Waleed Wafa Al-Dajani

Process modeling and analysis of pulp mill-based integrated biorefinery with hemicellulose pre-extraction for ethanol production: a comparative study.

Pulp and paper mills represent a major platform to use more effectively an abundant, renewable bio-resource - wood. Modification of the modern day pulp mills into integrated forest biorefineries (IFBR) presents an excellent opportunity to produce, in addition to valuable cellulose fiber, co-products including fuel grade ethanol and additional energy, thus resulting in increased revenue streams and profitability and potentially lower the greenhouse gas emissions. A process model to simulate the integrate forest biorefinery manufacturing pulp and other co-products has been developed. This model has been used to compare three integrated biorefinery scenarios: the conventional Kraft pulping process, the pulp mill-based IFBR with hemicelluloses extraction prior to pulping for ethanol production, and the pulp mill-based IFBR with both pre-extracted hemicelluloses and the short fiber for ethanol production. Based on a fixed feedstock throughput of 2000 dry Mg wood/day, results show that the pulp mill-based IFBR with both pre-extracted hemicelluloses and the short fiber cellulose converted to ethanol can produce 0.038 MM m(3) (10.04 MM gal) ethanol per year at a minimum ethanol selling price (MESP) of

Improved pretreatment of lignocellulosic biomass using enzymatically-generated peracetic acid.

491/m(3) (

Bleachability of alkaline pulps : Part 1. The importance of β-aryl ether linkages in lignin

1.86/gal). The economic feasibility of IFBR can be further improved by using further improvements in the pre-extraction process, other biomass such as corn stover for producing ethanol, and taking advantage of the economies of scale.

On the isolation and structure of softwood residual lignins

Release of sugars from lignocellulosic biomass is inefficient because lignin, an aromatic polymer, blocks access of enzymes to the sugar polymers. Pretreatments remove lignin and disrupt its structure, thereby enhancing sugar release. In previous work, enzymatically generated peracetic acid was used to pretreat aspen wood. This pretreatment removed 45% of the lignin and the subsequent saccharification released 97% of the sugars remaining after pretreatment. In this paper, the amount of enzyme needed is reduced tenfold using first, an improved enzyme variant that makes twice as much peracetic acid and second, a two-phase reaction to generate the peracetic acid, which allows enzyme reuse. In addition, the eight pretreatment cycles are reduced to only one by increasing the volume of peracetic acid solution and increasing the temperature to 60 °C and the reaction time to 6h. For the pretreatment step, the weight ratio of peracetic acid to wood determines the amount of lignin removed.

Effect of biomass species and plant size on cellulosic ethanol: a comparative process and economic analysis.

Summary Analytical and structural studies were done on different types of alkaline pulps and their isolated residual lignins. Although having the same degree of delignification after cooking, some pulps were easier to bleach than others. All isolated residual lignins were found to contain β-aryl ether (β-O-4) structures in reasonable amounts when analysed by thioacidolysis (≥10 % of the native lignin value). At decreasing kappa numbers, there was also a corresponding decrease in the amount of β-aryl ether structures in the residual lignin. Moreover, a high β-aryl ether content in the unbleached residual lignin after cooking was found to contribute to a better bleachability of the pulp, especially when hydrogen peroxide stages were involved. At the same degree of delignification, the superior bleachability of alkaline sulfite pulps over kraft pulps was shown to be attributable to a higher content of β-aryl ether linkages in the former type of pulps.

Pre-extraction of hemicelluloses and subsequent kraft pulping Part I: Alkaline extraction

Different softwood residual lignins were isolated by acid hydrolysis of kraft and soda Pulps. Complete isolation of lignin Could not be achieved in one hydrolysis step. The yield of lignin varied b ...