title: Effects of temperature and pretreatment conditions on mixed-acid fermentation of water hyacinths using a mixed culture of thermophilic microorganisms.
abstract: The MixAlco process biologically converts biomass to carboxylate salts that may be chemically converted to a wide variety of chemicals and fuels. This study investigated the use of water hyacinths as a feedstock, comparing digestibility after each of four different pretreatments at two fermentation temperatures (40 and 55 degrees C). Water hyacinths were treated with excess lime (0.3g Ca(OH)(2)/g dry biomass). Short-term treatment occurred for 1 and 2h at 100 degrees C. Long-term treatment occurred for 4 and 6 weeks at 50 degrees C. Treated water hyacinths were fermented with marine microorganisms for 28 days and acid concentration (g/L), conversion (g volatile solids (VS) digested/g VS fed), and selectivity (g acid/g VS digested) were measured. All pretreatments out performed fresh feedstock fermentations. The 40 degrees C fermentations exhibited greater acid yields and selectivity than the 55 degrees C. The 1-h hot-lime pretreatment exhibited the best overall outcomes at approximately 250%, 200%, and 125% increases relative to the fresh water hyacinths in total acid, conversion, and selectivity, respectively. The results show that with a gentle 1-h hot-lime pretreatment, water hyacinths can be fermented to produce liquid fuels, thus creating an economic value to water hyacinths that are cleared from choked waterways.
authors.affiliation: Texas A&M University, Department of Chemical Engineering, College Station, TX 77843, USA. akf5219@chemail.tamu.edu
authors.forename: Andrea K
authors.initials: AK
authors.lastname: Forrest
authors.forename: Joan
authors.initials: J
authors.lastname: Hernandez
authors.forename: Mark T
authors.initials: MT
authors.lastname: Holtzapple
mesh_terms: D000693:Anaerobiosis / Q000187:drug effects; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism*; D018533:Biomass; D002264:Carboxylic Acids / Q000032:analysis; D031806:Eichhornia / Q000187:drug effects* / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects*; D008031:Lignin / Q000378:metabolism; D013464:Sulfuric Acids / Q000494:pharmacology*; D013696:Temperature
chemical_list: D002264:Carboxylic Acids; D013464:Sulfuric Acids; C036909:lignocellulose; D008031:Lignin; C033158:sulfuric acid