Integrated Paper Mill Research Articles

Dynamic-head space GC-MS analysis of volatile odorous compounds generated from unbleached and bleached pulps and effects on strength properties during ageing

Abstract Mixed hardwood unbleached (UB) and final bleached (FB) pulp along with the pulp of intermediate bleaching stages from an integrated paper mill have been undertaken for this study. Headspace GC-MS analysis of these pulps was made to identify the odorous compounds which are volatile organic compounds (VOCs), generated during ageing for 60 days. The result showed that a number of pre-generated VOCs such as aliphatic hydrocarbons and aldehydes are observed in the pulp sample which might be came from the process and it has been observed that upon ageing at ambient conditions, some acid functionalized VOC were generated in the pulp. The generation of these VOCs were established by ATR-FTIR analysis and the results showed that intensity of peak absorbance near 3340 cm − 1 {\text{cm}^{-1}} and 1641 cm − 1 {\text{cm}^{-1}} which represents the –OH stretching of acidic functional group and C=O stretch of aldehyde and acidic functional groups increased after ageing. Generation of acid functionalized volatile compounds were observed more in bleached pulp than in unbleached pulp. Degree of polymerization (DP) is pretty much related to the strength of paper. DP of both unbleached and bleached pulp gets reduced upon ageing while more reduction were observed in bleached pulp. Bleached pulps are more prone to degrade as compared to the unbleached pulp in terms of strength properties such as tensile index, breaking length, burst and double fold were observed. 12.3 % and 21.8 % reduction in tensile index was observed for UB and final bleached FB pulp respectively. Burst index of UB and FB pulp were found reduced to 23.8 % and 41.9 % respectively due to ageing. Reduction in the mechanical and optical properties was also observed in intermediate bleaching stages. There is much evidence for the contribution of VOCs to the degradation of paper. The results are strongly suggested that acid functionalized volatile compounds can have strong effects on degradation of cellulosic paper.

Simplified model of integrated paper mill for optimal bidding in energy and reserve markets

Due to the increased use of variable renewable energy sources, more capacity for reserves is required. Non-generating resources such as large industrial consumers can arbitrage energy prices and provide reserve capacity by exploiting the inherent flexibility in selected industrial processes. A large enough industrial consumer can capitalize on this flexibility through optimized bidding in electricity markets. In this work, the day-ahead cost minimization of a risk-averse pulp and paper mill is formulated as a two-stage stochastic problem, considering thermodynamic and electrical constraints. The bids in the energy and reserve markets are jointly optimized subject to price uncertainty as well as uncertainty of frequency realization. The results of a case study in Sweden display a significant economic benefit in exploiting the flexibility of integrated pulp and paper mills with electric boilers. The expected cost of the pulp and paper mill resulting from different strategies are compared and the risk-aversion of the pulp and paper mill is investigated. Reserve offers are mainly facilitated by fast-acting electric boilers and supported by flexibility in the steam network. We show that reserve offers can significantly improve the profitability of the pulp and paper mill.

Large data set analysis to determine refiner plate total cost of ownership

Efficient process data storage and its subsequent analysis are vital to the profitable operation of a paper mill. An evaluation of refiner plate performance was conducted for an integrated paper mill. Trials with two new plate patterns were compared with the incumbent pattern; the goal was to increase refiner plate life. Plate life increased with both new design patterns, and the mill selected one of the two new choices. However, additional impacts to paper machine performance and mill maintenance costs were not considered in the selection decision. A large data set analysis tool was used to identify unrealized savings of 1.5% with reduced fiber usage (basis weight) on the paper machine’s most prevalent grade. The large data analysis indicated that this unrealized benefit with the alternate plate design was not attainable with the chosen plate design.

Combining activated sludge process with membrane separation to obtain recyclable quality water from paper mill effluent

The present study was carried out for the treatment of paper mill effluent using combination of activated sludge process and membrane separation. An integrated paper mill employing OCEOPHH sequence (oxidation, chlorination, alkali extraction re-enforced by oxygen and peroxide, hypo-1, and hypo-2) for the bleaching of hardwood pulp was selected for the study. The purpose of this work was to examine the water quality and membrane performance when combining activated sludge process with different membrane separation processes in series. Pollutant removal including adsorbable organic halides (AOX) was compared among different treatment combinations; (i) ASP + microfiltration (MF), (ii) ASP +MF + ultrafiltration (UF), (iii) ASP +MF + UF + nanofiltration (NF), and (iv) ASP +MF + UF + NF + reverse osmosis (RO) to select the optimal treatment scheme for water recycling in the paper mill. Different initial inlet pressures were used for the UF and NF (6.8, 10.3, and 13.7 bar) and for RO (10.3, 13.7, and 17.2) The retentate from each membrane was recycled back to the feed and retreated until the inlet pressure increased to the maximum cut-off pressure for each membrane. After separation, 100 % total suspended solids, total dissolved solids, color removal and 94.2 % chemical oxygen demand, and 86 % AOX removal was observed. This study suggests the potential application of the combination of membrane separation with activated sludge process for recycling water in the paper industry.

