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Journal articles
Open Access
Data driven modeling to reduce fossil fuel consumption in a lime kiln integrated with biomass gasifier, TAPPI Journal September 2026

ABSTRACT: Biomass gasification, although already known and applied, is currently being consolidated as a sustainable alternative in the pulp industry, contributing to the reduction of fossil carbon dioxide (CO2) emissions and to the utilization of forest residues. In this context, pulp mills are beginning to adopt biomass gasification within their chemical recovery cycles by integrating the technology with lime kilns. However, further process studies are still needed to support and optimize this application. Thus, the present study aimed to analyze lime mud feed temperature by applying an artificial neural network model to a gasification system integrated with a lime kiln. For this evaluation, 10 periods of system stability throughout 2024 were selected under different operational conditions. Data from 28 potential predictive variables were collected, a total of 348 observations. This dataset was then processed using R software, where data treatment and model dimensionality reduction were performed, resulting in 10 predictive variables between gasifier and kiln. Next, the dataset was randomly divided into training (70% of the observations) and testing data. The established neural network model (using “neuralnet” package) was optimized, resulting in a configuration containing one hidden layer with three neurons. This setup enabled optimal estimation of the flue gas kiln outlet temperature, with mean absolute error (MAE) = 3.0°C and root mean square error (RMSE) = 4.1°C, applying the resilient backpropagation algorithm with backtracking — both below the thermocouple’s measurement error (±5.0°C) for the evaluated average temperature range (668.2°C). When the same dataset was modeled using the resilient backpropagation algorithm without backtracking, even better results were achieved: MAE = 2.5°C and RMSE = 3.7°C. Thus, after evaluating these and other configurations, it was concluded that the best model required 10 predictive variables and the backpropagation algorithm without backtracking to determine flue gas kiln outlet temperature. These results provide a better understanding of how gasifier and kiln variables influence the temperature in the lime kiln, which is essential to improve control and optimize the calcination process, avoiding supplementary fossil fuel consumption.

Journal articles
Open Access
Biomass gasification for green ammonia production in kraft mills, TAPPI Journal September 2026

ABSTRACT: As the global energy sector transitions toward net-zero emissions, kraft pulp mills present a compelling opportunity to produce green fuels and achieve net-negative emissions by capturing biogenic carbon, helping offset hard-to-abate sectors. This study explores the techno-economics of integrating biomass gasification for green ammonia production within kraft mills, using KraftSIM modeling to evaluate ammonia production, steam balance, emissions, and utility impacts. The proposed design enables energy and water system integration with the existing mill and allows for a gradual scale-up without disrupting the chemistry and operation of the recovery cycle. Across five scenarios representing different biomass gasification rates ranging from 100 to 1000 bone-dry metric tons per day (BDMT/d), the process yields ammonia at approximately 0.51 metric tons per bone-dry metric ton (t/ BDMT), while generating significant low- and medium-pressure steam and hot water that offset mill utility demands. The incineration of pressure swing adsorption tail gas and ammonia plant purge gas in the power boiler reduces biomass combustion and enhances power boiler efficiency. Economic analysis suggests a net revenue potential of approximately CA$380/BDMT, which could increase with the implementation of biogenic carbon pricing. Overall profitability is strongly influenced by biomass procurement costs, electricity prices, and prevailing green fuel and chemical market premium. This work outlines a practical, near-term decarbonization pathway for kraft mills by coupling green fuel production with potential opportunities for carbon removal.

