Anyone who consumes tap water or even bottled water is exposed to some degree of natural organic matter (NOM) that is ever present in our water bodies. In itself, NOM is relatively harmless, but when combined with disinfection chemicals, it can be very harmful.
Professor Thabo Nkambule, head of the Institute for Nanotechnology and Water Sustainability at the College of Science, Engineering and Technology, gave his inaugural lecture entitled “Abundance, scarcity, and innovation: a water quality tripartite alliance centred on NOM” on 21 February 2022. In his address he shared insights into his research over the years in tackling the challenges posed by the presence of natural organic matter in our water systems.
Click here to watch a recording of the lecture.
Natural organic matter (NOM) is a complex matrix that is formed from the natural breakdown of plant and animal material into water streams. “You can imagine a clustered accident on the N1 highway, involving cars, lorries, trucks and buses clustered together,” explained Nkambule. “That is typically what NOM looks like. The composition of NOM varies from region to region depending on the vegetation and the climate conditions of that particular region. As such, no single method on its own can be suitable for the complete removal of NOM from water.”
Traditional water treatment methods that are currently in use are not tailored to completely remove NOM in contaminated waters before it reaches the disinfection stage of the water treatment process. As such, the residual NOM gets mixed together with the disinfection chemicals such as chlorine, leading to the formation of what is known as disinfection
by-products (DPBs). The presence of some of the disinfection by-products in the final drinking water has been strongly linked with an increased risk of cancer in humans, amongst several other challenges that they pose. It has therefore been important for Nkambule’s research to find innovative ways of tackling the presence of NOM in water systems.
In the approach of Nkambule’s research group to solving the NOM issue, the first step generally involves decluttering the complex mixture that is NOM by using a process called fractionation, which separates NOM into its smaller identifiable constituents. From there, different strategies in which NOM can either be removed or treated in water are evaluated. “We look at conventional processes that are currently being used for the removal of NOM in water,” said Nkambule, “and identify how we can best modify these processes by making use of advanced techniques that will ensure adequate removal.”
One of the advanced techniques that Nkambule’s research group has made used of in the characterisation or identification of the smaller constituents NOM, is the fluorescence excitation-emission matrices (FEEM); a technique that Nkambule describes as being very dear to his heart. “FEEM gives you a map of different organics present in the tested water, ranging from the humics, fulvics, trytophans and tryosines”, he said. “I am pleased to say that our research group is the only one in the African continent that has worked with HORIBA Scientific in developing FEEM method for adequate characterization of NOM”, he continued.
Some of the innovative methods that have been adopted in Nkambule’s research to alleviate and treat NOM have included, but are not limited to, the use of advanced oxidation processes, high-performance polymeric and ceramic membranes, and electrochemical processes that make use of sustainable materials.
Peer praise
Responding to Nkambule’s lecture, Professor Peter Jarvis, from Cranefield University, reiterated the important role that innovation must play if we are to ensure safe access to drinking water across the globe. “This one small acronym, ‘NOM’, plays an important yet poorly understood role in controlling our water treatment and supply systems around the world,” he said. “It can be recognised as a global research field, a field in which Professor Nkambule has become a recognised name. Any decisions that are to be made around implementation and innovation, have to be backed up by the science and understanding and I believe this is where Thabo is really contributing.” In closing, he expressed his admiration of the personal attributes that Nkambule embodies, referring to him as an honourable recipient of this full professorship, who has developed a great team around him.
As a C3 NRF-rated researcher, Nkambule has published over 80 peer-reviewed journal articles, graduated 15 master’s and three doctoral students, and mentored four post-doctoral research fellows. He is currently involved in the supervision of 14 postgraduate students, who are either pursuing their master’s degrees or doctoral studies. Going forward, Nkambule plans on moving his research from bench-scale to pilot and commercial scale, and focusing on the means for resource recovery.
* Compiled by Dr Nozipho N Gumbi, Acting Communication and Marketing Specialist, College of Science, Engineering and Technology
Publish date: 2022-03-02 00:00:00.0