IIT-Guwahati researchers develop novel technology to minimize biodegradation time

GUWAHATI: Researchers from the Waste Management Research Group (WMRG) at the Indian Institute of Technology, Guwahati, led by Prof. Ajay S. Kalamdhad, have developed a new approach to assist municipal corporations in managing organic waste. The novel two-stage biodegradation technique combines Rotary Drum Composting with Vermicomposting (RDVC), resulting in an efficient and environmentally friendly process that enables municipal corporations to derive value-added products from organic waste. This technique was also used to produce nutrient-rich soil conditioner from invasive aquatic weeds like water hyacinth.

Municipal solid waste deposited in open dumpsites often contains over 50% organic material, generating substantial heat due to long-term decomposition. This not only poses environmental challenges but also hinders the achievement of sustainable development goals. Compared to other waste biodegradation techniques that require 2-3 months, Rotary Drum Composting (RDC) can convert diverse organic feedstocks into nutrient-dense compost within just 20 days and significantly reduce the municipal waste volume by 60-70%. However, the limitation of RDC is inferior compost quality. Vermicomposting is a superior biodegradation process that traditionally requires a minimum of 60 days, making the process less adaptable for urban municipal corporations.

Clubbing the benefits of both of these processes, WMRG and IIT Guwahati have developed a unique strategy of two-stage biodegradation. Speaking about the novel technique, Prof. Ajay S. Kalamdhad, Department of Civil Engineering, IIT Guwahati, said, "We optimised the Rotary Drum Composting technique and combined it with vermicomposting to reduce the duration of biodegradation. The earthworms, Eisenia fetida, can acclimatise faster to partially degraded organic matter from the drum compost and produce vermicompost in just 27 days."

The microbial composition of the compost was identified with metagenomic analysis. The final product was proven to be non-toxic and safe to be used as a nutrient-rich soil conditioner from waste (4.2% total nitrogen).

The experimental verification of this combined technique was conducted both in the laboratory and on a large scale at the Solid Waste Laboratory of IIT Guwahati. A 5000-litre RDC unit and a 3000-litre stack vermicomposting unit were established to study the large-scale effect of the process, with the moisture content controlled using horticulture waste collected on campus.

Speaking about its application Prof. Ajay S. Kalamdhad said, "This proven technique not only handles sizable quantities of organic waste but also offers immediate application feasibility for municipal corporations, industries, sewage treatment facilities, aquatic weeds, and various organic waste management sectors. The scaled-up process successfully produced 100 to 150 kg of vermicompost within a month from 250 to 300 kg of daily waste fed. The increased earthworm count resulted in the secondary end product being the earthworm itself."

The findings of the study have been published in multiple research papers in the Journal of Biomass Conversion and Biorefinery, the Journal of Environmental Management, Bioresource Technology, and Waste Management, among others. They have been co-authored by Suryateja Pottipati and Prof. Ajay S. Kalamdhad, a press release said.

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