Dr. Siddhant Dash
Brief Details:
Graduated
in Civil Engineering from Veer Surendra Sai University of Technology Burla in
2014, I obtained my M. Tech and Ph.D. in Environmental Engineering from
Visvesvaraya National Institute of Technology (VNIT) Nagpur and Indian
Institute of Technology (IIT) Guwahati in 2017 and 2022, respectively.
Currently, I am undergoing my Postdoc Research at the Water Science and
Technology Division of the School of Engineering and Sciences at Tecnológico de
Monterrey, Mexico. I also serve as an Assistant Professor in the Department of
Civil Engineering at SRM University – A.P. (currently on-lien). My
research interests include, but are not limited to, aquatic toxicology,
surface and groundwater quality modelling, emerging contaminants, soil
contamination and its assessment, sedimentology, carbon and nutrient cycle in
the aquatic ecosystem, carbon sequestration potential of water bodies, water
and wastewater treatment, and environmental systems modelling. My research
outputs include 17 journal publications, 5 book chapters and 1
book. In addition to this, I have been awarded with best paper awards in
different conferences and was also the recipient of the prestigious Water
Advanced Research and Innovation (WARI) Fellowship, supported by the
Department of Science and Technology, Govt. of India, the University of
Nebraska-Lincoln (UNL), the Daugherty Water for Food Institute (DWFI) and the
Indo-US Science and Technology Forum (IUSSTF) for the year 2019-2020. I also
have a hand-on experience in different consultancy projects, and have attended
several workshops and seminars. Additional responsibilities include organizing
conferences at both national and international levels, and being a
peer-reviewer for several international journals. I embrace every research and
teaching opportunity that I can find, and I have worked enthusiastically and
effectively with students at various levels.
Vanishing wetlands have been a matter of grave concern to researchers worldwide
in recent decades. The chief reason for such a situation has been human
interventions through rapid changes in land-use patterns. With the continuation
of this scale of wetlands' deterioration, the shift in the natural world
balance is inevitable, given the various significant roles the wetlands play in
keeping the natural ecosystem in balance. The only option by which this may be
avoided is through sustainable measures of conserving the wetlands. This comes
through comprehensive yet effective monitoring programs that help understand
the symbiotic functioning of the wetland components.
This doctoral
research thesis presents and discusses the limnology of wetlands, thereby
attempting to understand the dynamic physico-chemical and biotic responses to
the anthropogenic contaminations within their ecosystems. Deepor Beel (a site
under the list of Ramsar sites) has been considered, owing to its rapid
anthropogenic deterioration in recent times. Although a Ramsar site, no proper
conservation measures have been carried out, making it highly vulnerable to
contamination. In the first stage, a reconnaissance survey was carried out.
Sampling locations for water, sediment, water hyacinth (representative of the
floral element), and three indigenous fish species were fixed. Twenty-three
sampling locations were identified for collecting water and sediment (abiotic)
samples. For collecting the fish and water hyacinth (biotic) samples, the
wetland was divided into three zones, based on the proximity to the pollution sources.
Comprehensive monitoring of all the components was carried out every month,
ranging from October 2017 to February 2019. Additional data such as rainfall,
evaporation, transpiration, discharge, etc., were also obtained.
To understand
the dynamics of responses of various components to different anthropogenic
contaminations, the present research was conducted involving five distinct
objectives. The first step involved identifying various latent pollution
sources and quantifying their contribution to the wetland contamination. For
this purpose, four Environmetrics tools, i.e., hierarchical cluster analysis
(HCA), discriminant analysis (DA), principal component analysis (PCA), and
positive matrix factorization (PMF), were employed. HCA categorized the sampling
locations into statistically significant clusters; DA helped identify the
parameters responsible for discrimination of the sampling locations; PCA helped
identify probable pollution sources through its component loadings; finally,
PMF quantified the significant factors of Deepor Beel's contamination.
Following
this, the second step was to assess the impacts of these sources on the water
body's health—this required evaluation of both water and sediment quality. For
the assessment of water quality, objective-based indexing techniques were
adopted. Two novel indexing approaches, one each for short-term and long-term
monitoring programs, and different end-uses of water were proposed. For
short-term programs, the use of multivariate statistics, i.e., the use of HCA
and PCA deemed more suitable. On the contrary, the modified entropy-weighted
approach proved highly reliable and efficient for long-term programs. Both
methods were checked for their reliability and correctness through sensitivity
analysis and were found to be better than the existing approaches.
For assessing
the sediment quality, various indices such as contamination factor (CF),
pollution load index (PLI), enrichment factor (EF), and the geo-accumulation
index (Igeo) were
employed. Results showed that Deepor Beel is most affected in the post-monsoon
season, compared to other seasons. At the same time, the monsoon remains the
best. The potential ecological risk of contaminants further displayed that the
post-monsoon period has the most significant number of sites under the moderate
risk category. The chemical speciation studies of seven heavy metals (Cr, Cd,
Fe, Mn, Cu, Pb and Mg) were conducted to determine their available forms in the
sediment column. Cd, Mn, and Mg were observed to profoundly negatively impact
aquatic ecology (available in F1 fraction in higher percentages). While Fe was
predominant in reducible (F3) form, Cr, Cu, and Pb had equal contributions from
reducible and oxidizable (F3 and F4, respectively) forms. The sediment samples were
further subjected to elemental analysis; X-ray powder diffraction (XRD)
followed by Scanning Electron Microscope-Energy Dispersive X-Ray Spectroscopy
(SEM-EDS), to determine the elemental composition and forms of heavy metals
present in the sediment columns from various parts of the wetland. Sediment
sample collected from the proximity of the landfill site was observed to be
affected the most, primarily due to leaching of heavy metals from the landfill.
