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In the development of integrated biorefinery process alternatives to produce value-added by-products, various black liquors from sulfur-free pulping processes offer potential feedstocks for recovering their main chemical constituents, lignin and aliphatic carboxylic acids. In this study, lignin fractions were obtained from silver birch (Betula pendula) soda-anthraquinone black liquor by carbonation (pH to about 8.5) or by acidification (pH to about 2) with H2SO4 after carbonation or directly. These fractions were characterized by Fourier transform infrared (FTIR), ultraviolet (UV), energy dispersive X-ray fluorescence (ED XRF), and 13C nuclear magnetic resonance (13C NMR) spectroscopy. In addition, the molecular weight distributions of these lignin fractions were determined. All the experimental data clearly suggested that only small differences between the precipitated lignins existed, and thus, their equal chemical utilization seems possible.

Untreated and hot-water-extracted (HWE) Norway spruce (Picea abies) sawdust was cooked using the sulfur-free oxygen-alkali (OA) method under the following conditions: temperature, 170 °C; liquor-to-wood ratio, 5:1 L/kg; and NaOH charge, 19% on the oven-dry sawdust. In comparison with earlier studies conducted with birch sawdust, the spruce cooking yield data, together with the amount of the pulp rejects (78% to 86% for reference pulps from the initial feedstock and 73% to 83% for pulps from the HWE feedstock), revealed that the pretreatment stage prior to spruce OA pulping caused different effects on pulping performance. The analyses of the three main compound groups (i.e., lignin, volatile acids, and hydroxy acids) in black liquor indicated that slightly higher contents (25.5 to 45.9 g/L) of dissolved lignin were detected in black liquors originating from the HWE sawdust than in the black liquors from the reference material (27.2 to 39.6 g/L). In contrast, considerably lower (~20% decrease) volatile acid contents and similar or slightly decreased hydroxy acids contents were detected in the black liquors from the HWE sawdust.

Soda black liquors from the Specel® process, which used wheat straw as the raw material, were subjected to an acid precipitation process to recover the lignin. Lignin was isolated by acid precipitation using three different inorganics acids (H3PO4, H2SO4, and HCl) at three concentration levels, and at pH values of 2 and 4. Even though the highest lignin yield was achieved using phosphoric acid, the most economical inorganic acid was sulphuric acid. Physico-chemical characterizations of the precipitated lignin samples were performed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) (for thermal properties), Fourier transform infrared spectroscopy (FT-IR), and heteronuclear single quantum correlation spectroscopy (HSQC) (for chemical structures). No significant differences were found in the thermal properties and chemical structures of the isolated lignins, except for the lignin obtained with phosphoric acid to lower the black liquor from pH 10.72 to pH 2. Apart from the lignin fraction collected, the soda pulp obtained by the Specel® process using wheat straw could represent a good alternative for packaging industries.

A new method involving the non-covalent binding of Coomassie Brilliant Blue G-250 (CBBG) to alkali-soluble lignin was developed. The binding of the dye to alkali-soluble lignin caused an increase in visible absorption at the maximum wavelength of 630 nm or 640 nm. A linear correlation of the absorbance at their maximum absorbing peak with alkali-soluble lignin concentration was observed. Lignin estimation in black liquor showed that the result of the new method and the gravimetric methods after acidification were closer to quantitative information than that obtained from UV spectroscopy. The isothermal titration calorimetric experiments, and Fourier Transform Infrared (FTIR) spectroscopy comparative analysis of precipitates washed by water, 4% ethanol, and 95% ethanol indicated that CBBG was bound to alkali-soluble lignin, and the binding was non-covalent. This potential method is reproducible, rapid, and cheap, and there is little or no inference from carbohydrate degradation products.

