Controlled denitrification process and system
AssigneeBoard of Regents, The University of Texas System
InventorsPhillip G. Lee, Philip E. Turk, John L. Whitson
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Abstract
A process and system for the reduction of nitrate to nitrogen in a fluid medium. Anaerobic bacteria fed by a carbon source are used for nitrate reduction. The addition rate of the carbon source and process residence time are controlled using the oxidation-reduction potential of the fluid medium to achieve a desired level of nitrate reduction. An industrial process control system may be used to monitor inputs and control outputs. A column of suspended beads may be used as the anaerobic bacterial bed for denitrification.
Claims30
A process for the reduction of nitrate to nitrogen in a fluid medium, comprising the steps of:
- providing an anaerobic or partially anaerobic fluid medium containing nitrate and having a variable oxidation-reduction potential;
- exposing the fluid medium to anaerobic bacteria for a process residence time;
- adding a fluid-miscible carbon source to the fluid medium whereby the anaerobic bacteria reduces at least some of the nitrate to nitrogen;
- measuring an oxidation-reduction potential in the fluid medium downstream from the anaerobic bacteria;
- and
- controlling the addition rate of the carbon source to the fluid medium and controlling the process residence time using the measured oxidation-reduction potential to achieve a desired level of reduction of the nitrate to nitrogen.
A process for the reduction of nitrate to nitrogen in an aqueous stream, comprising the steps of:
- providing an anaerobic or partially anaerobic aqueous stream containing nitrate and sulfate and having a variable oxidation-reduction potential;
- exposing the aqueous stream to anaerobic bacteria for a process residence time;
- adding a water-miscible carbon source to the aqueous stream whereby the anaerobic bacteria reduces at least some of the nitrate to nitrogen but does not substantially reduce the sulfate to hydrogen sulfide;
- measuring an oxidation-reduction potential in the aqueous stream downstream from the anaerobic bacteria;
- and
- controlling the addition rate of the carbon source to the aqueous stream and controlling the process residence time using the measured oxidation-reduction potential to achieve a desired level of reduction of the nitrate to nitrogen.
A system for the reduction of nitrate to nitrogen in an anaerobic or partially anaerobic fluid medium comprising:
- means for exposing the fluid medium to anaerobic bacteria for a process residence time;
- means for adding a fluid-miscible carbon source to the fluid medium to induce the anaerobic bacteria to reduce the nitrate to nitrogen;
- means for measuring oxidation-reduction potential in the fluid medium downstream from the exposing means;
- and
- means for controlling the addition rate of the carbon source to the fluid medium and for controlling the process residence time using the measured oxidation-reduction potential to achieve a desired level of reduction of the nitrate to nitrogen.
Dependencies are inferred from the claim text.