Rourkela: Researchers from Civil Engineering department of the National Institute of Technology (NIT) Rourkela have developed and patented a novel biological system for treating wastewater generated by the dairy industry.
The multi-layered process, which uses aquatic plants, earthworms, microbial activity and a hydroponic filtration system in an integrated setup, reduces organic pollution and prevents the accumulation of organic matter.
The dairy industry produces billions of litres of wastewater every day in the production process of products such as cheese, paneer and yogurt.
This wastewater is rich in fats, proteins, and carbohydrates, and has high Chemical Oxygen Demand (COD), which is a measure of the amount of organic matter in water.
High COD levels reduce the dissolved oxygen needed to sustain aquatic life when released into water bodies.
Conventional treatment methods, like membrane filtration, don’t directly address this challenge and clog frequently.
Looking to address this challenge, Prof. Kakoli Karar Paul of Civil Engineering NIT Rourkela’s Civil Engineering department, along with her research graduate (2025 batch) Dr Pragyan Das, developed the multi-layered system in which each layer performs a specific purification function while contributing to the overall stability of the process.
They have secured a patent titled ‘Method and System for Treating Dairy Wastewater’ for the developed system (Patent number: 583949; Application number: 202431032506).
Prof. Paul said that in a lab scale setup, the developed system costs about Rs 10,000 and is capable of treating 30 litres of dairy wastewater per day. It can be further increased as per requirement.
How it works
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 — 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.
“Through this system, we have developed an affordable wastewater treatment solution which can be easily used in regions where access to large-scale treatment infrastructure is either unavailable or limited. With our natural treatment approach, the treated wastewater can be directly reused in agricultural purposes, thus reducing environmental impact and resource-efficient waste management practices,” said Dr Das.
In lab tests, conducted using real dairy wastewater, the research team found the treated water to be suitable for irrigation as it retains useful phosphate nutrients.
The aquatic plants used in treatment system can also be used as cattle feed or processed for biogas and biodiesel production, providing resource recovery in addition to wastewater treatment.
The research team next plans to work on improving treatment speed and optimising reactor design for large-scale deployment of the developed system. The team is also looking for potential industry collaboration to bring the developed technology from lab to real-world applications.