Reducing the pretreatment cost of lignocellulosic biomass by utilizing alkali to alter its recalcitrant nature is an effective method for biofuel production. In this experiment, 1.5% KOH solution and its black liquor (spent liquor of KOH) (BL) were applied to pretreat corn stover (CS) at a temperature of 20 °C to enhance the digestibility for anaerobic digestion (AD). Results showed no significant difference in weighted average methane content on the basis of experimental methane and biogas yields between BL-treated and original KOH-treated CS after AD. The BL process significantly increased the overall methane yield by 52.4% compared with untreated CS (135.2 mL/gVS), whereas no significant difference between the overall methane yields of 1.5% KOH-treated and BL-treated CS was observed. In addition, the BL process significantly saved water and KOH consumption, by 56.2% and 57.4%, respectively, compared with the 1.5% KOH pretreatment. Overall methane production was well explained by the modified Gompertz model. The physiochemical changes to CS after BL pretreatment were confirmed by SEM, FTIR, and XRD analyses. Our findings collectively suggest that recycling and reuse of KOH black liquor might be an efficient method for lignocellulosic biomass treatment and have the capability to reduce input costs in future AD processes.

Sodium aluminosilicate scaling in evaporators during alkali recovery is often associated with the concentration of aluminum and silicon in black liquor. The scaling problems are widespread during the utilization of non-wood raw materials. This study established a fast, reliable, and precise method to determine the aluminum concentration in bamboo black liquor by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Prior to ICP-AES measurements, black liquor samples were digested in an automatic electric heating assisted digestion system. After optimizing the digestion, ICP-AES testing showed that the recovery of the element was 96.2% to 99.9% and the relative standard deviation (RSD) was 0.07% to 0.52%. Additionally, comparative data for the concentration of analytes was obtained by flame atomic absorption spectrometry (FAAS). This technique will be useful for assessing the scaling properties of black liquor in the alkali recovery phase.

Black liquor (BL) can be regarded as the energy and alkali resource of the pulping mill. In this work, the effects of the characteristics of black liquor derived from the alkali-oxygen pulping of rice straw were studied. Through analyses of the chemical and physical properties, especially the thermodynamics properties, which depend on suspended matter and alkalinity, it was shown that the removal of the suspended matter from the black liquor could effectively improve its thermodynamic properties, particularly in making its solids content reach up to more than 56% at the turning point of its viscosity. Moreover, sodium salt played an important role in the presence of macromolecules and silica in the BL. When the BL was adjusted to pH = 11 with NaOH, the filtered BL had the lowest silica content, the highest volumetric isothermal expansivity (VIE), was more susceptibility to thermal cracking, and was more suitable for processing for alkali recovery.

Research Highlights: As to fill the current knowledge gap and to deliver important findings to the scientific community, efficient sulfur recovery from black liquor gasifier syngas, comprising both gas cleaning and returning sulfur to the pulping process, was modeled and assessed from a techno-economic viewpoint. This manuscript proves that the associated investment and operational costs cannot be neglected and that they impact the black liquor gasification feasibility significantly. To prove its gasification as a sustainable and more efficient processing route over its combustion in recovery boilers, a substantial process efficiency improvement and operating costs reduction must be targeted in future research. Background and Objectives: Sulfur compounds found in black liquor partly turn into hydrogen sulfide during gasification and exit the gasifier in the syngas. Their efficient recovery in their sulfidic form to the pulping process is of utmost importance. Current studies focus on black liquor gasifier syngas desulfurization only. Materials and Methods: A mathematical model of two H2S absorption units from a 66.7 tDS/h (1600 tons dry solids per day) black liquor gasification process to 20 ppm H2S content in cleaned syngas using either white liquor plus NaOH or N-methyldiethanolamine (MDEA) was created using the Aspen Plus simulation software. Results: The results show that CO2 co-absorption significantly increases the lime kiln load: +20% in the MDEA alternative and +100% in the other one. The MDEA alternative requires almost the same investment costs but by around USD 9.7 million (>50%) lower annual operating costs compared to the other one. Economic evaluation was based on the assumed discount rate of 5% and on the expected plant operation time of 25 years. The estimated total investment cost of the whole plant is around USD 170 million for both alternatives. The whole plant including this alternative exhibits a positive net present value (over USD 19 million), an internal rate of return of 5% and a profitability index of 1.12, whereas that with the other alternative is economically infeasible. Conclusions: The MDEA-based syngas cleaning technology represents a more efficient and economically feasible option of sulfur recovery. A major drawback of both modeled syngas cleaning technologies is that their estimated annual operating costs significantly reduce the expected profit margin of gasification over the traditional black liquor combustion in a recovery boiler. Syngas cleaning and sulfur recovery have to be further optimized to reach a significant cut down in operational costs to improve the economic feasibility of black liquor gasification.

