Date of Award

12-2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Hydrogeology

Advisor

Castle, James W

Committee Member

Rodgers , John H

Committee Member

Huddleston , George M

Abstract

This investigation examined the feasibility of using free-water surface constructed wetland systems (CWTSs) to decrease the ammonia concentration in oil-field produced water. The objective of this research was to design constructed wetland experiments to determine specific conditions that decrease aqueous ammonia concentrations in simulated oilfield produced water. The design of these experiments was based on biogeochemical pathways of nitrification and denitrification. The experiments included three scales: bench-scale, single-cell, and pilot-scale. Bench-scale reactors contained wetland plants (Typha latifolia) and hydrosoil in 5-gallon buckets. Single wetland cells were constructed by adding hydrosoil and plants (T. latifolia and Schoenoplectus californicus) to 70-gallon containers. The pilot-scale CWTS included four constructed wetland series, each consisting of four cells. One series was designed as a control system, and the other three series were designed to test the effects of aeration and organic matter on ammonia removal.
Data from bench-scale experiments indicate that ammonia removal was enhanced by the addition of zeolite, organic matter, and shallow (3 to12 inches) water depth. In the single-cell experiments, ammonia removal was enhanced by the addition of sugar to the water as a carbon source for microbial activity. Ammonia removal ranged from 3.3 to 82.6% in the single-cell experiments, with total nitrogen removal of 1.2 to 53.6%. In the pilot-scale CWTS, ammonia removal ranged from 19.2 to 62.5%, and ammonia concentration decreased from 25 mg/L to 7.92 mg/L. To enhance the removal efficiency, sucrose and oyster shells were added to promote conditions favorable for the removal processes in a redesigned pilot-scale CWTS. The redesigned pilot-scale CWTS achieved ammonia removal ranging from 59.9 to 96.8% and a removal extent as low as 0.73 mg/L.

Included in

Hydrology Commons

Share

COinS