On-Site Nitrate Removal of Groundwater by an Immobilized Psychrophilic Denitrifier Using Soluble Starch as a Carbon Source

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On-site denitrification of nitrate-contaminated groundwater was conducted at 15℃ 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 (NO_3 -N ranging from 13.0 to 16.5 mgl^<-1>) was removed until an HRT of 0.75 h was reached. The maximum NO_3 -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 NO_3 -N.
社団法人日本生物工学会の論文
2002-03-25