To mitigate global warming, humankind has been forced to develop new efficient energy solutions based on renewable energy sources. Hydrothermal liquefaction (HTL) is a promising technology that can efficiently produce bio-oil from several biomass sources. The HTL process uses sub- or supercritical water for producing bio-oil, water-soluble organics, gaseous products and char. Black liquor mainly contains cooking chemicals (mainly alkali salts) lignin and the hemicellulose parts of the wood chips used for cellulose digestion. This review explores the effects of different process parameters, solvents and catalysts for the HTL of black liquor or black liquor-derived lignin. Using short residence times under near- or supercritical water conditions may improve both the quality and the quantity of the bio-oil yield. The quality and yield of bio-oil can be further improved by using solvents (e.g., phenol) and catalysts (e.g., alkali salts, zirconia). However, the solubility of alkali salts present in black liquor can lead to clogging problem in the HTL reactor and process tubes when approaching supercritical water conditions.

The desilication effects of aluminium sulphate and sodium aluminate on kraft bamboo pulp during the cooking process were investigated in this study. Furthermore, the residual aluminium ion concentration in the resulting black liquor was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) to evaluate the scaling properties of black liquor during the evaporation process. Atomic force microscopy (AFM) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) analysis showed that aluminium salts could react with silica to form a silica-alumina compound, which can adhere to the fibre surface during the cooking process. As a result, the silicon content in the black liquor could be effectively decreased by the addition of aluminium sulphate and sodium aluminate. A silica removal ratio of 74% could be achieved when the loadings of aluminium sulphate and sodium aluminate were 2.0 wt.% and 1.5 wt.%, respectively. Finally, the concentration of aluminium ions was 7.31 ppm under optimised conditions. Based on these considerations, any amounts of aluminum ion passing into the black liquor are unlikely to contribute to scaling problems.

Black liquor produced from pulping with a high value of chemical oxygen demand (COD) and biological oxygen demand (BOD) is highly harmful if discharged into the environment directly. One possible way to decrease the damage to the soil and water is to reuse the organic substances contained in it to cultivate yeasts for producing single-cell proteins (SCP) while reducing the COD. With this in mind, this study is devoted to treatment technology and the comprehensive utilization of black liquor. Various parameters were evaluated, and the COD of black liquor, initial pH, and nitrogen sources had significant influences on biomass and crude protein production. The research resulted in the maximum values of COD removal rate and crude protein production with 78.78 ±3.21% and 1.18 ±0.02 g/L achieved, respectively, under the optimized condition of black liquor concentration (60%), the recruitment of urea (0.5 g/L), initial pH (6.0), temperature (34 °C), shaking speed (180 rpm), and incubation time (36 h). Furthermore, this study provided a potential viable treatment of black liquor and revealed a feasible way to make full use of black liquor for the economical production of SCP.

