Denitrification of liquid radioactive waste containing nitric acid by bio-oxidation process

Low level liquid radioactive waste of 10^-4 Ci/m³ containing nitric acid of 10 % by weight is generated from des calling activity of evaporator, and nitric acid waste of (2-3) N from uranium recovery of the nuclear fuel fabrication failure. This waste is classified as the toxic-dangerous and radioactive materials, so the nitric acid must be degraded and the radionuclides must be precipitated. The denitrification by bio-oxidation process of simulation liquid radioactive waste containing nitric acid of 2,5 % (25000 ppm) and uranium activity of 10^-4 Ci/m³ (3700 Bq/l) using the mixture of aerobic mutant bacteria of bacillus sp, pseudomonas sp, aeromonas sp, and arthrobacter sp for nitric acid degradation and uranium precipitation has been performed. The bacteria giving nutrient and aeration needs the acclimatisation period of 82 hours on the liquid waste in which deviation value of the efficiencies of nitric acid degradation and uranium elimination be inferior to 10 %. On the process period of 88 hours, the nitric acid decreases to the value of 18,75 ppm and the period of 464 hours (19 days) is needed for decreasing the uranium concentration of 817,08 Bq/l, conforming its standard quality for releasing to the environment (nitric acid concentration of 20 ppm and uranium activity of 1000 Bq/l). (author)