Guwahati: Researchers at the Indian Institute of Technology Guwahati have developed a low-energy, nature-based system to treat highly polluted swine wastewater, offering a possible solution for livestock farms in rural areas where conventional treatment infrastructure is impractical.
The compact technology uses taro plants (Colocasia esculenta) and an engineered “zig-zag flow” design. It was developed by the Waste Management Research Group in the Department of Civil Engineering to address the safe handling of nutrient-rich, pathogen-laden piggery wastewater before it reaches rivers, lakes and agricultural land.
The wastewater used in the experiments came from the ICAR-National Research Centre on Pig in Assam, under an R&D collaboration with the institute.
How it works
Unlike conventional constructed wetlands, where wastewater flows directly through the treatment bed, the new system uses internal baffles, or built-in partitions, that force the water along a longer zig-zag path.
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The design creates aerobic-anoxic transitions and increases contact time between the wastewater, plant roots, microorganisms and gravel media, allowing multiple biological and chemical treatment processes to work more efficiently, said Monish Goswami, a PhD scholar at IIT Guwahati.
The engineered wetland substantially reduced organic pollutants, nutrients, suspended solids, metals and harmful microorganisms.
Total coliforms fell from about 60,000 to 1,200 MPN per 100 mL, while E. coli levels dropped from around 2,200 to 350 MPN per 100 mL. The taro plants also thrived in the system, with shoot length nearly doubling and biomass rising more than fourfold during the study.
The team also assessed toxicity, using an Allium cepa (onion) bioassay alongside standard water quality analysis to determine whether treated water remained hazardous to living organisms. Cytotoxic and phytotoxic effects declined significantly, indicating reduced biological risks associated with reuse.
“Our research team not only wanted to reduce pollution indicators but also to make wastewater biologically safer for the environment,” said Prof. Ajay S. Kalamdhad of the Department of Civil Engineering.
He said the compact, energy-efficient solution could be adapted for decentralised livestock farms by engineering the movement of wastewater and combining it with the natural treatment abilities of plants and microorganisms.
Potential applications
The researchers said the system operates passively with minimal maintenance, uses locally available plants and gravel, and suits small and medium-sized pig farms located far from centralised treatment facilities.
It removes organic matter, nutrients, metals and pathogens simultaneously, and the treated water could potentially be used for restricted irrigation and other non-potable purposes, subject to regulatory compliance and further validation. The concept could also be adapted for other decentralised agricultural and rural wastewater treatment needs.
The findings were published in the Journal of Environmental Management, a peer-reviewed Elsevier journal with an impact factor of 9.2. The paper was co-authored by Goswami, Sandip Ghosh and Prof. Kalamdhad.
The team’s next goal is to scale the laboratory-level innovation for long-term field validation, with the aim of making low-cost, sustainable wastewater treatment accessible to decentralised livestock farms across India.
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