Bagasse comes from sugarcane stems of which juice was already extracted. However, this agricultural remainder can be useful in various ways, namely a raw material for electricity generation. In order to make more use of bagasse in terms of producing effective fuel, Asst. Prof. Dr. Prapaipid Chairattanamanokorn, a lecturer of the Department of Technology and Environmental Management, the Faculty of Environment, Kasetsart University, has continuously studied about using bagasse as a major ingredient for methane production from two-stage fermentation. The first stage concerns hydrogen production whereas the second focuses on methane production.
How Methane is Derived from Bagasse
Firstly, as bagasse is a biological material for agriculture which mostly consists of organic substances, particularly 55% of carbon and 48.5% of cellulose respectively. Also, it can be degraded by microorganism. The initial stage therefore concerns production of hydrogen from non-air fermentation in a reactor tank under the temperature of 55 degree Celsius. The Clostridium thermopalmarium HM756303 will be used to ferment the bagasse at this stage, but, since bagasse has elements of Lignocellulose, in which Hemicellulose, Lignin and cellulose are found, it has to be neutralized by Sodium Hydroxide solution at the temperature of 100 degree Celsius for two hours. Doing so will get rid of Hemicellulose and Lignin.
After the process as above-mentioned, the initial pH balance, intensity of Peptone, Phosphate buffer and sodium bicarbonate play a major role in hydrogen production with significant implication. According to the results from a study under appropriate condition, bagasse is fermented together with Peptone at the intensity of 3 grams per liter and Ferrous Sulphate at the intensity of 50 milligrams per liter, with the pH balance of 5.5.
Besides, the Clostridium thermopalmarium HM756303 can work under non-sterile condition, as well. The amount of hydrogen from non-sterile fermentation is less than the one from sterile fermentation. The Clostridium thermopalmarium HM756303 fermented for six hours according to hydraulic retention time (HRT) will release the maximum amount of hydrogen of 2,745 milliliters per day with its 60% of highest intensity.
Also, it was found that neutralization of bagasse with NaOH had promoted hydrogen production and fermenting bagasse neutralized by 2% intensity NaOH solution would produce the highest amount of hydrogen.
Following the first stage, the fermented extraction obtained from hydrogen production will be further fermented to get methane. The second fermentation uses the temperature of 55 degree Celsius and produces methane of 65% intensity. The amount of methane from 24-hour fermentation is averagely 2906.95±253.93 milliliters per day while 1 kilogram of bagasse can produce 184.99±14.57 liters of methane at maximum.
As a result, if value of energy from hydrogen and methane is calculated according to the two-stage fermentation, 8102.45 kilojules of energy at the maximum will be gained from 1-kilogram bagasse. The intensity level of the two gases can be augmented when the biogases are produced under an absorption process with NaOH solution as the main neutralizer.