Lining landfills to keep the environment healthy

Why do we need landfills?

“Not all waste can be recycled. Engineered landfills are an environmentally responsible way to dispose waste which is not recyclable,” explains Neeraja V. S., a researcher with the IITB-Monash Research Academy, who is working on a project titled, ‘Thermo-hydro-mechanical behavior of geosynthetic clay liners in landfill cover systems’.

The IITB-Monash Research Academy is a collaboration between India and Australia that endeavours to strengthen scientific relationships between the two countries. Graduate research scholars like Neeraja study for a dually-badged PhD from both IIT Bombay and Monash University, spending time at both institutions to enrich their research experience.

Unregulated landfill or waste dump, poses harm to environment

Waste containment facilities form part of critical infrastructure that provides essential community services. In most cases, these facilities are designed to ensure negligible long-term environmental and human health impact.

Says Neeraja, “To achieve these aims, barrier systems need to be constructed, which effectively separates the waste and the associated leachate and biogas from the groundwater system and the atmosphere, respectively. One conventional approach to barrier systems has been to construct a ‘resistive barrier’ composed of a capping liner that reduces water ingress into the landfill and controls biogas escape into the atmosphere, as well as base liner having a low saturated permeability which minimises leachate migration out of the landfill.”

“Over the past decade,” she adds, “geosynthetic clay liners (GCLs) have become one of the dominant construction materials in landfills and have gained widespread acceptance for use in capping systems. GCLs typically comprise a thin layer of bentonite sandwiched between two layers of geotextile with the components being held together by needle-punching or stitch bonding. Once on-site, the GCL is unrolled in strips (panels), the panels overlapped without mechanical welding and self-seal at the overlaps when the bentonite hydrates.”

Neeraja’s project involves assessing the thermo-hydro-mechanical behaviour of the GCLs in waste management applications. The GCLs in cover system need to be kept hydrated to act as barrier, but on the field they are subjected to wet-dry cycles due to atmospheric exposure, and this impairs their performance. She plans to examine the long-term performance of GCLs with polymer bentonite, when subjected to daily cycles of temperature variation. The effect of wet-dry cycles on GCLs with different types of polymer bentonite have been studied by a few researchers but their long-term performance has not been ascertained well.

Says Prof Murali Sastry, CEO of the Academy, “The IITB-Monash Research Academy represents an extremely important collaboration between Australia and India. Established in 2008, the Academy now is a strong presence in the context of India-Australia scientific collaborations. In today’s scenario municipal solid waste management is an alarming issue in both countries, and engineered landfills are an inevitable part of the solution. Neeraja’s project targets an entirely new and emerging area where very limited research has been carried out. We wish her all success.”