Biodenitrification of uranium refinery wastewaters

Removal of nitrate from industrial wastewaters in a pilot plant by nitrate-tolerantKlebsiella oxytoca CECT 4460 andArthrobacter globiformis CECT 4500

“…The need to dilute waste streams with very high NO 3 − concentration was also noted to be necessary for the denitrification of wastes with high NO 3 − content from nuclear fuel processing (Clarkson et al, 1991, Francis & Makin, 1991, Lawson, 1981, Walker et al, 1989. It is important to note that for the biotreatment of wastewaters from DNEG manufacture, groundwater instead of deionized water was used on site in the factory; this represented a cost savings of between 1 and 2 orders of magnitude with respect to the cost of standard laboratory assays.…”

“…Bioremediation of pollution generated by organic compounds is feasible if microbes able to use the pollutant as a C-source are available (Gibson & Subramanian, 1984). However, bioremediation of sites polluted with inorganic N-sources such as ammonium, nitrate, and nitrite requires not only microbes able to use these compounds as an N-source, but also an assimilable C-source to provide the energy required for N-metabolism (Blaszczyk, 1993, Clarkson et al, 1991, Francis & Makin, 1991, Kaplan et al, 1987, Smith et al, 1994, Walker et al, 1989. Complex microbial communities in biological treatment plants are able to cope with low concentrations of nitrate (<50 mg/L) similar to those found in natural environments (Fossing et al, 1996).…”

“…Biological removal of high loads of nitrate in industrial wastewaters has been the focus of previous studies because this approach is believed to be more cost-effective than physical or chemical processes (Clifford & Liu, 1993;Kamath et al, 1992;Pitt et al, 1981). However, the elimination of NO 3 − in industrial wastestreams with a relatively high nitrate content-such as those resulting from the production of nitroaromatic compounds, the synthesis of nitroorganic compounds in pharmaceuticals, nitrogen-containing products in chemical fertilizers, wastewaters from nuclear fuel processing, and the cleaning of tanks in dairy factories-has been considered a difficult task for microorganisms (Clark et al, 1976;Clarkson et at., 1991;Francis and Makin, 1991;Kamath et al, 1992;Lawson, 1981;Walker et al, 1989). A limitation frequently found in the treatment of these wastes is that microbes are usually sensitive to nitrate loads above 100 mM and remove little nitrate when its concentration is above 50 mM .…”

An analysis of CH4/N2 rich biogas production, fuel treatment process and microturbine application

“…The highest contributor of TN removal was found to be the HYCEM digester rather than the aeration tank or SBR. This shows significant amount of biological carbon source was consumed for denitrification as shown in the general biological denitrification equation [18]: Balance gas with higher recirculation ratio and it directly supports the occurrence of the denitrification process in the digester. The correlation between NO 3 − removal rate and recirculation ratio was found to be strong from regression analysis (the coefficient of correlation ≒0.82).…”

Characterization of aCorynebacteriumStrain That Can Grow in Medium Containing up to 2 M Nitrate

“…A cheaper alternative is the application of bioremediative processes using microorganisms. However, when biological treatment plants receive wastewater with nitrate concentrations above 0.1 M, the system is poisoned and most of the cells are killed (Krishnamachari and Clarkson, 1993;Walker et al, 1989). One approach used to overcome this problem is the prior dilution of wastewater to relatively low nitrate levels before feeding it into the plant.…”