Bioethanol Production Fromseaweed and Grass

Production of Bioethanol from Seaweed and Grass

Ravindra Pogaku, Surentheran Seragam

Chemical Engineering Program, Universiti Malaysia Sabah, 88999, Kota Kinabalu, Sabah, Malaysia

Tel: +60-8832-0000, Fax: +60-8832-0348, Corresponding Author email: surent_87@hotmail.com

Abstract - Production of bioethanol from lignocellulosic material has drawn attention from worldwide as an alternative energy source. In the present study, two types of lignocelluloses was used, one from terrestrial biomass and another from aquatic biomass. Seaweed Sargassum muticum and Bermuda grass Cynodon dactylon were used in this study of bioethanol production. The aim of the study is to determine efficiency of bioethanol production at different sulfuric acid concentration for dilute sulfuric acid pre-treatment. Before ethanol production procedures were carried out, study on growth of yeast Saccharomyces cerevisiae is done to determine its exponential growth phase. This exponential growth phase of yeast will be utilized later on during simultaneous saccharification and fermentation (SSF) process. Procedure starts when raw materials were first introduced to pre-treatment process using different concentration of dilute sulfuric acid. Then, it is treated with simultaneous saccharification and fermentation (SSF) process using cellulase enzyme and yeast Saccharomyces cerevisiae. The fermented samples were analyzed with high performance liquid chromatography (HPLC) to identify and quantify bioethanol produced.

Keywords: Bioethanol, Seaweed, Bermuda grass, Dilute sulfuric acid pre-treatment

1.0 Introduction

Consumption of energy is being increase gradually in our current rat race world. Increment in energy usage is due to improvement of life quality, industrialization, an increase in population, rapid growth of economy and increase necessity for transportation. Generation, distribution and consumption are the three phases of energy utilization cycle. All three phases must be balanced with each other to achieve energy infrastructure. Any distortion from the cycle balance will affect the cycle as a limiting factor (Demirbas, 2009).

Requirement of alternative energy source is becoming essential in order to balance the energy utilization cycle. Therefore, development and improvement of renewable energy is becoming strategically implemented. Renewable energy is the energy obtained from

regenerative or virtually inexhaustible source of energy occurring in the natural environment

(Tiwari and Ghosal, 2005). This entire approach on alternative energy related strongly to one main energy source called fossil fuel because nearly 98% of the world's energy today comes from fossil fuel. Fossil fuels are oil, coal, and natural gas which have formed from the remains of dead plants and animals. Under very high pressure and temperature, these remains buried over millions of years and will be converted to energy that we are using today. Currently, our world depends mainly on fossil fuel energy. This is due to so far fossil fuel been relatively cost effective in a quick processing period (Gehrke, 2009).

One of the resources of renewable energy is biomass energy which applied to produce bio-power, bio-heat and bio-fuel. Among the biomass source are crop residue, animal wastes, woodlot arising, forest residues, lignocellulosic material municipal solid waste and energy crop. This biomass can be used to produce bio-fuel such as bio-diesel and bio-ethanol. These bio-fuels can replace current fossil fuel such as petroleum as an alternative source of energy. Bio-ethanol is one of the current most developing approaches as its carries a lot of benefit (Demirbas, 2009).

2.0 Methods

2.1 Yeast Preparation

2.1.1 Agar Plate Preparation

Potato dextrose agar of 39g was mixed with 1000ml of distilled water in a 1000ml corning bottle. Sterile glass rod used to mix the solution evenly. 1M of NaOH was used to adjust the solution pH to 7.2. The nutrient agar was sterile using autoclave at 121oC for 20 minutes. The bottle containing nutrient agar allowed cool to 50 oC.

After cooling, approximately 20ml of nutrient agar was carefully poured into petri dish in the laminar flow cabinets. The bottle was closed immediately after pouring the nutrient agar to prevent contamination.

The agar in the petri dish was allowed to cool, solidify and dry for two days in clean and closed cabinets. The agar plate placed in inverted position so condensation that might accumulate on the top of the lid from dripping onto the agar itself can be prevented. Elsewhere, it may cause contamination.

2.1.2 Isolation of Pure Culture of Yeast

Yeast strain of S.cerevisiae was obtained from the School of Food Science and Nutrition (SSMP), University Malaysia Sabah. A colony forming unit (CFU) is defined as a viable cell or a cluster of viable cells. Discrete colonies of individual CFUs were obtained by dilution streaking method.

The wire of inoculating loop was flamed with Bunsen burner fire until it was red-hot and allowed to cool for few seconds. To ensure the wire cooled, it was touched to the clean part of the agar first because yeast cell may damage by the hot loop.

Pure yeast culture in the universal bottle was gently shake and vortexed to disperse the culture. Lip of the universal bottle was flamed using Bunsen burner flame. A loopful culture taken from universal bottle using sterilised loop. The loop should not touch the side of the bottle. Lip of the universal bottle was flamed again before closed.

The loop was streaked to agar plate as shown in the figure 1. Using Bunsen burner flame, the loop flamed again. The loop was leave to cool for few second. To make sure the loop is already cooled, it is tested to side of the agar surface. If the agar surface did not melt, the loop is considered cooled. Yeast cells will be damaged by hot loop. To the second quadrant area, the streaking was allied and repeated to the third quadrant area. After the streaking process, lid was used to cover the agar plate. The inoculating lid was flamed again to kill remaining cells. The streaked plate was placed into incubator at 37 oC and for 48 hours. The plate was kept in the fridge at 4 oC after examined for further usage.

Figure 1: Streaking technique

2.1.3