BioBos (Biodiesel production from WWTP sludge)

About the project

Forecasts show that the number of wastewater treatment plants and the amount of sludge to be treated will increase in the years to come, due to industrialization and growing urbanization. Sludge treatment and disposal will be formidable environmental challenges. An alternative to the disposal methods currently employed (incineration, landfill, agricultural spreading) is to use the lipids present in sludge as a raw material for biodiesel production. Converting sludge lipids into biodiesel requires a specific conversion process. This strategy offers a number of advantages: sludge volume reduction, waste recovery, cheap lipid sources and no competition with agriculture. In addition, the recovery of the residue after extraction is assessed via different routes in order to optimize the profitability of the process as much as possible. European Directive 2009/28/EC sets a target of a 20% reduction in greenhouse gases and a 20% replacement of traditional fuels by renewable energy in the EU’s total energy consumption by 2020. As far as biofuels are concerned, the European Commission has set a 10% target for 2020. This project therefore fulfils a dual objective: sludge volume reduction with residue recovery and biodiesel production.


  • Assessment of lipid content in sludge from wastewater treatment plants in the Walloon region
  • Optimization of lipid extraction method for industrial-scale application
  • Evaluation of the conversion of lipids into biodiesel
  • Optimization of lipid conversion to biodiesel using a pilot reactor
  • Characterization of biodiesel using standard EN 14214:2012
  • Cost evaluation on an industrial scale
  • Evaluation of different ways to optimize extraction residue recovery

Scientific approach

  • Determination of lipid content in sludge and evaluation/optimization of extraction method
  • Preliminary laboratory-scale biodiesel conversion tests
  • Development of a pilot reactor to obtain initial performance parameters
  • Optimization of the biodiesel conversion reaction
  • Application of standard EN 14214:2012 (physicochemical analysis of biodiesel)
  • Assessment of energy consumption and energy integration of the process
  • Assessment of possible complementarity with the SLOG project currently under development
  • Determining the optimum recovery of the final residue :
    o Evaluation of energy recovery + ash recovery (CRM-ETP)
    o Evaluation of residue recovery in agriculture (CRA-W)
    o Assessment of the environmental impact of land application of extraction residue