Treating sewage sludge intelligently
EU Member States have the obligation to collect and treat domestic and industrial wastewater from urban areas under the Urban Wastewater Directive. This mandatory treatment is very costly, thus it is important to re-use the by-products thereby.
Soil-Concept has developed a range of innovative ways to deal with the problem of sewage sludge. From pioneering a new, improved process to produce compost out of sludge and green waste, the Diekirch-based company has recently progressed to taking the same base materials and using them to generate heat, electricity and biomass fuel pellets, in addition to compost.
Soil-Concept has always been a visionary leader in terms of innovative wastewater treatment solutions and always pushes the limits of R&D further. One of Soil-Concept´s best-known R&D projects is named ENERCOM. The purpose of this €5.2 million project, with funding from the Seventh Framework Programme for Research and Technological Development (FP7), was to develop a process in which multiple energy products would be created from sewage sludge and green waste. Known as polygeneration, the process would result in the production of electricity, thermal energy and solid fuels in the form of biomass pellets, as well as compost and fertiliser.
From sewage sludge to renewable energy
Unknown long-term effects of substances such as PCB, AOX, heavy metals or hormones combined with high transport costs for compost had led to a growing rejection of this utilisation type. The end result of ENERCOM was to be a new, safe, environmentally friendly and cost-effective way to dispose of sewage sludge while maximising energy output and reducing greenhouse gases. The new gasification process converts organic materials into a synthetic gas called syngas. Syngas is itself a fuel and is more efficient than combusting the original fuel, e.g. green waste. It is considered to be a form of renewable energy and can be used to generate electricity.
Partners from all over Europe gathered for this project: Soil-Concept and L.E.E from Luxembourg, IfaS and B.A.U.M from Germany, Kuhbier from Belgium and Kaunas Technological University from Lithuania. However, the main contribution came from Luxembourg since the different components of this innovative polygeneration demonstration plant are all situated in Diekirch at the composting site owned by Soil-Concept. Luxembourg engineering and environmental knowledge has been used in every single step of the project.
An important output of ENERCOM was the creation by three of its partners – BISANZ Anlagenbau GmbH, LEE S.A.R.L. and Soil -Concept S.A – of a spin-off, Synerco. Synerco offers comprehensive project services in power plants using fuels that include biomass, refuse-derived fuel (RDF), coal and sewage sludge.
The challenging part within this project concerned mostly communication issues in the beginning but the consortium rapidly sorted it out after a few meetings. “Organisation and exchange of information/data or results may sometimes require special attention when working with different partners because the dependence on each other’s performances is strong,” Thorsten Klaes of Soil-Concept explains.
A contribution to wastewater treatment in the EU
The technology that has been developed during the project could potentially be applied to any sludge and organic matter treatment plant in the European Union. This would represent more than 3,000 existing plants and the equivalent of 70 TWh in terms of recoverable energy. Considering population growth worldwide, demand for energy-efficient wastewater treatment will increase steadily over the coming years. This flexible technology thus has a bright future ahead and can be implemented everywhere on existing systems as well as future ones.
At the EU level, the development and use of this technology for treating wastewater residues could be useful to help implement the EU regulatory framework on water (in particular the Urban Waste Water Treatment Directive, but also the Water Framework Directive).
Project developers are grateful to the Luxembourg Ministry of the Economy and Foreign Trade as well as to Luxinnovation, the National Agency for Innovation and Research, for their support throughout the project. “ENERCOM will bring a greener future and the unconditional support of all actors was crucial for its completion,” Mr Klaes concludes.