Modifikation der Zellwand und Oberfläche von ungebleichten lignozellulosischen Fasern infolge einer Temperaturbehandlung – Einflüsse auf die Zugfestigkeit von ungemahlenem Kraftzellstoff

The effects of heating lab cooked never dried kraft pulp from pine and spruce at 5 % consistency to 80, 100 and 120 °C in a pressurized vessel were evaluated based on various fiber and sheet properties. The settings of pH and conductivity in the lab trial were chosen in accordance with operations such as oxygen delignification, alkaline extraction, washing or storage of pulp in an integrated paper mill. It was found that the tensile strength was reduced steadily with increasing temperature. Nuclear magnetic resonance spectroscopy showed that fiber crystallinity and pore size increased at high temperatures compared to the unheated reference. Crystallinity most likely affected the fiber flexibility and thus resulted in less and weaker fiber–fiber bonds. Atomic force microscopy indicated that the amount of precipitated lignin granules on the fiber surface was reduced with increasing temperature. The roughness of the fiber surface did not significantly change with temperature and hence did not negatively influence the tensile strength. It was remarkable that a so called reversed latency was observed. Instead of a decrease in fiber curl with temperature, the fiber became significantly more curled. A large portion of the losses in tensile strength was attributed to the increase in fiber curl and leaching of hemicelluloses from the fiber wall.

Membrane filtration of chlorination and extraction stage bleach plant effluent in Indian paper Industry

The present study was carried out for the treatment of effluent from the chlorination and extraction stages of a bleach plant at an Indian pulp and paper mill. The effluents were taken from an integrated paper mill employing OCEOPHH sequence for the bleaching of hardwood pulp. Effluent was treated via ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). Thin film composite spiral-wound modules, having cross flow membranes composed of polysulfone and polyamide, were used in the study. Three initial inlet pressures were used for the UF and NF; 6.8, 10.3, and 13.7 bar. For RO initial inlet pressures of 10.3 bar, 13.7 bar and 17.2 bar, were taken in different trials. The retentate from each experiment was recycled back to the feed and retreated until the inlet pressure increased to the maximum cut-of pressure for each membrane. The UF permeate was fed to the NF, which was subsequently fed to the RO. Variations in the trans-membrane pressure and permeate flux were assessed. The removal of pollutants and fouling indices were obtained for each membrane at each initial inlet pressure.

Monitoring colour and COD removal capacity of soil and assessment of growth performance of crop growth with paper mill wastewater—A lysimeter study

Evaluation studies on the effect on physico-chemical properties of soils and crops irrigated with paper mill wastewaters in field lysimeters were carried out for three years at the Integrated Paper Mill, Nepanagar, Madhya Pradesh (India). Lysimeters were prepared by excavating pits of 5m×2m×2m, lined with polyethylene sheet and filled with sandy loam, clay and loamy sand soils with different physicochemical characteristics and provided with percolate collection system. Lysimetric treatment was used and treated wastewater evaluated for crop irrigation complied to the irrigation water class ‘Moderate to Severe Restriction on use’ for the parameters salinity and specific ion toxicity, and with respect to SAR, it was categorized under the class ‘No Restriction on use’. Sandy loam and loamy sand soils in lysimeter I and III, the percolate was 17% and 20% of irrigation, while for clay soil in lysimeter II it only 15%. Sandy loam and loamy sand soils respectively showed 97% and 96%. The chemical oxygen demand (COD) removal in sandy loam and loamy sandy soils where 97% and 96% respectively while in clay the removal was 99%. The colour removal in both the cases was 100%. The percolates initially showed leaching of calcium and magnesium and retention of sodium, which got stabilized subsequently. The application of wastewater resulted in increase in water holding capacity, pH (0.6–1.3 units), electrical conductivity of saturated extract (ECe, 0.6–2.1dSm−1) and exchangeable sodium percent (ESP, 8.1–11.6), organic carbon and available nitrogen, phosphorus and potash content of soils; however there was decrease in bulk density. Wastewater irrigation did not affect germination; rather there was increase in grain and straw yield of jowar, wheat and moong. These results showed that the paper mill wastewater can be successfully utilized for crop production.

