title: Evaluation of sludge properties in a pilot-scale UASB reactor for sewage treatment in a temperate region.
abstract: In this study, continuous operation of a pilot-scale upflow anaerobic sludge blanket (UASB) reactor for sewage treatment was conducted for 630 days to investigate the physical and microbial characteristics of the retained sludge. The UASB reactor with a working volume of 20.2 m(3) was operated at ambient temperature (16-29 °C) and seeded with digested sludge. After 180 days of operation, when the sewage temperature had dropped to 20 °C or lower, the removal efficiency of both total suspended solids (TSS) and total biochemical oxygen demand (BOD) deteriorated due to washout of retained sludge. At low temperature, the cellulose concentration of the UASB sludge increased owing to the rate limitation of the hydrolytic reaction of suspended solids in the sewage. However, after an improvement in sludge retention (settleability and concentration) in the UASB reactor, the process performance stabilized and gave sufficient results (68% of TSS removal, 75% of total BOD removal) at an hydraulic retention time (HRT) of 9.7 h. The methanogenic activity of the retained sludge significantly increased after day 246 due to the accumulation of Methanosaeta and Methanobacterium following the improvement in sludge retention in the UASB reactor. Acid-forming bacteria from phylum Bacteroidetes were detected at high frequency; thus, these bacteria may have an important role in suspended solids degradation.
authors: Center for Regional Environmental Research, National Institute for Environmental Studies, Ibaraki, Japan. stubo@nies.go.jp
authors: K
authors: K
authors: Syutsubo
authors: W
authors: W
authors: Yoochatchaval
authors: I
authors: I
authors: Tsushima
authors: N
authors: N
authors: Araki
authors: K
authors: K
authors: Kubota
authors: T
authors: T
authors: Onodera
authors: M
authors: M
authors: Takahashi
authors: T
authors: T
authors: Yamaguchi
authors: Y
authors: Y
authors: Yoneyama
mesh_terms: D001421:Bacteria, Anaerobic / Q000254:growth & development / Q000302:isolation & purification; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D005160:Facility Design and Construction; D017018:Methanomicrobiales / Q000254:growth & development / Q000302:isolation & purification; D010865:Pilot Projects; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
chemical_list: D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012722:Sewage