Denitrification Using Denitrifying Bacterial Cells Immobilized by PVA-Boric

KAKIICHI Norihide, NAITO Tomonao, MINAGAWA Toshiyuki, HIGASHI Kazuhiro, KAMATA Shin-ichi, OTSUKA Hiroharu, OSHIDA Toshio

doi:10.2508/chikusan.65.815

The relation between pH levels and denitrifying activities was determined using free cells of three bacterial strains; Pseudomonas sp. IFO 13302 (PS), Paracoccus denitrificans IFO 12442 (PD) and NK-2G, belonging to CDC group Vd-1, isolated from activated sludge. After immobilization by the polyvinyl alcohol (PVA)-boric acid method, these strains were mixed and subjected to a long-term denitrification test. The pH levels of PS, PD and NK-2G at which the maximum denitrifying activities were demonstrated were 6, 8 and 8 respectively. At a pH range of 5-9, the strains maintained satisfactory levels of denitrifying activity. When the three strains which had different denitrifying activities with respect to pH levels were immobilized by the PVA-boric acid method and used in mixture, they retained a 98-100% denitrification efficiency for four months. After that, the denitrification efficiency was slightly decreased and varied at arange of 83-100%. When reactivated, a 100% denitrification efficiency was restored but the efficiency was again decreased and varied at a range of 80-100% after approximately one month.

Denitrification Using Denitrifying Bacterial Cells Immobilized by PVA-Boric

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