Vo’s research initiative focuses on reclaiming high-purity phosphorus from high-moisture sewage sludge while minimizing pollutant release through an energy-efficient technology. Specifically, it addresses two critical challenges: phosphorus depletion and microplastic pollution. As phosphorus is essential for agriculture but increasingly scarce, and microplastics in sludge pose environmental and health risks, his work aims to remove these contaminants to facilitate efficient nutrient recovery. The research presents a scalable and sustainable solution that advances resource circularity and environmental protection.
HTP is a thermochemical treatment that utilizes water at elevated temperatures and pressures to convert organic waste into valuable products. Unlike conventional thermal treatments such as pyrolysis and incineration, which require energy-intensive drying and high-temperature operation, HTP is particularly well-suited for high-moisture feedstocks like sewage sludge. It allows for the simultaneous recovery of essential nutrients and degradation of persistent pollutants.
In his research, Vo demonstrated that phosphorus recovers from HTP-derived products, particularly hydrochars, in combination with wet chemical extraction. This process achieves higher yields and faster extraction time compared to traditional approaches involving biochar or incineration ash. Moreover, Vo found that microplastic degradation occurs at substantially lower temperatures (200–300 °C) under HTP conditions compared to pyrolysis, which typically requires temperatures exceeding 450 °C. This lower temperature threshold reduces energy consumption while minimizing the release of potentially harmful byproducts.
“I have demonstrated that hydrothermal processing can both recover a critical agricultural nutrient and reduce persistent plastic pollutants in one integrated system. It’s a circular economy solution – transforming waste into value,” he says.
Vo’s findings contribute to the development of more sustainable waste management practices and could inform future policies on phosphorus recycling and plastic waste treatment. By demonstrating how waste can be turned into a valuable resource, his research supports efforts to build a more resilient and environmentally responsible society.
“With continued advancements, hydrothermal processing has the potential to revolutionize how we manage waste, making a significant impact on environmental sustainability and resource conservation,” Vo concludes.
Public defence on Friday 6 June
The doctoral dissertation of MSc (Tech) Tan Phat Vo in the field of Energy Technology titled Hydrothermal Processing of Sewage Sludge for Phosphorus Recovery will be publicly examined at the Faculty of Engineering and Natural Sciences at Tampere University at 13:15 on Friday 6 June 2025 at Hervanta, TB103, Tietotalo building and hall (Korkeakoulunkatu 1, Tampere).
The Opponent will be Dr. Olli Sippula from the University of Eastern Finland. The Custos will be Dr. Chao He from Tampere University.