IIT Roorkee Pioneers Affordable Solution for Hydroponic Wastewater Treatment
In a significant breakthrough for sustainable agriculture, researchers at the Indian Institute of Technology Roorkee have unveiled an indigenous, low-cost technology specifically designed to address the wastewater challenges associated with hydroponic farming. This innovation promises to mitigate environmental risks while supporting the growth of soil-less cultivation methods.
The Hydroponic Wastewater Problem
Hydroponics, the practice of growing plants without soil by using nutrient-rich water solutions, has gained popularity for its efficiency and space-saving benefits. However, it generates wastewater containing high concentrations of nitrate, phosphate, and ammonia. If released untreated into natural water bodies, this effluent can trigger eutrophication, leading to harmful algal blooms and oxygen depletion that severely threaten aquatic ecosystems.
Innovative Microalgal Photogranule Technology
To combat this issue, a team from IIT Roorkee's departments of hydrology and renewable energy has developed a cost-effective treatment system based on microalgal photogranules. Their study, published in the prestigious international journal ACS ES&T Water, details how this technology overcomes the limitations of conventional microalgae-based systems.
Traditional methods often struggle with harvesting microscopic algae, requiring energy-intensive processes like centrifugation or chemical additives. The IIT Roorkee solution ingeniously induces microalgae to self-aggregate into dense, spherical granules that incorporate bacteria and cyanobacteria in a symbiotic relationship.
How the Photogranule Reactor Works
The technology utilizes a light-driven photogranule reactor, where microorganisms form these granules under controlled mixing and illumination. These granules efficiently remove nitrogen, phosphorus, and organic pollutants through a combination of photosynthesis and microbial metabolism.
Professor Sanjeev Kumar Prajapati, the principal investigator, highlighted a key advantage: "Once mixing stops, the granules naturally settle due to their density, allowing clear treated water to be separated without expensive mechanical or chemical processes. This drastically lowers operational costs."
In the reactor, hydroponic wastewater is treated in a controlled environment with light and mild mixing. Microalgae perform photosynthesis, absorbing carbon dioxide and assimilating nitrate and phosphate, while associated bacteria degrade organic pollutants, reducing biological and chemical oxygen demand.
Over time, the microbial community produces extracellular polymeric substances that bind cells together, forming compact green granules approximately 4–6 mm in diameter.
Impressive Results and Environmental Benefits
Experimental outcomes have been highly promising. The system achieved:
- Nearly complete removal of biological and chemical oxygen demand
- Approximately 99% reduction in phosphate and ammonia
- Nearly 90% removal of nitrate within a few days of treatment
Additionally, the technology demonstrated substantial carbon dioxide fixation potential, contributing to climate mitigation. With its low energy requirements, chemical-free operation, and simplified biomass recovery, this microalgal photogranule-based approach offers a sustainable and scalable solution for the rapidly expanding hydroponics sector.
This innovation not only addresses immediate wastewater concerns but also supports the broader goals of environmental sustainability and resource efficiency in modern agriculture.
