Announcement of Ph.D. Dissertation/M.S. Thesis Oral Defense
Student: Ashani R. Samartunga
Advisor: Dr. Sandeep Kumar
Building: Room: Kaufman Hall, Room 136
Day: 03/24/2026 Time: 12:00 - 2:00 PM
Dissertation/Thesis Title: Integrated Resource Recovery from Waste and Biomass Streams Toward A Circular Bioeconomy: Process Development from Algal Conversion to Lithium Extraction
Abstract:
This dissertation investigates integrated strategies for resource recovery from waste and
biomass streams to support the transition toward a circular bioeconomy. The central problem
addressed is the limited efficiency and scalability of current methods for converting biological
and geochemical resources into valuable products. To overcome these limitations, the
research develops and evaluates innovative processes that couple biochemical, ecological,
and mineral recovery systems using experimental and simulation-based approaches.
Microalgal biomass was processed using a rapid, acid-assisted flash hydrolysis process
under subcritical conditions to improve the simultaneous recovery of fermentable sugars and
lipids. The optimized process achieved nearly complete carbohydrate solubilization with
minimal degradation and retained high lipid content, demonstrating a low-energy pathway
for integrated biorefinery applications. Complementary studies on benthic polyculture-based
Algal Turf Scrubber (ATS) systems established their effectiveness for concurrent nutrient
recovery and biomass generation, achieving stable productivity and high nutrient removal
rates under variable environmental conditions.
The framework was extended to mineral resource recovery through techno-economic
analysis (TEA) of lithium extraction from geothermal brine. A zirconium-doped hydrogenated
manganese oxide (Zr-HMZO) ion-sieve direct lithium extraction process achieved over 90%
lithium recovery, reduced water use by up to 90%, and shortened residence time by more
than 95% compared to solar evaporation. Integration with geothermal heat improved energy
efficiency and sustainability.
Overall, the results demonstrate that combining biochemical conversion, ecological
treatment, and mineral extraction processes enables high-efficiency resource recovery from
diverse waste and biomass streams. These integrated pathways provide scalable, low-carbon
solutions that advance the development of resilient circular bioeconomy systems.