Natural clays present a promising solution to the increasing challenge of managing pathogenic waste post-Covid-19 pandemic, according to a study led by researchers at the Indian Institute of Technology (IIT) Guwahati.
The study, published in the prestigious American Chemical Society journal Langmuir, suggests a dedicated biomedical waste disposal facility containing compacted bentonite/kaolin clays as liners or encapsulating the viral waste with these compacted clays in a sealed container and disposing it in the municipal solid waste landfills.
Biomedical waste that contains viruses poses significant risks to human health, food safety, animal health, and the environment. The recent Covid pandemic created an emergency and produced a huge quantity of potentially virulent waste from the hospitals and isolation facilities.
The Covid waste was treated similar to the municipal solid waste during this pandemic and was disposed off in the existing landfills.
However, the geosynthetic landfill liners become ineffective in the presence of landfill leachate containing high-concentration salt solutions thereby the infectious viral pathogen waste can then easily escape from such facilities to potentially cause secondary infections in humans. Thus, highlighting the urgent need for proper management and safe disposal protocols.
‘We wanted to understand the fate of viruses in the presence of compacted clays like bentonite and kaolin that contain various surface charge densities. We measured specific parameters like the equilibrium sorption parameters, diffusion coefficient and retardation factor of the virus in the compacted clays for the first time. These measurements showed 99.6 per cent reduction of viral contamination and very low diffusion rates,’ said Prof. T.V. Bharat, Dept. of Civil Engineering, IIT Guwahati, in a statement.
‘We were able to confirm that both bentonite and kaolin clays in powder form can prevent the viral contamination from entering into the environment. Our study for the first time provides experimental evidence of the efficiency of using compacted clays for containing viral waste,’ Bharat added.
To study the behaviour of viruses in clays, the researchers used a safe virus called the Newcastle disease virus (NDV) as a substitute for the coronavirus. They conducted experiments where they mixed different amounts of the virus with bentonite and kaolin clays, allowing them to interact for varying durations.
Also, through-diffusion tests are conducted with the viruses through compacted clays. The results demonstrated that both types of clays were highly effective in reducing the concentration of the virus in the source.
The research findings revealed that viral decay was quicker on bentonite compared to kaolin clay. It was observed that the removal efficiency of the NDV — an infectious and contagious viral infection that affects bird species — depended on the quality of bentonite, and multilayer sorption of the virus on clay surfaces.
In addition, the study also has implications for waste management during outbreaks of diseases like the Newcastle disease in poultry.
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