In this study, a composite bioactive membrane was developed and tested to generate and capture hydrogen (H2) during the process of wastewater treatment. Hollow fiber membranes were coated with encapsulated acetogenic bacteria to simultaneously produce and capture H2 from waste feedstocks. Acetogens were encapsulated with cast poly(vinylalcohol) or electrospun microfibers. Under anaerobic conditions the poly(vinylalcohol) and electrospun composite membranes produced an average of 44.6 ± 11.3 mL H2 g-1 hexose (0.33 ± 0.08 mol H2 mol-1 hexose) and 21.2 ± 4.8 mL H2 g-1 hexose (0.16 ± 0.04 mol H2 mol-1 hexose), respectively, and captured 73 ± 12% and 57 ± 11%, respectively, of the total H2 produced in bioreactors fed synthetic high strength wastewater. The H2 capture efficiency of the electrospun composite membrane was improved by coating the modules with a thin film of polymeric silica gel, improving the H2 production to 28.3 ± 2.3 mL H2 per hexose (0.21 ± 0.02 mol H2 mol-1 hexose) and the H2 capture efficiency to 73 ± 15%. Final composite membranes were built by immobilizing bacteria directly onto the membrane surface, again improving H2 yields from high strength synthetic wastewater to a maximum of 48.4 ± 9.4 mL H2 g-1 hexose (0.36 ± 0.07 mol H2 mol-1 hexose) with a maximum H2 capture efficiency of 86 ± 9%. The optimized composite membranes were also capable of generating and capturing H2 from real wastewaters, with yields and capture efficiencies of 19.2 ± 3.0 mL H2 g-1 hexose (0.14 ± 0.02 mol H2 mol-1 hexose) and 99.1 ± 0.2%, and 46.0 ± 15.5 mL H2 g-1 hexose (0.34 ± 0.12 mol H2 mol-1 hexose) and 79 ± 19% when tested with a feed of sugar beet wastewater and dairy production wastewater, respectively. After further optimization, the composite membrane system could allow the extraction of high-quality energy from wastewater.
|Original language||English (US)|
|Number of pages||10|
|Journal||Environmental Science: Water Research and Technology|
|State||Published - Sep 2016|
Bibliographical noteFunding Information:
This work was supported partially by the MRSEC Program of the National Science Foundation under Award Number DMR-0819885 and partially by the Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources. The authors would like to thank Goeun Heo and Julian Preciado in the Department of Mechanical Engineering at the University of Minnesota for providing the equipment and support for the preparation of the electrospun microfibers and silica coating. We would also like to thank Dr. Santiago Romero-Vargas Castrillon in the Department of Civil, Environmental, and Geo- Engineering at the University of Minnesota for his valuable insight on PDA and membrane chemistry. Competing financial interest: The authors have filed two patent applications related to this work.
© 2016 The Royal Society of Chemistry.