Women researchers at NIT Rourkela create eco-friendly wastewater solution

Researchers at NIT Rourkela have developed a low-cost, eco-friendly wastewater treatment system that converts dairy waste into water suitable for agriculture

With India’s dairy industry generating billions of litres of wastewater every day and conventional treatment systems remaining costly and difficult to maintain, researchers at the National Institute of Technology (NIT), Rourkela, have developed and patented a low-cost, eco-friendly wastewater treatment system that can convert dairy waste into water suitable for agricultural use.

 

Developed by women scientists from the Civil Engineering Department of the institute, the innovative system integrates earthworms, aquatic plants, microbial activity and hydroponic filtration in a multi-layered biological treatment process to reduce organic pollution and tackle clogging issues commonly faced in conventional wastewater treatment technologies.

 

Wastewater generated during the production process of dairy products such as paneer, cheese and yoghurt contains high levels of fats, proteins and carbohydrates, resulting in elevated chemical oxygen demand (COD). High COD levels reduce dissolved oxygen in water bodies, severely affecting aquatic ecosystems when untreated wastewater is discharged into rivers and ponds.

 

 

According to the researchers, existing treatment technologies such as membrane filtration often fail to address these challenges effectively and are prone to frequent clogging.

 

Kakoli Karar Paul, professor at the Civil Engineering Department at NIT, said they have developed a multi-layered system in which each layer performs a specific purification function while contributing to the overall stability of the process.

 

"The newly developed treatment model operates through a five-stage purification mechanism. In the first layer, wastewater enters a worm-active reactor containing earthworms and aquatic plants. The partially treated water passes through a sand filtration layer that removes suspended solids in the second phase. While the third layer uses fly ash pellets to adsorb pollutants and reduce phosphorus compounds, the fourth layer removes residual organic contaminants in a gravel bed through aerobic microbial action. The final treatment stage involves a hydroponic chamber where plant roots remain submerged in water and release oxygen," she said.

 

The combination of vermi-filtration, macrophyte-assisted treatment and hydroponic purification in a sustainable continuous system has enabled the NIT Rourkela research team to achieve improved pollutant removal efficiency and address the clogging issues faced during the wastewater treatment process.

 

Paul said the laboratory-scale setup costs nearly Rs 10,000 and can currently treat around 30 litres of dairy wastewater per day, though the capacity can be scaled up depending on industrial requirements.

 

Laboratory tests conducted using real dairy wastewater showed that the treated water was suitable for irrigation and retained useful phosphate nutrients beneficial for agriculture. The researchers also claimed that the aquatic plants used in the treatment process could be repurposed as cattle feed or processed for biogas and biodiesel production.

 

Highlighting its practical relevance, Pragyan Das, a research associate, said the technology offers an affordable wastewater treatment solution for areas where access to large-scale treatment infrastructure is limited or unavailable. "The treated wastewater can be directly reused for agricultural purposes, promoting resource-efficient waste management while reducing environmental pollution," she added.

 

The research team is now working on improving the treatment speed and optimising reactor design for large-scale deployment. They are also seeking industry collaboration to commercialise the technology and take it from laboratory research to field-level implementation.

 

How does the system work?

 

1st Layer - The wastewater treatment process starts in a worm-active reactor layer containing earthworms and aquatic plants (macrophytes). The earthworms break down organic waste into smaller particles and increase oxygen levels in the wastewater. This increase in oxygen levels enables the growth of microbes that break down pollutants. Additionally, the aquatic plants provide a dense root system that helps prevent blockages and offers a surface for these microbes to grow.

 

2nd Layer - The purified water then passes through a layer of sand that filters suspended solids through physical means.

 

3rd Layer - In the third layer, fly ash pellets adsorb pollutants and reduce phosphorus compounds in the wastewater.

 

4th Layer - The water then flows through a gravel bed where residual organic contaminants are removed by aerobic microbes.

 

5th Layer – In this stage, the treated water is pumped into a hydroponic (soil-free plant) treatment chamber in which the plants’ roots remain in the water and pump oxygen into the surrounding environment. This oxygen-rich environment encourages the growth of beneficial microbes that form biofilms around the roots and further break down pollutants. This process also helps improve the quality of the treated water.