Paper Mill Water Research Articles

Investigation of particle size distribution and ultrafiltration of digestates from short-fibre residues in paper mills

ABSTRACT Industrial digestates from short-fibre residues, generated in paper recycling mills, are driving interest in resource recovery. This study aims to explore their potential for water recovery. Understanding particle dynamics aids in optimizing dewatering for digestate management. The particle size distribution in this study revealed significant fractions: <0.63 μm (6–20%), 0.63–20 μm (38–52%), and >20 μm (11–16%). Pre-treatment with Na4P2O7 and H2O2 enhances settling and lowers total dissolved solids (TDSs) but results in variation of size distribution. Additionally, this study investigates further water reuse in paper mills, focusing on the quality of ultrafiltration (UF) permeate obtained from the digestate of short fibres. UF permeate analysis reveals deviations from freshwater standards in paper mills. Despite effective TS removal, UF permeate falls short of paper mill water standards due to high TDSs, electrical conductivity, and nutrient concentrations, necessitating further downstream treatment with nanofiltration or reverse osmosis. A substantial reduction of permeate flux from 31 to 5 L/(m2·h) over the time indicated fouling and inefficient membrane wash. The silt density index of the UF membrane at 30 min registered 2.1, suggesting potential fouling. Further investigations on optimizing UF operations to enhance permeate flux and exploring alternative UF membranes are required.

ISOLATION AND CHARACTERIZATION OF PHENOL DEGRADING BACTERIA FROM INDUSTRIAL WASTEWATER AND SEWAGE WATER

This study examines the isolation and characterization of phenol-degrading-bacteria, Five isolates named C2, P4, M4, O3, and S3, from the effluent of ceramic factories (C2), petrochemical (P4), the pulp paper mill (M4), crude oil (O3) and sewage water (S3) have been investigated. These isolates were characterized depending on their morphological, and biochemical characteristics, only one isolate was characterized as a Gram-positive, strictly aerobic, nonmotile, and cocci-shaped bacterium might be Micrococcus sp. (M4), two isolates (Pseudomonas sp.: (P4&S3) were recogniced as a Gram-negative, strictly aerobic, motile and short rod-shaped bacterium and two isolates(Bacillus sp.: (C2& O3) were idenihied as a Gram-positive, strictly aerobic, motile and long rod- shape bacterium. The five bacterial isolates were able to utilize phenol as a sole carbon source. These isolates were checked for growth on a minimal salt medium amended with different concentrations of phenol. The five tolerant bacterial isolates were able to grow at the higher concentrations of phenol and they were investigated for their ability to grow and degrade phenol. Among the five higher phenol degrading isolates, two isolates can tolerate up to 1500 ppm .of phenol concentrations, grow and degrade 90% of phenol within 72 hrs. The optimum temperature and pH were 35 0C and 7, respectively. The yeast extract and ammonium chloride is the best nitrogen source for the growth and degradation of phenol, respectively. The isolate P4 was efficient in removing about 90% of the initial 1000 ppm phenol within 48 hrs., and had a tolerance of phenol concentration as high as 1500 ppm. These results indicated that presumptive Pseudomonas spp. possesses a promising potential in treating phenolic wastewater

Treatment of Pulp and Paper Industrial Effluent Using Physicochemical Process for Recycling

Physicochemical treatment, consisting of a combination of primary settling, coagulation–flocculation-aided clarification (alum, lime and magnesium sulfate as coagulants) and activated carbon adsorption, was employed for the treatment of pulp and paper mill wastewater. Treatability studies were undertaken to assess the feasibility of recycling the effluents from a paper mill. The results of laboratory scale investigation showed that the hydraulic retention time (HRT) of four hours for plain settling was effective to reduce 30% of the pollution load from pulp and board mill wastewater (PBMWW). The chemical secondary treatment reduced turbidity (89%), Chemical Oxygen Demand (84%), total suspended solids (90%) and color (89%) at the mass loading of 3400 mg/L of magnesium sulfate (MgSO4), when primary-treated effluent was subsequently treated by the coagulation–flocculation process. The combination of primary settling and lime coagulation (optimum dosage of 1400 mg/L) resulted in a turbidity removal of 94%, a COD (Chemical Oxygen Demand) reduction of 86%, a Total Suspended Solids (TSS) removal of 93% and color removal of 91.6% at an initial pH of 11. The combination of this primary settling and coagulation–flocculation treatment trial indicated that the pollutant reduction efficiency of alum was better than the other two coagulants (MgSO4, lime), because the plain settling and coagulation–flocculation process with alum (optimum dosage of 1200 mg/L) resulted in a turbidity removal of 98%, COD reduction of 93%, TSS removal of 98% and color removal of 96% at the pH 6.0 with the sludge volume index of 156 mg/L. This chemically-treated water required further treatment with activated carbon in a batch reactor for up to four hours to meet the paper mill water quality standards. Pollutant reductions at the rate of 99.5%, 99.1%, 99.4% and 99.5% were obtained for turbidity, COD, TSS and color, respectively, with the combination of the sedimentation, coagulation–flocculation process and activated carbon adsorption meeting the production process quality standards. The study revealed that a hybrid end-of-pipe physicochemical treatment was effective in reducing the pollutant load of paper mills effluent and meeting the discharging standards.

