title: Alkaline subcritical-water treatment and alkaline heat treatment for the increase in biodegradability of newsprint waste.
abstract: This work describes two alkaline semicontinuous processes for the conversion of refractory organic materials into biodegradable substances. Newsprint was used as a lignocellulosic waste. Methane conversion efficiencies and cellulose removals were investigated for the two following processes: alkaline subcritical-water treatment (ASWT) coupled with methane fermentation and alkaline heat treatment (newsprint heated with steam in an autoclave; AHT) coupled with methane fermentation with a neutral subcritical-water treatment (NSWT) recycle. Results showed that for ASWT coupled with methane fermentation higher methane conversion efficiencies and higher cellulose removals were achieved as HRT increased. At HRT = 20 days, average CH4 conversion efficiency and average cellulose removal reached 26% and 44%, respectively. After a final HRT of 40 days, average CH4 conversion efficiency and average cellulose removal reached 50% and 60%, respectively. On the other hand, for AHT coupled with methane fermentation, methane conversion efficiencies did not show a greater improvement using this pretreatment process. Average conversion reached 9% with an average cellulose removal of 20%. In order to improve the yield of the reactor, approximately one-third of the effluent was recycled using NSWT (150 degrees C; neutral pH). Methane conversion efficiency of this process increased as more recycles were performed. For the fifth operation, the total average methane conversion efficiency was 44% with a total average cellulose removal of 55%.
authors.affiliation: Department of Civil Engineering, Graduate School of Engineering, Tohoku University, Aoba 06, Sendai 980-8579, Japan. smaug@epl1.civil.tohoku.ac.jp
authors.forename: M H
authors.initials: MH
authors.lastname: Fox
authors.forename: T
authors.initials: T
authors.lastname: Noike
authors.forename: T
authors.initials: T
authors.lastname: Ohki
mesh_terms: D001421:Bacteria, Anaerobic; D001673:Biodegradation, Environmental; D019149:Bioreactors; D002482:Cellulose / Q000378:metabolism; D005285:Fermentation; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000032:analysis / Q000737:chemistry; D010209:Paper; D012037:Refuse Disposal / Q000379:methods*
chemical_list: D002482:Cellulose; D008697:Methane