Fourteen local isolate Aphyllophorales fungi were screened their ligninolytic activity. The isolate with highest ligninolytic activity was tested it capability to degrade kraft blackliquor lignin. The biodegradability of black liquor is low because the presence of lignin and lignin derivative in the wastewater. These fungal were screened for ligninolytic activity by decolorization on solid mediacontaining RBBR dye. The ability of the fungal strains to biodegrade kraft black liquor lignin was performed by submerged fermentation condition with agitation and incubation time as treatment. The solid culture result in 3 isolates had ligninolytic activity and Ganoderma sp.BTA1 gave the highest ligninolytic. Agitation and incubation time influenced ligninbiodegradation of blackliquor significantly. Optimum condition for lignin biodegradation was at 200 rpm during 25 days with lignin reduction was 45,786%.

This paper evaluates the effect of addition of precipitated lignin, from spent pulping black liquor, to a wet single-ply linerboard handsheet followed by hot-pressing at different temperatures, on the improvement of its compressive strength. Linerboard handsheets for testing the effect of lignin addition were prepared so that the lignin-modified sheets would have the same basis weights as the control handsheets. Both the commercial and the black liquor lignin were added as a powder to wet handsheets after couching from the handsheet mold. The experiments and testing of the physical and strength properties of dried handsheets were conducted according to TAPPI test methods. The results revealed that the addition of the recovered lignin (at pH of 2) to the wet handsheet followed by hot-pressing at 150°C increased the compressive strength of linerboard handsheets by 10% to 20% above that for handsheets made without the addition of lignin. The same results were achieved using purchased lignin. However, with a 16% addition to linerboard, purchased lignin would be too expensive. These results indicate that inclusion of kraft lignin in linerboard sheets could be proved as an attractive option to reduce linerboard basis weight.

The mycelial growth ability of 13 white rot fungi were separately evaluated in kraft, organosolv, and soda black liquor agar-plates. The fungus able to best grow and decolorize black liquor agar-plates was grown in organosolv black liquor to investigate whether it reduced organosolv lignin molar mass. The fungus Bjerkandera adusta showed fair mycelial growth and decolorization ability in 10% black liquor-agar plates. To obtain low-molecular weight (MW) lignin, B. adusta was cultivated in 150-mL Erlenmeyer flasks containing 10% black liquor and maintained in a shaking culture for 15 days. Lignin was recovered from each Erlenmeyer flask by acid precipitation and was analysed by size exclusion chromatography (SEC) and Fourier transform infrared (FTIR) spectroscopy. The lowest MW of lignin from black liquor was observed on the 11th and 12th days, at 1461 and 1790 kDa, respectively, with the polydispersity close to 1.0, indicating that the molecules were similar in size. Fourier transform infrared spectra bands showed modification of the lignin structure during 9 days, with new bands appearing after five days of lignin biodegradation.

Lignin is an attractive, renewable raw material provided by all types of agricultural and silvicultural vegetation. The precipitation of lignin fractions through acidification of the black liquor was performed and the products characterized for the following parameters: C, H, N, and S elemental composition; zeta potential; electrophoretic mobility; heating value; molecular weight; content of non-conjugated, conjugated, and total phenolic hydroxyl groups; and total yield of oxidation products. Lignin was isolated from black liquor by adding sulphuric acid at four levels of concentration (5, 25, 50, and 72 wt%) and subsequently adjusting the pH to 5. A comparison study of the physico-chemical and surface properties was also performed. The acid concentration influenced the yield of precipitated lignin and had an effect on the properties of precipitated lignin and the content of non-conjugated, conjugated, and total amount of phenolic hydroxyl groups. However, the concentration of acid had no relevant effect on the heating value, molecular weight, polydispersity, total yield of oxidation products, or the elemental composition of isolated lignin.

