Removal of Chlorophenols and Chlorolignins from Bleaching Effluent by Combined Chemical and Biological Treatment

Abstract

Organic matter from spent bleaching effluents (from chlorination (C) or extraction (E) stages, or a mixture of both) was effectively precipitated as a water insoluble complex with polyethyleneimine (polyimine). Precipitation was performed in a pilot unit operating automatically. The colour, chemical oxygen demand (COD), and adsorbable organic halogens (AOX) were reduced in the C-effluent by up to 92%, 65%, and 84%, respectively. Regarding the E-stage effluent, reduction was up to 76% for colour, 70% for COD, and 73% for AOX. No significant reduction of BOD5 was observed in the supernatant of the treated effluent. Fish toxicity was greatly reduced. Laccase increased the molecular weight of the effluent constituents, thus facilitating subsequent precipitation. After treatment with laccase, the bulk of mono- and dichlorophenol is coprecipitated with the liquors from the C and E bleaching stages. Fungi (representatives of the genera Aspergillus and Penicillium) achieved an appreciable level of degradation of chlorophenols and other chloroorganic compounds from the bleaching effluent.

Laccases as a Potential Tool for the Efficient Conversion of Lignocellulosic Biomass: A Review

“…Laccases can also contribute to such an aim, assisting in certain processes during the manufacture of new value-added products. For instance, laccases have been typically applied in the pulp and paper industry (1) for pulp bleaching, removing the residual lignin responsible of pulp color [71], (2) for controlling pitch deposits that reduce pulp quality [75], or (3) for detoxification of bleaching effluents rich in phenolic compounds [139]. Laccases have been also evaluated for the synthesis of new materials and products from lignocellulosic feedstocks.…”

Biofuels and Biochemicals Production

“…Laccases can also contribute to such an aim, assisting in certain processes during the manufacture of new value-added products. For instance, laccases have been typically applied in the pulp and paper industry (1) for pulp bleaching, removing the residual lignin responsible of pulp color [71], (2) for controlling pitch deposits that reduce pulp quality [75], or (3) for detoxification of bleaching effluents rich in phenolic compounds [139]. Laccases have been also evaluated for the synthesis of new materials and products from lignocellulosic feedstocks.…”

Environmental applications of enzymes

“…Bollag et al (1988) concluded that the ability of laccase to detoxify a solution containing phenols appears to be function of the compound being treated, the source of the enzyme and other environmental factors. Laccase has also been cited as a possible candidate for the treatment of bleaching plant effluent (Milstein et al, 1988;Lankinen et al, 1991). In a study on the removal of chlorophenols and chlorolignins from bleaching effluents by precipitation, Milstein et al (1988) reported that laccase could polymerize low-molecular-mass phenols, thereby facilitating their removal by reaction and precipitation with polyethyleneimine.…”

“…Laccase has also been cited as a possible candidate for the treatment of bleaching plant effluent (Milstein et al, 1988;Lankinen et al, 1991). In a study on the removal of chlorophenols and chlorolignins from bleaching effluents by precipitation, Milstein et al (1988) reported that laccase could polymerize low-molecular-mass phenols, thereby facilitating their removal by reaction and precipitation with polyethyleneimine. Royer et al (1991) noted that intracellular enzymes (not identified) of the fungus Coriolus versicolor had some effect on effluent decolorization.…”