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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Preethi Konkathi L. Karthikeyan Centre of Studies in Resources Engineering Indian Institute of Technology Bombay Mumbai India Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai India

Vegetation optical Depth (VOD) obtained from low-frequency passive microwave radiometers aid in estimation of Vegetation Water Content (VWC) and Above Ground Biomass (AGB) at global scales. Recent studies have focused on simultaneous retrieval of soil moisture and VOD while using temporally constant model parameterizations (single scattering albedo-ω which represents vegetation scattering effects; surface roughness-h which accounts for soil surface undulations). In the case of VOD retrievals, the assumption of temporally constant model parameterizations may lead to improper representation of vegetation dynamics given the strong association between ω and VOD in Radiative Transfer Models (RTMs). In this study, we attempt to retrieve temporally varying VOD and ω along with temporally constant h parameter while inputting soil moisture using L-band Soil Moisture Active Passive (SMAP) Level-3 Product. We used the Two-Stream emission model, a first-order RTM that accounts for multiple scattering and reflections within an RTM. The retrieved VOD and ω are compared with optical vegetation indices and SMAP baseline VOD product (regularized DCA- regularized Dual Channel Algorithm). The lagged relationship of retrieved VOD and SMAP VOD with optical indices is also determined. We conducted sensitivity analysis to determine the effect of ω dynamics while retrieving VOD. We observed a large error in VOD retrievals while changing ω especially over low to moderate vegetated regions where vegetation phenology is subjected to greater variability. We found the retrieved VOD estimates to outperform the SMAP VOD in terms of correlation (R). The retrieval of dynamic ω helped to resolve errors in VOD, resulting in good correspondence with vegetation growth patterns compared to SMAP baseline VOD retrievals.

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Study of bioaerosol disinfection kinetics and application of nonlinear regression modeling for optimization of TiO2-based photocatalytic disinfection process

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Nanotechnology for Environmental engineering 2023年第4期8卷 911-922页

作者： Nishad, Vartika Mandal, Chinmoy Sahu, Manoranjan Aerosol and Nanoparticle Technology Laboratory Environmental Science and Engineering Department Indian Institute of Technology Bombay 507 Powai Mumbai400076 India Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai400076 India Centre for Machine Intelligence and Data Science Indian Institute of Technology Bombay Mumbai400076 India

Bacteria and viruses are some of the major sources of indoor air pollution. Many strategies are utilized to control indoor biopollutants. Among the new emerging technologies, this work focuses on the photocatalytic oxidation process and application of disinfection models to optimize the photocatalytic process in bioaerosol control. The kinetics of bioaerosol disinfection was investigated in the photocatalytic process with nonlinear regression analysis for Serratia marcescens and E. coli bacteria. The Chick–Watson model was found suitable and was applied for determination of the inactivation kinetics. The inactivation rate constant k’ was found to be 0.0038 min−1 for S. marcescens and 0.09 min−1 for E. coli. The outcomes showed that in the process of disinfection kinetics of bioaerosols, pseudo-first-order kinetics fits well. With nonlinear regression analysis, a model was developed based on functional parameters such as UV intensity (20 to 100 W/m2), relative humidity (30 to 85%) and air velocity (37 to 112 ft/min) for S. marcescens and TiO2 loading (960 and 1516 mg/m2), UV intensity (0.5 to 3.4 mW/cm2) and relative humidity (51 to 85%) for E. coli. For E. coli overall inactivation was found to increase with an increase in TiO2 loading, RH or UV intensities. The inactivation rate of S. marcescens increased with an increase in UV intensity;however, it was found to decrease at very high or low values of relative humidity and air velocity. Hence, the optimum values for relative velocity were found to be 50% and air velocity of 74 ft/min for S. marcescens. The rate expressions derived for both data can be utilized for predicting and optimizing the disinfection rate at different conditions. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

关键词： Titanium dioxide

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Impact of spatial distribution of light intensity on disinfection kinetics of Mycobacterium smegmatis and E. coli using TiO2-based photocatalyst

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Nanotechnology for Environmental engineering 2023年第2期8卷 567-579页

作者： Mandal, Chinmoy Nishad, Vartika Sahu, Manoranjan 507 Aerosol and Nanoparticle Technology Laboratory Environmental Science and Engineering Department Indian Institute of Technology Bombay Powai Mumbai400076 India Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai400076 India Centre for Machine Intelligence and Data Science Indian Institute of Technology Bombay Mumbai400076 India

