Pulp Bleaching Effluents Research Articles

Characterisation and utilization of steel industry waste sludge as heterogeneous catalyst for the abatement of chlorinated organics by advanced oxidation processes.

Catalytic advanced oxidation processes (AOPs) utilising UV irradiation have been reported to be highly efficient for the degradation of recalcitrant compounds. The focus of present study was to evaluate the potential of steel industry waste as an alternative to homogenous iron salts often used in AOPs. Iron rich sludge from effluent treatment plant (ETP) of a steel industry was subjected to acid washing and acid washing followed by calcination before using as catalyst for the oxidative removal of chlorinated organics present in synthetic and simulated bleaching effluents. The maximum total organic carbon removals of 64% and 25% from 4-chlorophenol solution and simulated pulp bleaching effluent, respectively were observed during photo-catalytic oxidation with acid washed steel sludge at stoichiometric H2O2 dose after 2 h reaction (catalyst dose = 1 g/L, and pH = 4.4). Low iron leaching (<2%) was observed from the catalyst even in acidic conditions and it could be reused twice without significant loss of catalytic activity.

A comparative study of advanced oxidative processes: Degradation of chlorinated organic compounds in ultrafiltration fractions of kraft pulp bleaching effluent

A comparative study of advanced oxidative processes: Degradation of chlorinated organic compounds in ultrafiltration fractions of kraft pulp bleaching effluent

A comparative study of advanced oxidative processes: Degradation of chlorinated organic compounds in ultrafiltration fractions of kraft pulp bleaching effluent

A comparative study of advanced oxidative processes: Degradation of chlorinated organic compounds in ultrafiltration fractions of kraft pulp bleaching effluent

A comparative study of advanced oxidative processes: Degradation of chlorinated organic compounds in ultrafiltration fractions of kraft pulp bleaching effluent

A comparative study of advanced oxidative processes: Degradation of chlorinated organic compounds in ultrafiltration fractions of kraft pulp bleaching effluent

A Novel Method for the Determination of Hydrogen Peroxide in Bleaching Effluents by Spectroscopy

A spectrophotometric method for the determination of hydrogen peroxide in pulp bleaching effluents is reported. The method is based on hydrogen peroxide instantly reacting with vanadium pentoxide in sulfuric acid solution, forming a peroxovanadate complex that has an absorption maximum at 454 nm. It was found that the optimum conditions were as follows: detection wavelength of 454 nm, a V2O5:H2O2 mole ratio of 2.2, and a sulfuric acid concentration of 0.5 mol/L. In order to eliminate the interference from dissolved lignin, fines, and suspended solids, the samples were acidified and centrifuged for spectroscopic quantification. The results showed that the method has an excellent measurement precision (RSD < 0.3%) and accuracy for the quantification of hydrogen peroxide content in pulp bleaching effluents. The present method is simple and accurate, making it suitable for applications in the pulp and paper industry.

Biological removal of chloro-organic compounds from bagasse soda pulp bleaching effluent by Coriolus versicolor

The potential of rainbow fungus (Coriolus versicolor) for bioremediation of bagasse soda pulp bleaching effluent containing chlorinated organic compounds was investigated without co-substrate addition. Initially, the effect of each of the operating variable including time, temperature, pH, and biomass on color reduction was investigated. The highest color reduction (percentage of the original value) was observed applying a treatment time of 6 days (58%), a pH of 3 (48%), a biomass dose of 9 g L-1 (59%), and a temperature of 35°C (48%). Then, the combined effect of parameters was studied to reach the best combinations of parameters leading to the highest color reduction. The highest performance of rainbow fungus on color reduction (66%) was observed when applying the combination of variables including temperature, treatment time, biomass dose, and pH combination of 35°C, 6 days, 9 g L-1, and 3, respectively. At this condition, COD and BOD of effluent were decreased by 45% and 53%, respectively. It was also found that Coriolus versicolor can efficiently reduced various toxic compounds; chlorophenols, chloroguaiacols, and chlorocatechols present in the effluent to the levels less than their lethal concentration (96LC50) even without addition of cosubstrate. In general, rainbow fungus can efficiently modify the undesirable physico-chemical characteristics of bagasse soda pulp bleaching effluent.

