Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Environmental Engineering and Science


Castle, James

Committee Member

Molz , Fred

Committee Member

Snider , Eric

Committee Member

Rodgers , John


Pilot-scale wetland treatment systems were designed and constructed to evaluate renovation of simulated oilfield produced water contaminated with ammonia (20 mg/L ammonia-N). A process-based pilot-scale constructed wetland was designed to meet specific biogeochemical conditions for conversion of ammonia to nitrogen gas through microbial nitrification and denitrification. The process-based constructed wetland treated the simulated produced water to meet stringent discharge requirements (less than 1.2 mg/L ammonia-N). Clinoptilolite, a zeolite mineral, was evaluated for use in constructed wetlands to increase ammonia sorption and nitrification activity. Clinoptilolite increased wetland ammonia sorption capacity and served as a microbial carrier for nitrifying bacteria when ranges of conditions (e.g. hydrosoil redox and equilibrium ammonia concentration) were met. Vertical tracer tests performed on bench-scale constructed wetlands demonstrated that plant transpiration enhances transport of water and dissolved constituents though the hydrosoil, where biogeochemical conditions for treatment reactions including denitrification occur. Evapotranspiration measured using a small, 2 m2 lysimeter was compared with evapotranspiration previously reported for large-stand wetlands (greater than 1 hectare) to compare differences in evapotranspiration water loss expected between pilot-scale and full-scale constructed wetlands. Although water loss by evapotranspiration from the pilot-scale wetland (Kc = 2.54) was greater than reported from large-stand wetlands (Kc = 1.0), performance differences predicted using a one-dimensional analytical model were negligible for treatable constituents (k = 1.2 d-1). This research demonstrates that constructed wetlands offer a solution to treating ammonia in produced water to meet surface discharge criteria and beneficial use guidelines.