However, the central zone was found to be devoid of any anthropogenic
contaminations, while the sediment column near the industrial complex was found
to be contaminated to a moderate extent.
Furthermore,
an investigation was carried out correlating the heavy metal contamination, its
distribution, and the human health risk associated with different aquatic
ecosystem components. For this purpose, water, sediment, and fish samples
(three species, notably Notopterus
notopterus, Clarias batrachus, and
Channa striata) from Deepor Beel were considered, and their heavy metal
contamination and distribution were determined. The corresponding health risks
(carcinogenic and non-carcinogenic) due to prolonged exposure levels were
evaluated for six different heavy metals; Cr, Cd, Fe, Mn, Cu, and Pb. Results
indicated that Pb and Mn significantly impacted the non-carcinogenic human
health risks concerning the water column. For all three components, children
were found to have considerably higher effects (both carcinogenic and
non-carcinogenic) of prolonged exposure to contamination than adults. Finally,
it was observed that the sediment column substantially contributed to the
bioaccumulation factor in the fish biota compared to the water column.
The final
study encompassed formulating a eutrophication-based ecological model,
assisting in determining the nutrient dynamics of the Deepor Beel ecosystem,
thereby providing an idea of the significant causative parameters aiding
eutrophication. A conceptual diagram was first constructed, and the
corresponding differential equations about different functions were formulated.
Subsequently, a code was developed in MATLAB based on the logic formulated
through the conceptual diagram. Sensitivity analysis was first performed on
various state variables, identifying the most sensitive parameters and
exhibiting maximum variability in the model. The model was then subjected to
calibration for defining the rate constants, which were further validated.
Finally, the model was simulated for two plausible management options to curb
the eutrophication levels in Deepor Beel; (i) Harvesting of water hyacinths and
(ii) Setting up a treatment unit for nitrogen and phosphorus removal. The
results obtained for both cases indicated that harvesting of water hyacinths
would not provide a suitable long-term and effective solution. However, setting
up a treatment unit for phosphorus and nitrogen removal can significantly
reduce the nutrient levels in the wetland, thereby assisting in curbing the
eutrophication levels.
Based on this investigation, it is anticipated that incorporating these researches will pave the way for a more sustainable future by protecting Deepor Beel and our other natural wetlands from plausible future degradation.
Keywords: wetlands; environmetrics tools; water quality indices; sediment quality;
heavy metals; toxicity and bioavailability assay; nutrient dynamics; ecological
model
Teaching: Urban Sanitation – Wastewater Engineering
With the
growing urban population, sewage generation has become a major concern. As per
the latest data released by the Central Pollution Control Board (CPCB), sewage
generation from urban centers are estimated as 72,368 MLD. To tackle such
humongous quantity, there are 1,631 STPs (including proposed STPs) with a total
capacity of 36,668MLD covering 35 States/UTs. Out of 1,631 STPs, 1,093 STPs are
operational, 102 are Non-operational, 274 are under construction and 162 STPs
are proposed for construction. Even with such progress, only an estimated 30%
of the sewage generated from the urban sources are actually treated prior to
discharging into the receiving water bodies.
Therefore, on the 1st of
October 2021, the Government of India launched its second phase of the Swachh
Bharat Mission for the urban population. The prime objectives that were
included other than sustainable solid waste management were sustainable
sanitation and treatment of used water. Hence, it is essential that we
understand the importance of urban sanitation and treatment of wastewater
through an urban context.
When it comes to urban sanitation,
there is a significant concern of handling a large volume of sewage that
eventually flows into the receiving environment, such as rivers, lakes,
wetlands, seas, etc. As a result, the surface water bodies tend to deteriorate
significantly over a period of time, thereby giving rise to serious water
security concerns. Hence, to avoid such scenarios to occur in the future, the
treatment of the sewage to levels where they can be discharged into the
receiving environment without posing any detriment to them is inevitable. So,
the question arises, “How the treatment process works, such that it converts
something as foul as sewage into a product without which sustenance of life on
this planet is not possible?”
This seminar presents a brief
understanding of the status of the sewage treatment plants in Indian urban
centers, the need for a sewage treatment unit and the various unit operations
and unit processes involved in a conventional sewage treatment unit. In
addition to this, the various factors essential for influencing the decisions
for implementation of a treatment unit and the concerning elements in the
present and future scenarios are discussed. Through this seminar, it is
anticipated that the audience will have an overview of understanding the
engineering aspects of wastewater treatment.
Keywords: urban sanitation; sewage treatment; sustainability
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