Optimization of Integrated Electro-Bio Process for Bleaching Effluent Treatment

The technical and economic feasibility of various electrochemical processes as pretreatment step for biological treatment for the management of kraft bagasse pulp bleach effluent has been studied, and the results are compared with that of the conventional chemical coagulation followed by biological treatment. A modeling methodology for integrating processes involving electrochemical and biological methods is proposed. Optimal combinations of operating variables giving a definite completion of pollutant removal are derived from the empirical models of each process. However, both the electrochemical steps as electrocoagulation and electro-oxidation were observed to perform technically better, and the former was noticeably more attractive based on the overall operating cost. The cost of electrocoagulation–biological (EC-Bio) treatment giving 80% COD removal was determined to be US $0.166/m3. A 41% reduction in the treatment cost was achieved when the conventional chemical coagulation–biological (CC-Bio) methodology replaced by an EC-Bio system. The research revealed the feasibility of electrochemical steps as a primer in the reduction of organic load and improvement in the biodegradability of pulp-bleaching effluent.

Rapid determination of hydrogen peroxide in pulp bleaching effluents by headspace gas chromatography

A headspace gas chromatographic (HS-GC) method has been developed for the determination of residual hydrogen peroxide in pulp bleaching effluents. The method is based on the reaction of hydrogen peroxide and permanganate in an acidic medium (0.1mol/L), in which hydrogen peroxide is quantitatively converted to oxygen within 10min at 60°C in a sealed headspace sample vial. The released oxygen is then determined by GC equipped with a thermal conductivity detector. The method is robust, sensitive, and accurate, with reproducibility characterized by a relative standard deviation of <0.5%, a sensitivity whose limit of quantification (LOQ) is 0.96μmol, and a demonstrated recovery ranging from 98 to 103%. Further, the method is simple, rapid, and automated.

Development of model for treatment of pulp and paper industry bleaching effluent using response surface methodology

AbstractThe treatment of bleaching‐effluent from pulp and paper industry was investigated in a batch electrocoagulation (EC) reactor using aluminium as sacrificial electrodes. The response surface methodology (RSM) was employed to evaluate the individual and interactive effects of four independent parameters viz., current density (j: 5–25 mA/cm2), initial pH (pHo: 5–9), electrolyte (NaCl) concentration (c: 0–2 g/L) and electrolysis time (t: 10–30 min) on Colour, COD and BOD removal efficiency. The results were analyzed using Pareto analysis of variance (ANOVA). Based on RSM analysis, a second‐order polynomial regression model was developed and found to be good fit with experimental results. © 2011 American Institute of Chemical Engineers Environ Prog, 2011

Studies on coupled biological and photochemical treatment of soda pulp bleaching effluents from agro residue based pulp and paper mill

AbstractBACKGROUND: The effect of coupled biological and photochemical processes for treatment of bio‐recalcitrant effluents from chlorination (C) and first alkaline extraction (E1) stages of soda pulp bleaching in an agro‐residue based pulp and paper mill has been investigated.RESULTS: The work aims to evaluate the coupled effect on the extent of degradation in terms of chemical oxygen demand (COD) reduction. Biological treatment of C and E1 effluent resulted in 30% and 57% COD, respectively, after 1 day of treatment with acclimatized activated sludge. However, further increase in retention time did not show any significant change in degradation efficiency. Investigations on photocatalytic treatment (at 365 nm and 0.625 W) of C effluent resulted in 47% degradation under optimized conditions (3 g L−1 TiO2, pH 6.0 and 0.01 mol L−1 NaOCl), and E1 effluent showed 37% degradation under optimized conditions (2.5 g L−1, pH 4.0 and 0.03 mol L−1 NaOCl) after 6 h of UV irradiation. However, photocatalytic treatment of biotreated (1 day) effluents under similar optimized conditions significantly enhanced the degradation to 81% and 93% in C and E1 effluent, respectively, after 2 h irradiation.CONCLUSION: Coupled biological treatment followed by photocatalysis is an effective method for the reduction of total organic carbon (TOC) of the test effluents and it would facilitate closed circuiting of water used for soda bleaching in an agro pulp and paper mill. Copyright © 2011 Society of Chemical Industry

