UPGRADING OF BIOGAS TO MARKETABLE PURIFIED METHANE EXPLOITING MICROALGAE FARMING

摘要

Raw biogas from organic waste anaerobic digestion is purified to marketable bio- methane by scrubbing raw biogas in an absorber using a sodium carbonate rich growth liquor of microalgae of an algae farming plant for absorbing carbon dioxide and other gaseous substances contained in the biogas and reacting carbon dioxide with the sodium carbonate to form sodium bicarbonate in the liquor; returning a bicarbonate enriched liquor leaving the absorber to the algae farming plant as bicarbonate feed to the growing algae for having the carbon dioxide metabolized and regenerating sodium carbonate in the liquor, which is thence reusable for scrubbing fresh raw biogas in said absorber. An outstandingly effective synergy is implemented in exploiting an on-going micro algae farming plant for regenerating the carbonate in the growth liquor while feeding on the bicarbonate for their growth, substantially avoiding any emission of carbon dioxide.