TY - JOUR
T1 - Sonication of pulp and paper effluent
AU - Shaw, Lawton E.
AU - Lee, Dana
N1 - Funding Information:
We gratefully acknowledge Shaun McNamara of Alberta-Pacific Forest Industries Inc. for making available the effluent samples and analytical information that made this work possible. The ultrasound system was purchased using a Research Incentive Grant from Athabasca University. The circulating chiller was purchased as part of a grant from Athabasca University’s Academic Research Fund. Elaine Birkigt is acknowledged for general assistance in the laboratory.
PY - 2009/3
Y1 - 2009/3
N2 - Final effluent from a pulp and paper kraft mill was exposed to power ultrasound at 357 kHz with the aim of reducing color, turbidity, and chemical oxygen demand (COD). Absorbance measurements showed a bleaching of the effluent at wavelengths above 250 nm, indicating loss of aromatic chromophores. Effluent turbidity also decreased. Surprisingly, there was no observable decrease in COD, within experimental error. This is attributed to the presence of bicarbonate and sulfate ions in the final effluent, which react with hydroxyl radicals and effectively block the oxidation of organics in the effluent. This was demonstrated by sonicating solutions of potassium hydrogen phthalate (KHP) containing chloride, bicarbonate, or sulfate ions, which are the major inorganic ions in the final effluent studied. A solution containing only 2.3 mM KHP showed a 19% reduction in COD after 6 h of sonication. An identical solution with 200 ppm chloride also showed a 19% COD reduction. However, solutions with 700 ppm sulfate and 400 ppm bicarbonate showed COD reductions of 11% and 3%, respectively.
AB - Final effluent from a pulp and paper kraft mill was exposed to power ultrasound at 357 kHz with the aim of reducing color, turbidity, and chemical oxygen demand (COD). Absorbance measurements showed a bleaching of the effluent at wavelengths above 250 nm, indicating loss of aromatic chromophores. Effluent turbidity also decreased. Surprisingly, there was no observable decrease in COD, within experimental error. This is attributed to the presence of bicarbonate and sulfate ions in the final effluent, which react with hydroxyl radicals and effectively block the oxidation of organics in the effluent. This was demonstrated by sonicating solutions of potassium hydrogen phthalate (KHP) containing chloride, bicarbonate, or sulfate ions, which are the major inorganic ions in the final effluent studied. A solution containing only 2.3 mM KHP showed a 19% reduction in COD after 6 h of sonication. An identical solution with 200 ppm chloride also showed a 19% COD reduction. However, solutions with 700 ppm sulfate and 400 ppm bicarbonate showed COD reductions of 11% and 3%, respectively.
KW - Bleaching
KW - Chemical oxygen demand
KW - Effluent
KW - Pulp and paper
KW - Turbidity
KW - Ultrasound
KW - Wastewater
UR - http://www.scopus.com/inward/record.url?scp=58049177784&partnerID=8YFLogxK
U2 - 10.1016/j.ultsonch.2008.10.011
DO - 10.1016/j.ultsonch.2008.10.011
M3 - Journal Article
C2 - 19058990
AN - SCOPUS:58049177784
SN - 1350-4177
VL - 16
SP - 321
EP - 324
JO - Ultrasonics Sonochemistry
JF - Ultrasonics Sonochemistry
IS - 3
ER -