Technical factsheet for thermal beneficiation and treatment of wastewater sludge

This technical factsheet by GreenCape outlines the use of thermal hydrolysis as a method for the thermal beneficiation of wastewater treatment works (WWTW) sludge in South Africa to improve energy efficiency and reduce waste disposal costs.

• Thermal hydrolysis is a process that uses heat, high pressure, and a rapid pressure drop to treat organic waste as a pre-treatment for anaerobic digestion. This process increases the rate and volume of biogas production, which can be used for electricity generation or to supplement the facility's heating needs. The resulting residues are stable, pasteurised, pathogen-free, and easier to dewater.
• The implementation of thermal hydrolysis in WWTWs offers several operational benefits, including increased digester throughput and efficiency by reducing retention time, and a reduction in the mass of solid residues. Technical characteristics include a typical biogas production increase of 15-60% and improved dewatering of 7-8% on a dry basis, with a typical scale exceeding 1,500 tonnes of dry feedstock per year.
• WWTW sludge disposal is a significant financial burden in South Africa, with annual costs estimated at over R300 million. Thermal hydrolysis addresses this by reducing sludge volumes and the associated health and environmental risks of landfilling or stockpiling.
• The business case for adding thermal hydrolysis to an existing anaerobic digester includes an estimated unit capital cost of R1,900 to R2,400 per tonne of dry solids treated and unit operating costs of R6 to R8 per kg of dry solids treated. The estimated payback period is 2-5 years with an internal rate of return between 31% and 53%.
• Financing for energy efficiency projects in municipalities can be achieved through various mechanisms: municipal budgets (via IDP, WSDP, SDBIP), government or donor grants (such as MIG, RBIG, WSIG, Green Fund, and EEDSM), concessional loans from foreign funders (AFD, SEFA, DBSA), commercial bank loans, energy performance contracts via ESCos, and climate financiers.

APA

GreenCape (n.d.). Technical factsheet for thermal beneficiation and treatment of wastewater sludge. https://greencape.co.za/wp-content/uploads/2023/08/Factsheet-9_Thermal-Beneficiation-and-treatment-of-Wastewater-Sludge.pdf

Chicago

GreenCape. Technical factsheet for thermal beneficiation and treatment of wastewater sludge. n.d. https://greencape.co.za/wp-content/uploads/2023/08/Factsheet-9_Thermal-Beneficiation-and-treatment-of-Wastewater-Sludge.pdf.

Wikipedia

{{cite report |author=GreenCape |title=Technical factsheet for thermal beneficiation and treatment of wastewater sludge |url=https://greencape.co.za/wp-content/uploads/2023/08/Factsheet-9_Thermal-Beneficiation-and-treatment-of-Wastewater-Sludge.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{greencapendtechnical, author = {{GreenCape}}, title = {{Technical factsheet for thermal beneficiation and treatment of wastewater sludge}}, institution = {GreenCape}, url = {https://greencape.co.za/wp-content/uploads/2023/08/Factsheet-9_Thermal-Beneficiation-and-treatment-of-Wastewater-Sludge.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }