Microalgae production on biogas digestate in Sub-Alpine region of Europe—development of simple management decision support tool

Resman, Lara (author), Berden Zrimec, Maja (author), Žitko, Vid (author), Lazar, Borut (author), Reinhardt, Robert (author), Cerar, Ana (author), Mihelič, Rok (author)

In a one-and-a-half-year study conducted in the ALS6 region in Europe (Ljubljana, Slovenia), the cultivation of microalgae in anaerobic digestate from food waste, mainly Scenedesmus dimorphus and Scenedesmus quadricauda, was investigated in three ponds (1260 L each) under a greenhouse. The effects of changing digestate quality and quantity as well as seasonal fluctuations on the productivity of the microalgae were investigated in three stages: Learning/Design (SI), Testing (SII), and Verification/Calibration (SIII). A decision support tool (DST) was developed using easy-to-measure parameters such as pH, temperature, electrical conductivity, mineral nitrogen forms and physical, biological parameters (OD, delayed fluorescence intensity). To control optimal pond operation, we proposed the photosynthetic culture index (PCI) as an early indicator for necessary interventions. Flocculation and nitrite levels (above 3 mg NO$_{2-}N$L$^{−1}$) were signals for the immediate remediation of the algae culture. Under optimal conditions in summer SIII, an average algal biomass production of 11 ± 1.5 g m$^{−2}$ day$^{−1}$ and a nitrogen use efficiency of 28 ± 2.6 g biomass/g N-input were achieved with the developed DST. The developed DST tool was, in this study, successfully implemented and used for the cultivation of microalgae consortia predominated by Scenedesmus dimorphus and S. quadricauda with biogas digestate. DST offers the possibility to be modified according to producers’ specific needs, facility, digestate and climate conditions, and as such, could be used for different microalgae cultivation processes with biogas digestate as a food source.

• Language: English
• Keywords: circular economy, anaerobic digestion, food waste digestate, microalgae Scenedesmus, open ponds, decision support tool
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 25 str.
• Numbering: Vol. 15, iss. 24 (16948)
• PID: 20.500.12556/RUL-153431
• UDC: 63
• ISSN on article: 2071-1050
• COBISS.SI-ID: 179545603
• Publication date in RUL: 05.01.2024

Record is a part of a journal

• Title: Sustainability
• Shortened title: Sustainability
• Publisher: MDPI
• ISSN: 2071-1050
• COBISS.SI-ID: 5324897

Licences

• License: CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International
• Link: http://creativecommons.org/licenses/by-nc/4.0/
• Description: A creative commons license that bans commercial use, but the users don’t have to license their derivative works on the same terms.

Secondary language

• Language: Slovenian
• Keywords: krožno gospodarstvo, anaerobna presnova, digestat živilskih odpadkov, živilski odpadki, mikroalge, Scenedesmus, odprti ribniki, orodja za podporo odločanju