Turning hydrothermal carbonization wastewater into fertilizer for sustainable agriculture

A new review in the journal Biochar looks at the liquid byproduct from hydrothermal carbonization, a process that converts wet biomass like sewage sludge and food waste into hydrochar. This process water is rich in ammonium nitrogen, phosphorus, and potassium, making it a potential liquid fertilizer. Studies cited in the review show yield improvements in paddy rice fields of nearly 30 percent when using this water as a soil amendment. The review also flags risks like high salinity and heavy metals that require careful management. Researchers recommend dilution, pH adjustment, and toxicity testing before field application. If handled correctly, this approach could cut reliance on synthetic fertilizers and reduce waste treatment costs for biomass processing facilities.