Hou min Chang

Kinetics of bleach plant effluent decolorization by Phanerochaete chrysosporium

Abstract Decolorization of the first alkaline extraction stage (E 1 ) effluent from a pulp mill bleach effluent using the white-rot fungus Phanerochaete chrysosporium was conducted in a rotating biological contactor (RBC) under improved conditions. The kinetic model developed for both 1 d and 2 d retention times showed a characteristic pattern. The overall decolorization process can be divided into three distinct stages, viz., a rapid color reduction in the first hour of contact between the effluent and fungus, followed by a zero order reaction, and then a first order reaction. The color removal rate on the second day of the 2 d batch treatment was less than that on the first day. The decolorization in a continuous flow reactor achieved approximately the same daily color removal rate, but had a longer working lifetime as compared to the batch reactor, thereby removing more color over the fungal lifetime.

Treatment of chlorine bleaching effluent using a white-rot fungus

This study was undertaken to better understand the reactions related to fungal treatment of pulp bleaching effluents. Color, COD (chemical oxygen demand), glucose, chloride and ammonium concentration were monitored during the course of treatment of alkali extraction stage liquor (E1) with a white-rot fungus Phanerochaete chrysosporium. n nThe color removal rate was independent on the initial glucose concentration. The earlier used glucose concentration of 10 g l−1 was found to be unnecessary high as the residual glucose accounted for about 50% of the final COD of the effluent. The lowest practical glucose concentration was 2 g l−1. Below this the fungus lost its decolorizing activity in a few days. The lignin-related COD decreased 32% and up to 16.5 mM inorganic chloride was liberated (being 34% increase from the original concentration) from the chlorinated organic material in the effluent in 2 d. The observed rapid depletion of added ammonium nitrogen is believed to indicate a switch of a part of the mycelium to primary growth which leads to higher activity and longer active period of time due to renewal of the cells.

Biological delignification of pulp by Phanerochaete chrysosporium

Biological delignification of wood pulp was studied using the white-rot fungus Phanerochaete chrysosporium in liquid cultures. Kraft pulp and chemithermo-mechanical pulp (CTMP) were used as substrates. Both types of pulp could readily be delignified by the shaking cultures of the fungus: the kappa number of kraft pulp decreased from 33 to less than 10 in two weeks and the Klason lignin content of CTMP decreased from 26.5 to 21.3% in the same time. Stationary cultures did not delignify pulps effectively. During the fungal treatment, the strength of CTMP increased substantially. At a freeness level of about 350 ml, the tensile and tear indices increased by 20% and the burst index by 40% as compared to the original pulp. Unfortunately, CTMP turned dark during the treatment. The ISO brightness was originally 52.5, but after the incubation with the fungus it was only 17.9. After peroxide bleaching the brightness was still low, only 41.6.

A continuous biological process to decolorize bleach plant effluents.

Although almost every U.S. pulp mill has a biological wastewater treatment system, these systems based on bacteria, are largely ineffective in the removal of color. For this reason, we have attempted to utilize Phanerochaete chrysosporium, a fungus known to degrade lignin, as the primary organism in a novel waste treatment scheme named the MyCoR Process. Color from bleached Kraft mills originates principally from the first extraction stage of the bleach plant. It is this waste stream which is sent to the MyCoR Process reactor, a rotating biological contactor, for decolorization. We have found that under optimal conditions up to 2,000 color units/L/day can be removed from the waste stream. There is also a concomitant removal of COD and BOD. In addition, chlorolignins originating from the bleaching process were found to be dechlorinated; this is of interest to those concerned with the impact of bleach plant effluents on the environment. The process uses conventional wastewater treatment equipment. However, the use of a pure culture of fungus in a secondary metabolic state has not been attempted previously in a waste treatment scheme. Minor equipment modification and close operator attention may therefore be required. A preliminary economic analysis shows that the MyCoR Process, in its present state, would cost about US

Role of glucose in fungal decolorization of wood pulp bleaching effluents

30/metric ton of bleached Kraft pulp produced. This cost will decrease as improved or new strains of fungi are developed for the process.

Dechlorination and detoxification of bleach plant effluent by Phanerochaete chrysosporium

The white-rot fungus Phanerochaete chrysosporium, when immobilized on discs in a rotating biological contactor (RBC), can effectively decolorize the first alkaline extraction stage (E1) effluent from the bleach plant of a wood pulp production facility. We have shown that to degrade lignin and lignin-derived chromophoric structures, a co-substrate such as glucose must be added.

Bleach plant effluent influences enzyme production by Phanerochaete chrysosporium

Abstract Dechlorination, detoxification, and decolorization of the first alkaline extraction stage (Ep) effluent from a pulp mill bleach plant were studied during fungal treatment. The original Ep effluent and Ep effluent fractionated by ultrafiltration were treated with the white-rot fungus Phanerochaete chrysosporium under agitated conditions. The fungus was grown from spores for 4 d. Decolorization was observed 2 d after the addition of fresh media containing reduced levels of nitrogen and carbon. After 2–3 d reaction time detoxification, dechlorination and decolorization were evaluated. Color removal was most effective in the MW > 10 000 (HMW) fraction. Toxicity as measured by the MICROTOX bioassay, increased in both the HMW and MW 1000–10000 (MMW) fraction after fungal treatment. Molecular weight decreased during fungal treatment, which may have caused the increase in toxicity. The amount of chlorinated organic compounds, as measured by adsorbable organic halide analysis (AOX), decreased in each fraction.

Investigation into the kinetic properties of immobilized lignin peroxidases

Abstract The effect of pulp mill bleach plant effluent on enzyme production by Phanerochaete chrysosporium is described. (Bleach plant effluent contains residual lignin removed for the purposes of making paper). F.p.l.c. analysis showed different protein profiles when comparing effluent-free and effluent-containing cultures. In addition to using unfractionated effluent, various molecular weight fractions were also prepared for use in separate cultures by ultrafiltration of the effluent. Once again, F.p.l.c. analysis revealed a different protein profile was obtained with each molecular weight fraction used as an adjunct to the growth medium. Analysis of these proteins by polyacrylamide gel electrophoresis verified these differences and showed that effluent-containing cultures contain proteins not found in the effluent-free cultures.

METHOD OBTAINS FUNGAL REDUCTION OF THE COLOR OF EXTRACTION-STAGE KRAFT BLEACH EFFLUENTS.

Abstract Mixtures of lignin peroxidase isozymes were immobilized onto controlled-pore glass (CPG) beads through three different functional groups (free amino groups, free carboxylate groups, or the aldehyde groups of the metaperiodate-oxidized carbohydrate portions of the proteins) and catalytic properties of the immobilized proteins were determined. Some loss of activity occurred in all immobilized samples, but relatively high activities were maintained with enzymes immobilized via the modified carbohydrate moieties. The effectiveness of using the immobilized enzymes to treat anthracene and pulp mill bleach plant effluent was tested. Bleach plant effluent precipitated onto the aminopropyl-CPG beads inactivating the enzymes, probably due to reactions with free amino groups. In contrast anthracene was rapidly and completely degraded by the immobilized lignin peroxidases.