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In 2015, two South African scientists – M.W. Matthews and S. Bernard – published a peer-reviewed paper in the South African Journal of Science showing that over two-thirds of our large dams are eutrophic.
They used satellite images to quantify the presence of blue-green algae, which is a manifestation of nutrient presence. Eutrophication is the enrichment of our water bodies by sewage (and other) return flows. This is now our national reality. Hartbeespoort Dam is where it all started, but no dams are exempt. More importantly, even with our best available science, engineering, and technology, we have been unable to reverse the process of eutrophication once it begins. This means that our best response to this new reality is an adaptive one, at least to protect what we can for as long as possible.
An accurate diagnosis of the problem is needed before we can apply an appropriate solution. We can divide water pollution into three broad categories, each with different manifestations and therefore different solutions.
The first category is plastic pollution. All modern products come with packaging, and all of this creates masses of landfills. Most packaging is plastic, and in South Africa, a lot of this ends up in rivers. We have some pioneering individuals who have been blazing the trail with innovative solutions. Leading among these initiatives is The Litterboom Project (https://www.thelitterboomproject.com), which uses a floating boom spanned across a flowing river to intercept plastics. They are operational across 10 rivers in South Africa with a source-to-sea focus. Their core philosophy is that prevention of plastic pollution in the oceans starts by intercepting it in our rivers. A thriving recycling economy has grown around each intervention. The Hennops Revival (https://hennopsrevival.co.za) is an example of a highly successful inland initiative that embraces cultural activities designed to change human behaviour.
When considering an interception boom, say on a stream that impacts a residential estate, it is important to understand that the engineering design of these things is complex. It is not simply a case of spanning a floating boom across a stream, because things become dangerous when masses of floating debris block the flow during a flood event. For this reason, it is best to link up with a registered NPO such as The Litterboom Project or Hennops Revival, as they have lots of experience, and can mitigate the risk of the unintended consequences of an inadequately designed intervention.
The second category is chemical pollution. Given that water is a universal solvent, almost every element present on the periodic table can be mobilised in one way or another. Exotic elements like heavy metals are increasingly finding their way into our rivers. In 2002, three of our top scientists – Drs Henk Coetzee, Peter Wade, and Frank Winde – published peer-reviewed research on the role of wetlands in sequestering uranium flows originating in the tailings dams of the Witwatersrand Goldfields. Pioneering work conducted in West Bengal resulted in the creation of the East Kolkata Wetlands (East Kolkata Wetlands – Wikipedia). This man-made intervention was the result of an observation made by an engineer working for the West Bengal Water and Sanitation Department, who initiated a study into the sewage flow out of the city of Kolkata. This engineered wetland became so successful in processing raw sewage that it was designated a RAMSAR Wetland in 2002. Following this success, a South African patented technology known as a Vertical Up Flow Modular Engineered Wetland System (VUF-MEWS) is a central element that has been adopted by the Unstoppable Movement for Community Restitution. The VUF-MEWS technology goes under the registered brand name of Wetland-in-a-Box ™ (WiaB) ) and has been nominated for the 2023 Ecologic Award hosted by Enviropedia. This is being offered as an alternative technology for the treatment of sewage and other effluent affecting South African rivers.
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When considering this type of approach, it is best to engage with a professional familiar with the complexity in design and management of such systems. An engineered wetland can become a central part of the estate landscape. As with the previous category, it is important to understand the limitations of the technology, as well as any embedded risk that might arise.
The third category is pathogenic pollution. Pathogens are bacteria, fungi or viruses that can cause disease. Given the known dysfunction of our sewage systems in South Africa, manifesting as our eutrophication problem, we will increasingly be confronted by unusual and exotic diseases. We already see some evidence of this in the form of elevated coliform contamination in almost all rivers. In South Africa we are increasingly familiar with Escherichia coli (known as E. coli for short). This is a gram-negative coliform bacterium that thrives in anaerobic conditions and is always associated with untreated sewage. We could potentially see a wider range of pathogens being reported as our waste management systems fail. For this reason, upstream mitigation might be considered.
The most appropriate solution is sterilisation in the form of chlorine, ozone or ultraviolet light. These are all complex treatments, requiring sophisticated engineering mostly beyond the capability of a residential estate. If on-site backup storage is used as a mitigation measure against water service delivery failure, then UV is probably the most appropriate and safest response. This has been dealt with in a separate article. However, it must be noted that peer-reviewed reports indicate that properly designed engineered wetland systems also reduce the pathogenic load. This is an added benefit from passive treatment systems of this nature.
When considering any intervention to mitigate upstream pollution, it is important that an accurate diagnosis be made of the problem you wish to solve. A misdiagnosed problem can easily result in an inappropriate solution, which will always be a costly and disappointing mistake. Given all that we know about South Africa at present, it is prudent to consider long-term strategies because our environmental problems are likely to get worse before they ever get better again. Adaptation is an appropriate response where mitigation is not possible. The two families of solutions that have been presented here – floating booms and constructed wetlands – will increasingly become mainstream. The body of knowledge growing within the institutions implementing these solutions is valuable, so your best approach would be to work through recognised entities that understand the limitations and risks.
Ingenuity happens on the cusp of chaos, and South Africa is an innovation incubator given the range of challenges we collectively face. These problems are here to stay, so how we adapt to maintain the lifestyle we choose will increasingly become a differentiator in all residential estates.
