Production of organic fertilizers from residues of the olive oil processing industry

This study proves that it is possible to convert digested residues from the olive oil processing industry into a compact organic soil improver. Moreover, it was demonstrated that drying and pelletizing digestate are excellent processes to stabilize and reduce the mass of the product (98%) creating a competitive commercial fertilizer.

Further authors:
M.S. Stoll, N.A. Valarezo - Fraunhofer Institute for Interfacial Engineering
and Biotechnology (IGB)

The olive oil processing industry generates large amounts of liquid and solid residues (olive-mill wastewater, OMWW and olive mill solid waste, OMSW, respectively). OMWW is mainly collected in storage ponds and evaporated during summer leading to serious environmental problems. OMSW is further processed in central pomace oil plants to recover the residual oil by chemical extraction. After this extraction a final residue, deoiled solid cake (DOC), is produced. Currently, DOC is composted, used directly as soil improver or sold as fuel. In previous studies, it has been demonstrated that anaerobic digestion can be a promising alternative to treat these residues. This process has the advantage that the residues are converted to energy in form of methane and that the digestate can be dried and used as a stabilized organic soil improver. In fact, land application of stabilized digestate is an excellent practice to increase soil fertility. However, in regions with intensive livestock production, land application is not always possible because of the already high nutrient content of the soil. In those regions, digestate must be either transported to other areas with nutrient demand or stored for long periods. Drying and pelletizing digestate could (1) stabilize the digestate, (2) reduce the transportation costs and storage requirements, and (3) facilitate handling and commercialization of the product. The objective of this study was to convert digested OMWW and DOC to a compact organic soil improver to create a commercial product, which could be stored, transported and spread with common fertilizer spreaders used in agriculture.
Two types of digestate: (A) from the co-digestion of OMWW and dairy wastewater, and (B) from the co-digestion of DOC and manure, were collected from two anaerobic reactors (100 L) at our laboratories. A solid-liquid separation was performed and the solid fraction was dried at 100°C until the sample had a total solid content (TS) of 85%. The dried solid was then milled and pelletized. The water content and plant nutrients concentration (TN, NH4, TP, K, Mg, Ca, S and Fe) were measured before and after each process to compute a complete water and nutrient balance of the whole process. To determine whether the obtained product could be used as an organic fertilizer relevant plant nutrients and potential pollutants (Tl, As, Pb, Cd, Cr, Ni, Hg, Cu, Zn) were measured.



Copyright: © European Compost Network ECN e.V.
Quelle: Orbit 2012 (Juni 2012)
Seiten: 8
Preis: € 0,00
Autor: Dr. Jennifer E. Bilbao
Siegfried Egner
Prof. Dr. Thomas Hirth
 
 Artikel nach Login kostenfrei anzeigen
 Artikel weiterempfehlen
 Artikel nach Login kommentieren


Login

ASK - Unser Kooperationspartner
 
 


Unsere content-Partner
zum aktuellen Verzeichnis



Unsere 3 aktuellsten Fachartikel

Wasserwirtschaftliche Fachexkursion nach Namibia
© Springer Vieweg | Springer Fachmedien Wiesbaden GmbH (8/2025)
Fachexkursionen dienen dazu, den Horizont für das Fachgebiet zu erweitern und vor allem die Sinnhaftigkeit der späteren Aufgaben sichtbar zu machen. In Zeiten der Widerstände bei der Gestaltung der Umwelt, ob Wasserwirtschaft, Wasserbau, Abfallwirtschaft oder die Anpassung an den Klimawandel, kann so eine Einordnung des Gelernten und der Herausforderungen erfolgen.

Digitale Zwillinge stützen eine handlungsfähige blau-grüne Infrastruktur in der Stadt von Morgen
© Springer Vieweg | Springer Fachmedien Wiesbaden GmbH (6/2025)
Blau-grüne Infrastrukturen kombinieren ökologische, hydrologische und soziale Funktionen und sind so essenziell für die klimaresiliente Stadtentwicklung. Deren Planung, Steuerung und langfristige Funktionssicherung erfordern eine präzise, flächenhafte Erfassung und fortlaufende Bewertung des urbanen Wasserhaushalts. Digitale Zwillinge ermöglichen eine präzise Erfassung und Steuerung dieser Strukturen.

Naturbasierte Lösungen für den Schutz der Halligen vor dem steigenden Meeresspiegel
© Springer Vieweg | Springer Fachmedien Wiesbaden GmbH (6/2025)
Die nordfriesischen Halligen sind vor dem steigenden Meeresspiegel zu schützen. In einem Multi- Stakeholder-Ansatz sollen langfristige naturbasierte Lösungen zur Verringerung der Kantenerosion und nachhaltigen Förderung des Oberflächenwachstums gefunden werden