Integrated system for hydrogen and methane production from industrial organic wastes and biomass

摘要

The present invention provides a system that has been devised to overcome the two most important limitations for sustained biological hydrogen production, namely contamination of the microbial hydrogen-producing cultures with methane-producing cultures necessitating frequent re-start-up and/or other methanogenic bacteria inactivation techniques, and the low bacterial yield of hydrogen-producers culminating in microbial washout from the system and failure. The system includes a continuously stirred bioreactor (CSTR) for biological hydrogen production, followed by a gravity settler positioned downstream of the CSTR, which combination forms a biohydrogenator. The biomass concentration in the hydrogen reactor is kept at the desired range through biomass recirculation from the bottom of the gravity settler and/or biomass wastage from the gravity settler's underflow. The gravity setter effluent is loaded with volatile fatty acids, as a result of microbiological breakdown of the influent waste constituents by hydrogen-producing bacteria, and is an excellent substrate for methane-forming bacteria in the downstream biomethanator.

主权项

1. A method for continuously producing hydrogen gas from organic waste, comprising:
a) seeding a completely mixed bioreactor with anaerobically digested sludge containing a mixture of microorganisms, the mixture of microorganisms including hydrogen producing microorganisms; b) continuously flowing organic waste into the completely mixed bioreactor; c) using the hydrogen producing microorganisms in the anaerobically digested sludge to continuously break down the organic waste in the completely mixed bioreactor and produce hydrogen gas, carbon dioxide gas, and a liquid effluent containing a mixture of volatile fatty acids, primary alcohols, and the mixture of microorganisms; d) continuously emitting the hydrogen gas and carbon dioxide gas from the completely mixed bioreactor; and e) decoupling a solid retention time from a hydraulic retention time of the liquid effluent by
flowing the liquid effluent containing the mixture of volatile fatty acids, the primary alcohols, and the mixture of microorganisms to a container located downstream of the completely mixed bioreactor, using gravity to settle and concentrate the hydrogen producing microorganisms to a bottom of the container and form a settled biomass at the bottom of the container and a liquid mixture above the settled biomass; andrecirculating a portion of the settled biomass from the bottom of the container to the completely mixed bioreactor, and discharging a remaining portion of the settled biomass from the bottom of the container in an excess waste stream for controlling a concentration of the hydrogen producing microorganisms in the completely mixed bioreactor; and f) discharging the liquid mixture from the container.