Photocatalysis using various nanomaterials of different characteristics has been investigated with various metrics for achieving optimal efficiency. However, the spatial distribution of light intensities from the light source, a key factor in photocatalysis process and the selection of an appropriate kinetic model for explaining disinfection characteristics of different microorganisms have not been given ample consideration. In this study, a suitable model has been applied to identify spatial distribution of light based on the light source used and applied in the kinetic models to identify the disinfection rate. Disinfection efficiencies of nanoparticles (TiO2 and Cu-doped TiO2) with different light intensities on gram-positive bacteria, Mycobacterium smegmatis and gram-negative bacteria E. coli was evaluated. The kinetic study revealed that Mycobacterium smegmatis fits well with Chick–Watson model, while E. coli fits well with delayed Chick–Watson model. The rate constants (k) were found to be 0.013 min−1 (TiO2), 0.021 min−1 (3%Cu–TiO2) and 0.020 min−1 (Cu2+) for Mycobacterium and 0.019 min−1 (TiO2) for E. coli. From model evaluation, light intensity decreased exponentially from 3.07 µW cm−2 (3 cm) to 0.98 µW cm−2 (6 cm) and 0.10 µW cm−2 (25 cm) resulting in a sharp decline in the inactivation potential;however, the effect was insignificant beyond 10 cm. On doubling the intensity, disinfection efficiency increased by 1.6 log CFUml−1 (TiO2) and 2.4 log CFU ml−1 (Cu–TiO2), but with one-fourth of intensity it decreased by 1.2 log CFUml−1 (TiO2) and 1.8 log CFUml−1 (Cu–TiO2). Therefore, by optimizing the combination of nanoparticles like TiO2 and Cu, light intensity at 6.14 µW cm−2 and optimal spatial distribution of the light source at 3 cm, increased efficiency of microbial disinfection could be achieved. Thus, this study provides an approach to optimize photocatalytic parameters with inclusion of spatial distribution of light intensity for enhancing the photocatalyt

关键词： Titanium dioxide

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Comparative Study of Testing Indigenous Air Filters for Fine PM Removal 1st

Comparative Study of Testing Indigenous Air Filters for Fine...

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1st International Conference on Pollution Control for Clean Environment, ICPCCE 2023

作者： Nawale, Prashant Sahu, Manoranjan Aerosol and Nanoparticle Technology Laboratory Environmental Science and Engineering Department Indian Institute of Technology Bombay Mumbai400076 India Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai400076 India Centre for Machine Intelligence and Data Science Indian Institute of Technology Bombay Mumbai400076 India

ISBN: (纸本)9789819778454

Air pollution has become a serious global issue, which has significant impacts on both human health and the environment. Over the past decade, air quality has deteriorated due to various anthropogenic activities including construction, urbanization and industrialization. These activities release hazardous particles and harmful gases into the atmosphere, contributing to poor air quality. Developing countries such as India have been particularly affected, with some of their cities among the most polluted worldwide. To address this serious concern, it is imperative to develop and implement air pollution control technologies for both indoor and outdoor environments. This study focuses on the structured investigation of the performance of locally available air filter media in terms of their removal efficiency for submicron and micron-size particles. Various indigenous air filter media are subjected to rigorous testing to evaluate their overall and size-specific filtration efficiency and corresponding differential pressure drop. The results of these performance evaluations are then compared to their effectiveness in removing coarse and fine particles from the air. This research aims to provide valuable insights into the development of effective air filtration systems to combat air pollution. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.

关键词： Air filters Air pollution control technology Air purification Coarse PM Fine PM

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Development of high-accuracy particle concentration prediction model. An application of remote sensing and machine learning 18

Development of high-accuracy particle concentration predicti...

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18th Healthy Buildings Europe Conference 2023: Beyond Disciplinary Boundaries

作者： Moni, Mufaddal Sahu, Manoranjan Aerosol and Nanoparticle Technology Laboratory Environmental Science and Engineering Department Indian Institute of Technology Bombay Mumbai400076 India Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai400076 India Centre for Machine Intelligence and Data Science Indian Institute of Technology Bombay Mumbai400076 India

ISBN: (纸本)9781713877158

Indoor air is a dominant exposure for humans as more than half of the body’s intake during a lifetime is air inhaled indoors. Most of the buildings in developing nations are openly ventilated, and there is no significant difference between the outside and indoor air. Efforts are being made by authorities to build well-controlled indoor environments. The lack of air pollution monitoring systems is one of the major challenges in identifying high-risk zones where the development of healthy buildings is critical. Ground-based monitoring systems are sparsely distributed in major cities only. Whereas low-cost sensors come with challenges related to calibration, accuracy, and reliability. Satellites provide continuous global coverage with high-resolution AOD data. Though significant work has been done correlating AOD and PM2.5, still the models lack accuracy and transferability. The vertical distribution profile of the aerosols significantly affects the surface level concentration which is not accounted for by the majority of the studies done for AOD-PM2.5 modeling. This study emphasizes the use of high-resolution AOD from CHRISTINE code and aerosol vertical distribution profile, along with meteorological parameters and factors affecting particle size distribution, to develop a step-down methodology for more accurate PM2.5 prediction and transferable a larger geographical range. © Healthy Buildings Europe 2023. All rights reserved.

