Industry Brief: Circular economy solutions for primary, waste activated and digested wastewater sludge
Jun 30, 2021
water sector desk,
value-add to organic residues
GreenCape, in partnership with the City of Cape Town's Department of Enterprise and Investment has published an industry brief titled: Circular economy solutions for primary, waste activated and digested wastewater sludge.
The industry brief highlights an upcoming opportunity for interested service providers offering circular solutions to manage primary and waste activated sludge in the short-to medium term, and to digestate cake in the medium-to-long term.
The City of Cape Town (CCT) currently spends ~ R60 million per year to dispose of (or apply to land) the ~200 dry tonnes per day of dewatered primary and waste activated wastewater sludge it generates, with an average moisture content of 83% (range 58 - 92%).
This waste is not only a growing liability to the CCT, but is increasingly being viewed as a valuable resource. This is largely driven by a number of regulatory changes, most notably the national ban on liquid wastes to landfill that was implemented in 2019, and a Western Cape provincial restriction of organic wastes to landfill which is being phased in.
As a result, the CCT is transitioning towards anaerobically digesting its wastewater sludges in bio-solids beneficiation facilities (BBFs) to:
- Produce A1a class treated digestate cake that is safe for unrestricted use, nutrient rich, odour free and low in contaminants.
- Work towards sustainable sludge treatment including electricity generation from biogas, reusable heat generation and recovery of nutrients.
- Reduce its climate change liability.
To download the industry brief, click here.