Low-grade waste heat recovery for wastewater treatment using clathrate hydrate based technology

Abstract

Effectively recycling low-grade waste heat is crucial for advancing decarbonization and achieving net-zero emissions, yet current methodologies are limited by inefficiencies in extracting energy from sources with low exergy. This study introduces an innovative approach leveraging hydrate formation and dissociation to utilize low-grade waste heat in purifying wastewater. By directly heating (low-grade waste heat) liquid R134a, our method induces bubble formation, thereby enhancing hydrate nucleation and growth. Our system demonstrates exceptional energy efficiencies, reaching up to 23.5%, and exhibits a high removal efficiency for wastewater with high concentrations of organic and heavy metal contaminants, including methylene blue (86.4%), Cr³⁺ (98.0%), Ni²⁺ (98.3%), Zn²⁺ (98.0%), and Cu²⁺ (97.1%). This approach not only offers a sustainable pathway for waste heat utilization but also addresses critical challenges in wastewater treatment. This technology demonstrates substantial potential in both low-grade waste heat recovery and wastewater treatment.