| 摘要 |
PROBLEM TO BE SOLVED: To improve the purification capacity of circulating feeding water by compact constitution by a method in which a nitrification reaction is carried out by nitrifying bacteria while circulating feeding water is passed constantly in a nitrification process, and a denitrification reaction is conducted by generating electrolyzed hydrogen while the circulating feeding water is passed intermittently to make an anaerobic atmosphere in a denitrification process. SOLUTION: In a denitrification tank (e) opposite to a feeding water tank (a), for example, a carbon electrode and a platinum electrode or the like are arranged in a cathode (i) and an anode (j) respectively, and a carrier (k) of high conductivity is packed to fix denitrifying bacteria. An ammonia nitrogen and nitrite nitrogen treatment tank (nitrification tank) (d) and a nitrification nitrogen treatment tank (denitrification tank) (e) are arranged in parallel, a solenoid valve (o) is installed in the outlet line of the tank (e), so that water is passed constantly through a line to the nitrification tank (d), while water is supplied intermittently to the denitrification tank (e). Circulating water is supplies intermittently to the denitrification tank (e) and held for a constant time so that the denitrification tank (e) is kept anaerobic, and the nitrate nitrogen can be treated.
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