Combination of an anaerobic process with O3, UV and O3/UV for cellulose pulp bleaching effluent treatment

Recent studies have shown that partial oxidation by advanced oxidation processes (AOP) is able to transform hard-to-degrade compounds and increase their biodegradability. In this work, anaerobic treatment was followed by ozonation, UV radiation and ozonation in the presence of UV radiation, to treat bleaching effluents from a cellulose kraft pulp plant. The anaerobic reactor (horizontal anaerobic immobilized sludge bed, HAISB) was used as a pretreatment to reduce the effluent organic load before applying AOP. The ozone treatments were applied in three different pH environments (3, 8 and 10) with retention times of 10, 30, 45 and 60 min. COD and adsorbable organic halogens (AOX) removal efficiencies at the HAISB were approximately 50%, while the BOD removal efficiency reached 80%. Ozonation promoted further removal of AOX and COD so that the combined efficiency reached 96% for AOX and 70% for COD. In the oxidation process, BOD was either removed in small quantities or actually increased, as intended, so th...

Homogeneous and Heterogeneous Catalytic Ozonation of Pulp Bleaching Effluent

AbstractCatalytic ozonation is a promising treatment method for both water and wastewater. In this study, in order to increase the biodegradability of bleaching wastewater from an integrated pulp- and -paper production plant, granulated activated carbon-(GAC), iron-(Fe

Effects of solvent, pH, salts and resin fatty acids on the dechlorination of pentachlorophenol using magnesium–silver and magnesium–palladium bimetallic systems

The effects of pH, organic co-solvent, salts such as sodium chloride, sodium sulfate, and co-pollutants, resin and fatty acids (RFAs) on the dechlorination of pentachlorophenol (PCP) by magnesium/silver (Mg/Ag) and magnesium/palladium (Mg/Pd) systems were examined in the present investigations. Such studies provide relevant information about the applicability of bimetallic systems for remediation of raw wastewaters (such as pulp bleaching effluents) or groundwater. Removal efficiencies of 10 mg L −1 PCP by Mg/Pd and Mg/Ag systems at the end of 1 h reaction were 93% and 78%, respectively, in the presence of acetone (1% v/v). On the other hand, the removal efficiencies were 86% and 70% for reactions conducted in alcoholic solvents (1% v/v) using Mg/Pd and Mg/Ag systems, respectively. The efficiencies of PCP removal by the two bimetallic systems could be correlated to the dipole moments of co-solvents used. The second order reaction rate constant for PCP removal by Mg/Ag system was highest (0.03 L mg −1 min −1) in the absence of any pH-control mechanism. Optimum pH for the dechlorination of PCP by Mg/Pd system was found to be ∼5.5 and >92% of the compound was removed within 15 min of reaction. Presence of chlorinated and non-chlorinated resin fatty acids (RFAs) resulted in substantial reduction in the rate and extent of PCP removal by Mg/Ag system whereas dechlorination by Mg/Pd remained unaffected. Presence of sodium sulfate or sodium chloride in the reaction phase reduced the rate and extent of PCP removal by Mg/Ag system. PCP dechlorination by Mg/Pd system was adversely impacted by the addition of sodium chloride and unaffected by the presence of sodium sulfate.

