Treatment Of Whitewater Research Articles

Treatment of whitewater from pulp and paper industry using membrane filtrations

Treatment of whitewater from pulp and paper industry using membrane filtrations

Isolation, Identification, and Selection of Bacteria With Proof-of-Concept for Bioaugmentation of Whitewater From Wood-Free Paper Mills.

In the wood-free paper industry, whitewater is usually a mixture of additives for paper production. We are currently lacking an efficient, cost-effective purification technology for their removal. In closed whitewater cycles the additives accumulate, causing adverse production problems, such as the formation of slime and pitch. The aim of our study was to find an effective bio-based strategy for whitewater treatment using a selection of indigenous bacterial isolates. We first obtained a large collection of bacterial isolates and then tested them individually by simple plate and spectrophotometric methods for their ability to degrade the papermaking additives, i.e., carbohydrates, resin acids, alkyl ketene dimers, polyvinyl alcohol, latex, and azo and fluorescent dyes. We examined correlation between carbon source use, genera, and inoculum source of isolates using two multivariate methods: principal component analysis and FreeViz projection. Of the 318 bacterial isolates, we selected a consortium of four strains (Xanthomonadales bacterium sp. CST37-CF, Sphingomonas sp. BLA14-CF, Cellulosimicrobium sp. AKD4-BF and Aeromonas sp. RES19-BTP) that degrade the entire spectrum of tested additives by means of dissolved organic carbon measurements. A proof-of-concept study on a pilot scale was then performed by immobilizing the artificial consortium of the four strains and inserting them into a 33-liter, tubular flow-through reactor with a retention time of < 15 h. The consortium caused an 88% reduction in the COD of the whitewater, even after 21 days.

Treatment of white water with combined predominant bacteria and immobilized enzyme

White water treatment with combined predominant bacterial species and immobilized enzyme was investigated. The use of the single predominant bacteria of Brevundimonas diminuta or Virgibacillus pantothenticus resulted in poor treatment responses. With the combined bacterial species, the treatment effect was clearly improved. When the dosage ratio of Brevundimonas diminuta to Virgibacillus pantothenticus was 1:2, the chemical oxygen demand (CODCr) removal rate reached 70.5%, the cationic demand decreased 46.0%, and the electrical conductivity decreased 18.6% after 16 h of treatment. When mixed with the immobilized enzyme, the treatment efficiency increased with the immobilized pectinase dosage. When 8 g/L immobilized pectinase was added, the treatment time was shortened from 16 h to 4 h, the highest removal rate of CODCr was 74.1%, the cationic demand decreased 68.7%, and the electrical conductivity in the white water decreased 30.1%. The results indicated that the combination of predominant bacterial species and immobilized pectinase could greatly improve the treatment efficiency of white water.

Immobilized enzyme on pulp fiber through layer-by-layer technique using cationic polyacrylamide for whitewater treatment from papermaking.

Anionic pectic substances in whitewater from papermaking are detrimental to machine operation and product quality. Pectinase was immobilized on pulp fiber using cationic polyacrylamide with layer-by-layer method to obtain bound enzyme with tunable activity and good performance for wastewater treatment. It was revealed that high charge density and low molecular weight for cationic polyacrylamide were advantageous for enzymatic activity. During the layer-by-layer adsorption process, the enzymatic activity of the immobilized enzyme increased nearly linearly with the layer number from 983 to 3074U/g until the fourth layer. The stability of the four-layer immobilized enzyme was improved. The multilayer immobilized enzyme exhibited good reusability and storage stability compared with monolayer enzyme. At dosage of 10U/mL, the cationic demand of the whitewater samples was reduced by 15% using four-layer immobilized enzyme. The results indicated a potential route to prepare immobilized enzyme with good performance for wastewater treatment in papermaking industry.

