Prj 9121 - Deactivation of radioactive water - Case Study
Although radioactive isotopes are engaged for many applications (i.e. medicine, metallurgy, etc.), the major sources of soil and water contamination with radioactive substances are connected to nuclear waste processing and to uranium mining operations. One of the principal carcinogens is plutonium and any soil or water contaminated by plutonium should be carefully removed and disposed in appropriate storage sites.
The most dangerous situation arises when radioactive substances infiltrate underground waters. In such event to deal with saturated radioactive strata become a complicated and expensive problem.
BIOMEDY demonstrated that a variant of its BIOREM engaging a very narrow consortium of microorganisms could effectively deactivate radioactive waters. Radionuclides concentration in heavy polluted technical waters from nuclear industry decreased several times under BIOREM activity.
BIOREM is typically an in-situ biological remediation technology but, due to the dangerously high level of radioactivity of the technological water to deactivate, this specific test was conducted ex-situ.
Initial sample was characterized by a beta and gamma activity mostly due to Cesium-137 and an alpha activity mostly due to Plutonium-238. The initial sample was split into two parts: one part remained as control sample and the second underwent biological deactivation by BIOREM. Comparative radiometric analyses show the BIOREM's high deactivation factor.
Sulfate and nitrate ions, present in the initial solution with a concentration of 1000 mg/l, were completely reduced. More specifically, the bacterial reduction of sulfates and the biochemical production of hydrogen disulfide (H2S) leaded to an increase of pH value and to the creation of a reducing media favoring the production of sulfides. In such sulfide enriched carrier cesium and strontium were trapped while the increased pH value caused the precipitation of plutonium in the form of hydroxide.