Highlights • Biomass conversion efficiency presents economic advantages over economy of scale. • Industrial integration is beneficial to reach cost-efficient biorefineries. • Replacing capital-intensive equipment at the host industry is beneficial. • No benefit for centralised or decentralised supply chain configurations. Abstract Biorefineries for the production of fuels, chemicals, or materials can be an important contributor to reducing dependence on fossil fuels. The economic performance of the biorefinery supply chain can be increased by, for example, industrial integration to utilise excess heat and products, increasing size to improve economy of scale, and using intermediate upgrading to reduce feedstock transport cost. To enable a large-scale introduction of biorefineries it is important to identify cost efficient supply chain configurations. This work investigates a lignocellulosic biorefinery concept integrated with forest industry, focusing on how different economic conditions affect the preferred supply chain configurations. The technology investigated is black liquor gasification, with and without the addition of pyrolysis liquids to increase production capacity. Primarily, it analyses trade-offs between high biomass conversion efficiency and economy of scale effects, as well as the selection of centralised vs. decentralised supply chain configurations. The results show the economic advantage for biomass efficient configurations, when the biorefinery investment is benefited from an alternative investment credit due to the replacement of current capital-intensive equipment at the host industry. However, the investment credit received heavily influenced the cost of the biorefinery and clearly illustrates the benefit for industrial integration to reduce the cost of biorefineries. There is a benefit for a decentralised supply chain configuration under very high biomass competition. However, for lower biomass competition, site-specific conditions will impact the favourability of either centralised or decentralised supply chain configurations. [ABSTRACT FROM AUTHOR]

Abstract 3D graphene (or graphene-like porous carbon) is prepared from precursor lignin separated and purified from alkaline pulp black liquor. The lignin is pretreated using rapid freeze-dry technique for the porous, soft and dispersive microstructure. A special temperature control program is designed to keep the porous structure of lignin particles in the carbonization and graphitization process, avoiding agglomeration. The 3D graphene from lignin consist of curve graphene sheets in dimensions around dozen micrometers, which merge each other with clear dihedral angle and form wood-ear like architecture, different from fullerene like carbon crystals. The porous carbon is characterized and analyzed with FTIR, Raman, XRD, SEM, TEM, XPS, and SSA. A possible chemical mechanism in the synthesis of 3D graphene from lignin precursor is proposed. The aromatic groups and alkane fragments in lignin are decomposed during pyrolysis under high temperature, then the benzene rings compose the graphene sheets, and the sp3 free carbon atoms join the graphene sheets with chemical bonds along the framework of lignin polymer, forming the self-supporting and self-constructing 3D graphene, or porous carbon. Graphical abstract Unlabelled Image Highlights • Lignin is separated from alkaline pulp black liquor, and reshaped into a porous form using liquid-nitrogen freezing method. • Graphene-like porous carbon has wood-ear like architecture consisting of curve graphene sheets. • 3D graphene was analyzed by using SEM, TEM, XPS, XRD, FTIR, Raman and surface area analysis. • A possible chemical mechanism in the synthesis of 3D graphene from lignin precursor is proposed. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate the feasibility of hydrothermal liquefaction (HTL) of Radiata pine with black liquor from an existing Kraft pulp mill. The biomass into the HTL process was assumed at 2000 t/day and converted into bio-crude through the HTL process and upgraded to produce a gasoline and diesel blend. The HTL process was scaled-up based on an existing published patent. Mass and heat balance of the process was obtained through the process simulator, Aspen Plus. Process Integration was carried out to minimise the hot and cold utility of the process. The production rate of the process is 78.7 kt/y of fuel. The minimum fuel selling price (MFSP) was estimated at 0.95 USD/LGE (litre gasoline equivalent). A sensitivity analysis was carried out to determine the MFSP in 2017 and to study the changes of MFSP due to the uncertainty in the capital cost estimation. [ABSTRACT FROM AUTHOR]