Effects of temperature on white water treatment by the dominant bacteria

Abstract Three dominant bacteria including Virgibacillus pantothenticus, Bacillus cereus, and Bacillus subtilis were screened from an activated sludge domesticated via white water in the laboratory. The treatment effects of chemical oxygen demand (COD), electrical conductivity and cationic demand (CD) of the white water by three dominant bacteria were studied in different temperatures. The results showed that the optimum metabolic temperature of the three dominant bacteria was 30 °C with the tested range of 20 °C to 60 °C. The best treatment effect was tended to be stable at a hydraulic retention time of 14 h, COD removal rate was 67.69 %, 77 % and 75.38 %, the electrical conductivity decreased by 0.86 mS/cm, 0.86 mS/cm and 0.62 mS/cm and the CD decreased by 45.61 %, 73.68 % and 50 % for V. pantothenticus, B. cereus, and B. subtilis, respectively.

Preparation of Immobilized Enzymes on Pulp Fiber with the Layer-by-layer Self-assembly Technique and its Application in Whitewater Treatment

Anionic pectic substances in whitewater are harmful to the papermaking process and product quality. To diminish their negative effect, immobilized pectinase was prepared to treat pectic compounds in whitewater. Pectinase was immobilized on pulp fiber via a layer-by-layer assembly technique using polyethyleneimine. The activity of the immobilized enzyme varied nearly linearly, from 2876 U/g to 4838 U/g, until the number of layers reached four. The properties of the bound enzymes and their free counterparts were investigated. After being fixed on the pulp fiber, the optimum pH of the enzymes shifted from 4.4 to 4.0 and the optimum temperature increased by 5 °C to 50 °C. It was shown that the Vm value was slightly reduced for the immobilized enzymes, while the Km value noticeably decreased. Furthermore, the immobilized enzyme was tested in papermaking whitewater treatment. The four-layer immobilized enzymes lowered the whitewater cationic demand by 18% and 30% at pH values of 7 and 4, respectively. The immobilized pectinase could potentially be employed to treat wastewater in the papermaking industry.

Effects of pH on biological treatment of paper mill white water with the addition of dominant bacteria

Virgibacillus pantothenticus, Bacillus cereus, and B. subtilis were screened from an activated sludge that had become acclimated to white water in the laboratory. The effects of the pH on the ability of biological treatment to reduce the biological oxygen demand of white water was studied for three dominant bacteria. The pH ranged from 4 to 8, and the optimum treatment efficiencies for white water treatments with the single dominant bacterium V. pantothenticus, B. cereus, and B. subtilis occurred at pH values of 5, 6, and 6, respectively. The results also indicated that the best treatment effect was achieved at a hydraulic retention time of 14 h. When each dominate species was tested under their optimum pH value and hydraulic retention time, the chemical oxygen demand removal rate was 67.7%, 77%, and 75.4%; the electrical conductivity decreased by 0.18 mS/cm, 0.93 mS/cm, and 0.51 mS/cm; and the cationic demand decreased by 69.7%, 70.0%, and 70.9% for V. pantothenticus, B. cereus, and B. subtilis, respectively. These results are helpful for promoting the practical application of dominant bacteria in white water treatment.

Screening Predominant Bacteria and Construction of Efficient Microflora for Treatment of Papermaking White Water

Three strains of bacteria were isolated and purified from activated sludge for white water treatment in the laboratory. These strains were identified as Bacillus subtilis, Bacillus cereus, and Virgibacillus pantothenticus through a morphological analysis, the MIDI Sherlock automatic microbial identification system, and 16S rRNA methods. The results of the construction of efficient microflora for white water showed that a mass percentage ratio of B. subtilis, B. cereus, and V. pantothenticus of 50%:35%:15% achieved an optimal treatment effect. Analysis by gas chromatograph-mass spectrometer (GC-MS) established that the content of characteristic pollutants in white water decreased notably after treatment with the efficient microflora, and detected the intermediate products of short chain fatty acids, alcohols, and other compounds. Moreover, through measuring the removal rate of chemical oxygen demand (COD), electrical conductivity, and cationic demand (CD), the optimal retention time for white water treatment with the efficient microflora was 4 h to 6 h, and when the removal rate of COD reached approximately 90%, the electrical conductivity and the cationic demand were reduced to lower values.