Economics of a Nordic paper mill: case study

PurposeThe purpose of this paper is to reveal how the prices, costs, and logistics develop in the case mill and how these variables correlate with profits, and finally to give suggestions for improvements.Design/methodology/approachA typical Finnish paper mill is selected for the basis of the case study. The complete data for the mill for the years 2001 to 2007 at a monthly level are used. The data are obtained from the mill's financial management system and transferred to Excel. Statistica 4.1 software is used to run the statistical correlation analyses. The results can be generalized with certain limitations to paper manufacturing located at a long distance from its customers.FindingsThis paper gives an important insight into the economics of the Finnish paper industry. From theory‐building point of view, the empirical process data show that the variation in production lines is minimal, but there are important variations in paper deliveries. A lot can be gained in the logistics processes. Larger volumes delivered in tons also tend to increase profits. From the mill to the consignees, fluctuations in the process and paper sales grow substantially, which indicates longer storage times.Research limitations/implicationsThe results of the case study are based on the data of a single large integrated paper mill in Finland covering the years 2001‐2007, so the results cannot be directly generalized to concern all Nordic paper mills. In May 2005, there was an industrial blackout, which considerably affected the production and deliveries of all Finnish paper mills in that year.Practical implicationsThe competitive advantages of the Finnish paper industry are undermined by low paper prices and costly logistics. The mill managers should increasingly focus on overcapacity and cost issues and also deliver volumes, which all could contribute to higher profits.Originality/valueIn this paper, the Finnish paper industry is studied through a time series, economic geography, and statistical tools. This approach is a novel method and gives new insights into this research object. The mill's economic variables, such as paper prices, profits, and logistics and manufacturing costs, and the characteristics of these issues in a spatial context are studied.

Long-range timber supply planning for a vertically integrated paper mill

We consider a vertically integrated papermaking operation composed of an integrated pulp and paper mill with its regional supply network. Considering land procurement and harvest rotation as strategic decision variables, we construct a model to establish a long-range timber supply plan that minimizes the total discounted cost of meeting annual virgin wood fiber demand over an infinite horizon. Under appropriate assumptions on costs and storage, the land procurement and harvest rotation decisions are separable with harvest rotation being determined via a forest economics-type equation and land procurement being determined by a newsvendor-type equation.

Chemical characterization and biotreatability of effluents from an integrated alkaline-peroxide mechanical pulping/machine finish coated (APMP/MFC) paper mill

As part of an extensive audit of the Alkaline-Peroxide Mechanical Pulping (APMPTM) plant at the Malette Quebec Inc. mill in St. Raymond, Que., effluents were sampled from various stages of the process for comprehensive chemical characterizations, aquatic toxicity testing and anaerobic biotreatability assessments. In addition, untreated and secondary treated combined effluent from the integrated paper mill were sampled to determine the effectiveness of a conventional activated sludge process at the mill site. During the one-day sampling period, the APMP plant processed a mixed wood furnish consisting of 50% spruce/balsam fir and 50% aspen, with a chemical charge of 3.5% sodium hydroxide and 3.8% hydrogen peroxide on oven-dry fibre, while the Machine Finish Coated (MFC) paper production rate was 100 odt/d (oven dry metric tonnes per day). Measured production-specific contaminant discharge loadings from the novel APMP process were 56 kg BOD5/odt and 155 kg COD/odt in a combined effluent flow of 28 m3/odt. Sources of process effluent were chip washing, three stages of wood chip pretreatment and chemical impregnation (i.e., Impressafiner stages), interstate washing and pulp cleaning. The three Impressafiner pressates were found to be the most concentrated (i.e., 12-26 g COD/L) and toxic streams. Microtox testing of the pressates revealed EC50 concentrations of 0.07-0.34% v/v. The warm and concentrated effluents generated by the non-sulphur APMP process were found to be highly amenable to anaerobic degradation as determined by batch bioassay testing. Filterable BOD5 and COD(f) of the process effluents were reduced by 87-95% and 70-77%, respectively, with corresponding theoretical methane yields being attained. Acid-soluble dissolved lignin compounds exhibited biorecalcitrance, as revealed by limited removals of 34-55%, and were the main constituents contributing to residual COD(f), while resin and fatty acids (RFA) were reduced by 80-94%. The conservatively operated full scale activated sludge treatment process achieved a similar high 74% COD(f) removal from the whole mill effluent, while BOD5 and RFA reductions were virtually complete and the treated effluent was non-toxic, as measured by Microtox.

