title: Improvement of dewatering characteristics by co-digestion of rice straw with sewage sludge.
abstract: A continuous mesophilic co-digestion of sewage sludge and softened rice straw was conducted and the dewatering characteristics of digested sludge were evaluated by a dewatering experiment using a belt press. The digestion was operated with solid retention time (SRT) of 25 days, and the feeding ratio of sludge to rice straw was 1:0.5 (total solids base). After 129 days of stable operation, the properties of digested sludge were analysed; then five kinds of cationic coagulants were tested to select the optimal coagulants for dewatering, and two coagulants were selected and used in the dewatering experiment because of lower doses and lower moisture of sludge cakes. Sludge property analysis showed that by the addition of rice straw, the fibrous materials in the digested sludge increased remarkably and the normalized capillary suction time (CST) decreased significantly, indicating that the dewatering properties was improved. The results of dewatering experiment showed that by the addition of rice straw, specific filtration rate of digested sludge increased by 81.2% and 174.6%, respectively; water content of dewatered sludge cakes decreased by 8.2% and 13.4%, respectively. The dewaterability of digested sludge was suggested to be improved due to rice straw addition.
authors.affiliation: a Graduate School of Natural Science & Technology , Kanazawa University , Kanazawa , Japan.
authors.forename: Tingting
authors.initials: T
authors.lastname: Gu
authors.affiliation: b Faculty of Environmental Design , Kanazawa University , Kanazawa , Japan.
authors.forename: Ryoko
authors.initials: R
authors.lastname: Yamamoto-Ikemoto
authors.affiliation: c Career Support Center for Young Researchers , Okayama University , Okayama , Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Tsuchiya-Nakakihara
authors.affiliation: d Ishigaki Company, Ltd , Sakaide-city , Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Watanabe
authors.affiliation: d Ishigaki Company, Ltd , Sakaide-city , Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Suetsugu
authors.affiliation: d Ishigaki Company, Ltd , Sakaide-city , Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yanai
mesh_terms: D019149:Bioreactors; D005374:Filtration; D008697:Methane / Q000378:metabolism; D012275:Oryza; D012722:Sewage / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D012722:Sewage; D014867:Water; D008697:Methane
keywords: Belt press; co-digestion; dewatering characteristics; rice straw; sewage sludge