GUWAHATI: Researchers at the Indian Institute of Technology Guwahati (IIT Guwahati) have developed a low-energy, compact, nature-based system to treat highly polluted swine wastewater, using taro plants (Colocasia esculenta) and an engineered "zig-zag flow" design.
ALSO READ: Assam STF Arrests Another Suspect Over Alleged Espionage For Pakistan
The technology is aimed at decentralised livestock farms, particularly in rural and resource-limited regions where conventional wastewater infrastructure is often impractical.
The research was carried out by the Waste Management Research Group in the Department of Civil Engineering. It addresses the safe management of nutrient-rich, pathogen-laden piggery wastewater before it reaches rivers, lakes and agricultural ecosystems, a challenge that is growing with the expansion of livestock production.
The swine wastewater used in the experiments was sourced from the ICAR-National Research Centre on Pig (ICAR-NRCP), Assam, under an R&D collaboration with IIT Guwahati.
The findings were published in the Journal of Environmental Management, a peer-reviewed international journal published by Elsevier. The paper was co-authored by Monish Goswami, Sandip Ghosh and Prof. Ajay S. Kalamdhad of IIT Guwahati.
Unlike conventional constructed wetlands, where wastewater flows directly through the treatment bed, the new system has internal baffles (built-in partitions) that force the wastewater along a longer zig-zag path and through aerobic-anoxic transitions.
"This increases the contact time between wastewater, plant roots, beneficial microorganisms and gravel media, allowing multiple biological and chemical treatment processes to occur more efficiently," said Monish Goswami, PhD scholar at IIT Guwahati.
Prof. Kalamdhad said the team wanted to do more than reduce pollution indicators. "Our research team not only wanted to reduce pollution indicators but also to make wastewater biologically safer for the environment," he said. He added that the team had demonstrated a compact, energy-efficient solution that could be adapted for decentralised livestock farms.
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 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 increasing more than fourfold during the study.
A distinctive aspect of the study was its focus on toxicity. Besides standard wastewater quality analysis, the researchers used the widely recognised Allium cepa (onion) bioassay to check whether the treated water remained hazardous to living organisms. They found a significant reduction in both cytotoxic and phytotoxic effects, indicating lower biological risks associated with reusing the treated water.
Key advantages of the system include passive, low-energy operation with minimal maintenance, a compact design suited to rural and distributed livestock farms, use of locally available plants and gravel-based media, and simultaneous removal of organic matter, nutrients, metals and pathogens. The treated water also has potential for restricted irrigation and other non-potable reuse, subject to regulatory compliance and further validation.
The technology holds particular promise for small and medium-sized pig farms located away from centralised treatment facilities. The researchers say the concept could also be adapted for other decentralised agricultural and rural wastewater treatment applications, contributing to cleaner water bodies and reduced nutrient pollution.
The team's next goal is to scale up the laboratory innovation for long-term field validation, with the vision of making sustainable, low-cost wastewater treatment accessible to decentralised livestock farming systems across India.
