Industrial Production of Humic and Fulvic Acid from Biomethan Digestate

Biostimulants are a growing class of sustainable agricultural inputs that enhance plant growth, nutrient use efficiency, and tolerance to environmental stress, offering an alternative to conventional agrochemicals. They are derived from diverse natural sources, including plant extracts, microbial metabolites, and humic substances, but achieving consistent quality, scalability, and sustainability remains challenging. Humic substances, particularly humic and fulvic acids, provide well-documented benefits by improving soil structure, fertility, and nutrient availability, enhancing microbial activity, and increasing fertilizer efficiency while reducing environmental losses. However, their extraction from soils, peat, or wild-harvested biomass is constrained by low abundance, compositional complexity, seasonal variability, and sustainability concerns, highlighting the need for more reliable and circular sourcing strategies.

Our solution integrates a series of processes to extract and concentrate humic substances, particularly fulvic acids, from anaerobic digestion residues. It begins with mechanical separation of liquid and solid phases, followed by sequential filtration to remove inorganic precipitates, large particles, and impurities. The purified liquid is then concentrated by reverse osmosis, removing water while retaining humic substances. This process recovers up to 60% of humic substances in a solution containing at least 50% fulvic acids, with optional further concentration to reach a minimum of 12% w/w.