Researchers at Indian Institute of Technology Guwahati, have studied the fate and transport of virus through compacted natural clays for pathogenic waste disposal. The study, published in the prestigious American Chemical Society journal, Langmuir, presents a promising solution to the increasing challenge of managing pathogenic waste post-COVID-19 pandemic. The published paper has been co-authored by Prof. Bharat Venkata Tadikonda, Prof. Sachin Kumar, and their research scholars, Himanshu Yadav and Shubham Gaurav.
Biomedical waste (BMW) that contains viruses poses significant risks to human health, food safety, animal health, and the environment. Recent COVID-19 pandemic created an emergency and produced a huge quantity of potentially virulent waste from the hospitals and isolation facilities. The Covid-19 waste was treated similar to the municipal solid waste (MSW) during this pandemic and was disposed of in the existing MSW 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.
Explaining the rationale of their research, Prof. T.V. Bharat, Dept. of Civil Engineering, IIT Guwahati, said, “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 % reduction of viral contamination and very low diffusion rates. Based on these findings, we were able to confirm that both bentonite and kaolin clays in powder form can prevent the viral contamination to enter into the environment. Our study for the first time provides experimental evidence of the efficiency of using compacted clays for containing viral waste”.
To study the behavior 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.
Speaking about the research, Sachin Kumar, Dept. of Biosciences and Bioengineering, IIT Guwahati, said, “Newcastle disease virus (NDV) could be a surrogate to the coronavirus and recent studies used NDV as surrogate for immunological studies. NDV is a single-stranded enveloped RNA virus like coronavirus. Thus, NDV was chosen for clay-virus interaction studies for the barrier applications. Further, Newcastle disease is an infectious and contagious viral infection that affects more than 250 different bird species worldwide with various degrees of vulnerability. A large amount of pathogenic waste gets generated from NDV outbreaks in the form of carcasses, potentially contaminated feces, litter, farm bedding, and fomites”
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 depended on the quality of bentonite, and multilayer sorption of the virus on clay surfaces.
In addition to addressing the disposal of pathogenic waste generated from the COVID-19 pandemic, this study also has implications for waste management during outbreaks of diseases like the Newcastle disease in poultry. The proposed handling protocol involves disposing waste in biomedical waste facilities containing compacted powder Bentonite/Kaolin clays as liners or placing the pathogenic waste in a closed container with compacted powder bentonite or kaolin clays to dispose of in existing MSW landfills.
This work was supported by Science and Research Board (SERB), Department of Science and Technology, Government of India and was conducted under the research project entitled “Attenuation ability of Municipal solid waste landfill liners for Viral pathogens”