Chularat Sakdaronnarong

Thermo-molded biocomposite from cassava starch, natural fibers and lignin associated by laccase-mediator system.

Treatment of cellulose fibers and lignin by laccase-mediator system was conducted to enhance the binding efficiency of natural fibers and lignin compounds into cassava starch composite matrix. Violuric acid (VA) was tested for its effect as a mediator for laccase treatment. Influence of different fiber, lignin and water contents of biocomposite was statistically investigated. The results showed that adding 15% (w/w) fibers into biocomposite at 44% (w/w) water content increased flexural strength and modulus for 4 times compared with the control. A combination of fibers+VA gave the greatest enhancement of modulus for 1140% and flexural strength for 375.8% as much as neat starch biocomposite. The presence of fibers, lignin and VA as mediator for laccase treatment substantially enhanced water resistance of starch biocomposite detected by a change in water drop contact angle on biocomposite surface.

Bioenergy potential of Wolffia arrhiza appraised through pyrolysis, kinetics, thermodynamics parameters and TG-FTIR-MS study of the evolved gases

This study evaluated the bioenergy potential of Wolffia arrhiza via pyrolysis. The biomass was collected from the pond receiving city wastewater. Oven dried powdered biomass was exposed to thermal degradation at three heating rates (10, 30 and 50° C min-1) using Thermogravimetry-Differential Scanning Calorimetry analyzer in an inert environment. Data obtained were subjected to the isoconversional models of Kissenger-Akahira-Sunose (KSA) and Flynn-Wall-Ozawa (FWO) to elucidate the reaction chemistry. Kinetic parameters including, Ea (136-172 kJmol-1) and Gibbs free energy (171 kJmol-1) showed the remarkable bioenergy potential of the biomass. The average enthalpies indicated that the product formation is favored during pyrolysis. Advanced coupled TG-FTIR-MS analyses showed the evolved gases to contain the compounds containing CO functional groups (aldehydes, ketones), aromatic and aliphatic hydrocarbons as major pyrolytic products. This low-cost abundant biomass may be used to produce energy and chemicals in a cost-efficient and environmentally friendly way.

Candida shehatae and Saccharomyces cerevisiae work synergistically to improve ethanol fermentation from sugarcane bagasse and rice straw hydrolysate in immobilized cell bioreactor

Sugarcane bagasse (SCB) and rice straw (RS), abundant lignocellulosic agro‐industrial residues in South‐East Asia, are potent feedstocks for bioethanol production as they contain significant amount of glucose and xylose monomers after fractionation and subsequent enzymatic hydrolysis. To simultaneously convert glucose and xylose to ethanol, it requires co‐cultivation of Saccharomyces cerevisiae and Candida shehatae which are hexose and pentose‐fermenting yeasts, respectively. Xylose‐fermenting strain grows slower than glucose‐fermenting one, therefore low efficiency of xylose‐to‐ethanol conversion was found. To enhance the efficiency of ethanol fermentation, the present work proposed to improve xylose assimilation by using co‐immobilization of two strains in a packed bed bioreactor and to increase oxygenation of the medium by applying a recycled batch system when the recycle stream was intervened by a mixing system in a naturally aerated vessel. Initially, conversion of glucose and xylose to ethanol using pure culture was investigated. Subsequently, influence of different immobilization techniques was investigated. Cells entrapment in Ca‐alginate beads provided considerably high ethanol yield over cells immobilized on delignified cellulose, and thus it was selected to use as inoculum in an immobilized cell bioreactor (ICB). The results showed that continuous ethanol production yielded 0.38 and 0.40 g/g corresponding to 74.5% and 78.4% theoretical yields from SCB and RS hydrolysate, respectively. However, recycled batch system produced significantly improved ethanol yield to 0.49 g/g and 0.50 g/g corresponding to 96.1% and 98.0% theoretical yields for SCB and RS hydrolysate, respectively. In this study, higher ethanol concentration and less unfermented sugar concentration was successfully achieved in the ICB with recycled batch system when using SCB and RS hydrolysate as the substrate.

Polyurethane Synthesis from Sugarcane Bagasse Organosolv and Kraft Lignin

Sugarcane bagasse (SCB) was subjected to a single-step fractionation and hydrolysis reaction in the presence of various organic solvents. The reaction was performed at 170 °C for 3 h when sodium hydroxide was used as catalyst. The results showed that suitable solvents significantly enhanced the yield of lignin fractionation and simultaneous hydrolysis reaction took place indicated by an increase of hydroxyl groups in lignin molecules. Lignin-based polyurethane (LPU) from SCB organosolv lignin polyols had relatively better mechanical and thermal resistant properties compared to LPU from liquefied Kraft lignin from pulp and paper industry.

Saccharification of Delignified Sugarcane Bagasse for Lactic Acid Fermentation using Lactobacillus sp.

Delignified sugarcane bagasse (SCB) by solvent extraction was carried out at moderate condition (90°C, 4 h) in the presence of acid catalyst. To investigate the dissolution of lignin into solvent, different solvents were utilized during lignin extraction process. Delignified SCB was further hydrolyzed by cell wall degrading enzyme complexes prior to sugar determination. The results showed that n-butanol was the most promising solvent enhancing lignin dissolution which in turn led to highest yield of glucose (63.1% based on treated SCB) and no xylose was detected in hydrolysate. The lignin extraction by n-butanol in the presence of H2SO4 and subsequent saccharification process were then scaled up for lactic acid production. The maximum lactic acid was obtained at 25.7 ± 0.2 g/l from L. casei fermentation after 96 hours when sugarcane bagasse hydrolysate containing 25.6±1.4 g/l initial glucose concentration was used as substrate.

Hydrogen and electricity production from anaerobic digestion of rice vermicelli wastewater by mixed acidophilic consortia in a microbial fuel cell

Industrial wastewater pretreatment through the anaerobic digestion is able to generate both biogas and electricity in microbial fuel cells (MFCs). In this work, hydrogen was produced in MFC combining rice vermicelli wastewater treatment using enriched hydrogen producing consortia. Effects of sludge pretreatment and addition of supplements, mediator (lignin) and glucose were studied to determine the optimum condition for the operation in MFC. The results showed that the pretreatment of sludge inhibited methanogenesis and higher content of hydrogen gas was substantially produced. Adding glucose and lignin was found to facilitate hydrogen production (50.2%). In MFC, pretreated sludge was able to produce more fermentative hydrogen, higher COD removal and solid removal, nevertheless generated electricity was reduced compared with untreated sludge. An increase of amount of granular activated carbon (GAC) used as anode from 700 to 1200 g considerably enhanced hydrogen production from 20.02 to 73.25 % (115 to 926 mL), increased power density from 11.92 to 20.33 mW/m2 (at 750A) and increased COD removal from 45.45 to 57.14%.