Combining Thermal Hydrolysis with Advanced Thermal Conversion to Reduce Energy Demands for Microcontaminant Destruction

Barber, W. P. F.

The 19th IWA Conference on Sludge Management Toward material cycle and low carbon society (2025)

Abstract

Thermal hydrolysis of sewage sludge prior to subsequent anaerobic digestion is a wellestablished process with approximately 130 facilities worldwide, of which over 90 are supplied by Cambi, the market leader. The majority of plants are combined with land use of the biosolids as a fertilizer due to the biosolids meeting the criteria for advanced biosolids under various regulations. In addition, the dewatered biosolids are friable, have low odour and high dry solids, which make it a desirable product. However, there is growing concern over the presence of microcontaminants, such as microplastics and PFAS-related compounds, in the biosolids. However, these processes rely on dried sludge as a feedstock and are therefore highly energy-intensive. The aim of this paper is to demonstrate how combining thermal hydrolysis with digestion prior to thermal processing can reduce the energy demands of processing. Additionally, work looking at the impact of thermal hydrolysis when combined with pyrolysis are presented.

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