50    ANAEROBIC TOXICITY OF RESIN ACIDS IN
CHEMITHERMOMECHANICAL PULP WASTEWATER
P. J. McCarthy, Environmental Scientist
R. C. Landine, Vice President
ADI Limited
Fredericton, N.B.
Canada E3B 4Y2
K. J. Kennedy, Research Associate
National Research Council
Ottawa, Ontario,
Canada K1A 0R6
R. L. Droste, Associate Professor
Department of Civil Engineering
University of Ottawa
Ottawa, Ontario
Canada KIN 6N5
INTRODUCTION
Resin acids are present in a number of wood processing wastewaters. These wastewaters are being
treated anaerobically although, at present, little is known about the effects that resin acids have on
anaerobic bacteria or of their fate in an anaerobic environment. Andersson and Welander' reported
an abietic acid/oleic acid mixture to be inhibitory at 1,178 mg/L. However Koster and Cramer2
reported inhibition to 50% of control activity by oleic acid at 1,235 mg/L which left some doubt as to
the effect of abietic acid. Field et al.3 found 50% of control activity for an abietic acid concentration
of 114 mg/L. McFarlane and Clark4 reported that resin acids are degraded in an upflow anaerobic
sludge blanket (UASB) reactor with the exception of dehydroabietic acid. It was also concluded by the
same authors that anaerobic bacteria could acclimatize to high levels of dehydroabietic acid.
It has been stated by Welander5 and Hall and Cornacchio6 that chemithermomechanical pulp
(CTMP) wastewater can be toxic to anaerobic bacteria. The objective of this study was to characterize
the toxicity of BCTMP wastewater for fiber and nonfiber components and to compare BCTMP
wastewater anaerobic toxicity to toxicity caused by pure resin acids.
MATERIALS AND METHODS
Materials
Pure resin acids were purchased from Helix Biotech. Scientific Ltd., Richmond, B.C. Resin acid
analysis was carried out by Econotech Laboratory, New Westminister, British Columbia. Anaerobic
granular sludge was provided by Paques Lavalin and originated in Roermond, Holland where it was
used for the treatment of recycled paper wastewater and therefore was not acclimatized to CTMP
wastewater. The sludge was stored at 4°C until used. BCTMP-N wastewater, with a resin acid
concentration of 36 m/L, was provided by Quesnel River Pulp Company, Quesnel, British Columbia.
The mill has an alternating thermomechanical/BCTMP process with peroxide bleaching. The "N" in
BCTMP-N indicates that the wastewater has normal fines/fiber content. Quesnel River Pulp Company also produces a high fines/fiber wastewater when producing certain special grades of pulp.
Wastewater was stored upon receipt at -20°C until it was used.
Anaerobic Toxicity Assay
A slightly modified anaerobic toxicity assay (ATA) described by Cornacchio et al.7 was used for all
assays. The modifications were:
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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