Biogas production from the aquatic weed Pistia ( Pistia stratiotes)

Abstract

Pistia stratiotes, an aquatic weed, was investigated as a substrate for biogas production in batch digestion. An inoculum was necessary to obtain biogas production from the weed. With Pistia only, production of carbon dioxide alone was high during the first five days of digestion but began to level off thereafter. With inoculated Pistia, a high rate of biogas production was sustained for nearly 10 days and the average methane content was 58–68%. The digesters charged with Pistia alone had significant concentrations of propionic, butyric, isobutyric, valeric, and isovaleric acids. These acids were not present in detectable concentrations, in the digesters running with inoculated Pistia, except during the first 4 days of the digestion when propionic acid was formed. When an inoculum was added to a ‘soured’ digester the performance of the latter improved dramatically.