Agricultural digestate ultrafiltrate outperforms synthetic media for microalgal biomass production while enabling biostimulant generation
- 1University of Verona
Abstract
Livestock digestate ultrafiltrate (UF), obtained through membrane treatment of anaerobic digestate, is a nutrient-rich stream whose valorization remains largely unexplored. By removing suspended solids while retaining dissolved nutrients, ultrafiltration reduces turbidity and overcomes major limitations associated with using digestate for microalgal cultivation. This study evaluated UF as a nutrient source for Chlorella sorokiniana and Nannochloropsis oceanica, coupling ammonium recovery and biomass production with biomass valorization as a plant biostimulant. Given the high ammonium content of UF, ammonium tolerance was assessed in both species using ammonium bicarbonate as the nitrogen source. Increasing UF concentrations were then tested in laboratory photobioreactors and compared with synthetic media. Biomass productivity, nutrient removal, biomass composition, and biostimulant activity were evaluated. Both species tolerated ammonium-rich conditions and grew efficiently in UF-based media. UF significantly outperformed synthetic media, increasing biomass accumulation by up to 104% in N. oceanica and 133% in C. sorokiniana, while ammonium removal exceeded 99% and 98%, respectively. C. sorokiniana maintained high productivity when UF was diluted exclusively with water, indicating that UF supplied most nutrients required for growth. The enhanced productivity could not be explained solely by ammonium availability, suggesting a contribution from the complex nutrient composition retained during ultrafiltration. UF-derived biomass exhibited biostimulant activity, promoting tomato root development and increasing root and shoot biomass under reduced nitrogen availability. Digestate-derived UF therefore acts as both an efficient nutrient-recovery stream and a growth-promoting microalgal medium, enabling the conversion of membrane-treated digestate into biostimulant biomass within a circular biorefinery framework.
Related
- Strategies Used to Improve the Performance of Plant Growth-Promoting Rhizobacteria Under Agricultural Greenhouse and Field Production Scenarios in Semi-Arid Conditions
- Analysis of the spatiotemporal evolution of agricultural production efficiency and its determinants in China
- Estimation of agricultural carbon abatement costs using a marginal-productivity-based production-input model: evidence from Fujian Province, China
- Valorization of agricultural residue for the production of fructose using fungal inulinase from Talaromyces domesticus ITCC 9483.
- Risk assessment and climate adaptation research for agricultural cultivation and water resource systems within rural green production models
BibTeX
@misc{miotti2026agricultural,
title = {{Agricultural digestate ultrafiltrate outperforms synthetic media for microalgal biomass production while enabling biostimulant generation}},
author = {T. Miotti and M. Maver and M. Peli and R. Lo Coco and G. Rodegher and G. Viglioli and N. Frison and D. Bolzonella and A. Zamboni and M. Ballottari and S. Cazzaniga},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.29.762777},
url = {https://www.biorxiv.org/content/10.64898/2026.10.29.762777v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - Agricultural digestate ultrafiltrate outperforms synthetic media for microalgal biomass production while enabling biostimulant generation
AU - T. Miotti
AU - M. Maver
AU - M. Peli
AU - R. Lo Coco
AU - G. Rodegher
AU - G. Viglioli
AU - N. Frison
AU - D. Bolzonella
AU - A. Zamboni
AU - M. Ballottari
AU - S. Cazzaniga
PY - 2026
DA - 2026/10/29
PB - bioRxiv
DO - 10.64898/2026.10.29.762777
UR - https://www.biorxiv.org/content/10.64898/2026.10.29.762777v1
AB - Livestock digestate ultrafiltrate (UF), obtained through membrane treatment of anaerobic digestate, is a nutrient-rich stream whose valorization remains largely unexplored. By removing suspended solids while retaining dissolved nutrients, ultrafiltration reduces turbidity and overcomes major limitations associated with using digestate for microalgal cultivation. This study evaluated UF as a nutrient source for Chlorella sorokiniana and Nannochloropsis oceanica, coupling ammonium recovery and biomass production with biomass valorization as a plant biostimulant. Given the high ammonium content of UF, ammonium tolerance was assessed in both species using ammonium bicarbonate as the nitrogen source. Increasing UF concentrations were then tested in laboratory photobioreactors and compared with synthetic media. Biomass productivity, nutrient removal, biomass composition, and biostimulant activity were evaluated. Both species tolerated ammonium-rich conditions and grew efficiently in UF-based media. UF significantly outperformed synthetic media, increasing biomass accumulation by up to 104% in N. oceanica and 133% in C. sorokiniana, while ammonium removal exceeded 99% and 98%, respectively. C. sorokiniana maintained high productivity when UF was diluted exclusively with water, indicating that UF supplied most nutrients required for growth. The enhanced productivity could not be explained solely by ammonium availability, suggesting a contribution from the complex nutrient composition retained during ultrafiltration. UF-derived biomass exhibited biostimulant activity, promoting tomato root development and increasing root and shoot biomass under reduced nitrogen availability. Digestate-derived UF therefore acts as both an efficient nutrient-recovery stream and a growth-promoting microalgal medium, enabling the conversion of membrane-treated digestate into biostimulant biomass within a circular biorefinery framework.
ER -