GC-MS Analysis of Biogas from Pineapple Peels and Toxicological Evaluation of Generated Effluent

Abstract

Aim: To determine the composition of gases in the biogas produced from pineapple peels and to evaluate the effect of effluent from pineapple peel biodigester (EPB) on the liver functions of Catfish (Clarias gariepinus). Methodology: Pineapple peels were grounded, fed into an anaerobic biodigester and emitted biogas was collected for GC-MS analysis. Twenty Catfish (Clarias gariepinus) were grouped into four: Group I: Control (placed in fresh water for 2 days); Group II: (placed in undiluted EPB for six hours), Group III: (placed in undiluted EPB for 2 days), Group IV:  (placed in 1:10 dilution of EPB for 2 days). The serum activities of alkaline phosphatase (ALP), alanine transaminase (ALT) and aspartate transaminase (AST) in catfish were determined using standard methods. Results: The identified gases (percentage per volume) were: hydrogen (0.42%), methane (94.02%), carbon monoxide (0.36%), carbon dioxide (2.03%), hydrogen sulphide (0.89%), water (0.13%), nitrogen (1.52) and oxygen (0.63). Aside from methane, the rest gases were impurities. Emission of biogas was observed under 24 hours. All the fish in group III died before the twelfth hour. Compared with control, similar results for serum activities of AST, ALT and ALP were found in group IV. On the contrary, a significant increase (P < 0.05) in the activities of serum AST, ALT, and ALP was found in group II. In conclusion, biogas with a high percentage per volume of methane gas (94.02%) with negligible impurities was produced from pineapple peels in the present study. The present study also found that undiluted effluent from pineapple peels anaerobic biodigester was toxic to the liver of catfish, while a 1:10 dilution of the effluent was nontoxic to the liver of catfish. Therefore, the disposal of pineapple peels by converting it to biogas is highly recommended, however effluents generated should be diluted before disposal into the environment.