Control of amphibious weed ipomoea (Ipomoea carnea) by utilizing it for the extraction of volatile fatty acids as energy precursors

Abstract

Volatile fatty acids (VFAs), comprising mainly of acetic acid and lesser quantities of propionic and butyric acids, are generated when zoomass or phytomass is acted upon by acidogenic and acetogenic microorganisms. VFAs can be utilized by methanogens under anaerobic conditions to generate flammable methane–carbon dioxide mixtures known as ‘biogas’. Acting on the premise that this manner of VFA utilization for generating relatively clean energy can be easily accomplished in a controlled fashion in conventional biogas plants as well as higher-rate anaerobic digesters, we have carried out studies aimed to generate VFAs from the pernicious weed ipomoea (Ipomoea carnea). The VFA extraction was accomplished by a simple yet effective technology, appropriate for use even by laypersons. For this acid-phase reactors were set, to which measured quantities of ipomoea leaves were charged along with water inoculated with cow dung. The reactors were stirred intermittently. It was found that VFA production started within hours of the mixing of the reactants and peaked by the 10th or 11th day in all the reactors, effecting a conversion of over 10% of the biomass into VFAs. The reactor performance had good reproducibility and the process appeared easily controllable, frugal and robust.