关键词： Air quality

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Flood Modelling for an Urban Indian Catchment: Challenges and Way Forward

Flood Modelling for an Urban Indian Catchment: Challenges an...

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Virtual Conference on Disaster Risk Reduction, VCDRR 2021

作者： Ghosh, Mousumi Karmakar, Subhankar Ghosh, Subimal Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai400076 India Environmental Science and Engineering Department Indian Institute of Technology Bombay Mumbai400076 India Centre for Urban Science and Engineering Indian Institute of Technology Bombay Mumbai400076 India Department of Civil Engineering Indian Institute of Technology Bombay Mumbai400076 India

ISBN: (纸本)9789811655005

The current study aims to develop a holistic hydrodynamic flood modelling framework for the Mithi catchment of Mumbai city, India, which is subjected to flooding almost every year causing huge losses and inconvenience. A one-dimensional flood model (MIKE 11) which accounts for the river discharge along with stormwater drainage discharge is coupled with a two-dimensional flood model (MIKE 21) which simulates the overland flow in the MIKE FLOOD platform along with the major flood influencers such as rainfall and tidal elevation to develop a three-way coupled flood modelling framework. The flood parameters obtained from this framework are translated into flood inundation maps which account for flood depth and flood hazard maps which account for flood depth along with spatial velocity and can help to identify the potential areas at risk. However, hydrodynamic flood modelling is highly data-intensive and requires good resolution meteorological, hydraulic, and topographical data sets. Therefore, the unavailability of long-term and reliable data sets in developing and underdeveloping countries cause a major hindrance for modelling in such catchments. The current study also adapts alternate robust methods to address the challenge of data scarcity of rainfall, discharge, tidal elevation, and drainage network. The proposed framework and methods are generic and can be incorporated in similar data-scarce urban catchments for effective flood management. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Hydrodynamics

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Performance Evaluation of Sulfidated Nanoscale Iron for Hexavalent Chromium Removal from Groundwater in Sequential Batch Study

SSRN

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SSRN 2023年

作者： Bhattacharya, Mainak Barbhuiya, Najmul Haque Singh, Swatantra Pratap Environmental Science and Engineering Department Indian Institute of Technology Bombay Mumbai India Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai400076 India Centre for Research in Nanotechnology & Science Indian Institute of Technology Bombay Mumbai400076 India

Chromium [Cr] contamination in groundwater is one of the serious environmental concerns due to the carcinogenicity of its water-soluble and mobile hexavalent [Cr(VI)] form. In spite of the existence of multiple precipitation and adsorption-based Cr(VI) remediation technologies, the usage of sulfidated nano zerovalent iron (S-nZVI) has recently attracted researchers due to its high selectivity. Although S-nZVI effectively immobilized Cr(VI), its long-term performance in multiple shifted equilibrium has not been explored. In this contribution, a comparative study between conventional nano zerovalent iron (nZVI) and S-nZVI was conducted to investigate their respective efficiencies during repeated usage. First, influences of S-nZVI dosage, initial concentration of Cr(VI), pH, ionic strength, total hardness, sulfate, carbonate, and silicate were probed in ultrapure water. Further experiments were performed in synthetic groundwater to investigate the effects of the initial concentration of Cr(VI) in the pH range of 4 – 8 for 1 g L-1 S-nZVI dosage. The removal rate of Cr(VI) was quantified in groundwater without pH fixation. Finally, a set of sequential batch studies was performed to compare the performance of nZVI and S-nZVI due to repeated usage in Cr(VI)-spiked ultrapure water and groundwater matrices. Mechanistic interpretation of the processes governing the immobilization of Cr(VI) was done by integrating the results of these experiments with the metadata. While aggregation due to magnetic properties and rapid oxidation of Fe decreased the efficiency of nZVI with repeated usage, sulfidation minimized the passivation and favored an extended reducing environment because of continuous electron transfer from iron and sulfur components. © 2023, The Authors. All rights reserved.