Heat-killing of Legionella in biological sludge from a paper and pulp mill water treatment plant

Paper and pulp mills use biological water treatment plants to reduce Chemical Oxygen Demand (COD) release to the environment. In the end of the process, microorganisms are concentrated into a biolo ...

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.

Potential Generation of Oxidizing Radicals in Synthetic Paper Mill Water By Electrochemical Treatment Combined with Biocides

Potential Generation of Oxidizing Radicals in Synthetic Paper Mill Water By Electrochemical Treatment Combined with Biocides

Load shifting aids energy saving: part 2

A South African initiative to encourage load shifting prompted an in-depth review of pumping processes at the Tugela paper mill's water supply plant. After a general overview of the project, the first part of this two-handed case study1 focused on the plant's high-lift pumping station. In this concluding part, Graeme Harding considers flow control, and assesses the transfer and low-lift pumping stages, and plant piping and instrumentation, before presenting the final solution.

Magnetic force control technique in industrial application

Techniques of the magnetic force control have been examined for industrial application. The problems and the technique are different in dispersion medium of gas and that of liquid. In addition, the method is different depending on the magnetic characteristic of the target objects. In case of the liquid, the dispersion medium having different viscosity was examined. The separation speed is decided with the magnitude of the magnetic force because a drag force increases with the viscosity. When the water is the dispersion medium, magnetic seeding is possible and hence the nonmagnetic materials can be separated and even the dissolved material could be separated. The separation technique has been used for purifying the waste water form paper mill or wash water of drum. On the other hand when the water is not dispersion medium, mainly the ferromagnetism particle becomes the target object because the magnetic seeding becomes difficult. The iron fragments have been separated from the slurry of slicing machine of solar battery. It has been clarified high gradient magnetic separation (HGMS) can be applied for the viscous fluid of which viscosity was as high as 10Pas. When the dispersion medium is gaseous material, the air is important. The drag force from air depends greatly on Reynolds number. When speed of the air is small, the Reynolds number is small, and the drag force is calculated by the Stokes’ law of resistance. The study with gaseous dispersion medium is not carried out much. The magnetic separation will discuss the possibility of the industrial application of this technique.

Application of the water cascade analysis technique for water minimisation in a paper mill plant

The Water Cascade Analysis (WCA) technique was used to identify opportunities for reduction in freshwater usage as well as wastewater generation and to assist in the retrofit of an existing paper mill water distribution network. This procedure involves three key steps; i.e., a global analysis of the present water distribution and consumption, setting the baseline minimum water targets using WCA technique and retrofit of water network to achieve the minimum water targets. Notwithstanding the extensive water recycling currently employed in the paper mill, this study identified a potential scope of reducing 13.3% freshwater and 13.3% wastewater. Water reduction represents a total potential annual savings of RM 595,232, taking into account the raw water and wastewater treatment costs, pumping and chemical costs.

Simultaneous determination of DTPA, EDTA, and NTA by capillary electrophoresis after complexation with copper

We present a method for simultaneous determination of the aminopolycarboxylic acids DTPA, EDTA and NTA in dishwashing detergents, paper mill waters, and natural waters by capillary electrophoresis (CE). The complexing agents were examined as their copper(II) complexes and separated by conventional CE with reversed polarity of the applied voltage. The optimum separation conditions were established by varying the pH and phosphate and tetradecyltrimethylammonium bromide (TTAB) concentrations in the run buffer. The separations were carried out in a fused-silica capillary (61 cmx75 microm i.d.) filled with phosphate buffer (80 mmol L(-1), TTAB concentration 0.5 mmol L(-1), pH 7.1, voltage -20 kV) using direct UV detection at 191 and 254 nm. With this CE method all the peaks in the electropherograms were properly separated, the calibration plots gave good correlation coefficients and all three complexing agents could be detected in less than 4 min. Linear calibration plots were obtained for CuDTPA, CuEDTA and CuNTA; limits of detection were 0.03 mmol L(-1) for all complexing agents and recoveries for all tested samples were within the range 104+/-7%. Results obtained from dishwashing detergent samples were found to be reliable and comparable with those from HPLC (R2=0.989) and UV-Vis (R(2)=0.985) methods.

