In a significant development for sustainable environmental management, scientists at the Indian Institute of Technology Bombay (IIT Bombay) have introduced AroTrack, an economical and portable device to accurately detect harmful pollutants such as phenol or benzene in water.  

Scientists claim that the device can be a game-changer given the increasing water pollution due to industrialisation, urbanisation, and unregulated effluent discharge.  

AroTrack device uses proteins typically found in bacteria living in heavily polluted environments to effectively identify multiple aromatic pollutants in water. Once mixed in the water sample, the protein undergoes a highly selective ATP hydrolysis chemical reaction if an aromatic compound is present in the sample. This reaction is expressed with a change in the colour of the protein solution, which AroTrack can then detect. The device is highly robust and compact, measuring slightly smaller than a small projector. 

Professor Ruchi Anand from the Department of Chemistry, Professor Rajdip Bandyopadhyaya from the Department of Chemical Engineering and their team at IIT Bombay introduced a simple and affordable biosensing device capable of detecting harmful compounds such as, phenol, benzene, and xylenols.  

The key component of the device is a biosensing module called MopR – a sensitive sensor for detecting phenol. Ms. Anand’s research team engineered it from the Acinetobacter calcoaceticus bacteria in 2017. MopR is both selective and stable, meaning it can detect pollutants even in complex environments with a high degree of precision. 

Researchers at IIT Bombay have further diversified the MopR biosensor to detect other pollutants from the benzene and xylenol groups by engineering mutations in the bacterial protein. “The protein biosensing is very specific as the protein sensing pocket is tailor-made for the ligand (ion or molecule, like phenol or benzene). We have engineered mutations in the DNA of the protein sequence that can give mutant versions of the protein that now sense different molecules, creating a battery of sensors. Each sensor is particularly designed for a ligand,” Ms. Anand explains. 

Once interfaced with an in-house, multi-channel monitoring apparatus, the MopR-based sensor forms the core of the newly developed aromatics tracking device—AroTrack. Talking about how the AroTrack detects the pollutants using the biosensor modules, Mr. Bandyopadhyaya explained, “AroTrack contains a light emitting diode [LED]-phototransistor assembly, that shines a light of appropriate wavelength through the sample and detects how much is absorbed. A more intense colour generates a higher absorbance.”  

The overall cost of the device is a minimum of $ 50 [less than ₹5,000]. Mr. Bandyopadhyaya said that AroTrack was born out of the philosophy to make field-usable analytical devices, based on translating analytical capabilities generated in the laboratory into actual field-ready devices. “It is designed so that almost any user, technically trained or layman, may quickly learn and generate accurate data for traditionally difficult to measure and distinguish aromatic xenobiotic pollutants,” he said. 

“Using in-house 3D printing in our laboratory, we were able to economically design, fabricate and iterate a fully functional device. Also, the cost could be kept down by using basic electronics and open-source, mass-produced microcontrollers for data processing and analysis,” Mr. Bandyopadhyaya added. 

AroTrack can detect several aromatic contaminants, including phenol, benzene, and 2, 3 dimethylphenol, even when these pollutants are present in low concentrations – usually in the 10-200 parts per billion range. 

Tests in simulated wastewater and actual environmental samples have found that the AroTrack is highly reliable, offering a degree of accuracy and efficiency on par with modern spectrophotometers, which are currently used for detection. The device also reliably worked in water temperatures up to 50 degrees Celsius and completed the tests in under 30 minutes, the scientists said. 

Due to its low cost, battery-operated nature, and portability, AroTrack can be ideal for rural and low-income settings that often lack resources and have difficulty accessing expensive laboratory tests, Ms. Anand said, “We are currently trying to increase the type of pollutants to biphenyl aromatics and pollutants that are complex aromatics.” 

Speaking about its market readiness, Mr. Bandyopadhyaya said, “The product is ready as an initial functional prototype, which can demonstrate all the reported functions. To make it fully market-ready, more field trials and quality analysis are needed to assess its robustness under more varied working conditions in the field, with a wider variety of water sources and compositions.”