Technical, economic and environmental benchmarking of advanced sludge processing routes

The legislative framework in force in Europe requires the achievement of restrictive effluent standards for sensitive areas, and quite severe restrictions of properties of residual sewage sludge, both for landfill disposal and for agricultural use. Several technologies and management strategies have been proposed and applied in wastewater treatment plants to minimize sludge production and contamination. However, their techno-economic and environmental feasibility has to be carefully evaluated. The ROUTES project, funded within the EU 7th framework programme, aims to find new routes (hence the project name) for wastewater treatment and sludge management and so guiding the EU members in their future choices. Within this project, the authors have developed and applied a procedure for technical-economic-environmental assessment of new sludge processing lines in comparison to reference cases. The reference cases are model conventional plants that experience different types of problems and the new cases are modified such plants in which different innovative technologies have been added to solve these problems. The procedure involves a rating of selected technical issues (e.g. system reliability, complexity, safety aspects, modularity, etcetera), and estimates of capital and operating costs, as well as environmental impacts from a life cycle perspective. This paper reports on the procedure and some results.