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Effect of coagulation and flocculation technology on bleached kraft mill effluent quality Hodgson, Andrew Trevor

Abstract

Since January 1995 the tertiary colour removal clarifier at Crestbrook Forest Industries' Pulp Division in Skookumchuck, B.C. has removed 60±4% of the biologically treated effluent colour. Over the same period, BOD5 was reduced by 26% and TSS was increased by 19 mg/L across tertiary treatment. This study revealed that the colour removal system removed 24%, 23%, 80%, and 18% of the COD, AOX, 2,3,7,8-TCDF, and mixed function oxygenase induction, respectively. A study of the effect that basic effluent parameters had on system performance revealed that the dual polymer system used at Crestbrook Forest Industries operated well over a wide range of temperature, pH, and BOD₅. Colour removal improved when pH was decreased to pH 3; below this pH the system performance declined. The increased colour removal at lower pH values could not be achieved by an increase in coagulant dose. Decreasing the temperature improved colour removal slightly, and different levels of BOD5 had no effect on the percentage of colour removed. Bench scale tests with segregated effluent streams (bleach plant filtrates and pulping area sewers), indicated that there are no possible reductions in polymer usage when these streams are treated separately from the rest of the mill effluent. Polymers used in the full scale system were well suited to treat chlorination stage effluent, achieving acceptable floe formation at relatively low polymer applications. The extraction stage effluent did not produce quality floes when treated, and required high polymer doses to achieve moderate floe quality.

Item Metadata

Title
Effect of coagulation and flocculation technology on bleached kraft mill effluent quality
Creator
Hodgson, Andrew Trevor
Publisher
University of British Columbia
Date Issued
1998
Description
Since January 1995 the tertiary colour removal clarifier at Crestbrook Forest Industries' Pulp Division in Skookumchuck, B.C. has removed 60±4% of the biologically treated effluent colour. Over the same period, BOD5 was reduced by 26% and TSS was increased by 19 mg/L across tertiary treatment. This study revealed that the colour removal system removed 24%, 23%, 80%, and 18% of the COD, AOX, 2,3,7,8-TCDF, and mixed function oxygenase induction, respectively. A study of the effect that basic effluent parameters had on system performance revealed that the dual polymer system used at Crestbrook Forest Industries operated well over a wide range of temperature, pH, and BOD₅. Colour removal improved when pH was decreased to pH 3; below this pH the system performance declined. The increased colour removal at lower pH values could not be achieved by an increase in coagulant dose. Decreasing the temperature improved colour removal slightly, and different levels of BOD5 had no effect on the percentage of colour removed. Bench scale tests with segregated effluent streams (bleach plant filtrates and pulping area sewers), indicated that there are no possible reductions in polymer usage when these streams are treated separately from the rest of the mill effluent. Polymers used in the full scale system were well suited to treat chlorination stage effluent, achieving acceptable floe formation at relatively low polymer applications. The extraction stage effluent did not produce quality floes when treated, and required high polymer doses to achieve moderate floe quality.
Extent
7245915 bytes
Genre
Thesis/Dissertation
Type
Text
File Format
application/pdf
Language
eng
Date Available
2009-04-30
Provider
Vancouver : University of British Columbia Library
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.
DOI
10.14288/1.0058526
URI
http://hdl.handle.net/2429/7763
Degree
Master of Applied Science - MASc
Program
Chemical and Biological Engineering
Affiliation
Applied Science, Faculty of; Chemical and Biological Engineering, Department of
Degree Grantor
University of British Columbia
Graduation Date
1997-11
Campus
UBCV
Scholarly Level
Graduate
Aggregated Source Repository
DSpace

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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.