The study was conducted to evaluate the effect of alkali pretreatment of rice straw on enzymatic hydrolysis for bioethanol production. The experiments conducted were divided into two studies. For Study 1, rice straw was treated with different concentrations (0.5%, 1.0%, and 1.5%) of sodium hydroxide (NaOH) and steeping durations (15, 30, and 45 hours). Alkali pretreated rice straws were subjected to enzymatic hydrolysis using cellulase complex (NS22074). In the second study, untreated rice straw as well as rice straw treated with NaOH (conditions as determined in the first study), were subjected to enzymatic hydrolysis using three different enzyme combinations of cellulase complex (NS22074), xylanase (NS22036), and hemicellulase (NS22002), and yeast fermentation using Saccharomyces cerevisae.Results of Study 1 revealed that NaOH concentrations and steeping durations significantly affect the enzymatic hydrolysis of rice straw to fermentable sugars. Rice straws treated with 1.5% NaOH solution steeped for 45 hours had the highest reducing sugar of 0.5402 g and conversion efficiency at 56.85%. Thus, these conditions were used in Study 2. In this study, it was found that pretreatment and different enzyme combinations have a highly significant effect on enzymatic conversion of rice straw to fermentable sugars. Alkali pretreated rice straw hydrolyzed using three enzyme combinations-cellulose complex, xylanase, and hemicellulase-obtained the highest reducing sugar of 0.7396 g and conversion efficiency at 77.88%.Alkali pretreatment, specifically sodium hydroxide (NaOH) at 1.5% concentration, and steeping for 45 hours of rice straw was an effective pretreatment to enhance enzymatic hydrolysis in terms of increase in reducing sugar and conversion efficiency. Similarly, alkali pretreatment of rice straw had significant advantage over untreated rice straw in enhancing the effect of enzymes cellulase complex, xylanase, and hemicellulase in enzymatic hydrolysis. After yeast fermentation using Saccharomyces cerevisiae, ethanol yield of the study ranged from 0.0354 g to 0.0781 g/g glucose, or 41.18 to 51.51% of the maximum theoretical yield.

Abstract. The study aimed to evaluate the effect of modified photoperiods and light intensities on grow-out production of tilapia under indoor tank culture system; specifically on water quality and on growth performance of tilapia. The study was conducted inside the greenhouse and considered two factors: photoperiod (24L:0D, 20L:4D and 16L:8D); and light intensity (40 watts m -2 , 60 watts m -2 and 80 watts m -2 ); also, a control treatment was set-up outside the greenhouse to receive the normal environmental condition. Light manipulations inside the greenhouse were able to sustain the water quality within the desirable level for tilapia cultured in tank; while control tanks shows high water quality variation. Growth performance of tilapia cultured in tank responds positively in prolonged photoperiod at different light intensities. However, light manipulation gave insignificant difference on feed conversion ratio and survival rate compared to normal condition. Results indicated that 20-hours photoperiod and 40 watts m -2 light intensity is just enough to sustain the recommended water quality and better growth performance of the cultured tilapia in indoor tank system. It can be concluded that longer photoperiod and restrained light intensity can improved the growth performance of tilapia under indoor tank culture.

While the Philippine Biofuels Act of 2006 mandates the use of anhydrous bioethanol as blend for gasoline, the potential of hydrous ethanol as an alternative fuel for spark-ignition engines has not been fully realized. This study explored the possibility of using hydrous ethanol as fuel for spark-ignition engines with minimal modifications and without the need for gasoline blend.A fuel feeding device was developed to feed hydrous ethanol fuel into the intake manifold of the engine, bypassing the carburetor. By replacing the components that are not compatible with hydrous ethanol and installing a fuel feeding device developed at PhilRice, two spark-ignition engines were able to run solely on 80-95% hydrous ethanol fuel. The fuel economy was found to be a significant issue in the utilization of hydrous ethanol fuel as there is a 75% increase in fuel consumption when using hydrous ethanol. There is potential for hydrous ethanol to be used as fuel if it can be produced locally and sold at half the pump price of gasoline.

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