Ehly Hall 114
M.S. Environmental and Conservation Sciences
Minors in Microbiology and Chemistry
As part of my doctorate I am studying biodegradability and mineralization of dissolved organic nitrogen (DON) by heterotrophic bacteria. DON is ubiquitously found in the environment and is essential part of the nitrogen cycle. Wastewater treatment plant effluent and agricultural run-off are two of the major sources for DON in the environment. The complex composition of the DON pool is not completely characterized. One of the major concerns associated with DON is its ability to support growth of microorganisms in the rivers, lakes and other water bodies. DON can also support biological growth, and react with disinfectants to form carcinogenic disinfection byproducts, in drinking water.
Biodegradable DON, also known as BDON, forms a large fraction of DON which can either be assimilated by microorganisms or be mineralized into dissolved inorganic nitrogen (DIN). In both natural and artificial environments, mixed cultures of heterotrophic and nitrifying bacteria work in a consortium to consume both DON and DIN. Role of nitrifying bacteria and the mechanism of nitrification has been very well studied. However, very few studies have investigated the role played by heterotrophic bacteria in the environment to biodegrade and/or minerlize DON. It is important to investigate the ability of heterotrophic bacteria in consuming DON to better understand the nitrogen cycle and treatment treatment process.
In a separate project, unrelated to my Ph.D. research, I am studying the fate and transport of Cryptosporidium in soils, with a specific focus on how artificial drainage affects transport. Cryptosporidium is an infective protozoan which is one of the most important contaminants found in drinking water and is known to cause a parasitic gastrointestinal disease called cryptosporidiosis. Several outbreaks of cryptosporidiosis due to both groundwater and surface water contamination have been reported in North America. The use of manure for farm applications can be a major source of Cryptosporidium in the environment. Cryptosporidium in manure can infiltrate through soil and reach groundwater. Recent findings suggest Cryptosporidium in surface water comes from the overland runoff from the field. In this project, an alternative route for Cryptosporidium contamination in surface water has been proposed. Subsurface drain tiles are a network of subsurface drains that are used to enhance the drainage of agricultural land. These drains play a significant role in facilitating the transfer of Cryptosporidium from land to surface waters.
- Second Place, National Student Poster Competition at American Water Works Association (AWWA) Conference and Exhibition 2012, Dallas, Texas.
- First Place, Regional Student Poster Competition at North Dakota Water Pollution Control Conference 2012, Bismarck, North Dakota.
- First Place, Design Competition at 2011 26th Annual Conference on the Environment, Minneapolis, Minnesota.
- Third Place, Design Competition at Water Environmental Federation’s Technical Exhibition and Conference (WEFTEC) 2011, Los Angeles, California.
- Runner up, Design Competition at WEFTEC 2010, New Orleans, Louisiana.
- Winner, Paper Competition at WEFTEC 2010, New Orleans, Louisiana.
- Simsek, H., Wadhawan, T., Khan, K. Biodegradable and Photodegradable Dissolved Organic Nitrogen in Wastewater: Association Characterization and Quantification. Submitted to Environmental Science and Technology. Under Review.
- Kasi, M., Wadhawan, T., McEvoy, J., Padmanabhan, G., Khan, E. Enricher Reactor - Permeable Reactive Biobarrier Approach for Removing a Mixture of Contaminants with Substrate Interactions. Submitted to Journal of Hazardous Material. Under Review.
- Simsek, H., Kasi, M., Wadhawan, T., Bye, C., Blonigen, M., Khan, E. Fate of dissolved organic nitrogen in two stage trickling filter process Water Research 2012; 46(16): 5115-5126.
- Kasi, M., Wadhawan, T., McEvoy, J., Padmanabhan, G., Khan, E. Effect of carbon source during enrichment on BTEX degradation by anaerobic mixed bacterial cultures Biodegradation 2012; 24(2): 279-293.
- Wadhawan, T., Maruska, J.B., Siripattanakul, S., Hill, C.B., Gupta, A., Prüβ, B., McEvoy, J., Khan, E. A new method to determine initial viability of entrapped cells Using Fluorescent Nucleic Acid Staining Bioresource Technology 2011; 102(2): 1622-1627.
- Wadhawan, T., McEvoy, J., Prüβ, B., Khan, E. Assessing Tetrazolium and ATP Assays for Rapid In-Situ Viability Quantification of Bacterial Cells Entrapped in Hydrogel Beads Enzyme and Microbial Technology 2010; 47(4):166-173.
- Sule, P., Wadhawan, T., Carr, N.J., Horne, S.M., Wolfe, A.J., Prüß, B.M. A combination of assays reveals biomass differences in biofilms formed by Escherichia coli mutants Letters of Applied Microbiology 2009; 49(3):299-304.
Presentation with Proceedings/Reports
- Wadhawan, T., Kasi, M., McEvoy, J., Chu, M., Khan, E. 2012. Investigating transport of Cryptosporidium under snowmelt conditions. World Environmental and Water Resources Congress. Albuquerque, New Mexico, USA.
