| cope and method of study. The basic purpose of this study was to explore the potential use of waste paper as feedstock for anaerobic reactors to produce methane. Implementation of such systems requires knowledge of the potential limiting factors on the process, which would have to be overcome to maximize efficiency. In addition to limits on biological processing of cellulose, physical and chemical factors such as particle size, presence of surface treatments of printing inks, the ratio of cellulose to lignin and other complex polymers in the paper, and permeating air to the reactor may limit conversion rates. This study used both semicontinuous reactors and serum bottle tests to quantify rate and extent of waste paper conversion to methane and to define limiting steps. Then, alkali and acid pretreatments were performed to investigate the effectiveness of these treatments to disturb cellulose-lignin association and improve bioconversion of newsprint.;Findings and conclusions. It was found that the ultimate limiting step for lignocellulose is the cellulose-lignin association. The conversion efficiencies of newsprint (31-41% in 300-600 days) observed in this study were relatively low compared with that of office paper (80% in 20-40 days). However, they were significantly higher than the generally believed 20% level obtained in other shorter-term studies to date. It was also found that different inocula, physical size of paper, and printing ink did not have significant effects on waste paper methane yields. Both alkali and acid pretreatments can improve bioconversion rate and probably also extent. Alkali pretreatment can partially solubilize lignin and hemicellulose, however, some limit on bioconversion of solubilization products may exist. Alkali treated samples can be neutralized with... |
