In recent years, there have been numerous reports about the degradation of river systems in South Africa, largely linked to municipalities’ inability to effectively treat wastewater, which has far-reaching implications for human and environmental health. These challenges are the driving force behind the research by Professor Patricks Voua Otomo and Sanele Mnkhandla from the University of the Free State’s research into utilising mushrooms and microfiltration techniques to enhance the quality of contaminated water. In an interview with BizNews, Mnkandla said that they had found they could remove up to 94% of iron and 31% of insecticides from contaminated water with common edible mushrooms. Mnkandla says a TED Talk inspired her to investigate the use of mushrooms to purify contaminated water. The next step would involve designing a pilot plant, and if successful, UFS could collaborate with municipal engineers to scale it further. This method could also be used to purify water farmers use to clean equipment, which often contains pesticides and harmful chemicals, for irrigation systems in farming and for filtering rainwater running off roofs for washing.
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Highlights from the interview
In a recent interview, Sanele Mnkandla, a researcher at the University of the Free State, discussed the severe pollution of South Africa’s river systems, primarily due to municipalities’ inadequate wastewater treatment. The 2023 Green Drop Report highlights that many treatment plants are critically malfunctioning, leading to the discharge of untreated effluent laden with various pollutants, including pharmaceuticals and heavy metals. This contamination poses significant health risks, including potential outbreaks of diseases like cholera and chronic conditions linked to heavy metal exposure.
Mnkandla’s research focuses on utilizing fungi for bioremediation to improve water quality. Fungi, particularly saprophytic types like oyster mushrooms, possess unique enzymes to break down pollutants. The process involves growing these mushrooms on organic substrates, allowing them to secrete enzymes that degrade contaminants. Preliminary lab results show promising efficacy, with significant reductions in metals like ferric iron, mercury and phosphorus, which contributes to eutrophication.
To scale this innovative approach for larger wastewater treatment facilities, Mnkandla emphasises the need for funding and pilot plant designs that mimic conventional treatment conditions. With a background in biochemistry and a passion for environmental issues sparked by a TED talk, Mnkandla is dedicated to exploring the potential of fungi to address critical water challenges in Southern Africa. He also shares a love for mushrooms, further fueling his commitment to this research.
Edited transcript of the interview
Linda van Tilburg (00:07.892)
In recent years, there have been numerous reports about the degradation of river systems in South Africa, largely linked to municipalities’ inability to effectively treat wastewater. These challenges are the driving force behind research at the University of the Free State into utilizing mushrooms and microfiltration techniques to enhance the quality of contaminated water. I have Sanele Mnkandla, a researcher at the university, here to explain how this works.
Sanele Mnkandla (00:47.252)
Hi Linda, thank you for having me.
Linda van Tilburg (00:51.201)
Before we discuss mushrooms’ role, can you provide an overview of the pollution levels in our rivers due to insufficient municipal water treatment? How bad is the problem?
Sanele Mnkandla (01:03.252)
The problem is quite severe. Although we didn’t specifically assess the pollutants and their levels, we conducted a study in 2020. We know from the 2023 Green Drop Report, which assesses wastewater treatment plant systems in South Africa, that in our municipalities, all the wastewater treatment plants are in a critical state. They’re either not working at all or performing very poorly. Consequently, the effluent discharged into water bodies is loaded with high levels of pollutants. This issue is a problem for our rivers here and extends to other provinces since our rivers feed into the Vaal River basin, which serves provinces like Mpumalanga and Gauteng. The problem is indeed quite extensive.
Linda van Tilburg (02:24.605)
So, what did you find in the water? Are pharmaceuticals a problem?
Sanele Mnkandla (02:29.256)
Yes, pharmaceuticals are present, as my colleague in our research group found while examining water bodies in QwaQwa. They discovered various medicines for treating HIV, anti-inflammatories, antibiotics, and treatments for TB and diabetes in the water. Additionally, there are metals, including heavy metals. While we haven’t specifically looked into microbial contaminants like E. coli, they are likely present since these are commonly found in wastewater. If the wastewater isn’t treated properly, these contaminants end up in water bodies.
