A study was conducted to estimate the possible environmental impacts arising from the generation of bioethanol from oil palm frond sugar juice in a theoretical oil palm based biorefinery model. A life cycle assessment (LCA) with the gate-to-gate approach was performed with the aid of SimaPro version 8.0 whereby ten impact categories were evaluated. The scope included frond collection and transportation, frond sugar juice extraction, and bioethanol fermentation and purification. Evaluation on the processes involved indicated that fermentation contributed to the environmental problems the most, with a contribution range of 52% to 97% for all the impact categories. This was due to a substantial usage of nutrient during this process, which consumes high energy for its production thus contributing a significant burden to the surrounding. Nevertheless, the present system offers a great option for biofuel generation as it utilizes sugar juice from the readily available oil palm waste. Not only solving the issue of land utilization for feedstock cultivation, the enzymatic saccharification step, which commonly necessary for lignocellulosic sugar recovery could also be eliminated.

Fruit peel waste (FPW) is a renewable and cheaper source of fermentable sugars for biofuel production. In this research, three types of FPW which are banana peel, orange peel, and pineapple peel were investigated for reducing sugar generation using microwave pretreatment. Pineapple peel waste was found to produce the highest yield of total reducing sugar compared to banana peel and orange peel, with the value of 10.58 g/L. The optimization condition for microwave pretreatment was studied by using the Central Composite Design under Response Surface Methodology. Microwave power (180 – 450 watt), time (3 – 7 minutes) and biomass loading (5 -15 % w/v) were the parameters used to optimize the reducing sugar yield from pineapple peel. The optimum condition for microwave pretreatment was found at biomass loading of pineapple peel of 15% (w/v), power of 450 watt with 5 minutes of treatment time with the concentration of 12.52 g/L. It was apparent that the structure of hemicellulose, cellulose, and lignin of the pineapple peel was affected by the microwave pretreatment condition based on Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscope (SEM) analysis. FTIR showed alteration in a functional group while the SEM micrographs showed a marked change on the pretreated sample when compared with the untreated sample. In conclusion, microwave pretreatment is a promising approach for reducing sugar production from the agricultural residue such as FPW.

Spent coffee ground (SCG) is a solid waste that is generated in the coffee brewing process for coffee beverage production. SCG hold a great potential in reducing sugar production as it consists of high amount of carbohydrates. However, SCG is a lignocellulosic biomass (LCB) which requires pretreatment to degrade the lignocellulosic structure and enhance enzyme accessibility during saccharification process. Hence, this research aims to study the performance of microwave-assisted inorganic salt pretreatment for generation of reducing sugars. Different concentrations of NaCl was applied to determine their effects on reducing sugar produced as well as pH, and solid recovery. Pretreatment with 3% NaCl was found to yield the highest reducing sugar concentration of 43.56 mg/mL, hence it was selected for the subsequent optimization study. Process optimization was designed by using the Response Surface Methodology approach (RSM) with Central Composite Design (CCD), based on three pretreatment parameters; solid to liquid ratio (1:50 - 8:50), microwave power (300W – 800W) and irradiation time (1-10 minutes). The optimized conditions were achieved at solid to liquid of 8:50, microwave power of 800 watt and irradiation time of 10 minutes for a maximum response of 40.89 mg/mL. Moreover, it was observed that microwave-assisted NaCl pretreatment had significantly caused surface morphological changes of the SCG and the removal of functional groups in lignin, resulted in increment of the crystallinity value. In conclusion, microwave pretreatment is a promising green technology for fermentable sugar production from SCG.