Abstract Hydrogen (H 2) is considered as a clean energy carrier in the future with high efficiency and various utilization technologies. The H 2 can be produced from biomass as primary energy source to reduce environmental impact. Currently, some projects are underway to achieve efficient conversion and reduce costs associated with H 2 generation. High energy efficiency can be achieved by minimizing exergy loss through process integration and exergy recovery. In this study, co-production of H 2 and power from black liquor (BL) is proposed based on process integration and exergy recovery. The proposed system consists of BL evaporation, gasification, syngas chemical looping (SCL), and power generation. The evaporation process employs exergy recovery using steam tube rotary evaporator. The effect of target moisture content on the evaporator performance is evaluated. Furthermore, the thermodynamics analysis of gasification is performed in circulating fluidized bed reactor based on Gibbs energy minimization. The SCL process comprises reducer, oxidizer and combustor and integrates with power generation. The result shows that the proposed integrated system can achieve higher efficiency of nearly 70%. In addition, the concentrated CO 2 can be generated during the SCL process, avoiding additional cost for separation. [ABSTRACT FROM AUTHOR]

In this work, an eco-friendly solution for the remediation of wastewater generated in the lignin recovery process from eco-industrial paper mill has been proposed in their way towards a more circular economy strategy. Thus, the application of the electro-Fenton process for the degradation of the non-recovered lignin and other organic compounds form a scarcely studied acid black liquor waste (ABLW) was successfully performed. This treatment was able to operate in a range of COD loads (0.5–19.5 mg O 2 ·L –1 ) showing high degradation values of the ABLW determined by the abatement of color, total phenolic content and COD. Then, the optimization of the working conditions for the design of a sustainable treatment system with optimum efficiency was carried out using a response surface methodology. The experiment carried out in the calculated optimal conditions for the electro-Fenton degradation process (current intensity 132.5 mA, catalyst dosage of 0.10 mM, and temperature 40 °C) showed a COD removal of 74.82% and current efficiency 77.79%, close to the theoretical value predicted by the model 73.12% and 77.06%, respectively. In addition, the identification of the final products permitted to confirm the mineralization efficiency. [ABSTRACT FROM AUTHOR]

Entrained flow gasification of black liquor combined with downstream-gas-derived synthesis of biofuels in Kraft pulp mills has shown advantages regarding energy efficiency and economic performance when compared to combustion in a recovery boiler. To further increase the operation flexibility and the profitability of the biofuel plant while at the same time increase biofuel production, black liquor can be co-gasified with a secondary feedstock (blend-in feedstock). This work has evaluated the prospects of producing biofuels via co-gasification of black liquor and different blend-in feedstocks (crude glycerol, fermentation residues, pyrolysis liquids) at different blend ratios. Process modelling tools were used, in combination with techno-economic assessment methods. Two methanol grades, crude and grade AA methanol, were investigated. The results showed that the co-gasification concepts resulted in significant increases in methanol production volumes, as well as in improved conversion efficiencies, when compared with black liquor gasification; 5–11 and 4–10 percentage point in terms of cold gas efficiency and methanol conversion efficiency, respectively. The economic analysis showed that required methanol selling prices ranging from 55 to 101 €/MWh for crude methanol and 58–104 €/MWh for grade AA methanol were obtained for an IRR of 15%. Blend-in led to positive economies-of-scale effects and subsequently decreased required methanol selling prices, in particular for low cost blend-in feedstocks (prices below approximately 20 €/MWh). The co-gasification concepts showed economic competitiveness to other biofuel production routes. When compared with fossil fuels, the resulting crude methanol selling prices were above maritime gas oil prices. Nonetheless, for fossil derived methanol prices higher than 80 €/MWh, crude methanol from co-gasification could be an economically competitive option. Grade AA methanol could also compete with taxed gasoline. Crude glycerol turned out as the most attractive blend-in feedstock, from an economic perspective. When mixed with black liquor in a ratio of 50/50, grade AA methanol could even be cost competitive with untaxed gasoline. [ABSTRACT FROM AUTHOR]

