Solving treatment of wastewater sewage sludge with new HTL technology to produce hydrocarbons, asphalts and fertilizers

PROJECT DESCRIPTION

BACKGROUND

In Europe, sewage sludge production reached 10.9 million tons in 2005 and is expected to exceed 13 million tons by the end of 2020. About 50% of this quantity is recovered directly for use in agriculture and the rest is disposed of in landfills or incinerators. However, the traditional disposal systems present many problems, including: unpleasant odours and the possible presence of heavy metals or organic pollutants in agricultural applications; CO2 emissions due to transportation and issues in the leachate in landfills; and high costs and opposition of citizens to incineration plants. Therefore, there is a need for environmentally-friendly alternatives to disposal, including creating innovative and economically-sustainable plants for the recovery of sewage sludge waste. Hydrothermal liquefaction (HTL) technology shows promise as a means of transforming municipal wastewater solids into feedstocks for biofuels and other industrially-useful materials.

OBJECTIVES

The objective of the LIFE FREEDOM project is to demonstrate at pilot-scale the technical and economic viability of hydrothermal liquefaction (HTL) technology for the treatment of sewage sludge. The aim is to use the new HTL technology to reduce the volume of waste sent to landfill and incineration, and to produce secondary raw materials of widespread industrial use, including asphalts for roads, binders for industrial applications, and fertilizers for agricultural use. The project beneficiaries will install HTL equipmentin an urban wastewater treatment facility in Cassano DAdda, in Milan (Italy), connecting the LIFE FREEDOM system directly to the purifier. A range of environmental benefits will also be evaluated.

By doing this, the project will contribute to the implementation of the following EU policies: Urban Waste Water Treatment Directive (1991/271/EEC), Sewage Sludge Directive (1986/278/EC), Landfill Directive (1999/31/EC), Water Framework Directive (2000/60/EC), and Closing the loop: An EU action plan for the Circular Economy.

RESULTS

Expected results:

Elimination of waste sewage sludge in the plant located in the Municipality of Cassano DAdda, thus avoiding the landfilling/incineration of about 4 000 tons per year of biological sewage sludge;

Sludge transport from the purifier plant to the disposal site will be avoided, with a saving of 13 160 kg of CO2 emissions per year due to fuel consumption;

A significant reduction of sludge management costs;

Instead of sludge disposal, the purifier is expected to produce from the treated sewage sludge, during the project lifetime, the following materials: -380 tons of hydrocarbons to be used in bituminous conglomerates for the production of 9 500 m2 per year of road surfaces; - About 3 800 MWth for thermal energy use; - 250 tons of mineral fraction for the production of binders; and - 50 tons of phosphorus (as P2O5) per year for the fertilizer industry.