Virginia Tech
The Kinetics, Biochemical Patterns, and Microbial Ecology in Multiredox (Anoxic, Microaerobic, Aerobic) Activated Sludge Systems Treating BTX Containing Wastewater
Abstract
dc:description.abstractBTX biodegradation rates, biochemical expression patterns and microbial ecology were studied under anoxic (denitrifying), anoxic/microaerobic/aerobic, and anoxic/microaerobic conditions in activated sludge sequencing batch reactors. The studies showed that toluene and m-xylene were denitrified via benzoyl-CoA reductase. Although benzene, o-, and p-xylene were recalcitrant under denitrifying conditions, they were biodegraded under microaerobic (< 0.2 mg/L dissolved oxygen) and nitrate or nitrite (NOx)-supplemented microaerobic conditions. The patterns of the specific enzymes associated with BTX biodegradation under microaerobic conditions indicated that the three compounds were metabolized by oxygen-dependent pathways. The expression levels of catechol 1, 2-dioxygenase and catechol 2, 3-dioxygenase under microaerobic conditions were induced to levels as high as under aerobic conditions (> 4 mg/L dissolved oxygen). Benzene, o-, and p-xylene biodegradation rates were twice as fast under NO<sub>x</sub>-supplemented compared to NO<sub>x</sub>-free microaerobic conditions, and the specific biodegradation rates under aerobic and NO<sub>x</sub>-supplemented microaerobic conditions were comparable. 16S rRNA probes targeting representative toluene-degraders were used to investigate the microbial communities in the three sequencing batch reactors by using a dot blot hybridization technique. The hybridization results suggest that multiple redox environments fostered a more diverse microbial community and the activities of the target organisms in the reactors with multiple redox environments were higher than in the single redox reactor. Additionally, facultative toluene-degraders appeared to play a less significant role than the strict anoxic and aerobic toluene-degraders in all three SBRs.
Degree
thesis:*- Name thesis:degree_name
- Ph. D.
- Level thesis:degree_level
- doctoral
- Discipline thesis:degree_discipline
- Civil Engineering
- Department dc:contributor.department
- Civil Engineering
- Grantor dc:publisher
- Virginia Tech
- Year dc:date.issued
- 1999
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Ma, Guihua
- Chair dc:contributor.committeechair
-
- Love, Nancy G.
- Committee members dc:contributor.committeemember
-
- Novak, John T.
- Dietrich, Andrea M.
- Stevens, Ann M.
- Terlesky, Kathy C.
- Benoit, Robert E.
Subjects
dc:subject × 12Rights
dc:rights- Statement dc:rights
-
- In Copyright
- Licence dc:rights.uri
Identifiers
dc:identifier.*- Dc Identifier Other
- etd-090699-164851
- OAI identifier oai:identifier
- oai:vtechworks.lib.vt.edu:10919/28883