Biological Conversion of Algefiber® (Seaweed Sludge) to Carboxylic Acids for Chemical Upgrading to Higher Alcohols Liquid Biofuel

Concern about biofuel production from renewable resources has increased globally. Among different approaches to produce biofuels, the MixAlco^™ process is an innovative technology operating on the carboxylate platform, which converts any biodegradable material into mixed alcohol fuels through anaerobic digestion and chemical upgrading. In this study, carboxylic acids were produced from Algefiber^® which is an alkaline-treated waste biomass from carrageenan processing (FMC Biopolymer). Carboxylic acids make up a platform of chemical intermediates, which can be converted in to mixed alcohol fuels and chemicals.

Algefiber^® was anaerobically digested using a mixed-culture of marine-derived microorganisms at two temperatures of 35⁰C (mesophilic) and 55⁰C (thermophilic) in bench scale batch fermentors. Further studies were done using leaching columns to simulate the fermentation under field conditions. Calcium carbonate and ammonium bicarbonate were added to maintain the pH of the fermentation by neutralizing the acids to their corresponding carboxylate salts. Iodoform was used as a methane inhibitor to suppress the methanogenesis. Mesophilic temperature gave a higher acid yield with higher percentage of longer chain organic acids. Acetic, propionic and butyric acids were prominent in the produced acid mixture.