Biological Activity on Granular Activated Carbon in the Presence of Ozonated Naturally Occurring Humic Substances
Public Deposited- Last Modified
- February 28, 2019
- Creator
-
DeWaters, Jan
- Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
- Abstract
- Biological activity on granular activated carbon may significantly enhance the water purification process. Shifting the pathway for contaminant removal from adsorption to biodegradation results in steady state reduction across the GAC bed, and increases filter run time through regeneration of sorptive capacity for non- or slowly-biodegradable compounds. Trace contaminants present at low concentrations and/or only seasonally may not meet minimum growth and energy requirements of a biofilm population. The presence of a bulk substrate source such as humic substances could stimulate the growth of a biofilm which will, in turn, degrade trace pollutants as secondary metabolites. A fixed-bed column reactor with a high recycle ratio was used to examine biodegradation and adsorption of ozonated humic substances (HS). The percent biodegraded at steady state increased with pre-ozonation, and with an increase in EBCT (slower flowrate) and feed TOC concentration. At an ozone dose of 1 mg 03/mg TOC, EBCT = 3.9 min, and feed TOC = 7 mg/L, approximately 43% of the HS were biodegraded. Steady state biological activity, as evidenced by CO2 production, was achieved within 1 day; steady state TOC removal occurred after about 160 hours. Phenol, when added at 50 μg/L to the HS system, was degraded within 60 hours. When phenol was added to an established biofilm, it was immediately biodegraded. A method is presented for recovering viable cells from a GAC biofilm. Kinetic studies with samples recovered from an HS grown biofilm indicate that the biokinetics of phenol utilization by these microorganisms are comparable to utilization kinetics by suspended cultures. The enumeration of viable cells from samples recovered at different stages of biofilm growth indicates that the density of viable cells continues to increase in the GAC bed, despite the achievement of steady state biological activity. The density of viable cells in the GAC reactor bed, as enumerated by plate counts, was on the order of 10^6 to 10^7 cells/gm.
- Date of publication
- December 1987
- DOI
- Resource type
- Rights statement
- In Copyright
- Advisor
- Pfaender, Frederic K.
- Singer, Philip
- DiGiano, Francis A.
- Degree
- Master of Science in Environmental Engineering
- Academic concentration
- Water Resources Engineering
- Degree granting institution
- University of North Carolina at Chapel Hill
- Graduation year
- 1987
- Language
- Deposit record
- 4229e0fb-b010-4ede-aa50-9d4a2f0726fb
Relations
- Parents:
This work has no parents.