RESEARCH AND DEVELOPMENT: New process for the treatment of purification sludge based on pyrolysis, energy recovery and biochar enhancement

The PYROCHAR project, funded by the Seventh Framework Program of the European Union and co-ordinated by the French company E.T.I.A., is developing an efficient and cost-effective energy management solution for sludge produced by the small municipal companies in the member states.
Oltread E.T.I.A. The project includes 4 P.M.I .: Enviro-Pharm LTD (Hungary), Hydro ItaliaSRL (Italy), Turguc (Turkey) and Biboaqua S.L. (Spain); and 3 research centers: University of Teeside (United Kingdom), Technology Avanzadas Inspiralia S.L. (Spain) and Messag (Switzerland).
The implementation of the European Water Framework Directive - including, inter alia, the Waste Water Treatment Directive 91/271 / EEC and the Sludge Directive 86/278 / EEC - improving the overall quality and management of water resources in 'Union, has led to a complex situation in which today, 10 million tons of sludge are produced annually in the 26 member states. In particular, small wastewater treatment plants (eg, less than 10,000 equivalent municipal wastewater treatment plants), which account for more than 60% of plants in Europe, must not only account for more and more European and national legislation restrictive but also lack of infrastructure and limited disposal of sludge, since landfill disposal is not permitted in most member countries and will soon be completely banned. Officially launched on November 1, 2013, the PYROCHAR project aims to demonstrate the technical feasibility and economic convenience of an innovative process of thermo-chemical conversion of municipal sewage sludge into biochar (pyrolysis coal) and synthesis gas ( syngas).
Since high heat (slow drying + pyrolysis) treatments are used to reduce the 95% mud volume and convert the same mud into a stable bio-by-product, the PYROCHAR project is based on recovery and the reuse of energy contained in the mud in order to minimize total energy consumption. This is made possible by two factors: 1) burn syngas from pyrolysis into a gas turbine to produce the thermal and electrical energy needed for the system; 2) Use the residual heat of the biochar to compensate for part of the hot gas requirement in the dryer. In practice, the process will incorporate a flexible control system with specific pyrolysis operating settings to ensure that the syngas produced does not contain condensable gases (mainly H2, CO, CH4, CO2) and hydrocarbons in various proportions that depend on not only by the composition and humidity of the input raw materials, but also by the type of pyrolysis reactor and operating parameters (eg residence time and temperature). To minimize the level of pollutants to an acceptable content for turbine operation, an innovative catalytic technology for the system is under development. This will allow both the cleaning of the hot syngas and the improvement of carbon efficiency through the removal of the crates so as to produce more syngas. In addition, the biochar product will be valued and its market value valued in 3 main applications: energy, environmented agriculture.

The PYROCHAR project lasts 24 months and is organized as follows:
· A first 9-month period focused mainly on two main aspects: 1 / characterization of purification mud and pyrolysis product and 2 / syngas pollutant scientific study and evaluation and production of efficient catalysts. This first period ended at the end of July 2014.
· A second period of 15 months dedicated to the design / dimensioning of the syngas, gas turbine, heat recovery and total monitoring system, and the construction, testing and validation of a semi-prototype -industrial (capable of handling up to 50 kg of dehydrated sludge per hour). In the following, further research work will be carried out during the first nine months of the project.
Characterization of sewage sludge, pyrolysis process and its byproducts The aim of the first part of the project was to carry out in-depth analysis of the composition, yield and the main chemical and physical characteristics of both the purification mud and the byproducts of the pyrolysis. The collected data were used to obtain a first integrated characterization and optimization of the pyrolysis process. In this regard, in order to ensure a sufficient variety of mud, representative mud samples were collected from different water treatment plants located in 4 different countries (Spain, France, United Kingdom and Hungary).