Biogas Production Potential Analysis on Wastewater Treatment Plants
Sewage sludge that is inevitably produced at sewage treatment plants is an immediately available resource that can be fed into an anaerobic digester for sludge stabilization and biogas production. In addition to the energy production, the anaerobic digestion process reduces waste disposal costs by decreasing the organic material content and improving dewaterability of the remaining sludge. Unlike on farm biogas plants, there is no demand of substrate transport to the plant, since the sludge is directly available.
In this project, the biogas production potential from waste-stream sludge in the State of Baden-Württemberg was analyzed. In particular, the possibility of retrofitting existing sewage plants from aerobic to anaerobic sludge stabilization was evaluated. Additional potentials through process improvement of existing anaerobic digesters to high load digesters were also analyzed. This process improvement, combined with proper sludge management, can result in higher biogas production and the increase of digester capacity to treat co-substrates.
The combination of literature review, evaluation of operational data books, visits of wastewater treatment plants (Fig. 1) and several interviews, as well as plausibility checks and calculations, showed the still available untapped biogas potential. In the state of Baden-Wuerttemberg, there are, in principle, 63 sewage treatment plants of size class 4 which could be converted from aerobic to anaerobic sludge stabilization. Many existing digesters could be operated under significantly higher loads (Fig. 2). The identified underused reactor volumes could be filled with other locally available co-substrates. Overall, a potential increase in biogas production from sewage sludge / on wastewater treatment plants of approx. 23.5 million m3 / year was identified.
| Project Title | Biogas Production Potential Analysis on Wastewater Treatment Plants |
| Institution | University of Stuttgart, Institute of Interfacial Process Engineering and Plasma Technology (IGVP) |
| Research Group | Dr.-Ing. Ursula Schließmann, Barbara Waelkens, Alfonso Vidal |
| Project Status | completed |