Available at: https://digitalcommons.calpoly.edu/theses/3197
Date of Award
12-2025
Degree Name
MS in Civil and Environmental Engineering
Department/Program
Civil and Environmental Engineering
College
College of Engineering
Advisor
Tryg Lundquist
Advisor Department
Civil and Environmental Engineering
Advisor College
College of Engineering
Abstract
Many municipal wastewater treatment plants must meet effluent standards for nitrogenous compounds. Biofilm and suspended growth reactors are commonly used at full-scale to nitrify ammonia as part of nitrogen removal. The present research was a step in exploring whether an aerated biofilm supported on geomembrane panels could nitrify efficiently enough to have lower total costs compared to existing technologies. The research was conducted in a Mediterranean climate using four 1-m3 pilot tanks – two for panel biofilms and two for reference suspended growth treatment.
Over four months, tests were conducted on two hydraulic residence times (nominally 10 h and 20 h), two aeration intensities, and thick and thin biofilms. They were continuously fed municipal primary clarifier effluent (total ammonia nitrogen [TAN] averaged 48 mg/L). Biofilm tanks removed an average of 15 mg/L-d and reference tanks achieved average removal rates of 25 mg/L-d in an activated sludge mode and 19 mg/L-d in aerated lagoon mode.
For the biofilm, the best performance was achieved in the tank with thin biofilm and 20 h residence time. Its biofilm area-specific TAN removal rate averaged 1.06 g/m2-d, which is comparable to conventional biofilm technologies such as moving bed bioreactors. However, at a TAN loading rate of ~1 g/m2-d, scaling-up a panel configuration to achieve low effluent TAN concentrations would be challenging.