- Wadhawan, T., Kasi, M., Chu, M., Khan, E., McEvoy, J. 2012. Bench-scale rainfall and snowfall simulations to understand Cryptosporidium parvum transport in subsurface groundwater regimes. IV International Giardia and Cryptosporidium Conference, Wellington, New Zealand.
- Wadhawan, T., Kasi, M., McEvoy, J., Chu, M., Khan, E. 2011. Role of Manure Application on Soil in Preventing Groundwater Contamination by Cryptosporidium. 84rd Water Environment Federation’s Annual Technical Exhibition and Conference, Los Angeles, USA.
- Kasi, M., Simsek, H., Wadhawan, T., Bye, C., Blonigen, M., Khan, E. 2011. Modeling a Two-Stage Trickling Filter Wastewater Treatment Plant to Simulate the Fate of Dissolved Organic Nitrogen and Its Biodegradability. 84rd Water Environment Federation’s Annual Technical Exhibition and Conference, Los Angeles, USA.
- Wadhawan, T., Simsek, H., Kasi, M., Knutson, K., McEvoy, J., Pruess, B., Khan, E. 2011. A Method to Determine Biodegradable Dissolved Organic Nitrogen in Water. Fourth IWA Specialty Conference on Natural Organic Matter: From Source to Tap and Beyond, Irvine, California, USA.
- Wadhawan, T., Joshi, R., McEvoy, J., Pruess, B., Khan, E. 2011. An ATP Based Method to Determine Bacterial Regrowth Potential in Drinking Water. Fourth IWA Specialty Conference on Natural Organic Matter: From Source to Tap and Beyond, Irvine, California, USA.
- Baker, J., Berthe, D., LaFontain, A., Portlock, D., Strombeck, J., Wadhawan, T. 2010. Solids Handling Modifications, Grand Forks Wastewater Treatment Plant. Student Wastewater Design Competition at 83rd Water Environment Federation’s Annual Technical Exhibition and Conference, Morial Convention Center, New Orleans, Louisiana, USA.
- Baker, J., Halvorson, C., Jensen, S., LaFontain, A., Namrou, A., Strombeck, J., Storlie, L., Wadhawan, T., Young, K. 2011. Water and Environmental Issues Due to Oil Production in North Dakota. Student Wastewater Design Competition at 84th Water Environment Federation’s Annual Technical Exhibition and Conference, Las Angeles Convention Center, Las Angeles, California, USA.
- Wadhawan, T., McEvoy, J., Pruess, B., Khan, E. 2009. In-situ viability assessment of hydrogel immobilized bacteria: An essential tool for bio-fuel cell systems. SRK-ISA-RC-24- International Conference on Water, Environment, Energy and Society, S. R. K. (P.G.) College, Agra University, Agra, India.
- Wadhawan, T., and B.M. Prüß. 2008. Scanning electron microscopy used to study quantitative variation in biofilms among different mutants of Escherichia coli. Proceedings of the North Dakota Academy of Science.
- Wadhawan, T., and B.M. Prüß. 2008. Use of electron microscopy to study biofilm formation. Northern Plains Biology Symposium, Fargo, ND, USA.
- Wadhawan, T., McEvoy, J., Pruess, B., Khan, E. 2011. An ATP Based Method to Determine Bacterial Regrowth Potential in Drinking Water. American Society of Microbiology General Meeting, New Orleans, LA, USA.
- Kasi, M., Wadhawan, T., McEvoy, J., Khan, E. 2011. Effect of Enrichment on BTEX Degradation by Anaerobic Mixed Bacterial Cultures. American Society of Microbiology General Meeting, New Orleans, LA, USA.
- Wadhawan, T., Khan, E., Chu, X., McEvoy, J. 2011. Adsorption of Cryptosporidium parvum oocyst on soil samples obtained from North Dakota. 2011 Land Grant & Sea Grant National Water Conference, Washington DC, USA.
- Wadhawan, T. 2010. Understanding exposure of nanoparticles from commercially available sunscreens. 83rd Water Environment Federation’s Annual Technical Exhibition and Conference, New Orleans Morial Convention Center, New Orleans, Louisiana, USA.
- Wadhawan, T., McEvoy, J., Pruess, B., Khan, E. 2009. An ATP assay for in-situ viability estimation of calcium alginate entrapped bacteria. ND EPSCoR State Conference, NDSU, Fargo, ND, USA.
- Sule, P., Wadhawan, T., and B.M. Prüß. 2008. Use of new assay to quantitate biofilms in mutants in fimbriae and flagellar genes. American Society of Microbiology General Meeting, Boston, MA, USA.
Technical committees – Active member
Water Environmental Federation
- Biofilm Interest Group
- Municipal Wastewater Design Committee
- Academic Committee
- Student and Young Professional Committee
American Water Works Association
- Student and Young Professional Committee
- Biological Drinking Water Treatment Committee
American Society of Civil Engineers
- Environmental Health and Water Quality Committee