Converting food waste from Cape landfills

The large amount of food waste ending up in Western Cape landfills has prompted a new project to recycle this waste more effectively. A local ecofarming initiative is working alongside Cape Town eateries to fight against food waste, by converting it into compost and methane gas that can be used for cooking, lighting and heating.

The Rainbow Warriors International organisation developed the initiative to not only help divert organic waste from overloaded landfills but also to convert it into a useful resource. Rainbow Warriors International is a registered non-profit organisation, founded with the aim of educating rural communities and small-scale farmers about the impacts of climate change.

The organisation conducted a self-funded feasibility study in November 2019, which involved the daily collection of kitchen waste from eight restaurants, juice bars and coffee shops in Observatory, Cape Town.

Each establishment was given a 20 litre plastic bucket with a lid, which they used to throw all pre- and post-consumer food waste into. The bucket was then collected the next day for two weeks. The study was aimed at looking at the volume of waste produced by each restaurant.

Eatery waste volumes

“The juice bars and vegan-only establishments produced much more organic food waste than others, sometimes requiring two buckets a day. We found that education about food waste and how best to deal with it was the biggest obstacle to compliance,” says Ryan Fortune, executive director, Rainbow Warriors International.

Following the findings, the organisation is continuing its work by partnering with six restaurants, who were part of the initial study. Over the next three months, they will collect about 200 kg of food waste weekly from the hospitality businesses.

The food waste will then be transformed into methane gas or composting through processing methods known as red wiggler composting.

Organic composting

Red wiggler earthworms consume the waste and excrete worm castings, also known as vermicompost. The compost is an odourless, clean, organic material containing several micronutrients essential for plant growth, making it an excellent fertiliser for plants.

The organisation has also recently invested in black soldier fly larvae, which are able to consume a much wider variety of food waste than earthworms, at a greater speed. Before they pupate and become flies, these larvae can be dried, powdered and pelletised into high-protein animal feed.

“We are also in advanced discussions with John Holmes at the Oude Molen EcoVillage in Pinelands, who has a biogas digester, to see how much waste he will take from us to create methane gas for local household energy use.”

The processing through red wiggler earthworms and black soldier fly larvae will be done at a processing site in Woodstock, while methane gas will be produced through the biogas digester located at Oude Molen EcoVillage. Fortune says they developed the campaign to create greater awareness about this food waste issues.

“The main aim is to create awareness among restaurant owners and the general public, as well as demonstrate efficient and environmentally sound waste treatment options.”