Kit Ling Chin

Optimization study of ethanolic fermentation from oil palm trunk, rubberwood and mixed hardwood hydrolysates using Saccharomyces cerevisiae

Ethanolic fermentation using Saccharomyces cerevisiae was carried out on three types of hydrolysates produced from lignocelulosic biomass which are commonly found in Malaysia such as oil palm trunk, rubberwood and mixed hardwood. The effect of fermentation temperature and pH of hydrolysate was evaluated to optimize the fermentation efficiency which defined as maximum ethanol yield in minimum fermentation time. The fermentation process using different temperature of 25 degrees Celsius, 30 degrees Celsius and 40 degrees Celsius were performed on the prepared fermentation medium adjusted to pH 4, pH 6 and pH 7, respectively. Results showed that the fermentation time was significantly reduced with the increase of temperature but an adverse reduction in ethanol yield was observed using temperature of 40 degrees Celsius. As the pH of hydrolysate became more acidic, the ethanol yield increased. Optimum fermentation efficiency for ethanolic fermentation of lignocellulosic hydrolysates using S. cerevisiae can be obtained using 33.2 degrees Celsius and pH 5.3.

Physical and mechanical properties of thin high density fiberboard bonded with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU)

ABSTRACT 1,3-dimethyl-4,5-dihydroxyethyleneurea (DDHEU) and 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) were used as the binders in 3-mm high density fiberboard (HDF) manufacturing. The studies focus on the physical and mechanical properties of boards bonded with DDHEU or DMDHEU as a potential substitute for typically used urea-formaldehyde (UF) resins. The adhesive loads were 8% or 12%. The UF-bonded boards of same resin load were used as the controls. Applied pressing time ranged between 4 and 5 minutes. The results indicate that the use of DDHEU or DMDHEU as binders enhanced physical and mechanical properties of the boards. It was found that properly set pressing scheme and resin type allowed produce DDHEU- and DMDHEU-bonded HDF that exhibited comparable or superior performance when compared to the UF-bonded reference series and complied with European Standards. The best performing boards exhibited internal bond 1.3 MPa, modulus of elasticity 9656 MPa, modulus of rupture 56.5 MPa, thickness swelling 14% and formaldehyde release below 3.0 mg/m2h. Due to low reactivity of DDHEU and DMDHEU at temperatures below 160°C, the approach is effective for thin boards only.

Evolution of Organic Matter Within Sixty Days of Composting of Lignocellulosic Food Industry Waste in Malaysia

ABSTRACT Empty fruit bunches (EFB), coffee grounds (CG), and palm oil mill sludge (POMS) were composted in the laboratory for 60 days in order to study the composting process of lignocellulosic food industry wastes. In the first part of the experiment, EFB, CG, and POMS were composted alone (composting of single lignocellulosic material), and in the second part, EFB was composted with CG (1EFB:1CG ratio) and POMS (1EFB:1POMS ratio). The effects of different turning frequencies on the physical and chemical properties of composting were observed and its relation with the degradation process was highlighted. Results showed that oil and grease were first degraded, followed by recalcitrant compounds like alpha-cellulose, hemicellulose, and lignin. Cellulose and hemicellulose were degraded mainly during the 60 days of composting, and the progressive reduction of the cellulose/lignin ratio proved that the main evolution of these wastes took place. It was observed that 3, 6, and 9 days of turning frequency did not affect the physicochemical properties of the compost. Composting EFB alone failed to achieve the required quality of maturity compost within 60 days, while CG and POMS recorded low in biological activity. Better results were shown in composting of EFB mixed with coffee grounds and POMS, the C/N ratio dropped to less than 20 by the 8th week of the composting period. Composting of mixed lignocellulosic materials showed larger changes compared to composting of single lignocellulosic material, reaching a C/N ratio below 20 within 8 weeks.