Desalting aqueous streams via filled cell electrodialysis
AssigneeArcher Daniels Midland Company
InventorKrishnamurity Nagasubramanian Mani
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Abstract
The invention is a process for desalting aqueous solutions, which are initially acidified to a pH of about 3 or less. Then, the acidified solution is fed into a desalting compartment of an electrodeionization cell which contains a suitable ion exchange material and is isolated from an adjacent concentrating compartments by an anion and a cation exchange membrane. The concentrate compartment contains a netting or another suitable material that promotes turbulence in a flowing feed stream. Water is supplied to the concentrate compartment. A DC current passes through the electrodeionization cell to produce a substantial desalination of the feed solution. A less acidic desalted solution and a concentrate waste solution are withdrawn from the electrodeionization cell.
Claims26
A process for desalting aqueous salt solutions, said process comprising the steps of:
- a. providing an aqueous feed stream containing salts to be removed by a desalting process;
- b. providing at least one electrodeionization cell having at least a feed compartment and an adjacent concentration compartment, said feed compartment containing an ion exchange material and being isolated from the adjacent concentration compartments by an anion and a cation exchange membrane, said concentration compartment containing a turbulence promoter material;
- c. acidifying the feed stream to have a pH in a range of about 0-3;
- d. feeding the acidified feed stream of step c. to the feed compartment of the electrodeionization cell;
- e. supplying a liquid including water to the concentrate compartment;
- f. passing a DC current through the electrodeionization cell to effect a substantial desalination of the feed stream and to transport salts and acid to the concentration compartment;
- and
- g. withdrawing a less acidic desalted product and concentrate waste solutions from the feed and concentration compartments respectively of the electrodeionization cell.
A process for desalting sugar containing solutions, said process comprising the steps of:
- a. providing at least one electrodionization cell having at least a feed compartment and an adjacent concentration compartment, said feed compartment containing an ion exchange material and being isolated from the adjacent concentration compartment by an anion membrane and a cation exchange membrane, said concentration compartment containing a turbulence promoter;
- b. providing a feed stream containing a sugar solution having unwanted salts therein;
- c. acidifying said feed stream of step b. to a pH in a range of about 0-3;
- d. feeding the acidified feed stream of step c. to the feed compartments of said electrodeionization cell;
- e. supplying a liquid including water to the concentration compartment;
- f. passing a DC current through the electrodeionization cell to effect a substantial desalination of the feed stream;
- and
- g. withdrawing a less acidic desalted solution and a concentrated waste solution containing salts and acid as well as any sugars transported out of the feed solution.
A process comprising the steps of:
- a. electrodeionizing a feed stream of a high fructose sugar solution and desalting said feed stream;
- b. performing a nanofiltration of a concentrated waste for recovering magnesium and sugar values from said feed stream;
- and
- c. recycling said magnesium and sugar values to an upstream enzymatic conversion step for enabling a high fructose sugar production.
A process comprising the steps of:
- a. electrodeionizing a feed stream of a solution containing a material selected from a group consisting essentially of dextrose or fructose, and desalting said feed stream;
- b. performing an operation on a concentrated waste solution derived from step a. for recovering multivalent cations and sugars and for generating a waste stream;
- said operation being selected from a group consisting of a nanofiltration or electrodialysis;
- c. pH adjusting the solution from step b. with an alkali to precipate and remove the multivalent cations;
- and
- d. recycle sugar values resulting from step c to an upstream sugar production step.
Dependencies are inferred from the claim text.