Abstract
The two-tank accelerator/aerator modification of activated sludge significantly increases the biodegradation of hydrocarbons requiring initial monooxygenation reactions, such as phenol and 2,4-dichlorophenol (DCP). The small accelerator tank has a controlled low dissolved oxygen (DO) concentration that can enrich the biomass in NADH + H+. It also has a very high specific growth rate (μ acc) that up-regulates the biomass's content of the monooxygenase enzyme. Here, we develop and test the ACCEL model, which quantifies all key phenomena taking place when the accelerator/aerator system is used to enhance biodegradation of hydrocarbons requiring initial monooxygenations. Monooxygenation kinetics follow a multiplicative relationship in which the organic substrates (phenol or DCP) and DO have separate Monod terms, while the biomass's content of NADH + H+ has a first-order term. The monooxygenase enzyme has different affinities (K values) for phenol and DCP. The biomass's NADH + H+ content is based on a proportioning of NAD(H) according to the relative rates of NADH + H+ sources and sinks. Biomass synthesis occurs simultaneously through utilization of acetate, phenol, and DCP, but each has its own true yield. The ACCEL model accurately simulates all trends for one-tank and two-tank experiments in which acetate, phenol, and DCP are biodegraded together. In particular, DCP removal is affected most by DOacc and the retention-time ratio, Θacc/ Θtotal. Adding an accelerator tank dramatically increases DCP removal, and the best DCP removal occurs for 0.2 < DOacc< 0.5 mg/l and 0.08 < Θacc/Θtotal < 0.2. The rates of phenol and DCP utilization follow the multiplicative relationship with a maximum specific rate coefficient proportional to μacc. Finally, μ acc increases rapidly for Θacc/ Θtotal < 0.25, acetate removal in the accelerator fuels the high μ acc, and the biomass's NADH + H+ content increases very dramatically for DOacc < 0.25 mg/l.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 237-250 |
| Number of pages | 14 |
| Journal | Biodegradation |
| Volume | 17 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jun 2006 |
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Keywords
- Activated sludge
- Dichlorophenol
- Monooxygenation
- Nicotinamide adenine dinucleotide
- Phenolics
- Specific growth rate
ASJC Scopus subject areas
- Biotechnology
Cite this
The ACCEL model for accelerating the detoxification kinetics of hydrocarbons requiring initial monooxygenation reactions. / Dahlen, Elizabeth P.; Rittmann, Bruce.
In: Biodegradation, Vol. 17, No. 3, 06.2006, p. 237-250.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The ACCEL model for accelerating the detoxification kinetics of hydrocarbons requiring initial monooxygenation reactions
AU - Dahlen, Elizabeth P.
AU - Rittmann, Bruce
PY - 2006/6
Y1 - 2006/6
N2 - The two-tank accelerator/aerator modification of activated sludge significantly increases the biodegradation of hydrocarbons requiring initial monooxygenation reactions, such as phenol and 2,4-dichlorophenol (DCP). The small accelerator tank has a controlled low dissolved oxygen (DO) concentration that can enrich the biomass in NADH + H+. It also has a very high specific growth rate (μ acc) that up-regulates the biomass's content of the monooxygenase enzyme. Here, we develop and test the ACCEL model, which quantifies all key phenomena taking place when the accelerator/aerator system is used to enhance biodegradation of hydrocarbons requiring initial monooxygenations. Monooxygenation kinetics follow a multiplicative relationship in which the organic substrates (phenol or DCP) and DO have separate Monod terms, while the biomass's content of NADH + H+ has a first-order term. The monooxygenase enzyme has different affinities (K values) for phenol and DCP. The biomass's NADH + H+ content is based on a proportioning of NAD(H) according to the relative rates of NADH + H+ sources and sinks. Biomass synthesis occurs simultaneously through utilization of acetate, phenol, and DCP, but each has its own true yield. The ACCEL model accurately simulates all trends for one-tank and two-tank experiments in which acetate, phenol, and DCP are biodegraded together. In particular, DCP removal is affected most by DOacc and the retention-time ratio, Θacc/ Θtotal. Adding an accelerator tank dramatically increases DCP removal, and the best DCP removal occurs for 0.2 < DOacc< 0.5 mg/l and 0.08 < Θacc/Θtotal < 0.2. The rates of phenol and DCP utilization follow the multiplicative relationship with a maximum specific rate coefficient proportional to μacc. Finally, μ acc increases rapidly for Θacc/ Θtotal < 0.25, acetate removal in the accelerator fuels the high μ acc, and the biomass's NADH + H+ content increases very dramatically for DOacc < 0.25 mg/l.
AB - The two-tank accelerator/aerator modification of activated sludge significantly increases the biodegradation of hydrocarbons requiring initial monooxygenation reactions, such as phenol and 2,4-dichlorophenol (DCP). The small accelerator tank has a controlled low dissolved oxygen (DO) concentration that can enrich the biomass in NADH + H+. It also has a very high specific growth rate (μ acc) that up-regulates the biomass's content of the monooxygenase enzyme. Here, we develop and test the ACCEL model, which quantifies all key phenomena taking place when the accelerator/aerator system is used to enhance biodegradation of hydrocarbons requiring initial monooxygenations. Monooxygenation kinetics follow a multiplicative relationship in which the organic substrates (phenol or DCP) and DO have separate Monod terms, while the biomass's content of NADH + H+ has a first-order term. The monooxygenase enzyme has different affinities (K values) for phenol and DCP. The biomass's NADH + H+ content is based on a proportioning of NAD(H) according to the relative rates of NADH + H+ sources and sinks. Biomass synthesis occurs simultaneously through utilization of acetate, phenol, and DCP, but each has its own true yield. The ACCEL model accurately simulates all trends for one-tank and two-tank experiments in which acetate, phenol, and DCP are biodegraded together. In particular, DCP removal is affected most by DOacc and the retention-time ratio, Θacc/ Θtotal. Adding an accelerator tank dramatically increases DCP removal, and the best DCP removal occurs for 0.2 < DOacc< 0.5 mg/l and 0.08 < Θacc/Θtotal < 0.2. The rates of phenol and DCP utilization follow the multiplicative relationship with a maximum specific rate coefficient proportional to μacc. Finally, μ acc increases rapidly for Θacc/ Θtotal < 0.25, acetate removal in the accelerator fuels the high μ acc, and the biomass's NADH + H+ content increases very dramatically for DOacc < 0.25 mg/l.
KW - Activated sludge
KW - Dichlorophenol
KW - Monooxygenation
KW - Nicotinamide adenine dinucleotide
KW - Phenolics
KW - Specific growth rate
UR - http://www.scopus.com/inward/record.url?scp=33646879812&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33646879812&partnerID=8YFLogxK
U2 - 10.1007/s10532-005-5019-8
DO - 10.1007/s10532-005-5019-8
M3 - Article
C2 - 16715403
AN - SCOPUS:33646879812
VL - 17
SP - 237
EP - 250
JO - Biodegradation
JF - Biodegradation
SN - 0923-9820
IS - 3
ER -