Namita Shrestha
South Dakota School of Mines and Technology
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Publication
Featured researches published by Namita Shrestha.
Bioelectrochemistry | 2016
Namita Shrestha; Alex Fogg; Joseph Wilder; Daniel Franco; Simeon Komisar; Venkataramana Gadhamshetty
The United States faces a significant burden in treating 0.61billionkg of defective tomatoes (culls) every year. We present a proof-of-concept for generating electricity from culled tomatoes in microbial-electrochemical systems (MESs). This study delineates impedance behavior of the culled tomatoes in MESs and compares its impedance spectra with that of soluble substrates (dextrose, acetate, and wastewater). A series of AC and DC diagnostic tests have revealed the superior performance of the culled tomatoes compared to the pure substrates. Cyclic voltammetry results have indicated the active role of indigenous, diffusible redox-active pigments in the culled tomatoes on overall electricity production. Electrochemical impedance spectroscopy results have elucidated the role of peel and seed on the oxidation behavior of the culled tomatoes.
Bioresource Technology | 2018
Namita Shrestha; Govinda Chilkoor; Bhuvan Vemuri; Navanietha Krishnaraj Rathinam; Rajesh K. Sani; Venkataramana Gadhamshetty
Extremophiles, notably archaea and bacteria, offer a good platform for treating industrial waste streams that were previously perceived as hostile to the model organisms in microbial electrochemical systems (MESs). Here we present a critical overview of the fundamental and applied biology aspects of halophiles and thermophiles in MESs. The current study suggests that extremophiles enable the MES operations under a seemingly harsh conditions imposed by the physical (pressure, radiation, and temperature) and geochemical extremes (oxygen levels, pH, and salinity). We highlight a need to identify the underpinning mechanisms that define the exceptional electrocatalytic performance of extremophiles in MESs.
Bioresource Technology | 2018
Saurabh Sudha Dhiman; Namita Shrestha; Aditi David; Neha Basotra; Glenn R. Johnson; Bhupinder Singh Chadha; Venkataramana Gadhamshetty; Rajesh K. Sani
Residual solid and liquid streams from the one-pot CRUDE (Conversion of Raw and Untreated Disposal into Ethanol) process were treated with two separate biochemical routes for renewable energy transformation. The solid residual stream was subjected to thermophilic anaerobic digestion (TAD), which produced 95 ± 7 L methane kg-1 volatile solid with an overall energy efficiency of 12.9 ± 1.7%. A methanotroph, Methyloferula sp., was deployed for oxidation of mixed TAD biogas into methanol. The residual liquid stream from CRUDE process was used in a Microbial Fuel Cell (MFC) to produce electricity. Material balance calculations confirmed the integration of biochemical routes (i.e. CRUDE, TAD, and MFC) for developing a sustainable approach of energy regeneration. The current work demonstrates the utilization of different residual streams originated after food waste processing to release minimal organic load to the environment.
Bioelectrochemistry | 2018
Namita Shrestha; Govinda Chilkoor; Joseph Wilder; Zhiyong Jason Ren; Venkataramana Gadhamshetty
This study evaluates and compares the performance of microbial fuel cells (MFCs) and microbial capacitive deionization cells (MCDCs) fed with wastewater produced from the Bakken shale. The produced water was characterized by high levels of dissolved solids and chemical oxygen demand (COD). Two-compartment MFCs and three-compartment MCDCs were evaluated under batch-fed mode using mixed microbial consortia in the anode, ferricyanide in the cathode, and produced water as the electrolyte in the anode and capacitive deionization units. COD removal in the MFCs was 88%, while that in the MCDCs was limited to 76%. The lower performance of the MCDCs was due to the large impedance (6600 Ω cm2) compared with the MFCs (870 Ω cm2). However, the MCDCs achieved two-fold higher removal of dissolved solids. Both the MFCs and MCDCs suffered from a higher impedance induced by fouling in the latter stages of the operation.
