High density cultivation of anaerobic protists in UASB reactors fed with domestic sewage

2015 Fiscal Year Final Research Report

• Project/Area Number: 25289174
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Civil and environmental engineering
• Research Institution: Nagaoka National College of Technology
• Principal Investigator: ARAKI Nobuo 長岡工業高等専門学校, 環境都市工学科, 教授 (30193072)
• Co-Investigator(Kenkyū-buntansha): YAMAGUCHI Takashi 長岡技術科学大学, 工学部, 教授 (10280447) ; OSHIKI Mamoru 長岡工業高等専門学校, 環境都市工学科, 助教 (90540865)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 都市下水処理 / 嫌気性処理 / メタン生成 / 原生動物 / 共生微生物

Outline of Final Research Achievements

This study aimed to investigate influences of anaerobic protozoa on treatment efficiencies of UASB reactor including COD removal, methane production and sludge volume and on bacterial and archaeal community structures in anaerobic sludge. Two UASB reactors fed with domestic sewage were operated for 171 days at COD loading rates of 0.5 to 4 gCOD L-1 day-1, and protozoa in one UASB reactor was killed by addition of cycloheximide. Methane production by the sludge with protozoa was higher than the sludge without protozoa. Phylogetic diversity was higher in the sludge with protozoa, where syntrophic bacteria affiliated with the class Deltaproteobacteria were more abundant. And this present study illuminates prokaryotic community structure in Metopus ciliates, identifying M. boonei- and C. aminobutyricum-like prokaryotes as endosymbionts.

Free Research Field

工学