Journal articles
Magazine articles
Open Access
Evaluation of rice straw for purification of lovastatin, TAPPI Journal November 2021

ABSTRACT: Cholesterol synthesis in the human body can be catalyzed by the coenzyme HMG-CoA reductase, and lovastatin, a key enzyme inhibitor, can reduce hypercholesterolemia. Lovastatin can be obtained as a secondary metabolite of Aspergillus terreus ATCC 20542. In this study, rice straw of lignocellulose was used in aeration and agitation bath fermentation in a 1-L flask, and a maximal crude extraction rate of 473 mg/L lovastatin was obtained. The crude extract was treated with silica gel (230•400 mesh) column chromatography. Ethyl acetate/ethanol (95%) was used as the mobile phase, and isolation was performed through elution with various ethyl acetate/ethanol ratios. The highest production rate of 153 mg/L was achieved with ethyl acetate/ethanol in a ratio of 8:2. The lovastatin gained from the crude extract was added to 12 fractions treated with 0.001 N alkali, and acetone was then added. After 24 h of recrystallization at 4°C, the extract underwent high-performance liquid chromatography. The purity had increased from 25% to 84.6%, and the recovery rate was 65.2%.

Journal articles
Magazine articles
Open Access
Control of malodorous gases emission from wet-end white water with hydrogen peroxide, TAPPI Journal October 2021

ABSTRACT: White water is highly recycled in the papermaking process so that its quality is easily deteriorated, thus producing lots of malodorous gases that are extremely harmful to human health and the environment. In this paper, the effect of hydrogen peroxide (H2O2) on the control of malodorous gases released from white water was investigated. The results showed that the released amount of total volatile organic compounds (TVOC) decreased gradually with the increase of H2O2 dosage. Specifically, the TVOC emission reached the minimum as the H2O2 dosage was 1.5 mmol/L, and meanwhile, the hydrogen sulfide (H2S) and ammonia (NH3) were almost completely removed. It was also found that pH had little effect on the release of TVOC as H2O2 was added, but it evidently affect-ed the release of H2S and NH3. When the pH value of the white water was changed to 4.0 or 9.0, the emission of TVOC decreased slightly, while both H2S and NH3 were completely removed in both cases. The ferrous ions (Fe2+) and the copper ions (Cu2+) were found to promote the generation of hydroxyl radicals (HOœ) out of H2O2, enhancing its inhibition on the release of malodorous gases from white water. The Fe2+/H2O2 system and Cu2+/H2O2 system exhibited similar efficiency in inhibiting the TVOC releasing, whereas the Cu2+/H2O2 system showed better perfor-mance in removing H2S and NH3.

Journal articles
Open Access
Biobleaching of softwood kraft pulp with white-rot fungus izu-154, TAPPI JOURNAL, January 1993, Vol. 76(1)

Biobleaching of softwood kraft pulp with white-rot fungus izu-154, TAPPI JOURNAL, January 1993, Vol. 76(1)

Journal articles
Open Access
Formation of acidic sulfates in kraft recovery boilers, TAPPI JOURNAL, July 1993, Vol. 76(7)

Formation of acidic sulfates in kraft recovery boilers, TAPPI JOURNAL, July 1993, Vol. 76(7)

Journal articles
Open Access
Prediction of hogged-fuel drying times, TAPPI JOURNAL, June 1993, Vol. 76(6)

Prediction of hogged-fuel drying times, TAPPI JOURNAL, June 1993, Vol. 76(6)

Journal articles
Open Access
Print mottle effect of binder migration and latex film formation during coating consolidation, TAPPI JOURNAL, May 1993, Vol. 76(5)

Print mottle effect of binder migration and latex film formation during coating consolidation, TAPPI JOURNAL, May 1993, Vol. 76(5)

Journal articles
Open Access
An overview of strategies for reducing the environmental impact of bleach-plant effluents, TAPPI JOURNAL, May 1993, Vol. 76(5)

An overview of strategies for reducing the environmental impact of bleach-plant effluents, TAPPI JOURNAL, May 1993, Vol. 76(5)

Journal articles
Open Access
Effect of papermaking and coating variables on offset-print quality - part 1: papermaking variables, TAPPI JOURNAL, October 1993, Vol. 76(10)

Effect of papermaking and coating variables on offset-print quality - part 1: papermaking variables, TAPPI JOURNAL, October 1993, Vol. 76(10)

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