Current Focus

Pump Station Hydraulics

  • Improving Approach Flow Hydraulics 
  • Reduce Vortex Activity
  • Avoid Air Entrainment  

Flocculation/Sedimentation
  • Multi-phase Flow Simulation
  • Mechanism and Kinetics Model of Coagulation and Flocculation
  • Floc/Sed Basin Design Optimization

Chemical Mixing

  • Rapid Mixing with Minimum Energy Input
  • Evaluation of Injection Approaches 
  • Impact of Interaction of Injection and Main Stream on Mixing

UV Disinfection
  • Improve Approaching Flow 
  • Methods of Calculating UV Dose
  • UV Distribution Model

Hydraulics in Other Drinking Water/Wastewater Treatment Facilities

Hydraulics in Conveyance Infrastructure
Headworks; BAC Filter Backwash; Clearwell; 

Dam Culvert; Pipelines 

Projects in Academia

NATURAL SYSTEMS

Upper Ocean (Method: CFD; Tools: OpenFOAM, In-house Codes, ROMS)

  • Juha, M. J., Zhang, J. and Tejada-Martínez, A. E. (2017) Large scale structures in LES of an oscillating open channel flow under the influence of surface cooling. Computers & Fluids, accepted.​ 
  • Walker E., Zhang, J., Juha, M., Gosch, C., Tejada-Martinez, A. E. (2015) LES of Langmuir supercells under constant crosswind tidal forcing. 68th Annual Meeting of the APS Division of Fluid Dynamics, Boston, MA, November, 2015.
  • Juha, M., Zhang, J., Tejada-Martinez, A. E. (2015) LES of oscillating boundary layers under neutrally stratified and unstably stratified conditions. 68th Annual Meeting of the APS Division of Fluid Dynamics, Boston, MA, November, 2015.

ENGINEERED SYSTEMS

Ozone Disinfection (Method: CFD; Tools: OpenFOAM etc.)

I developed a modeling framework by combining computational fluid dynamics (CFD) with a kinetics-based reaction model for ozone disinfection of drinking water. The modeling framework is capable of predicting chemical species distribution in reactors. It is a powerful and efficient tool for troubleshooting the existing contactors in water and wastewater treatment systems and improving future contactor designs. 
TOPICS:
  • Application to evaluate the hydraulics and disinfection efficiency of the ozone contactor operated by the City of Tampa Water Department, FL 
  • the applicability of different strategies of modeling turbulent flow (i.e. Reynolds-averaged Navier-Stokes equation (RANS) simulation and large eddy simulation (LES)), 
  • the applicability of different RANS models (i.e. the standard k-epsilon model and Launder-Sharma k-epsilon  model)
  • the relationship between energy consumption, disinfection efficiency and contactor configuration.
CORRESPONDING PUBLICATIONS:
  • J. Zhang, A. E. Tejada-Martinez, Q. Zhang, and H. Lei (2014) Evaluating Hydraulic and Disinfection Efficiencies of a Full-Scale Ozone Contactor using a RANS-based Modeling Framework, Water Research, 52, 155-167. Link
  • J. Zhang, A. E. Tejada-Martinez, and Q. Zhang (2014) Evaluation of LES and RANS for Determining Hydraulic Performance of Water Disinfection Systems, Journal of Fluids Engineering, 136(12), 121102. Link
  • J. Zhang, A. E. Tejada-Martinez, and Q. Zhang (2013) RANS Simulation of the Flow and Tracer Transport in a Multi-chambered Ozone Contactor, Journal of Environmental Engineering, 139(3), 450–454. Link
  • J. Zhang, A. E. Tejada-Martinez, and Q. Zhang (2013) Hydraulic Efficiency in RANS of the Flow in a Multi-Chambered Contactor, Journal of Hydraulic Engineering, 139(11), 1150–1157. Link

Ion Exchange (Methods: Process Modeling, LCA; Tools: MATLAB, SimaPro)

In collaboration with Adib Amini and Dr. Qiong Zhang from Univ. of South Florida (USF) and Dr. Treavor Boyer from Univ. of Florida (UF).
  • A. Amini, Y. Kim, J. Zhang, T. Boyer, Q. Zhang (2015) Environmental and Economic Sustainability of Ion Exchange Drinking Water Treatment for Organics Removal. Journal of Cleaner Production,104, 413-421. Link
  • J. Zhang, A. Amini, J. O’Neal, T. Boyer, Q. Zhang (2015) An Integrated Framework of Modeling Ion Exchange & Regeneration Process for Drinking Water. Water Research. Link
  • A. Amini, K. Payne, J. Zhang, Q. Zhang. (2015) A Novel Method for Evaluation of Environmental and Economic Sustainability by Process Model Integration with Life Cycle Assessment and Optimization Using a Genetic Algorithm. The World Environmental and Water Resources (EWRI) Congress 2015, May, 2015, Austin, Texas. 
  • A. Amini, Y. Kim, J. Zhang, T. Boyer, Q. Zhang. (2014) Environmental Impact and Cost Assessment of Ion Exchange Drinking Water Treatment for Organics Removal in Florida. AWWA Florida Section 2014 Fall Conference, Orlando, Florida, December, 2014.

Stabilization Pond System (Method: CFD; Tools: OpenFOAM etc.)

In collaboration with Matt Verbyla, Faissal Ouedraogo, and Dr. James Mihelcic from USF and Dr. Stewart Oakley from California State University, Chico.
  • M. E. Verbyla, S. M. Oakley, L. A. Lizima, J. Zhang, M. Iriarte, A. E. Tejada-Martinez, and J. R. Mihelcic (2013) Taenia eggs in waste stabilization pond systems with poor hydraulics: Concern for human cysticercosis?, Water Science and Technology, 68(12),2698-2703. Link
  • Ouedraogo, F., Zhang, J., Cornejo-Warner, P., Tejada-Martínez, A. E., Zhang, Q., Mihelcic, J. R. (2016) Impact of Sludge Layer Geometry on Hydraulic Performance of the Waste Stabilization Pond in Bolivia. Water Research, 99, 253-262.

Anaerobic Digestion (Method: CFD; Tools: OpenFOAM etc.)

In collaboration with Maureen Kinyua and Dr. Sarina Ergas from USF
  • Kinyua, M. N., Zhang, J., Camacho-Céspedes, F., Tejada-Martínez, A. E., Ergas, S. J. (2016) Use of physical and biological process models to understand the performance of tubular anaerobic digesters. Biochemical Engineering Journal, doi:10.1016/j.bej.2015.11.017. Link
  • M. N. Kinyua, J. Zhang, A. Tejada-Martinez, S. J. Ergas. (2015) Influence of mean residence time, mixing and transport mechanisms on the performance of small-scale anaerobic digesters in the Monteverde Region of Costa Rica. Water and Energy 2015: Opportunities for Energy and Resource Recovery in the Changing World, Washington, DC, June, 2015.