Linda van Tilburg (03:30.873)
And what would be the effect on people if they consumed water with all that in it? It must be detrimental.
Sanele Mnkandla (03:38.906)
Yes, it poses significant health challenges and risks. For instance, exposure to E. coli can lead to outbreaks of cholera. Consuming heavy metals can lead to oxidative stress in our bodies, triggering a domino effect that causes various diseases. It’s certainly a health risk, and urgent action is needed.
Linda van Tilburg (04:27.096)
So, what makes mushrooms or fungi effective for filtering wastewater?
Sanele Mnkandla (04:32.744)
The beauty of fungi is their mere existence brings about the benefits we need to clean up water. Their natural features and processes make them suitable for bioremediation. For example, the enzymes that fungi secrete aren’t specific in nature, enabling them to break down various pollutants in the water. Their surfaces, particularly the cell walls, comprise components like carbohydrates, proteins, and lipids, each with functional groups involved in trapping contaminants. Fungi can bioaccumulate these contaminants into their cells, where various processes break them down. They are truly remarkable organisms capable of environmental cleanup simply by existing.
Linda van Tilburg (06:01.5)
Can you describe this process in detail? Are mushrooms used as they are or transformed into another material?
Sanele Mnkandla (06:13.64)
The process is similar to growing mushrooms. We use saprophytic fungi, like oyster mushrooms, which feed on dead organic matter. You need a substrate, like thatching straw, and mushroom spawn. You mix them and allow incubation in a dark and humid environment. The mycelia spread over the substrate, secreting enzymes to break down the straw, their food source. Before the mushrooms form, we use this unit as the microfilter.
Linda van Tilburg (07:20.264)
How did you come up with this idea?
Sanele Mnkandla (07:24.23)
A TED talk by Paul Stamets from the United States inspired me. He spoke about how mushrooms can save the world, and I was intrigued since my knowledge of mushrooms was limited to their role as a food source. I delved into his work, read his papers, and listened to more talks. Given the water problems in Southern Africa, I thought this could be a potential solution.
Linda van Tilburg (08:18.514)
How effective is this method in practice compared to other water filtering methods?
Sanele Mnkandla (08:26.988)
It’s quite effective. In our lab, we’ve filtered various solutions and real wastewater. For instance, we achieved over 80% removal of ferric iron, a metal common in acid mine drainage. We removed about 30% of pesticides like imidacloprid. There was variation with real wastewater, but we managed up to 50% removal of mercury and more than 90% removal of phosphorus, contributing to eutrophication. Thus, using these microfilters can help reduce chances of eutrophication. Overall, it’s quite promising.
Linda van Tilburg (10:10.791)
What steps are needed to scale this to large wastewater treatment facilities? Is it possible to scale it up?
Sanele Mnkandla (10:19.312)
Scaling up is possible, but it comes down to funding. We’ve worked at a lab scale, and the next step is a pilot scale, designing a pilot plant that mimics conventional wastewater treatment conditions and seeing how our microfilters can be integrated. If successful, we could collaborate with municipal engineers to scale it further. This would involve designing and upscaling calculations. There’s a way to go, but with adequate funding, it’s feasible.
Linda van Tilburg (11:22.258)
Could you share a bit about your background? Why are you interested in wastewater and mushrooms? You’ve mentioned the TED talk, but who are you?
Sanele Mnkandla (11:32.913)
I’m originally from Zimbabwe, and I’ve always been interested in the sciences, with biology being my favourite subject. My passion started in high school, and I pursued biology at university. I hold undergraduate and master’s degrees in biochemistry. I joined the National University of Science and Technology in Zimbabwe as a research fellow, where I became part of the ecotoxicology research group, sparking my interest in environmental issues and remediation. I listened to that TED talk while working in the lab at NAST, which led me to explore this field further and think about how I could apply it to improve our water situation.
Linda van Tilburg (13:05.074)
Do you eat mushrooms?
Sanele Mnkandla (13:07.228)
I love mushrooms, so I was intrigued when I heard the talk about mushrooms saving the world. I know mushrooms on pizza, and I love mushrooms on pizza. But the idea that they can save the world was fascinating, so I had to learn more, and that’s what led us here.
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