PROBLEM TO BE SOLVED: To continuously reduce nitric acid accumulated in fish and shellfish rearing water to nitrogen without accumulating hydrogen sulfide in the fish and shellfish rearing water and efficiently remove the nitric acid from the fish and shellfish rearing water.SOLUTION: A denitrification apparatus for removing nitric acid in fish and shellfish rearing water, includes: a denitrification tank for taking in rearing water water feeding means for feeding the rearing water into the denitrification tank oxidation/reduction potential detection means for detecting an oxidation/reduction potential in the denitrification tank and a bacterium holding material disposed in the denitrification tank for holding an anaerobic bacterium. In the denitrification apparatus, the water in the denitrification tank is controlled by the oxidation/reduction potential detection means so as not to become a reduced state, which allows nitric acid to be efficiently reduced to nitrogen without accumulating hydrogen sulfide in the fish and shellfish rearing water.COPYRIGHT: (C)2015,JPO&INPIT【課題】魚介飼育水に蓄積される硝酸を、連続して、硫化水素が蓄積することなく窒素まで還元し、魚介類飼育水より効率よく除去する。【解決手段】魚介類飼育水中の硝酸を除去する脱窒装置において、飼育水を取り込むための脱窒槽と、飼育水を脱窒槽に送り込む送水手段と、脱窒槽内の酸化還元電位を検知する酸化還元電位検知手段と、脱窒槽内に配設される嫌気性細菌を保持するための細菌保持材で構成され、酸化還元電位検知手段により脱窒槽内の水が還元状態にならないように制御することで、魚介類飼育海水に硫化水素を蓄積することなく、効率よく硝酸を窒素まで還元する。【選択図】図1
