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The influence of the high molecular weight fraction of bleached kraft mill effluent on the biological activity of activated sludge Bullock, Christopher Mark
Abstract
Bleached kraft mills have reduced the environmental impact of their effluent discharges by investing in biological treatment processes such as activated sludge treatment. Since the high molecular weight (HMW) fraction of bleached kraft mill effluent (BKME) represents a significant fraction of the adsorbable organic halide (AOX) and chemical oxygen demand (COD) load on biological treatment systems, the influence of this material on activated sludge activity was studied. Initially, we used ultrafiltration to fractionate the BKME from a mill producing elemental chlorine free softwood pulp. The HMW material (> 1000 Da) fraction contained 20% of the chemical oxygen demand and 75-85% of the AOX. Most of the nitrogen present in the effluent from the pulping and bleaching process was detected in the HMW fraction. Transition metals were associated with the BMW material to a greater extent than the less charged alkaline earth metals. Batch growth trials with microorganisms from a laboratory-scale activated sludge reactor were performed using the low molecular weight (LMW) fraction as the substrate and supplementing it with varying amounts of the HMW material. While both the LMW and HMW fractions alone supported little microbial growth, the HMW material stimulated microbial activity in the LMW fraction, by apparently providing the limiting nutrient, nitrogen. The addition of the BMW material to the LMW effluent increased the removal of various chlorinated phenols (6-chiorovanillin (6-CVa), 4,5-dichloroguaiacol (4,5-DCG), and 2,4-dichiorophenol (2,4-DCP)), which had been added (1.0 mgIL) to the effluent fractions. Supplementing the LMW effluent with nutrients also stimulated chlorinated phenol removal. The relative removal rates of the chlorophenols decreased in the order 6-CVa > 4,5-DCG > 2,4-DCP. Spiking the unfractionated effluent with up to 10 mgfL of 6-CVa, 4,5-DCG, and 2,4-DCP had no effect on the biomass production or substrate removal. These results seemed to demonstrate that the BMW material in the BKME had a stimulatory effect on the microorganisms present in the activated sludge by providing the limiting nutrient, nitrogen.
Item Metadata
Title |
The influence of the high molecular weight fraction of bleached kraft mill effluent on the biological activity of activated sludge
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1994
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Description |
Bleached kraft mills have reduced the environmental impact of their effluent discharges by investing
in biological treatment processes such as activated sludge treatment. Since the high molecular weight
(HMW) fraction of bleached kraft mill effluent (BKME) represents a significant fraction of the
adsorbable organic halide (AOX) and chemical oxygen demand (COD) load on biological treatment
systems, the influence of this material on activated sludge activity was studied. Initially, we used
ultrafiltration to fractionate the BKME from a mill producing elemental chlorine free softwood pulp.
The HMW material (> 1000 Da) fraction contained 20% of the chemical oxygen demand and 75-85%
of the AOX. Most of the nitrogen present in the effluent from the pulping and bleaching process was
detected in the HMW fraction. Transition metals were associated with the BMW material to a greater
extent than the less charged alkaline earth metals. Batch growth trials with microorganisms from a
laboratory-scale activated sludge reactor were performed using the low molecular weight (LMW)
fraction as the substrate and supplementing it with varying amounts of the HMW material. While both
the LMW and HMW fractions alone supported little microbial growth, the HMW material stimulated
microbial activity in the LMW fraction, by apparently providing the limiting nutrient, nitrogen. The
addition of the BMW material to the LMW effluent increased the removal of various chlorinated
phenols (6-chiorovanillin (6-CVa), 4,5-dichloroguaiacol (4,5-DCG), and 2,4-dichiorophenol (2,4-DCP)),
which had been added (1.0 mgIL) to the effluent fractions. Supplementing the LMW effluent with
nutrients also stimulated chlorinated phenol removal. The relative removal rates of the chlorophenols
decreased in the order 6-CVa > 4,5-DCG > 2,4-DCP. Spiking the unfractionated effluent with up to
10 mgfL of 6-CVa, 4,5-DCG, and 2,4-DCP had no effect on the biomass production or substrate
removal. These results seemed to demonstrate that the BMW material in the BKME had a stimulatory
effect on the microorganisms present in the activated sludge by providing the limiting nutrient, nitrogen.
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Extent |
2693676 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-03-03
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0075255
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.