Research
The long-term objective is to be able to predict the passive release (flux or rate) of bioaerosols from different surfaces bearing solid food wastes found in domestic and municipal waste. Bioaerosol release rates can be used as input to dispersion models to predict ambient concentrations and consequent health effects and also in global climate models. Current work is in progress to characterise the release of fungal spores from simulated solid waste surfaces in laboratory microcosms. In controlled experiments, the sensitivity of passive release to different air velocity and relative humidity are measured. A preliminary energy-balance based mathematical model is being developed to provide a framework for predicting the fungal spore release. Future work is also planned on the visualisation of the aerodynamics of fungal spore release using microscopy and particle image velocimetry (PIV). This is being done in collaboration with Prof. Baburaj (Applied Mechanics) currently funded by SERB - DST (2023-2026). Other long term objectives are to develop and execute methodologies to measure bioaerosol release fluxes from real solid waste processing facilities using drones and compare with model predictions. Some of this work is being done in collaboration with Prof. Sachin Gunthe (Civil Engg.)
The objective is to estimate the anti-microbial resistance (AMR) genes in Buckingham canal in Chennai - a water body flowing through Chennai city. This canal connects to the other water bodies in the Chennai watershed. Additional interest is in the estimation of the propagation of AMR to ambient air from water bodies. The project scope includes the analysis of various factors in water quality that influence the incidence of AMR in the Buckingham canal system. This work is in collaboration with Prof. Indumathi Nambi in the department of Civil engineering. This project includes the presence and transport of related micropollutants in the sediment-soil-water system.
The objective is to simulate the behavior and interaction of vehicle exhaust plumes in dense urban traffic to assess the specific behavior for the formation of hot spots in the micro-environemnt at the surface of roads. This affects the exposure to vehicle occupants in a dense traffic system. This is an experimentally challenging measurement and therefore the objective s to attempt to map the pollutant plumes using computational fluid dynamics (CFD). Factors that influence this are the wake formation from moving vehicles, composition of road traffic and vehicle arrangement; interaction of plumes of variosu vehicles; interaction of plumes on a variety of surfaces on the road and in adjacent areas. Other problems of interest in the general domain of aerosol dynamics including aerosol behavior (deposition and resuspension) on paved roads, unpaved road shoulders, leaves on plants, indoor fans, cleaning tools, vehicle surfaces and on different filters used in urban traffic by humans. The goal is to obtain robust mathematical or empirical models to characterise all the processes to for better predictive capacity for various scenarios. This project is in collaboration with Prof. Vagesh Narasimhamurthy in the Department of Applied Mechanics
Fate and Transport of Non Aqueous Phase Liquids (NAPLs) under environments of moisture cycling
(drying and rewetting) in Earthen Porous Media
Redistribution of NAPL due to Water Evaporation
Many contaminated earthen porous media (such as soils, dredged materials, sludges) may contain a significant amount of non aqueous phase liquids (NAPLs), which are often mixtures of several organic compounds. Often these are present in addition to other organic pollutants as well. Since these porous media are exposed to air, they can potentially undergo drying (due to evaporation) and rewetting (due to rain). In preliminary experiments conducted in the laboratory, it was observed that the NAPL phase undergoes redistribution under conditions of water evaporation. This redistribution (or spreading) is significantly higher than that observed due to normal capillary rise. The fate and transport of the NAPL bulk phase under these conditions can be important in understanding the fate and transport of individual constituents present in the porous media. Characterisation of the fate and transport of the individual solutes require the realistic prediction of the NAPL bulk phase transport. The objective of this project are to characterise the NAPL bulk phase transport as a function of different rates of drying, NAPL and soil characteristics. A non-invasive technique – magnetic resonance imaging (MRI) in collaboration with Prof. Chandrakumar (Chemistry) at the IIT-Madras MRI center was also used to assess the 3-d imaging of this transport. This project was funded by SERB-DST with Co-PIs – Prof. Chandrakumar (Chemistry) and Prof. Abhijit Deshpande (Chemical Engineering) (2016-2022).
National Carbonaceous Aerosol Program (NCAP) – IITM is an Associate Institution in the Consortia of several Institutes in India led by IIT Bombay. (Co-Coordinators in IITM – Dr. S. M. Shiva Nagendra and Dr. Sachin Gunthe – Civil Engg., IIT-Madras) (2017-2024) The objectives of the program and our role are • Developing a national carbonaceous aerosol emission inventory. • Field emission factor measurement in four major sectors – Residential (cooking and lighting), Transport (diesel), Agriculture (field burning), Informal industry (brick production). • PMF modelling for quantitative source apportionment of carbonaceous aerosols. • Regional chemical transport modelling with the India carbonaceous aerosol emission inventory for quantitative estimation of carbonaceous aerosol source contribution. • Obtain reconciliation of carbonaceous aerosol sources through top-down and bottom-up approaches at limited locations to evaluate and correct the emission inventory. • Understanding climate and clean air impact of carbonaceous aerosols through regional climate modelling. • Understanding influence of carbonaceous aerosols, on clouds and rainfall, through multi-scale models and general circulation modelling. This project has been funded by the Ministry of Environments and Forest – Climate Change Division (Government of India).
The objective is to study photocatalytic degradation of organic wastes using mixtures of carbon and titania. One of the applications for this is to explore the photocatalytic regeneration of spent activated carbon using titania embedded with the carbon. This problem has several engineering challenges including those of mass transfer, catalyst illumination and configuration of the carbon-titania mixture that need resolution. Laboratory experiments as well as modeling studies are being explored to study this.
Contaminated sediments in rivers, lakes and coastal regions are a source of chemical release to the overlying water and possible to air. General research interest is in the various aspects associated with the prediction of the fate and transport of chemicals a) within contaminated sediments and across the sediment-water interface and b) during various remedial options such as dredging, capping and monitored natural recovery. There is specific interest in the measurement and modeling of chemical release during dredging and post-dredging operations. One of the research interests in this area is to develop a model to take into account the effect of particle-size dependent contaminant loading in the bed sediment and the consequences to contaminant fate and transport during dredging-induced resuspension.