High performance of hydrophilic polymers on the crosslinked polystyrene spheres for controlling contaminants in white water

ABSTRACTThe accumulation of dissolved and colloidal substances (DCS) and inorganic salts in the white water of papermaking circulation system will result in the abnormal runnability of paper machine and low quality of products. Contaminant adsorption on a solid adsorbent in a fluidized bed reactor has been applied for white water treatment. In this study, three kinds of hydrophilic polymers {i.e., poly[methacryloxyethyltrimethyl ammonium chloride] (poly‐MAC), polyacrylamide, and poly[acrylic acid] (poly‐AA)} had been grafted on the surface of the polystyrene (PS) spheres through two‐step reactions. Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analysis, Zeta potential were evaluated the characteristics of modified PS spheres. The results showed that PS‐poly(MAC) had good affinity to DCS. Cationic demand, total DCS, and turbidity of white water had been reduced by 79.5%, 40.0%, and 38.4%, respectively, when the amount of PS‐poly(MAC) was 50 g/L. While PS‐poly(AA) played an important role in removal of metal ions so as to cut down the conductivity of white water. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45169.

Pitch Control of Recycled Whitewater from Papermaking by Aspergillus oryzae

Whole cells of Aspergillus oryzae 35 were used as a biocatalyst for the degradation of glycerol trioleate, which largely contributes to pitch deposits in papermaking. Different types of inducers in culture media showed various effects on both the biomass and lipase activity of whole-cell biocatalysts. The cells of A. oryzae 35 cultured with Tween 80 showed higher catalytic activity than the others. The effects of several key factors on A. oryzae 35-catalyzed treatment of a glycerol trioleate-containing whitewater model were investigated, and the optimal pH value, reaction temperature, substrate concentration, and shaking speed were determined to be 7.5, 45 °C, 50%, and 200 rpm, respectively. Results from a practical treatment of whitewater resin sediments with A. oryzae showed that the mean particle size of the original whitewater was sharply reduced from 534 nm to 356 nm after biocatalytic degradation. Aspergillus oryzae whole-cells are newly promising biocatalysts for whitewater treatment in papermaking industries because of their cost-effectiveness, simple preparation, and environmental friendliness.

Cationic polystyrene spheres for removal of anionic contaminants in white water of papermaking

ABSTRACTIn a paper mill's water circuit, normal runnability of the paper machine is often disturbed due to the buildup of dissolved and colloidal substances (DCS). Contaminant adsorption on a solid adsorbent in a fluidized bed reactor has been applied for white water treatment. In the present study, polystyrene (PS) spheres were firstly acylated by acryloyl chloride, then poly(methacryloxyethyltrimethyl ammonium chloride) (PMAC) was grafted onto the acylated PS spheres, induced by surface‐initiated free‐radical polymerization. Fourier transform infrared spectroscopy, thermal gravimetric analysis, and scanning electron microscopy were used to characterize the changes of PS spheres in chemical structures and surface morphology. The results showed that acylated PS spheres could be easily grafted with PMAC in 53.83% weight increase. Polyelectrolyte loading of PS spheres reached up to 1.72 mmol/g. The resulted cationic modified PS spheres could effectively decrease the cationic demand in white water and it still maintained high performance after operating repeatedly for 10 batches. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 10.1002/app.41379.

Immobilization of pectinase on polyethyleneimine-coated pulp fiber for treatment of whitewater from papermaking

Abstract After being coated with polyethyleneimine (PEI), pulp fiber was used as carrier for pectinase. When PEI concentration, enzyme concentration and pH of enzyme solution were 0.01% (w/v), 0.25% (v/v) and 7, respectively, the resultant immobilized enzyme exhibited the highest enzymatic activity as about 670 μg min−1 g−1. Higher thermo and pH stabilities than those of the free enzyme were achieved after immobilizing the enzyme on PEI-coated pulp fiber. Furthermore, the bound pectinase effectively decreased the cationic demand of whitewater in papermaking under the practical industrial conditions and still maintained high activity after operating repeatedly for 8 batches. The results presented that through a simple, facile and inexpensive method, pectinase can be effectively immobilized on pulp fiber and the immobilized pectinase showed the potential application in practical industrial treatment of whitewater in papermaking industry.