Electrochemical treatment of pentachlorophenol in water and pulp bleaching effluent

Adsorbable organic halides (AOX) compounds produced during bleaching of pulp are recalcitrant and known to have eco-toxic effect. We have studied the removal of pentachlorophenol (PCP) as a model AOX compound in water as well as in pulp bleaching effluent of a bamboo based mill by electrochemical treatment in batch mode. It was found that 10 mg L −1 of PCP in water was removed almost completely in <10 min at a current density of 6 mA cm −2 in the presence of 1000 mg L −1 NaCl serving as an electrolyte and source of chloride ions. The initial rate of PCP removal was found to decrease at alkaline pH (9.3) as compared to that at acidic pH (5.5). PCP removal in neutralized raw pulp bleach effluent (containing ∼1830 mg L −1 of chloride) was very slow and incomplete even after 2 h of electrochemical treatment at a current density of 15 mA cm −2. Various pretreatments of raw bleach effluent such as, alkaline sulfide using sodium sulfide, alkaline reduction using ferrous sulfate and coagulation using potash alum were evaluated. Electrochemical treatment of potash alum pretreated effluent (spiked with PCP) could achieve >90% removal of initial colour, COD and PCP in <1 h. The treatment scheme presented here may be a promising technology for removal of AOX, COD and colour from pulp bleaching effluent. The estimated cost of combined treatment (potash alum coagulation + electrochemical) is US$ 0.7–0.9 per cubic meter of the raw pulp bleach effluent.

Decolorization of kraft pulp bleaching effluent by a newly isolated fungus,Geotrichum candidum Dec 1

Kraft pulp bleaching effluent supplemented with glucose was decolorized by a newly isolated fungusGeotrichum candidum Dec 1 (Dec 1) that showed a wide decolorizing spectrum to synthetic dyes. When the glucose concentration in the effluent was 30 g/l, the color removal and the reduction of absorbable organic halogens were 78% and 43% after 7 days culture, respectively. The average molecular weight of colored substances measured by gel filtration chromatography was lowered to less than 3000 from 5600 after 7 days culture. As the contribution of extracellular enzymes such as peroxidase (DyP), manganese peroxidase, and laccase to the decolorization of the kraft pulp bleaching effluent was small, Dec 1 appears to have a different mechanism of decolorizing kraft pulp bleaching effluent when compared with enzymes used to decolorize synthetic dyes.

Dihydroxybenzenes: driven Fenton reactions

Different compounds that reduce Fe(III) and that simultaneously increase the oxidation potential of the H2O2/Fe2+ system, have been evaluated. In this work, the improving of Fenton reactions by 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DHBA) or 1,2-dihydroxybenzene (CAT) were studied. The three compounds are able to reduce Fe(III) to Fe(II), but the kinetic results depend on the method used to determine the Fe(II) ion. The dihydroxybenzenes (DHBs) degrades veratryl alcohol (VA), a lignin model compound, to a greater extent than observed in a typical Fenton reaction. The rate of VA degradation was associated with the duration of the chemiluminescence (CAT > 2,3-DHBA > 3,4-DHBA) and not with the sum of integrated counts. The treatment of a cellulose pulp bleaching effluent with DHBs/Fe(III)/H2O2 was evaluated by analyzing their depolymerization at pH 4 and 7 through molecular mass distribution determinations.

Pulp Mill Effluent Treatment by Fenton-Type Reactions Catalyzed by Iron Complexes

Fenton reaction, which involves hydrogen peroxide and ferrous ion, has been proposed as an efficient option for effluent treatment. In this work, the treatment of a pulp bleaching effluent using Fenton-type reactions assisted by either, 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DHBA) and 1,2-dihydroxybenzene (CAT), were studied. The treatment was evaluated by the removal of adsorbable organochloride compounds (AOX) and toxicity. Furthermore, the degradation of 2-chlorophenol and 4-chlorophenol in aqueous solutions were carried out, separately. Increase in oxidative activities of Fenton-type reactions mediated by the dihydroxybenzenes (DHBs) were found. These activities enhancement were related with a higher production of activated species by Fe/DHBs/H2O2, as indicted by chemiluminesce. The large decrease in AOX values and toxicity of the treated bleaching effluent by DHBs at pH 4.0 and 7.0 showed that 2,3-DHBA enhanced the activity of the Fenton reaction. The use of 3,4-DHBA and CAT resulted in loss of efficiencies of Fenton reaction to effluent treatment but not to pure chlorophenol solutions. At pH 7.0 lower efficiencies than those at pH 4.0 were achieved.