NF270, a new membrane having promising characteristics and being suitable for treatment of dilute effluents from the paper industry

A good nanofiltration membrane for the paper mill waters is hydrophilic, having both high retention and high permeability, and it should be resistant to fouling and temperature increase. The membrane should also withstand alkaline and acidic cleaning and mechanical wear. Membranes having all these properties do not exit. Based on laboratory- and pilot-scale experiments one promising membrane is the NF270 from Dow. The membrane is rather hydrophilic and it has fairly high retention and permeability. However, its resistance to temperature is not sufficient for all applications in the paper industry. By using this membrane or other similar NF membranes in the high-shear cross-rotational CR-filter fluxes above 100 L/(m 2 h) and retentions over 80% for conductivity and total carbon are obtainable with many rather dilute effluents from the paper industry.

Analysis of the functional diversity of the microbial communities in a paper-mill water system

Most microbiological studies of wastewater treatment systems rely on methods that are dependent on culturing. However, due to the limitation of conventional microbiological methods, alternative assays, such as the analysis of the functional diversity of the microbial communities using Biolog substrate utilisation profiles, have been proposed. The Biolog method was thus evaluated in a paper-mill water system. The influence of the production of various paper grades, biocide combinations and monthly maintenance shut-downs on the functional diversity of the microbial communities were determined using the Biolog technique. The communities in the planktonic as well as the sessile phases were analysed approximately every second week for a period of one year. The average well colour development (AWCD) technique was used to transform the data obtained from the Biolog plates prior to multivariate statistical analysis. Our results indicated that different microbial communities developed during the production of the different paper grades. A difference in substrate utilisation was evident after a single day of production of fluting or linerboard in the planktonic communities, while differences in the sessile communities only became significant after an extended period of production. The effect of the application of different biocides was more distinct in the planktonic than in the sessile populations. No clear trends concerning the influence of maintenance shut-downs and cleaning of machines could be observed in the sessile phase, while a shift in the microbial community could be observed in the planktonic phase. Biodiversity indices indicated that a high functional diversity existed in both the planktonic and sessile phases. It was concluded that the substrate utilisation profiles obtained with Biolog plates were a sensitive measure, which enabled the detection of shifts in the microbial community function and possibly structure within the same water system. Water SA Vol.29(1) 2003: 31-34

Recovery of brightness in paper mill water

This paper investigates the utilisation of nanofiltration (NF), agitation (by pump or sonication), freezing and acetone extraction methods to purify paper machine o-water. The results were judged by regained pulp brightness and reduction of various components. In the NF experiments the brightness was almost totally regained. Also the reduction of most measured components like lignin and carbon were retained well by the membrane (PES). The metal ions (Si, Al, Mg, Na, K, Mn, Ca, Fe and Cu) were reduced in the permeate (retained by the membrane) to the level found in the clear filtrate. This indicated that the metal ions (Si, Al, Mg, Na, K, Mn, Ca, Fe and Cu) were not brightness-reducing components. The flux was rather low for a commercial application because the membrane was a low-flux membrane. The reduction of sugar, colour and lignin residuals was quite high (>80%), and it was considered that these were possibly brightness-reducing components. It was found that by treating the fines with acetone and then returning them to the original water, the colour was reduced to a high enough degree that approximately 50% of the brightness reduction was recovered. It was considered that coloured contaminants that were absorbed on the fines were removed or destroyed. The brightness recovery was >50% for both the TMP and PK4 o-water. The brightness recovery was greater using NF, but in that case so many substances were reduced in the permeate that it was difficult to determine which were the brightness-reducing substances. However, in the case of acetone washing, the only component that was reduced was the colour. For both o-water PK4 and TMP the colour was reduced by 50% and the brightness recovery was 50%, suggesting a direct correlation. Agitation of the water samples by the means of a pump and sonication showed no change in the water, which included no changes in the brightness. The same was also found for water samples that were frozen. These experiments also showed that temperature changes did not affect water composition.

