Regulating phosphorus bioavailability and dissolved organic matter dynamics through deep eutectic solvent addition in...

Area of Science:

• Environmental Science
• Soil Science
• Biotechnology

Background:

• Sustainable fertilizer production is crucial for agriculture.
• Organic waste composting offers a viable route for nutrient recovery.
• Phosphorus (P) bioavailability in compost is a key factor for plant uptake.

Purpose of the Study:

• To investigate the effect of choline chloride-based deep eutectic solvents (DES) on phosphorus transformation during co-composting.
• To analyze the impact of DES on dissolved organic matter (DOM) characteristics and microbial communities.
• To evaluate the potential of DES-amended compost as a sustainable phosphorus fertilizer.

Main Methods:

• Co-composting of dewatered sludge and distiller's grains with and without DES (ethylene glycol/citric acid).
• Analysis of phosphorus fractions, dissolved organic matter (DOM), and microbial community composition.
• Statistical analysis including correlation and partial least squares path modeling (PLS-PM).

Main Results:

• DES significantly increased P bioavailability in compost, with increases up to 99.49%.
• DES promoted the conversion of organic P to inorganic P, enhancing nutrient availability.
• Specific bacterial groups (Proteobacteria, Firmicutes) correlated positively with inorganic P fractions.
• DES improved P bioavailability directly and indirectly via physicochemical and microbial regulation.
• DOM characteristics remained unaffected, but humic-like components may contribute to P release.

Conclusions:

• Choline chloride-based DES effectively enhance phosphorus bioavailability during organic waste co-composting.
• DES treatment offers a sustainable approach for producing P-rich compost from sludge and winery waste.
• The use of DES in composting presents a valuable waste-to-resource strategy for long-term phosphorus utilization.