Preparation of immobilized pectinase on regenerated cellulose beads for removing anionic trash in whitewater from papermaking

BACKGROUND Anionic pectic compounds in whitewater (the aqueous solution that drains from a wet sheet of paper as it is being formed) negatively impact the papermaking process as well as the product quality. In order to remove these substances, regenerated cellulose beads were prepared and used as a new carrier for commercially available pectinase via physical adsorption to treat whitewater. RESULTS The optimum immobilization temperature, time and pH of the immobilized pectinase on regenerated cellulose beads were 20°C, 2 h and 7.0, respectively, under which the enzyme showed high protein loading and enzymatic activity of 2.9 mg g-1 and 178 U g-1 of the immobilized biocatalyst, respectively. Compared with the free pectinase, the immobilized enzyme on regenerated cellulose beads showed higher thermo and pH stabilities. Furthermore, the immobilized pectinase showed good mechanical strength and high catalytic capability in lowering the cationic demand of whitewater. CONCLUSION The preparation of immobilized enzyme on regenerated cellulose beads was simple, facile, cost effective and environmentally friendly. It was also demonstrated that the resultant pectinase thus obtained could potentially be utilized for treatment of whitewater in the papermaking industry due to its effectiveness in reducing cationic demand. © 2013 Society of Chemical Industry

Immobilization of pectinase on oxidized pulp fiber and its application in whitewater treatment

Modified pulp fiber was originally used as a new type of carrier for pectinase immobilization. Pulp fiber was oxidized by sodium periodate to produce aldehyde groups for covalently binding with amino groups of pectinase. Results showed that the enzymatic activity of immobilized pectinase on pulp fiber reached 65μgg−1min−1 when immobilization pH value, temperature and time were of 7.0, 20°C and 15min, respectively. The immobilized pectinase showed higher thermo stability in a wider temperature range of 40–70°C than its free type and its optimal pH shifted from 8.0 to 8.8. Furthermore, the immobilized pectinase exhibited good operational stability. When employed in whitewater treatment of papermaking industry, it still efficiently decreased the cationic demand after operating repeatedly for six batches. The results obtained demonstrate a promising route to prepare available, cheap and biodegradable carrier for immobilizing enzymes with potential application in wastewater treatment in papermaking industry.

Immobilization of pectinase and lipase on macroporous resin coated with chitosan for treatment of whitewater from papermaking

Anionic residues and pitch deposits in whitewater negatively impact the operation of paper-forming equipment. In order to remove these substances, a macroporous resin based on a methyl acrylate matrix was synthesized and coated with chitosan of various molecular weights through glutaraldehyde cross-linking. Pectinase from Bacillus licheniformis and lipase from Thermomyces lanuginosus were immobilized on the resin coated with chitosan by a Schiff base reaction. The highest hydrolysis activities of the immobilized enzymes were achieved by using chitosan with 10×105DaMW for coating and 0.0025% glutaraldehyde for cross-linking chitosan. The cationic demand and pitch deposits in whitewater were reduced by 58% and 74%, respectively, when treating whitewater with immobilized dual-enzymes for 15min at 55°C and pH 7.5. This method is useful for treatment of whitewater in the papermaking industry.

Cationisation of silicon wafers to assess the development of a solid sorbent for the removal of anionic contaminants in paper machine white water