Organic compounds in paper-mill process waters and effluents

Paper-mill effluents are characterized by the presence of color and suspended solids, bad smell, high concentration of nutrients that cause eutrophication of receiving waters, and high toxicity overall. This study attempts to give an overview of organic compounds that contribute to the toxicity of paper-mill waters and effluents, their levels, toxicological characterization and the methodologies used for their analysis. Families included are natural products, such as resin and fatty acids (wood extractives), additives used during paper-making, such as biocides, surfactants and phenolic compounds and by-products generated during bleaching, such as dioxins and furans. Several extraction methods, such as liquid-liquid extraction (LLE) or solid phase extraction (SPE) followed by gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS) with atmospheric pressure chemical ionization (APCI) or electrospray (ESP) are described and method performance is discussed for each family of compounds. This study contributes to the characterization of the organic fraction of paper-mill effluents and highlights elimination strategies.

Closing pulp and paper mill water circuits with membrane filtration.

In this study membrane filtration, ultrafiltration, and nanofiltration alone and as part of hybrid processes are considered as means to purify pulp and paper mill process waters suitable for reuse. Thermophilic aerobic biological treatment, pH adjustment, flocculation, and ozonation were tested as pretreatment methods on pilot or on laboratory scale. The aim was to increase flux and reduce fouling by various pretreatment steps and, thus, increase the competitiveness of the membrane process. The results were also evaluated by comparing the benefits obtained against the costs. It was discovered that benefits could be obtained with all the pretreatments tried. Thermophilic aerobic biology assisted in the removal of organic material and increased flux significantly, but the costs were the highest. The most cost-effective processes, however, seem to be pH-adjusted nanofiltration and flocculation nanofiltration hybrid processes, which is understandable because of their significantly lower investment costs compared to, for example, those of biological process. The pH adjustment increased the electrostatic repulsion between negatively charged solutes and membrane, thereby increasing the flux. Flocculation removed the foulants effectively from the feed and it both increased flux and reduced fouling. Yet, many noteworthy benefits were obtained also with ultrafiltration and ozonation. All of the hybrid processes tested could be applied at various points of the water circuit of an integrated pulp and paper mill for purification purposes. The eventual superiority and cost-effectiveness of the applied process remains to be determined case by case.

Analysis of the structural diversity of the microbial community in a paper-mill water system

Microbial populations in paper-mill water systems are usually enumerated using microbiological techniques such as plate counts and the most probable number technique. These conventional methods can only quantify a limited percentage of the microbial populations and the microbial numbers are, therefore, generally underestimated. One possible alternative to these methods involves the analysis of signature lipid biomarkers to study the structural diversity of microbial populations. The aim of this study was, therefore, to evaluate the applicability of signature lipid biomarker analysis in a paper-mill water system. Samples from the sessile and planktonic phases were collected over a period of one year at the Sappi Cape Kraft paper-mill. The samples were subjected to analysis of signature lipid biomarkers as well as conventional culturing. Analysis of the phospholipid fatty acids revealed the presence of a large diversity of micro-organisms. The same trends in the number of cultured cells and the counts obtained with signature lipid biomarker analysis were observed, although the numbers obtained with signature lipid biomarker analysis were at least 1 000 times higher. Profiles of signature lipid biomarkers reflected changes in production and water management practices, which could not be detected with culturing techniques. The analysis of signature lipid biomarkers provided more information for the characterisation of microbial communities in paper-mill water systems and has potential for application in other industrial water systems. WaterSA Vol.28(4) 2002: 407-412

Sugar composition of biofilms produced by paper mill bacteria.

Biofilms of paper mill bacteria were cultivated in paper mill white water-simulating conditions on glass slides or stainless steel coupons in a laboratory culture system. The sugar content and composition of the biofilms were analysed and compared with the sugar composition of paper mill slimes. Acid methanolysis followed by gas chromatography revealed that Burkholderia was the major biofilm producer in pure culture, producing up to 50 microg of biofilm sugar cm(-2) in 5 days in rich medium and 10 microg in paper mill simulating medium. A mixture of simulated paper mill water with a culture medium yielded more biofilm (100 microg cm(-2)) than either of the media alone, so the biofilm accumulation was not proportional to the available substrate. More biofilm accumulated on stainless steel coupons than on glass slides, and the steel-coupon biofilms contained slightly more uronic acids. The biofilm sugars contained mainly galactose, glucose, mannose, and rhamnose. In paper mill medium, the Burkholderia biofilm contained more galactose and glucose, and less rhamnose, than in rich laboratory medium. The sugar composition of paper mill slimes was quite similar to those of steel-cultured Burkholderia cepacia biofilms. This suggests that Burkholderia cepacia is responsible for much of the slime in the paper mill.

