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Document Type

Thesis - University Access Only

Award Date

2015

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Christopher Schmit

Abstract

For the design and operation of wastewater treatment systems, mainly activated sludge systems, information on biodegradation kinetics plays an important role for removal of soluble and insoluble substrates. Extant respirometry was used to determine the Monod kinetic parameters of both ethanol and acetic acid separately and with acetone to find the impact of acetone on the determination of Monod kinetics. The activated sludge biomass used for this research was obtained from a local waste water treatment plant. A total of three substrates were used in this test. Ethanol and acetic acid was used as the primary substrates. Acetone can be used to solubilize insoluble substrates and was added to ethanol and acetic acid to determine if it affected the kinetic parameters. Acetone was also added to the biomass as an individual substrate to determine its oxygen uptake response. Four primary kinetic parameters were determined from each test result namely the yield (Y), half saturation coefficient (Ks), maximum specific growth rate (μm), and maximum specific substrate utilization rate (qm). A total of 16 runs were conducted. The Theoretical chemical oxygen demand (COD) value of acetone was found to be 2.21 mg of O2/ mg of acetone and the measured value was found to be 2.055 gm COD/ mL . To simulate the addition of acetone to increase substrate solubility, acetone was xvii xvii injected directly into the test vessels containing ethanol and acetic acid. Acetone was added at a rate of 0.63 gm COD/L with ethanol and acetic acid. Various amounts of acetone were also injected separately to determine the oxygen uptake response. Ethanol was found to have a mean values for yield (Y), half saturation coefficient (Ks), maximum specific growth rate (μm), and maximum specific substrate utilization rate (qm) of 0.63 mg COD/mg COD, 1.34 mg SCOD/L, 0.2/hr, and 0.32 mg SCOD/mg MLSS-hr, respectively. For these four kinetics Y, Ks, μm, and qm, the 95% confidence interval was found 0.052 mg COD/mg COD, 1.106 mg SCOD/L, 0.048 /hr, and 0.065 mg SCOD/mg MLSS-hr, respectively. The competent biomass and initial substrates used for ethanol tests ranges from 84.40 mg/L to 144.22 mg/L and 39.08 mg COD/L to 117.24 mg COD/L, respectively. Ethanol with acetone were found to have mean values for yield (Y), half saturation coefficient (Ks), maximum specific growth rate (μm), and maximum specific substrate utilization rate (qm) of 0.68 mg COD/mg COD, 0.71 mg SCOD/L, 0.24/hr, and 0.34 mg SCOD/mg MLSS-hr, respectively. For these four kinetics Y, Ks, μm, and qm, the 95% confidence interval was found to be 0.013 mg COD/mg COD, 0.512 mg SCOD/L, 0.097 /hr, and 0.134 mg SCOD/mg MLSS-hr, respectively. The competent biomass and initial substrates used for ethanol with acetone tests ranges from 69.00 mg/L to 143.20 mg/L and 58.62 mg COD/L to 78.16 mg COD/L, respectively. Acetic acid was found to have mean values for yield (Y), half saturation coefficient (Ks), maximum specific growth rate (μm), and maximum specific substrate utilization rate (qm) of 0.71 mg COD/mg COD, 1.03 mg SCOD/L, 0.68/hr, and 0.95 mg SCOD/ mg MLSS-hr, respectively. For these four kinetics Y, Ks, μm, and qm, the 95% xviii xviii confidence interval was found 0.008 mg COD/mg COD, 0.302 mg SCOD/L, 0.081 /hr, and 0.11 mg SCOD/mg MLSS-hr, respectively. The competent biomass and initial substrates used for acetic acid tests ranges from 81.40 mg/L to 130.00 mg/L mg and 40.00 mg COD/L to 80.00 mg COD/L, respectively. Acetic acid with acetone was found to have mean values for yield (Y), half saturation coefficient (Ks), maximum specific growth rate (μm), and maximum specific substrate utilization rate (qm) of 0.69 mg COD/mg COD, 0.53 mg SCOD/L, 0.69 /hr, and 1.00 mg SCOD/ mg MLSS-hr, respectively. For these four kinetics Y, Ks, μm, and qm, the 95% confidence interval was found 0.009 mg COD/mg COD, 0.031 mg SCOD/L, 0.037 /hr, and 0.045 mg SCOD/mg MLSS-hr, respectively. The competent biomass and initial substrates used for acetic acid with acetone tests were 81.40 mg/L and 80.00 mg COD/L, respectively. A t test applied for both ethanol with and without acetone, and acetic acid with and without acetone did not show any significant difference in the mean values of the biological parameters. Therefore, the hypothesis that there is no difference in the mean among the two group of substrates was accepted. Therefore, it was concluded that acetone has no effect on the respirometric kinetic parameter results when added to both ethanol and acetic acid.

Library of Congress Subject Headings

Sewage--Purification--Activated sludge process
Biodegradation
Ethanol
Acetic acid
Acetone
Microbial respiration
Chemical kinetics

Description

Includes bibliographical references (pages 75-80)

Format

application/pdf

Number of Pages

139

Publisher

South Dakota State University

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Rights Statement

In Copyright