Date of Award
Master of Science
Civil, Construction, and Environmental Engineering
Timothy G. Ellis
The nutrient load at the Cedar Rapids Water and Pollution Control Facility is a significant consideration for future treatment goals. In an effort to include total nitrogen removal, possible electron donors were evaluated to drive denitrification at the plant. Since a portion of the industrial influent to the facility includes pulp and paper wastewater that contains high concentrations of sulfate, reduced sulfur species were considered as an energy source for autotrophic denitrifying bacteria. During anaerobic pretreatment of the industrial wastewater, some of the sulfate is converted to hydrogen sulfide gas which in itself can cause potential safety hazard to the plant operators and an odor nuisance. Autotrophic denitrification is a microbially driven process which can reduce nitrate to nitrogen gas in the presence of reduced sulfur. By having nitrate as the electron acceptor and reduced sulfur as the electron donor during the lab-scale experiment, the nitrogen in the wastewater was effectively removed, and the removal efficiency of nitrate exceeded 95%. Both the sequencing batch and static granular bed reactor exhibited similar performance. Thiobacillus and Shinella bacteria were determined to contribute to the denitrification process. The process was effective at a near neutral pH. The experimental results illustrated that the autotrophic denitrification process was able to reduce nitrate in industrial wastewater with reduced sulfur as the sole electron donor available. The experimental results also showed that the reduction from nitrate to nitrite was faster than that from nitrate to nitrogen gas during the autotrophic denitrification process.
Tan, Yuan, "Feasibility test of autotrophic denitrification of industrial wastewater in sequencing batch and static granular bed reactors" (2018). Graduate Theses and Dissertations. 16676.