The Ecology of “fecal indicator” bacteria commonly found in Pulp and paper mill water systems

Coliform bacteria have long been used to indicate fecal contamination of water and thus a health hazard. In this study, the in-mill water and external effluent treatment systems of seven typical Canadian pulp and paper mills were all shown to support the growth of numerous coliforms, especially Klebsiella spp., Escherichia coli, Enterobacter spp., and Citrobacter spp. In all mills and most sampled locations, klebsiellas were the predominant coliforms. Although all but one of the mills had no sewage input and most disinfected their feed (input) water, all contained the most typical fecal indicator bacterium, E. coli. Many of the mill coliforms were classified as fecal coliforms by standard “MPN” and metabolic tests, but this was shown to be due to their thermotolerance, not their origin. Mill coliforms were shown not to be just simple transients from feedwater or furnish (wood), but to be continuously growing, especially in some of the primary clarifiers. Isolated mill coliforms grew very well on a sterilized raw combined mill effluent. The fecal streptococci (enterococci), alternative indicators of fecal health hazards, were common in all mills in the absence of sewage. Ten strains of E. coli isolated from four mills were all shown to be non-toxigenic strains of harmless serotypes. No salmonellas were found. Therefore, the use of total coliform, fecal coliform, enterococci, or E. coli counts as indicators of fecal contamination, and thus of health hazard in pulp and paper mill effluents or biosolids (sludges) known to be free of fecal input is invalid.

Degradation of paper mill water components in laboratory tests with pure cultures of bacteria.

The degradation of dissolved and colloidal substances from thermomechanical pulp (TMP) by bacteria isolated from a paper mill was studied in a laboratory slide culture system. Burkholderia cepacia strains hydrolysed triglycerides to free fatty acids, and the liberated unsaturated fatty acids were then degraded to some extent. Saturated fatty acids were not notably degraded. However, the branched anteiso-heptadecanoic fatty acid was degraded almost like the unsaturated fatty acids. About 30% of the steryl esters were degraded during 11 days, increasing the concentrations of free sterols. Approximately 25% of the dehydroabietic, and 45% of the abietic and isopimaric resin acids were degraded during 11 days. The degree of unsaturation seemed to be of greater importance for the degradation of fatty acids than the molar mass. No degradation of dissolved hemicelluloses could be observed with any of the nine bacterial strains studied. Burkholderia cepacia strains and one Bacillus coagulans strain degraded monomeric fructose and glucose in winter TMP water, but in summer TMP water, with much lower sugar concentrations, also other Bacillus strains degraded monomeric sugars.

Coliform bacteria and nitrogen fixation in pulp and paper mill effluent treatment systems.

The majority of pulp and paper mills now biotreat their combined effluents using activated sludge. On the assumption that their wood-based effluents have negligible fixed N, and that activated-sludge microorganisms will not fix significant N, these mills routinely spend large amounts adding ammonia or urea to their aeration tanks (bioreactors) to permit normal biomass growth. N(2) fixation in seven Eastern Canadian pulp and paper mill effluent treatment systems was analyzed using acetylene reduction assays, quantitative nitrogenase (nifH) gene probing, and bacterial isolations. In situ N(2) fixation was undetectable in all seven bioreactors but was present in six associated primary clarifiers. One primary clarifier was studied in greater detail. Approximately 50% of all culturable cells in the clarifier contained nifH, of which >90% were Klebsiella strains. All primary-clarifier coliform bacteria growing on MacConkey agar were identified as klebsiellas, and all those probed contained nifH. In contrast, analysis of 48 random coliform isolates from other mill water system locations showed that only 24 (50%) possessed the nifH gene, and only 13 (27%) showed inducible N(2)-fixing activity. Thus, all the pulp and paper mill primary clarifiers tested appeared to be sites of active N(2) fixation (0.87 to 4.90 mg of N liter(-1) day(-1)) and a microbial community strongly biased toward this activity. This may also explain why coliform bacteria, especially klebsiellas, are indigenous in pulp and paper mill water systems.