricultural use or incineration. The first upgrading (1) proposes the separated thickening: primary sludge is thickened by gravity while dynamic thickening is applied to secondary sludge. The second upgrading (2) introduces a post-aerobic digestion stage (after the anaerobic one), in addition to separate thickening. Technical-economic and environmental assessments have been performed in comparison to a conventional wastewater treatment plant, which operates with gravity thickening and anaerobic digestion of mixed sludge. In the post-aerobic stage, operated with intermittent aeration, additional volatile solids removal of 45% and nitrification and denitrification efficiencies of 97% and 70%, respectively, were achieved. Both upgrading alternatives gained a positive technical evaluation with the only exceptions of the item "Thermal energy consumption" in upgrading 1 for agricultural reuse, and, to a minor extent, the "Energy available for external recovery" for incineration in both upgrading options. Cost analysis showed that the two upgrading alternatives are generally cheaper than the conventional plant, even if the results are dependent on local conditions, which have to be considered. Results of the environmental assessment showed that the upgrades with incineration perform better than the reference for all impact categories except freshwater eutrophication, with upgrading 2 as the best option. For the agricultural use, different results were obtained for the different impact categories with critical aspects mainly related to phosphorus and ammonia emissions for upgrading

Sludge stabilization

Techno-economic assessment

Environmental assessment

Decision support system

Wastewater treatment plant upgrading

Life cycle assessment


Maria Concetta Tomei

Giorgio Bertanza

Matteo Canato

Sara Heimersson

Chalmers, Chemical and Biological Engineering, Chemical Environmental Science

Giuseppe Laera

Magdalena Svanström

Chalmers, Chemical and Biological Engineering, Chemical Environmental Science

Journal of Cleaner Production

0959-6526 (ISSN)

Vol. 112 4 3106-3115

Driving Forces

Sustainable development

Areas of Advance

Building Futures (2010-2018)

Subject Categories

Water Engineering

Other Environmental Engineering



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