Dr. Ajay S. Kalamdhad and IIT-Guwahati researchers have developed a groundbreaking two-stage fast biodegradation technique for eco-friendly organic waste management. This innovation helps municipal corporations and produces high-quality Mati Dhan compost, enriched with essential nutrients like NPK, benefiting farmers.

Dr. Ajay S. Kalamdhad, a professor of civil engineering at IIT Guwahati, led researchers from the institute Waste Management Research Group (WMRG) in developing an innovative, eco-friendly method that combines Rotary Drum Composting with Vermicomposting (RDVC). This novel approach significantly reduces biodegradation time, producing high-quality vermicompost with 4.2% total nitrogen in just 27 days—much faster than the usual 45 to 60 days—while also decreasing waste volume by 71% for efficient urban waste management.

Furthermore, the researchers claim that this technique has also been successfully applied to produce nutrient-rich vermicompost from invasive aquatic weeds, such as water hyacinth, turning a waste material into a valuable soil conditioner.

Professor Ajay S. Kalamdhad, from the Department of Civil Engineering at IIT Guwahati, explained, “We optimized the Rotary Drum Composting technique and integrated it with vermicomposting to shorten the biodegradation process. The earthworms, Eisenia fetida, quickly adapt to the partially degraded organic matter from the drum compost, enabling the production of vermicompost in just 27 days.

The institute has transferred this technology to AMER Private Ltd, a startup incubated at IIT Guwahati, which is now producing and selling Mati Dhan Organic Vermicompost Fertilizer Manure for Plants. The product is available on Amazon and other online marketplaces.

This innovative approach goes beyond urban waste management, effectively converting invasive aquatic weeds like Water Hyacinth into a nutrient-rich soil conditioner. MatiDhan, the high-quality organic vermicompost produced through this method, is now available in the market, offering benefits to local farmers and promoting sustainable agricultural practices.

Solution for Efficient Organic Waste Processing

Traditional waste management methods often lack both efficiency and adaptability. While Rotary Drum Composting quickly processes organic feedstocks into compost, the resulting compost quality is typically low. Vermicomposting, on the other hand, produces higher-quality compost but is time-consuming, making it less suitable for urban settings.

The two-stage biodegradation strategy developed by WMRG at IIT Guwahati bridges this gap, providing a fast and high-quality solution. Professor Ajay S. Kalamdhad highlights its broad applicability, saying, “This proven technique not only efficiently processes large amounts of organic waste but also offers immediate feasibility for Municipal Corporations, industries, sewage treatment facilities, aquatic weed management, and various other organic waste sectors.

The scaled-up process, tested in the Solid Waste Laboratory at IIT Guwahati, successfully produced 100 to 150 kg of MatiDhan vermicompost within a month from 250 to 300 kg of daily waste. The increased earthworm population also resulted in a secondary byproduct—the earthworms themselves.

How the Two-Stage Biodegradation Process Works

Organic material constitutes over half of the municipal solid waste in open dumpsites across many Indian cities, generating significant heat due to prolonged decomposition. This poses serious environmental challenges over time.

Unlike other waste biodegradation techniques that take two to three months, Rotary Drum Composting (RDC) can transform diverse organic feedstocks into nutrient-rich compost in just 20 days. RDC also reduces municipal waste volume by 60 to 70%, as highlighted in a recent press release from the institute.

That said, RDC is known to produce compost of “moderate quality compared to vermicompost.” Vermicomposting, while superior, requires 45 to 60 days, making it less practical for large-scale use by municipal corporations.

To address this, the Waste Management Research Group (WMRG) under Professor Kalamdhad developed a unique two-stage biodegradation technique that combines the strengths of both RDC and vermicomposting, significantly reducing the biodegradation time. “The earthworms, Eisenia fetida, can acclimatize faster to the partially degraded organic matter from the drum compost and produce high-quality vermicompost in just 27 days,” says Professor Kalamdhad.

Professor Kalamdhad explains, “The developed technique combines the thermophilic biodegradation of RDC with the mesophilic biodegradation of vermicomposting. We found that RDC takes seven days, while vermicomposting requires 20 days. We studied how diverse organic waste responded to this technique before finalizing it. To put it simply, using RDC before vermicomposting helps the earthworms (vermiculture) stabilize the organic waste more quickly.”

Wide Applicability and Large-Scale Potential

“We have used a variety of biomasses for the study, including vegetable waste, aquatic weeds, terrestrial weeds, and sewage sludge,” Professor Kalamdhad explains. “The experimental verification of this combined technique was carried out both in the laboratory and on a large scale at the Solid Waste Laboratory of IIT Guwahati. A 5,000-litre RDC unit and a 3,000-litre stack vermicomposting unit were set up to study the large-scale impact of the process, with moisture content controlled using horticulture waste collected from the campus.”

Producing High-Quality Soil Conditioner

The final product was proven to be non-toxic and safe as a high-quality, nutrient-rich vermicompost soil conditioner, containing 4.2% total nitrogen, ideal for enhancing soil health.

Academic Validation and Global Impact

He explains, “The study focused on vegetable waste and aquatic weeds (such as water hyacinth) as primary substrates, both in mono-substrate composting and co-composting.”

“In the course of the study, we processed 15 tonnes of waste collected from markets and ponds around the IIT Guwahati campus (350 kg per day). The confidence gained from this study forms the foundation for our belief that the technology can handle large-scale waste. We are confident that this process has the potential to transform organic waste treatment facilities globally, offering an environmentally friendly solution to mitigate contamination hazards while producing an excellent soil conditioner,” he adds.

Assisting in verifying the technique is PhD student Mr. Suryateja Pottipati, who experimentally proved the hypothesis. Their findings have been published in several respected international academic journals, including the Journal of Biomass Conversion and Biorefinery, Journal of Environmental Management, Bioresource Technology, and Waste Management, among others.

Edited by Gayathri