title: On-site nitrate removal of groundwater by an immobilized psychrophilic denitrifier using soluble starch as a carbon source.
abstract: On-site denitrification of nitrate-contaminated groundwater was conducted at 15 degrees C using a facultative psychrophilic denitrifier (strain 47) immobilized on macro-porous cellulose carriers and utilizing soluble starch as a non-toxic carbon source. A C/N ratio of 2.5 to 3.0 and a P/N ratio of 0.05 to 0.10 were found to allow complete denitrification of the groundwater used in this study. Under these conditions, the long-term performance of the system (4 months) was examined by decreasing the HRT (hydraulic retention time) from 4 h to 0.25 h. The process was stable and 95 to 100% of the influent nitrogen (NO3-N ranging from 13.0 to 16.5 mgl(-1) was removed until an HRT of 0.75 h was reached. The maximum NO3-N removal rate was 0.46 kg-Nm(-3)d(-1) at an HRT of 0.75 h. Nitrogen removal efficiency of 99.5% at an HRT of 1 h was obtained with a C/N ratio 2.58, corresponding to 4.3 g of soluble starch per 1 g of NO3-N.
authors.affiliation: Institute of Applied Biochemistry, University of Tsukuba, 1-1-1 Tennodai, Tsukuba City, Ibaraki 305-8572, Japan.
authors.forename: Yong-Seok
authors.initials: YS
authors.lastname: Kim
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nakano
authors.forename: Tae-Jong
authors.initials: TJ
authors.lastname: Lee
authors.forename: Sunthorn
authors.initials: S
authors.lastname: Kanchanatawee
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Matsumura