IIT Hyderabad Turns Sewage Sludge and Eggshell Waste Into Sustainable Packaging Film

Researchers at the Indian Institute of Technology Hyderabad (IIT-H) have developed an innovative biodegradable packaging material using two problematic urban waste streams: sewage sludge and discarded eggshells. The work, published in the Journal of Environmental Chemical Engineering, demonstrates how everyday organic waste can be repurposed into high-performance packaging films that degrade naturally and could help reduce dependence on fossil fuel-based plastics.

The team, led by Dr. Debraj Bhattacharyya from the Department of Civil Engineering in collaboration with the Department of Chemistry, extracted extracellular polymeric substances (EPS) from centrifuged sewage sludge collected at IIT Hyderabad’s on-site treatment facility. These EPS, naturally rich in biopolymers, were combined with chitosan derived from shrimp shells and reinforced with calcium oxide nanoparticles sourced from eggshell waste. Using a simple solution-casting technique, the researchers produced thin, flexible films.

Performance testing showed that the optimized formulation containing 10% sludge-derived polymer outperformed conventional biopolymer films in several key ways. Tensile strength improved by 16.2%, elongation at break increased by 186%, and water barrier capability rose by nearly 80% compared to pure chitosan films. The material also exhibited better resistance to water absorption (up to 71.6%), higher thermal stability, and effective UV light blocking. These properties make the film suitable for protective wrapping of non-food items such as flowers, industrial products, and UV-sensitive goods.

Importantly, the researchers caution that these films are not intended for direct food contact because of the sensitivities around the origin of the raw materials. However, in non-food sectors, such as horticulture, electronics, and light industrial packaging, they present a sustainable, low-cost alternative to petroleum-based plastics. When disposed of in soil, the films degrade naturally and release calcium oxide, which can enrich soils by acting as a micronutrient for beneficial microorganisms.

This innovation addresses two environmental challenges simultaneously: waste disposal and plastic pollution. Urban sewage sludge is difficult to manage, often ending up in landfills or incineration, both of which carry environmental risks. Eggshells, a by-product of food services and poultry industries, are frequently discarded in bulk. Converting these materials into functional products can reduce greenhouse gas emissions associated with waste processing while decreasing demand for virgin plastic production, which is energy-intensive and carbon-heavy.

The packaging industry, valued at over USD 1 trillion globally, has been seeking alternatives as governments tighten regulations on single-use plastics. India banned certain single-use plastic items in 2022, and similar restrictions exist across Europe and parts of North America. Biodegradable materials are one solution, but cost and performance often limit adoption. The IIT-H approach leverages low-cost waste feedstocks and avoids complex chemical processing, potentially making scale-up more feasible.

According to the researchers, the next step involves pilot-scale production and evaluating lifecycle impacts, including greenhouse gas savings compared to conventional plastics. If manufacturing can be standardized, municipal sewage treatment plants could integrate polymer recovery, while food industry players could supply eggshell waste. Such closed-loop systems could create local supply chains for sustainable packaging, aligning with circular economy and net-zero carbon strategies.

Experts note that for meaningful impact, biodegradable packaging must also be paired with proper collection and composting or soil degradation pathways. Inadequate waste handling could still lead to littering and microplastic formation. However, early evidence suggests the IIT-H film breaks down effectively in natural soil conditions without releasing harmful by-products.

This breakthrough reinforces India’s growing role in sustainable materials research. Similar studies are emerging worldwide, but this one is distinctive for its use of sewage sludge, which is abundantly available yet underutilized. If commercialized, the technology could support both waste reduction and emissions goals in line with India’s 2070 net-zero pledge.

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