关键词： Groundwater

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Long-Term Performance of Sulfidated Nanoscale Iron for Hexavalent Chromium Removal from Groundwater in Sequential Batch Study

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SSRN 2023年

Chromium [Cr] contamination in groundwater is one of the serious environmental concerns due to the carcinogenicity of its water-soluble and mobile hexavalent [Cr(VI)] form. In spite of the existence of multiple precipitation and adsorption-based Cr(VI) remediation technologies, the usage of sulfidated nano zerovalent iron (S-nZVI) has recently attracted researchers due to its high selectivity. Although S-nZVI has been proven to be effective towards Cr(VI) immobilization, its long-term performance in groundwater matrix has not been explored. In this contribution, a comparative study between conventional nano zerovalent iron (nZVI) and S-nZVI was conducted to investigate their respective efficiencies due to repeated usage. First, influences of S-nZVI dosage, initial concentration of Cr(VI), pH, ionic strength, total hardness, sulfate, carbonate, and silicate were probed in ultrapure water. Further experiments were performed in synthetic groundwater to investigate the effects of the initial concentration of Cr(VI) in the pH range of 4 – 8 for 1 g L-1 S-nZVI dosage. The removal rate of Cr(VI) was quantified in groundwater without pH fixation, following the second-order reaction kinetics. Finally, a set of sequential batch studies was performed to compare the performance of nZVI and S-nZVI due to repeated usage in Cr(VI)-spiked ultrapure water and groundwater matrices. Mechanistic interpretation of the processes governing the immobilization of Cr(VI) was done by integrating the results of these experiments with the metadata. While aggregation due to magnetic properties and rapid oxidation of Fe decreased the efficiency of nZVI with repeated usage, sulfidation minimized the passivation and favored an extended reducing environment because of continuous electron transfer from Fe and S. © 2023, The Authors. All rights reserved.

关键词： Groundwater

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Design, Development and Performance Evaluation of a Miniature Electrostatic Precipitator in an Indoor Environment

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SSRN 2024年

作者： Kumar, Aiswarya Nawale, Prashant Rohidas Sahu, Manoranjan Aerosol and Nanoparticle Technology Laboratory Environmental Science and Engineering Department Indian Institute of Technology Bombay Mumbai400076 India Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai400076 India Centre for Machine Intelligence and Data Science Indian Institute of Technology Bombay Mumbai400076 India

Different PM capture technologies are available in market as well as on lab scale, they pose several drawbacks. Therefore, a miniature ESP was designed in laboratory and operated at optimal operating conditions to obtain maximised capture of PM. Results from study confirmed that designed ESP was capable of capturing various standard aerosol, major indoor sources and infiltrated PM with a total removal efficiency of 97.87% to 99.97% in PM sizes from 10 nm to 800 nm. Additionally, energy consumed/clean air delivery rate and emission of by-products were found to be comparatively lesser compared to commercial purifiers. © 2024, The Authors. All rights reserved.

关键词： Electrostatic precipitators

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Hexavalent Chromium Remediation Using Single-Step Synthesized Sulfidated Nanoscale Iron Particles Modified Kaolin

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SSRN 2023年

The occurrence of dissolved hexavalent chromium [Cr(VI)] in freshwater systems is a serious environmental hazard because of its high toxicity. Although different types of nZVI effectively removed Cr(VI), performance evaluation of nZVI modified with a suitable clay adsorbent—kaolinite—was not thoroughly studied. In the present research, kaolin was modified with nZVI (K-nZVI) and SnZVI (K-SnZVI) at two different kaolin to iron mass ratios (kaolin: Fe) to remove Cr(VI) under varying geochemical conditions. Both K-nZVI and K-SnZVI were synthesized by a simple one step process, avoiding complicated synthesis protocols of modified nZVI mostly reported in the literature. Usage of Fe in the nanoparticles was minimized by increasing the kaolin: Fe ratio, and effects of ionic strength of the background solution, pH, major cations, and anions in Cr(VI) remediation efficiencies were probed. Kinetics of Cr(VI) removal by K-nZVI and K-SnZVI were quantified from sacrificial batch studies. The uptake of Cr(VI) by K-nZVI and K-SnZVI was fitted to the Freundlich isotherm model. With maximum Cr(VI) remediation efficiencies of 100% and 98% in synthetic groundwater contaminated with 2 - 100 mg L-1 Cr(VI). Using kaolin, an analog of the naturally available kaolinite clay, with relatively decreased Fe content in the nanoparticles, would also aid in reducing the treatment cost. © 2023, The Authors. All rights reserved.

关键词： Groundwater

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