| 摘要 |
<p>PROBLEM TO BE SOLVED: To remove nitrogen from wastewater efficiently at a low cost. SOLUTION: Nitrogen is removed from wastewater by putting an organic substance and a sulfur source into a denitrification tank without adjusting the pH in the denitrification tank; that is, in a biological denitrification process for wastewater, an organic substance and a sulfur source are put into a denitrification tank to reduce and remove nitrite nitrogen and/or nitrate nitrogen from the wastewater. The sulfur source is mixed in advance with the organic substance in a dissolution tank, and the mixture is supplied to the denitrification tank. Methanol or ethanol is used as the organic substance. Elemental sulfur is used as the sulfur source. The mass ratio of the organic substance to sulfur contained in the sulfur source is 1-2. The organic substance and the sulfur source are put into the denitrification tank so that the oxidation/reduction potential (ORP) in the denitrification tank is kept in the range of -200 to 0 mV (silver/silver chloride base).</p> |
