Advancing the Circular Economy in the Wastewater Sector

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 This project investigated the role of emerging wastewater sludge processing technologies in accelerating the transition to a circular economy (CE) in the wastewater sector, using wastewater treatment plants (WWTPs) as resource-recovery centres. A comprehensive literature review on the global status of CE in the water sector and the International Water Association (IWA) framework was conducted. The emerging multi-biomass processing Enhanced Hydrothermal Polymerization (EHTP) technology was selected as the case study. An EHTP pilot reactor was installed at a WWTP  in Tshwane, processing sludge, community waste biomass, and faecal sludge from VIP toilets. Laboratory analyses were performed on the feedstock, hydrochar, and process effluent. The hydrochar showed potential uses as biofuel, soil conditioner, adsorption media, and building material. Technologies that can be coupled with the EHTPprocess within the IWA pathways were identified. Key factors impacting the transition to a CE in the water sector were evaluated in the South African context, with recommendations for WSAs to address these factors. The project demonstrated that multi-biomass processing technologies like EHTP can be incorporated into WWTPs to convert them into resource recovery centres, with strong government leadership needed to drive the transition.

Key Insights

The main challenges and barriers for the sanitation sector to transitioning to a circular economy are (i) legislation, regulation & governance, (ii) economics, (iii) technology and (iv) public perception of sanitation waste by-products. To overcome these barriers, requires a standardized multi pronged approach to put in place adequate regulatory mechanisms, financial instruments and incentives to support public and private engagement in CE pathways.