Chemical characterization and biotreatability of effluents from an integrated alkaline peroxide mechanical pulping/machine finish coated (APMP/MFC) paper mill

As part of an extensive audit of the Alkaline-Peroxide Mechanical Pulping (APMP™) plant at the Malette Quebec Inc. mill in St. Raymond, Que., effluents were sampled from various stages of the process for comprehensive chemical characterizations, aquatic toxicity testing and anaerobic biotreatability assessments. In addition, untreated and secondary treated combined effluent from the integrated paper mill were sampled to determine the effectiveness of a conventional activated sludge process at the mill site. During the one-day sampling period, the APMP plant processed a mixed wood furnish consisting of 50% spruce/balsam fir and 50% aspen, with a chemical charge of 3.5% sodium hydroxide and 3.8% hydrogen peroxide on oven-dry fibre, while the Machine Finish Coated (MFC) paper production rate was 100 odt/d (oven dry metric tonnes per day).Measured production-specific contaminant discharge loadings from the novel APMP process were 56 kg BOD5/odt and 155 kg COD/odt in a combined effluent flow of 28 m3/odt. Sources of process effluent were chip washing, three stages of wood chip pretreatment and chemical impregnation (i.e., Impressafiner stages), interstage washing and pulp cleaning. The three Impressafiner pressates were found to be the most concentrated (i.e., 12–26 g COD/L) and toxic streams. Microtox testing of the pressates revealed EC50 concentrations of 0.07–0.34% v/v. The warm and concentrated effluents generated by the non-sulphur APMP process were found to be highly amenable to anaerobic degradation as determined by batch bioassay testing. Filterable BOD5 and COD(f) of the process effluents were reduced by 87–95% and 70–77%, respectively, with corresponding theoretical methane yields being attained. Acid-soluble dissolved lignin compounds exhibited biorecalcitrance, as revealed by limited removals of 34–55%, and were the main constituents contributing to residual COD(f), while resin and fatty acids (RFA) were reduced by 80–94%. The conservatively operated full scale activated sludge treatment process achieved a similar high 74% COD(f) removal from the whole mill effluent, while BOD5 and RFA reductions were virtually complete and the treated effluent was non-toxic, as measured by Microtox.

Characterization of anaerobic non-spore-forming bacteria in municipal sewage sludge and integrated paper-mill waste water

Forty-three isolates of Gram-negative, mesophilic, non-spore-forming anaerobic cellulolytic bacteria were obtained from (i) an anaerobic reactor treating waste water from an integrated paper mill and (ii) an anaerobic sewage-sludge digestor. These isolates were studied for carbohydrate fermentation and fermentation products. By numerical techniques, 22 isolates could be placed in two groups: group A (10 isolates) and group B (12 isolates). The isolates belonging to group A showed degradation of filter paper in 2–7 days. They were slightly-curved long rods and similar toBacteroides cellulosolvens andAcetivibrio cellulolyticus. Acetic acid was produced as major product. The bacteria also produced ethanol, isobutanol, pyruvic and lactic acids. Group B strains degraded filter paper in 4–5 weeks. They were short rods and produced propionic, lactic, succinic and acetic acids as fermentation products. The remaining 21 isolates could disintegrate filter paper in 2–5 weeks. They showed variable fermentation patterns, both as to fermentable carbohydrates and end products. Except for one isolate, which showed obvious similarity toButyrivibrio fibrisolvens, the isolate differed distinctly from reference strains of ruminai origin.

Treatment of Different Wastewaters from Pulp and Paper Industry in Methane Reactors

A wastewater from an integrated paper mill with a COD of 1200 mg/dm3 was anaerobically treated in a multi-stage reactor. The BOD7 removal efficiencies of 60-75 % were achieved at maximal loading rates of 5-6 kg COD/m3d and HRT of 4-6 hours due to the granular sludge. Industrial sulphite evaporator condensates from Ca- and Na-processes were treated in anaerobic filters containing light gravel, plastic foam and power plant slag as filter media. The BOD7 removals of 78 % on average were achieved at loading rates of 1.8-3.3 kg COD/m3d with Ca-process evaporator condensates and 80 % BOD7 removals were achieved with Na-process condensates at loading rates of 3.5-4.1 kg COD/m3d.