ACS Nano | 2018
Govinda Chilkoor; Sushma Priyanka Karanam; Shane Star; Namita Shrestha; Rajesh K. Sani; Venkata Krishna Kumar Upadhyayula; Debjit Ghoshal; Nikhil Koratkar; M. Meyyappan; Venkataramana Gadhamshetty
We report the use of a single layer of two-dimensional hexagonal boron nitride (SL-hBN) as the thinnest insulating barrier to microbial corrosion induced by the sulfate-reducing bacteria Desulfovibrio alaskensis G20. We used electrochemical methods to assess the corrosion resistance of SL-hBN on copper against the effects of both the planktonic and sessile forms of the sulfate-reducing bacteria. Cyclic voltammetry results show that SL-hBN-Cu is effective in suppressing corrosion effects of the planktonic cells at potentials as high as 0.2 V ( vs Ag/AgCl). The peak anodic current for the SL-hBN coatings is ∼36 times lower than that of bare Cu. Linear polarization resistance tests confirm that the SL-hBN coatings serve as a barrier against corrosive effects of the G20 biofilm when compared to bare Cu. The SL-hBN serves as an impermeable barrier to aggressive metabolites and offers ∼91% corrosion inhibition efficiency, which is comparable to much thicker commercial coatings such as polyaniline. In addition to impermeability, the insulating nature of SL-hBN suppresses galvanic effects and improves its ability to combat microbial corrosion.
Bioresource Technology | 2017
Saurabh Sudha Dhiman; Aditi David; Namita Shrestha; Glenn R. Johnson; Kenneth M. Benjamin; Venkataramana Gadhamshetty; Rajesh K. Sani
The one-pot CRUDE (Conversion of Raw and Untreated Disposal into Ethanol) process was developed for simultaneous hydrolysis and fermentation of unprocessed food waste into ethanol using thermophilic (growing at 65°C) anaerobic bacteria. Unlike existing waste to energy technologies, the CRUDE process obviates the need for any pre-treatment or enzyme addition. A High-Temperature-High-Pressure (HTHP) distillation technique was also applied that facilitated efficient use of fermentation medium, inoculum recycling, and in-situ ethanol collection. For material balancing of the process, each characterized component was represented in terms of C-mol. Recovery of 94% carbon at the end confirmed the operational efficiency of CRUDE process. The overall energy retaining efficiency calculated from sugars to ethanol was 1262.7kJdryweightkg-1 of volatile solids using HTHP. These results suggest that the CRUDE process can be a starting point for the development of a commercial ethanol production process.
Journal of Professional Issues in Engineering Education and Practice | 2016
Venkataramana Gadhamshetty; Namita Shrestha; James E. Kilduff
AbstractThe National Academy of Engineering has called for the reinvention of engineering education by exposing students to the iterative process of designing, predicting performance, building, and testing; incorporating research into engineering education; and introducing interdisciplinary learning in the undergraduate environment. Here we describe a novel effort to integrate an undergraduate research project into the problem-based design environment of a second-year introduction to engineering design course at Rensselaer Polytechnic Institute, providing a design and research experience early in the curriculum. The project-based environment allows students to learn technical communication (technical writing and oral presentations) and teamwork (including conflict management and team coordination) in parallel. Approximately 600 sophomores from different science, technology, engineering, and mathematics (STEM) disciplines take the course, working in multidisciplinary teams to address a complex challenge fa...
Water Research | 2017
Namita Shrestha; Govinda Chilkoor; Joseph Wilder; Venkataramana Gadhamshetty; James J. Stone
Archive | 2015
Venkataramana Gadhamshetty; Namita Shrestha; Govinda Chilkoor; Jejal Reddy Bathi
Water Research | 2017
Namita Shrestha; Govinda Chilkoor; Lichao Xia; Catalina Alvarado; James E. Kilduff; John J. Keating; Georges Belfort; Venkataramana Gadhamshetty