Simha, Prithvi
- Department of Energy and Technology, Swedish University of Agricultural Sciences
- Gobabeb Namib Research Institute
Abstract
Human urine and woody biomass are two abundant biological resources that can be co-valorized through biological wood oxidation (BWO), a meso-thermophilic composting process that generates low-temperature heat and nutrient-rich soil amendment. Here, we investigated the potential of three urine-derived solid formulations as nutrient supplements to enhance microbial wood degradation at 40 °C: phosphoric acid-dehydrated urine (PDU), oxalic acid-dehydrated urine (ODU), and struvite. Among these, PDU achieved the highest wood dry mass loss (27.5 % after 42 days) and oxygen consumption, with its effectiveness attributed to greater phosphorus availability, biochemically stabilized urea that gradually hydrolyzed in situ, and a sustained mildly acidic pH, conditions which collectively supported fungal colonization and carbohydrate degradation in wood. In contrast, struvite exhibited low solubility, high alkalinity, and an unfavorable N/P ratio (0.4) that limited nutrient availability and suppressed microbial activity, resulting in minor wood degradation. Complementary experiments with synthetic nutrient solutions showed that N supplied as urea was more effective than its hydrolyzed products (ammonium bicarbonate and ammonium hydroxide) and ammonium sulfate, likely because it released ammonium gradually and buffered pH shifts during composting. These findings highlight the potential of integrating acid urine dehydration with BWO as a means to advance nutrient circularity and energy sustainability.
Keywords
Compost heat recovery; Lignocellulose; Phosphorus; Struvite; Urine dehydration
Published in
Chemical Engineering Journal
2025, volume: 522, article number: 167178
SLU Authors
UKÄ Subject classification
Wood Science
Bioenergy
Publication identifier
- DOI: https://doi.org/10.1016/j.cej.2025.167178
Permanent link to this page (URI)
https://res.slu.se/id/publ/143526