Treatability of kraft pulp bleaching wastewater by biochemical and photocatalytic oxidation

In this study the biological treatability and TiO2 photocatalyzed oxidation characteristics of sulfate pulp bleaching effluents were investigated. The original wastes had a low biodegradability as determined by BOD5/COD ratios. Biological treatment was conducted in a batch activated sludge reactor. The non-biodegradable fraction amounted to 60% of the initial COD and compounds specific to these wastes were not removed during biotreatment. In order to enhance the biodegradability of these wastes, mixed raw effluent, C/E-H stage effluent, D/E-D stage effluent and biologically pretreated wastes were subjected to TiO2 photocatalyzed oxidation. Photocatalytic oxidation led to an increase in the BOD5/COD ratio of D/E-H stage raw and biologically treated wastewater, while chloride formation was observed in both cases in a five-hour reaction period in the presence of 1g 1−1 TiO2 and 15×10−3 M H2O2 at pH=6.5. The specific absorption values (A272nm/CODs, A254nm/CODs, A346nm/CODs, A436nm/CODs) exhibited parallel decreases during photocatalytic oxidation which indicate that oxidation reactions were nonspecific with respect to the organics present in these wastes. As a conclusion it can be suggested that biological treatment should be placed before the photocatalytic oxidation method. Even in this scheme, the application of photocatalytic oxidation could only then be favored when the COD and chloride concentrations in the wastewater were below certain values or when wastewater was diluted.

Pulp mill effluent treatment by Fenton-type reactions catalyzed by iron complexes

Fenton reaction, which involves hydrogen peroxide and ferrous ion, has been proposed as an efficient option for effluent treatment. In this work, the treatment of a pulp bleaching effluent using Fenton-type reactions assisted by either, 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DHBA) and 1,2-dihydroxybenzene (CAT), were studied. The treatment was evaluated by the removal of adsorbable organochloride compounds (AOX) and toxicity. Furthermore, the degradation of 2-chlorophenol and 4-chlorophenol in aqueous solutions were carried out, separately. Increase in oxidative activities of Fenton-type reactions mediated by the dihydroxybenzenes (DHBs) were found. These activities enhancement were related with a higher production of activated species by Fe/DHBs/H 2 O 2 , as indicted by chemiluminesce. The large decrease in AOX values and toxicity of the treated bleaching effluent by DHBs at pH 4.0 and 7.0 showed that 2,3-DHBA enhanced the activity of the Fenton reaction. The use of 3,4-DHBA and CAT resulted in loss of efficiencies of Fenton reaction to effluent treatment but not to pure chlorophenol solutions. At pH 7.0 lower efficiencies than those at pH 4.0 were achieved.

Treatability of kraft pulp bleaching wastewater by biochemical and photocatalytic oxidation

In this study the biological treatability and TiO 2 photocatalyzed oxidation characteristics of sulfate pulp bleaching effluents were investigated. The original wastes had a low biodegradability as determined by BOD 5 /COD ratios. Biological treatment was conducted in a batch activated sludge reactor. The non-biodegradable fraction amounted to 60% of the initial COD and compounds specific to these wastes were not removed during biotreatment. In order to enhance the biodegradability of these wastes, mixed raw effluent, C/E-H stage effluent, D/E-D stage effluent and biologically pretreated wastes were subjected to TiO 2 photocatalyzed oxidation. Photocatalytic oxidation led to an increase in the BOD 5 /COD ratio of D/E-H stage raw and biologically treated wastewater, while chloride formation was observed in both cases in a five-hour reaction period in the presence of 1g 1 −1 TiO 2 and 15×10 −3 M H 2 O 2 at pH=6.5. The specific absorption values (A 272nm /COD s , A 254nm /COD s , A 346nm /COD s , A 436nm /COD s ) exhibited parallel decreases during photocatalytic oxidation which indicate that oxidation reactions were nonspecific with respect to the organics present in these wastes. As a conclusion it can be suggested that biological treatment should be placed before the photocatalytic oxidation method. Even in this scheme, the application of photocatalytic oxidation could only then be favored when the COD and chloride concentrations in the wastewater were below certain values or when wastewater was diluted.