Identification And Quantification Of Hydrocarbons Produced From The Acid-Pretreated Kitchen Waste By Using Fungal And Bacterial Strains

Abstract

This study was conducted to identify and quantify hydrocarbons produced during bio-fuel production using kitchen waste (KW). KW is a complex mixture of hardly digestible compounds, mainly lignin, cellulose and hemicellulose, and easily digestible compounds, mostly starchy materials. Therefore, KW has a high potential for the production of biofuel after the chemical hydrolysis of lignocellulose, starch and carbohydrates. In this study, after the physically pretreatment (dried and crushed) of KW, dilute-acid hydrolysis was used for the hydrolysis of lignocellulose and starchy materials, eliminating the enzymes requirement. The dilute acid hydrolysis was conducted with 1, 3 and 5% (w/w) sulfuric acid at 90 and 120°C for 30, 60, 90 and 120 min. The hydrolysis with 5% acid at 120°C for 120 min resulted in the hydrolysate with the highest reducing sugar concentration of 97.917 ± 0.5 g/kg and Energy of 1.567 ± 0.008 MJ/kg. The reducing sugars were used as substrate in fermentation by fungal strain Aspergillus niger, bacterial strains Lacto-bacillus and Escherichia coli, to produce hydrocarbons. The fermented product was quantified after every day till the fermentation time is over i.e. no more products were formed. Biofuel production from Aspergillus niger, Escherichia coli and Lacto-bacillus was 64%, 45% and 50% after 72 hr. Fermented product contains mainly hydrocarbons as identified by GC-MS analysis. Calorific value of sample and biofuel determined on Differential Scanning Calorimetry were 0.6MJ kg− 1 for sample before fermentation and 3.56 MJ kg− 1, 3.33 MJ kg− 1 and 2.67 MJ kg− 1 for KW fermented by Aspergillus niger, Escherichia coli and Lacto-bacillus, respectively. Hence, maximum of 64% reducing sugars were converted into hydrocarbons (biofuel) after fermentation by Aspergillus niger.