PhD Candidate
Degrees
- M.S. in Molecular Biosciences and Bioengineering (University of Hawaii at Manoa)
- B.Sc. in Microbiology (Tribhuvan University)
Areas of Interest
Environmental biotechnology; Resource recovery; Anaerobic digestion; Microbial ecology
Research Projects
My PhD goal is centered on learning from natural systems to develop sustainable technologies for bioenergy recovery from various organic waste streams. In doing so, I aim to integrate microbial ecology with process engineering to better understand the microbial communities that drive these biochemical processes.
IBET: As part of the IBET team, I am involved in operation of two-phase anaerobic dynamic membrane bioreactors. My primary focus lies in exploring the microbial communities and their functions within the first-phase or hydrolysis rumen reactor. The rumen reactor simulates the conditions present in the rumen of ruminants due to its longer solids retention time and constantly maintained environmental conditions, such as pH.
I am also keen on investigating the integration of micro-aeration into the anaerobic digestion process. My research is directed towards developing a mechanistic understanding of both the recovery of unstable reactors and the enhancement of hydrolysis in anaerobic digesters.
Fun Facts/Hobbies
Cooking, baking, hiking
Publications:
Khadir, A., Nakhla, G., Karki, R., Raskin, L., Muller, C., Guevarra, K., Summers, A., Pierce, L., Shahbaz, P., Bell, K., Skerlos, S., & Bronstad, E., 2025. Micro-aeration for hydrogen sulfide reduction in full-scale anaerobic digesters with limited headspace: Performance and sulfide reduction kinetics. Process Safety and Environmental Protection, 196, 106911. https://doi.org/10.1016/j.psep.2025.106911
Karki, R., Chuenchart, W., Surendra, K.C., Sung, S., Raskin, L., Khanal, S.K., 2022. Anaerobic co-digestion of various organic wastes: Kinetic modeling and synergistic impact evaluation. Bioresour. Technol. 343, 126063. https://doi.org/10.1016/j.biortech.2021.126063
Karki, R., Chuenchart, W., Surendra, K.C., Shrestha, S., Raskin, L., Sung, S., Hashimoto, A., Kumar Khanal, S., 2021. Anaerobic co-digestion: Current status and perspectives. Bioresour. Technol. 330, 125001. https://doi.org/10.1016/j.biortech.2021.125001
Chuenchart, W., Karki, R., Shitanaka, T., Marcelino, K.R., Lu, H., Khanal, S.K., 2021. Nanobubble technology in anaerobic digestion: A review. Bioresour. Technol. 329, 124916. https://doi.org/10.1016/j.biortech.2021.124916
Conference presentations:
Karki, R., Zhu, K., Fairley-Wax, T., Puente, P., Starostka, R., Skerlos, S., Raskin, L. Two phase Anaerobic Digestion for the Recovery of Energy. Oral presentation at Waste-to-Energy Student Symposium, 2023. Ann Arbor, MI, 2023
Zhu, K., Lippert, T., Fairley-Wax, T., Amouhamouha, M., Puente, P., Karki, R., Starostka, R., Nielsen, H., Stockard, D., Algren, M., Dunn, J., Wells, G., Demirtas, M., Lin, Y., Skerlos, S., Raskin, L. Integrated biochemical and electrochemical technologies (IBET) to recover biomethane from organic waste. Oral presentation at Borchardt Conference, 2023. Ann Arbor, MI, 2023
Zhu, K., Fairley-Wax, T., Puente, P., Karki, R., Starostka, R., Skerlos, S., Raskin, L. Novel Anaerobic Dynamic Membrane Bioreactor System for High-rate Co-digestion of Food Waste and Wastewater Sludge. Oral presentation at WEFTEC 2022. New Orleans, LA, 2022
Zhu, K., Fairley-Wax, T., Puente, P., Karki, R., Starostka, R., Skerlos, S., Raskin, L. Modeling the performance of a two-phase anaerobic dynamic membrane bioreactor system for high-rate digestion of food waste. Oral presentation at AEESP Conference. St. Louis, MO, 2022
Zhu, K., Fairley-Wax, T., Puente, P., Karki, R., Starostka, R., Skerlos, S., Raskin, L. Two-phase anaerobic dynamic membrane bioreactor system treats food waste with high hydrolysis rate and methane yield. Oral presentation and conference proceedings at IWA 17th World Conference on Anaerobic Digestion, Ann Arbor, MI, 2022.
Karki, R., Chuenchart, W., Surendra, K.C., and Khanal, S.K.*. Anaerobic co-digestion of coffee pulp and cattle manure for enhanced biomethane production. Poster presentation at 2021 International Conference on Sustainable Biowaste Management. Hong Kong SAR, P.R. China, 2021
Raskin Research Group 