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In this work, high-silica MFI zeolite adsorbent was evaluated for selective recovery of butanol from a real ABE (acetone, butanol, and ethanol) fermentation broth by batch adsorption measurements. The fermentation broth was produced using a hydrolyzate originating from Kraft black liquor, an internal stream in pulp mills, i.e., a low-cost substrate. The adsorbent was very selective towards butanol and butyric acid and became nearly saturated with a mixture of butanol and butyric acid with relative amounts of butanol and butyric acid depending on the pH. The presence of phenolic compounds in significant amounts in the fermentation broths, originating from the black liquor hydrolyzate, did not affect the adsorption of butanol and butyric acid. [ABSTRACT FROM AUTHOR]

Supercritical water gasification (SCWG) is a promising innovative black liquor handling method. The low concentration of black liquor is a burden for the system scale and investment cost. In this study, we introduced black liquor evaporator to increase the concentration using self-generated steam and power, and studied its influence on the energy and exergy efficiency. The results showed that increasing black liquor concentration from 10 wt% to 20 wt% reduced the energy efficiency but increased the exergy efficiency of the system without evaporator. With the evaporator, an optimal target concentration existed for the exergy efficiency owing to the influence of the target concentration on the balance between the energy consumption and saving brought by the evaporator. With black liquor condensed from 15 wt% to 21.82 wt%, maximum exergy efficiency of the system (41.95%) was obtained. For lower-concentration black liquor, more water needs to be evaporated to get the optimal concentration and evaporator was more desired because it brought greater improvement on the exergy efficiency. The increasing effect number of multi-effect evaporator shifted the optimal concentration to higher values, which increased from 19.93 wt% to 23.13 wt% when the effect number increased from 4 to 7. The exergy efficiency of the system was also improved, and the improvement was more significant at higher target concentration. [ABSTRACT FROM AUTHOR]

The influence of sodium ion concentration [Na+] on the dissolution of carbohydrates in black liquor (BL) during flow-through kraft cooking of Scots pine wood meal (Pinus sylvestris) was studied. Fractions of BL were collected at different times and the carbohydrate content of the various fractions was analysed. Lignin was precipitated from the BL by lowering the pH, and the carbohydrate content of the precipitated lignins (Lprec) was also examined. The molecular weight distribution (MWD) of the Lprec samples was analysed. Xylose (Xyl) was found to be the most predominant sugar in BL aside from arabinose (Ara) and galactose (Gal), while the amounts of these sugars decreased with increasing levels of [Na+] in the cooking liquor. The minor amounts of mannose (Man) found in BL was not influenced by the [Na+]. The effects of NaCl and Na2CO3 on the carbohydrate dissolution were similar, but slightly lower concentrations of Ara and Xyl were found in the case of NaCl application. All of the Lprec samples contained some carbohydrate residues, the contents of which increased with increasing cooking time and decreased with higher [Na+]. It can be concluded that arabinoglucuronoxylan (AGX) along with arabinogalactans (AG) and arabinan, are covalently linked to lignin. The glucose (Glc) residue detected in Lprec may originate from 1,3-β-glucan linked to lignin. [ABSTRACT FROM AUTHOR]

The economic feasibility of producing ammonia through the gasification of three different feedstocks produced in pulp and paper mills is investigated in this paper. The first case uses black liquor, the main by-product of the kraft pulping process, as the feedstock, and in the other two cases pulp sludge (PS) and waste sludge (WS) are co-gasified with black liquor. For all three cases, a process model in which mass and energy balances were calculated was developed. The model results were used to estimate the equipment size and estimate costs. Techno-economic models were developed and ammonia production costs were calculated. A case study for Alberta, a western Canadian province, was conducted. The results indicated that for a 10% discount rate (or internal rate of return [IRR]), ammonia production in all three cases is cost competitive with current ammonia prices. The cost of production (COP) of ammonia for all three cases ranges from 743 to 748 $/t. Sensitivity and uncertainty analyses were conducted on the estimated COP, and the results show that the COP is the most sensitive to the capital cost, discount rate, electricity price and plant lifetime. [ABSTRACT FROM AUTHOR]