Growing concerns about water availability is becoming of major interest for governments around the world. Various water initiatives are under study to establish recommendations on water governance and policies to ensure the sustainability of water supply for people and industries. As the pulp and paper industry is one of the major users of water, the implementation of such water initiatives will force the industry to improve their water management programs by moving further towards closed-cycle papermaking. Fresh water consumption reduction induces a gradual accumulation of dissolved and colloidal substances (DCSs) in process waters with detrimental effects on papermaking operations and paper quality. DCS removal is the key factor to meet targeted fresh water consumption levels. Contaminant adsorption on a modified solid sorbent in a fluidized bed reactor has been proposed for paper machine white water treatment. Cationic solid sorbents were synthesized by two different methods: (1) Silica nanoparticles were deposited on silicon wafers and silanized by quaternary ammonium organosilanes (TMAC, TDDMAC, and ODDMAC) and (2) Silicon wafers grafted with cationic polymer (MeDMA) were synthesized via atom transfer radical polymerization (ATRP). The growth of silica nanoparticles on the surface was investigated by scanning electron microscopy (SEM). Both sorbent surfaces were characterized by X-ray photoelectron spectrometry (XPS), contact angles (CA), and conductometric titration to determine quaternary ammonium surface density. Results show that silica particles deposited on silicon wafers increased the specific surface area and the number of active sites for the silanization reaction. The shorter silane alkyl chains increases the silanization rate. The quaternary ammonium quantification by conductometric titration showed that ATRP exhibits higher amine groups/unit surface comparatively to the silanization with TMAC. Both techniques can be used to assess the development of a solid sorbent that will be used in a fluidized bed reactor for paper machine white water treatment.

Structure of cake layer in a submerged anaerobic membrane bioreactor

A laboratory-scale submerged anaerobic membrane bioreactor (SAnMBR) was used for thermomechanical pulping whitewater treatment. Sludge cake formation on membrane surfaces was identified as the dominant mechanism of membrane fouling. The spatial distribution of physical, chemical and microbiological structure of cake layers was characterized by various analytical techniques, including micro-tome slicing technique, confocal laser scanning microscopy (CLSM), conventional optical microscopy (COM), scanning electron microscopy (SEM)-energy-dispersive X-ray analyzer (EDX), particle size distribution (PSD) analysis, Fourier transform infrared (FTIR) spectroscopy, extraction and chemical analysis of extracellular polymeric substances (EPS), and polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). The results showed that the areal porosity decreased from the top layer to the bottom layer. Smaller flocs had a higher tendency to accumulate on membrane surfaces but the consolidation of cake sludge in the bottom layers resulted in larger flocs as compared to the fresh cake sludge formed on the top layers. There was an increase in the bound EPS density (mg EPS/cm 3 wet sludge) and a decrease in the ratio of proteins to polysaccharides in bound EPS from the top to bottom layers. PCR-DGGE study showed that there were significant differences in microbial community population density along the cake layer depth. Through the CLSM and COM images, cake layer was found to have a loose outer surface when compared with the cake bottom. The results provide a new insight in cake layer structure and suggest that structures change significantly from the top layer to the bottom layer.

Magnetic Ion Exchange for White Water Treatment and Recycling

Magnetic Ion Exchange for White Water Treatment and Recycling

Biological treatment of whitewater in a laboratory process in order to determine kinetic parameters for model development

Implementation of an in-mill biological treatment plant is one solution to the problems associated with closure of whitewater systems. It is, however, important to operate the treatment with low concentration of nutrients in the effluent. The effect on the COD reduction from decreased additions of NH4-N and PO4-P were investigated in three parallel aerobic suspended carrier reactors during treatment at 46 to 48 degrees C of whitewater from a recycled paper mill producing liner and fluting. In the reference reactor, a COD reduction of 89% was achieved and 45.6 mg NH4-N/(g COD reduced) and 11.6 mg PO4-P/(g COD reduced) was consumed at an organic load around 20 kg COD/(m3 x d). Reduced additions of NH4-N decreased the COD reduction. Addition of 56% of the consumption of NH4-N in the reference reactor resulted in a COD reduction of 80%. The response from decreased addition of PO4-P was different compared to NH4-N but it could not be determined if this is due to unsuitable experimental design or a different reaction mechanism. Reducing the addition of PO4-P to 26% of the consumption of PO4-P in the reference reactor, decreased the COD reduction to 83%. The main conclusion from the experiment is: biological treatment has the potential of treating whitewater from recycled paper mills with low effluent nutrient concentrations.

Effects of white water treatment on the paper properties of mechanical pulp - A laboratory study

Article Effects of white water treatment on the paper properties of mechanical pulp - A laboratory study was published on August 1, 2004 in the journal Nordic Pulp & Paper Research Journal (volume 19, issue 3).