Sigifredo Castro Diaz | Teaching Assistant Professor

Photo of Sigifredo Castro DiazPh.D. – 2003, Kansas State University
Chemical Engineering
M.S. – 2001, Kansas State University
Chemical Engineering
B.S. – 1998, Universidad Nacional de Colombia
Chemical Engineering

Contact information

2005 Durland Hall

Professional experience

After receiving his doctorate from Kansas State University in 2003, Castro joined K-State’s department of chemical engineering as an instructor, where he taught undergraduate courses in materials science and engineering and engineering materials laboratory, as well as graduate level courses in biochemical engineering, bioseparations, and polymer science and engineering. He also participated in upgrading and designing new laboratory setups for the Transport Phenomena and Unit Operations Laboratories. He continued to be active in research projects, performing investigations on different fields, including a study on the comparative solubility of nanoparticles and bulk oxides of magnesium in water and lung-simulant fluids, an investigation on appropriate growth conditions for bacteria capable of anaerobic oxidation of ammonia and a study in the optimization of an anaerobic digester for treating swine waste to maximize biogas production.

In 2007, Castro joined K-State’s Advanced Manufacturing Institute (AMI) where he worked as a chemical and bioprocessing engineer. At AMI, he assisted a diverse group of engineers in assessing the technical and economic feasibility of a variety of projects brought by industry in areas related to chemical and bioprocessing engineering. Among others, Castro collaborated on the conceptualization, development, design, scale-up and implementation of bench, pilot, and large-scale processes for the recovery of phosphate minerals from wastewaters and by-product streams from a variety of industries. He also led the design, installation, and preparation of operating guidelines for a cooking-oil-to-biodiesel pilot–scale conversion facility for K-State’s Manhattan campus. He also completed numerous feasibility studies and developed designs of wastewater treatment systems in a variety of industries. Castro actively participated in the conceptualization, design, construction, operation, and retrofitting of a fluidized bed reactor for the recovery of phosphate compounds from cattle feedlot wastewater. He is listed as inventor of this technology in the US Patent No. 8017019 B2. The technology was registered as “PHRED®” (phosphorus reduction) and is now commercialized by the Kansas Environmental Management Associates, LLC (KEMA). In 2014, Castro was the main engineering consultant for KEMA leading the design, construction and operation of reactors to perform bench-scale and pilot-scale experiments to investigate reaction kinetics, particle growth kinetics, and recovery of magnesium phosphate minerals from phosphate-rich by-product streams from dry-mill corn ethanol plants using magnesium compounds as seed materials.


Castro’s main research interests are in the field of recovery of potentially valuable products from industrial waste streams. From biogas to biodiesel and from phosphate-based fertilizers to biopolymers, he applies chemical engineering concepts and methodologies for designing equipment and experiments to test the feasibility of product recovery or energy generation from streams that otherwise would be deemed wasteful. With an environmentally-responsible mindset, Castro strives to develop strategies for developing economically feasible and profit-driven projects that could turn a waste into a valuable product. Castro has been awarded grants from the Kansas Corn Commission and the Kansas Soybean Commission and has been a key participant in numerous research projects sponsored by state and federal grants from the USDA and NSF. The Ad Astra Kansas Initiative named Castro as one of the Top 150 scientists ever to work in Kansas throughout its 150 years of statehood (2011). He was also awarded the “Outstanding Junior Scientist Award” by the Sigma Xi Scientific Research Society, Kansas State University Chapter (2007), and the “Outstanding Leadership Award”, by the Alliance for Hispanic Affairs, Kansas State University (2005).

At this time, Dr. Castro's appointment is for teaching and thus, he is not funding graduate research assistants. For inquiries regarding research activities at our department, please contact Dr. Placidus Amama, our current graduate student coordinator.

Academic highlights

Castro is the co-inventor of the U.S. Patent No. 8017019 B2, “Fluidized bed precipitator with optimized solids settling and solids handling features for use in recovering phosphorus from wastewater” (2011) and has been the main author and co-author of several publications in the fields of bioremediation and phytoremediation. He has been co-adviser in a number of senior-level engineering design projects, and has been the mentor for over a dozen chemical engineering student interns.