50    BIOLOGICAL POST-TREATMENT OF
ANAEROBICALLY-TREATED BLACK LIQUOR SPILLS
FROM KRAFT PULP-MILL
C. Estrada-Vazquez, R. Hernandez-Vera, I. Magana-Plaza,
and A. Hernandez-Gonzalez
Centre for Advanced Studies and Research (CINVESTAV)
Environmental Biotechnology and Anaerobic Processes R&D Group-DBB
Mexico City, Mexico
H.M. Poggi-Varaldo
P3 Consulting Engineers and Ecatepec Institute of Technology-TESE
P.O. Box 75-202
Mexico D.F., 07300, Mexico
G. Fernandez-Villag Mex
Centre for Disaster and Hazards Prevention (CENAPRED)
Mexico City, Mexico
ABSTRACT
Previous research has shown that anaerobic treatment in biological fluidized bed reactors of
kraft black liquor spills effluents (DL) is an effective alternative. However, important concentrations of recalcitrant organic matter and color still remain in the anaerobic effluent (AnE). Aerobic bacterial post-treatment was ineffective, while adsorption onto activated carbon removed
both color and organic matter, but at potentially unfeasible costs.
The purpose of this work was to evaluate the post-treatment of the AnE by the application of
selected ligninolytic fungi strains under a variety of experimental conditions. A factorial experiment 23x3 with repetition was planned, the factors being: fungal strain (2 levels, Lentinus
edodes, L.e., and Trametes versicolor, and T.v.); effluent concentration (2 levels, 50% and 100%
v/v); carbon source supplementation (2 levels, 0.0 and 0.5 g/L glucose), and fungus immobilization (none, alginate, and activated carbon). The experimental responses were the net specific removals of color (1/mg biomass) and ligninoid substances (g lignin/mg biomass) discounted for
adsorptive removal.
It was found that L.e. effected significantly higher color and ligninoid removals (0.008 1/mg
and 0.012 g lg/mg biomass) than T.v. Interestingly, whole AnE (100% concentration) resulted in
higher responses (approximately 0.011 1/mg and 0.011 g lg/mg biomass) than dilute effluent
(50%). Glucose supplementation at 0.5 g did not have a conclusive effect: supplemented flasks
showed a slightly higher ligninoid reduction than the nonsupplemented, but the color removal
was significantly lower than the corresponding to nonsupplemented flasks. Fungi immobilization
on alginate showed the highest pollutant removals (0.012 1/mg and 0.012 g lg/mg biomass). Free
mycelium was second, while immobilization on activated carbon was last. Overall, the best color
and recalcitrant organic matter removals were obtained for Lentinus edodes, whole AnE. no carbon-source supplementation, and fungus immobilizaton on alginate.
INTRODUCTION
Several works have shown that aerobic post-treatment (using bacterial consortia) of anaerobi-
cally-pretreated pulp mill effluents cannot remove more than 10 to 15% (as chemical oxygen demand, COD) of the remaining organic matter load (activated sludge for bleaching effluents.' ro-
52nd Purdue Industrial Waste Conference Proceedings. 1997, Ann Arbor Press. Chelsea. Michigan 48118. Printed in
U.S.A.
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