High-concentration nitrogen removal in industrial wastewater by nitrous biological reaction and subcritical hydrothermal reaction

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Acclimated nitrifying bacteria from Effective Micro-organism groups for a highly concentrated ammonium sulfate as high as 5,300 mg/L or above were physically immobilized on polymeric spherical hydrogel. The immobilized nitrifying bacteria which produced only NO2- from NH4+ could reach an equilibrium condition after about 30 days. Especially, at pH 7.7, it could reach equilibrium in only 22 days, the velocity of the removal of NH4-N (Vr) = 160 mg/(L*d), showed an excellent value, and then the molar ratio of NH4+ and NO2 was almost the same (NH4+ : NO2- = 1.3 : 1).60mL of model raw wastewater containing fixed amounts of NH4-N and NO2-N in a molar ratio of 1:1 was poured into a pressure bottle. The subcritical hydrothermal reaction was carried out for 1h. In the case of 3,000 mg/L, full decomposition and over 90% decomposition was shown at reaction temp. of over 180 and 160 centigrade temp. At 5,000 mg/L, a lower reaction temp. at 140 centigrade temp. showed 95% decomposition.