Geochemical Modeling of the Uranium Behavior in Groundwater near the Sludge Storages during Bioremediation.

The paper presents experimental and numerical simulation of the bioremediation in nitrate-, -sulfate-ions and uranium polluted aquifers near the Novosibirsk Chemical Concentrates Plant (NCPP) sludge storage facility. We used two HCh 4.4 (MSU) and PHREEQC 2.18 (USGS) software packages for geochemical modeling and found that the microbial consumption of oxidizers (oxygen and nitrate ions) led to a decrease in the redox potential to –400 mV. The latter plays a key role in the reduction of uranyl ions and stabilization (immobilization) of uranium in low soluble biogenic sediments containing calcium phosphates, sulfides of iron and associated heavy metals. Results of experimental and numerical simulation turned out to be consistent with the composition of mineral phase collected in situ in a discharge area of polluted aquifer. [ABSTRACT FROM AUTHOR]