A modular technology for fermentative hydrogen production and capture from wastewater

Abstract

Despite the inherent chemical energy in wastewater, current wastewater treatment practices expend a considerable amount of energy to aerobically remove organic pollutants. Anaerobic fermentation of these dissolved organics to produce hydrogen could instead provide a positive energy output while delivering the ancillary benefit of lessening aeration demands for downstream treatment processes. A scalable and modular technology, based on the membrane-encapsulation of hydrogen-producing mixed consortia onto hollow fiber membranes for efficient hydrogen collection, was developed to produce and capture hydrogen from dissolved phase organics in wastewater. The membranes were tested in a continuously stirred tank reactor (CSTR) and monitored for hydrogen production and capture. The results showed that two different membrane polymer chemistries were successful in producing and capturing hydrogen from high-strength synthetic wastewater, with maximum captured yields of 25-50 mL/g hexose. Low available carbohydrate content, pH conditions, and leakage of microorganisms into and out of the membranes may have contributed to the failure of hydrogen production in trials using municipal wastewater. Batch tests of dairy manufacturing waste demonstrated the potential for future application of this technology for producing hydrogen from a real industrial wastewater.