Evaluation of biogas potential and antimicrobial activities of different parts of Jatropha curcus Linn fruit

Abstract

Anaerobic digestion of those organic materials which yield biogas (mixture of methane and carbon dioxide) along with other byproducts are the needs of present era to increase the economy of a country. The production of biogas as well as other products by Jatropha curcus Linn plant not only fulfill fuel needs of a society but also provide the other environmental friendly and medically valuable products for daily life purposes and is considered best option for waste management. Pretreatment and carbon to nitrogen ratios are the most important factors that affect biogas (methane) yield and rate of methane production. Phosphoric acid pretreatment and anaerobic codigestion of deoiled seed kernel with other fruit wastes (mango peels) can be used to enhance biogas production rate and methane yield. The research presented in this thesis deals with the assessment of biogas potential of all the parts ( deoiled seed kernel, seed coat and fruit coat) of Jatropha curcus Linn fruit as well as phosphoric acid pretreatment and codigestion to optimize C/N ratio for biogas production. The antimicrobial activities of two different samples of Jatropha curcus Linn fruit obtained from district Bannu and Peshawar were also evaluated in this study. In batch anaerobic digestion, the biogas yield of fruit coat was 11%, 38%, 62%, 105%, 444% higher than the seed kernel, fruit coat (non-pretreated), seed kernel plus seed coat pretreated (1.7:1), seed coat (pretreated) and seed coat (non-pretreated). In order to study the effects of dilute phosphoric acid pretreatment on biogas production rate, the fruit coat and seed coat were pretreated with 1% dilute H3PO4 that produced 38% and 98% more biogas compared to the non-pretreated fruit coat and seed coat in anaerobic batch experiment. Similarly, for C/N ratio optimization, biogas and methane yield of codigestion of mango peel and seed kernel (1:1) ratio was 104 % and 116 % higher compare to calculated biogas and methane yield of mango peel plus seed kernel, respectively. In addition, biogas and methane yield of codigestion mango peel plus seed kernel (2:1) was 110 % and 101 % compare to calculated biogas and methane yield of mango peel and seed kernel, respectively. On the other hand, antimicrobial activities of aqueous, ethanolic and n-hexane extracts of all three parts of Peshawar and Bannu samples of Jatropha curcus Linn fruit were determined against selected pathogenic bacterial (Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 10536), Klebsiella pneumoniae (ATCC 43816) and Bacillus spizizenii (ATCC 6633)) and clinical isolates of Candida albicans and