Anaerobic Digestion of Olive MillWastewater and Process Derivatives—Biomethane Potential, Operation of a Continuous Fixed Bed Digester, and Germination Index

• Published in: Applied Sciences
• Main Authors: Pluschke, Jonas, Faßlrinner, Katharina, Hadrich, fatma, Loukil, Slim, Chamkha, Mohamed, Geißen, Sven-Uwe, Sayadi, Sami
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI
• Subjects: olive mill wastewater; biomethane potential; fixed bed biogas digester polyphenols; germination index; Sven; sami
• Online Access: http://hdl.handle.net/10576/46980; https://doi.org/10.3390/app13179613

Olive mill wastewater (OMW) management is an economic and environmental challenge for olive oil-producing countries. The recovery of components with high added value, such as antioxidants, is a highly researched approach that could help refinance performant wastewater treatment systems. Anaerobic (co-)digestion is a suitable process to valorize the energetic and nutritional content of OMW and OMW-derived waste streams from resource recovery processes. Issues of process stability, operation, and yields discourage industrial application. Deepening the understanding of biomethane potential, continuous anaerobic digester operational parameters, and co-substrates is key to large-scale implementation. The biomethane potential of different OMWderived samples and organic solid market waste as co-substrate was 106–350 NL methane per kg volatile solids (VS). The highest yields were obtained with the co-substrate and depolyphenolized OMW mixed with retentate from an ultrafiltration pretreatment. Over 150 days, an anaerobic fixed-bed 300 L digester was operated with different OMW-derived substrates, including OMW with selectively reduced polyphenol concentrations. Different combinations of organic loading rate and hydraulic retention time were set. The biogas yields ranged from 0.97 to 0.99 L of biogas per g of volatile solids (VS) eliminated, with an average methane content in the produced biogas of 64%. Potential inhibition of the process due to high polyphenol concentrations or over-acidification through volatile fatty acids was avoided in the continuous process through process and substrate manipulation. The InnoVa research project (2nd German-African Innovation Promotion Prize: Prof. Sami Sayadi, Prof. Sven Geißen) was funded by the Bundesministerium für Bildung und Forschung, grant number 01DG20005, and managed by the Deutsche Luft-und Raumfahrtzentrum—Projektträger. This research was supported by the Ministry of Higher Education and Scientific Research-Tunisia under a contract program for the Laboratory of ...