Pre-treatment and regenerate method of food grade resins.

ZHEJIANG ZHENGGUANG INDUSTRIAL CO.,LTD
NINGBO ZHENGGUANG RESIN CO., LTD

Pre-treatment and regenerate method of food grade resins.

In the process of producing ion exchange resins, it always comes with small number of organic low polymers and inorganic impurities, also, some impurities may come with the products in the process of transportation and filling. These impurities will release in the beginning of usage, and then affect the quality of output water and products. Thus, all the new resins should go through pre-treatment process before usage. Ion exchange resins should be pre-treated to remove the impurities before usage to assure the stable quality of sugar liquor. Before filling the resins to equipment, all the columns of ion exchange resins and all the pipes and valves should wash by water until the output water is clean, make sure there is no leak, then fill water to the exchange column to 1/4 height, then load resins to column, inlet water from the bottom and outlet water from top to backwashing resins, rinse until there is no small particles and water is clean. (To avoid large particle size resin come out, please pay attention to adjust flow rate)
1. Filling and pre-treat resins
(1) Load resins to the column
Load resin to the exchange column, use softening water to backwashing resin until output water is clean. Use 8-10% NaCL that two time volume of resin to soak resin for 4-8h, then using softening water to wash until output water is clean.
(2) Pre-treatment of cation resin
(2.1) Fill 4% HCL at the speed of 1.5-2.0BV/h to exchange column, when pH is 1 continue fill for 15 min then stop. After soak resin for 4-8h, using softening water to wash until pH is around 3.
(2.2) Fill 4% NaOH at the speed of 1.5-2.0BV/h to the column, when pH 2 is 14 continue to fill for 15min then stop. After soak resin for 4-8h, using softening water to wash until pH is around 10.
(2.3) Fill 4% HCL at the speed of 1.5-2.0BV/h to the column, when pH is 1 continue fill for 15 min then stop. After soak resin for 4-8h, using softening water to wash until pH is around 3. So far, pre-treatment of cation resin is finished, could process regeneration as usual. (Use two times of normal volume regenerate agent to process the first regeneration)
(3) Pre-treatment of anion resin
(3.1) Fill 4% NaOH at the speed of 1.5-2.0BV/h to the column, when pH is 14 continue fill for 15min then stop. After soak resin for 4-8h, using softening water to wash until pH is around 10.
(3.2) Fill 4% HCL at the speed of 1.5-2.0BV/h to the column, when pH is 1 continue fill for 15min then stop. After soak resin for 4-8h, using softening water to wash until pH is around 3.
(3.3) Fill 4% NaOH at the speed of 1.5-2.0BV/h to the column, when pH is 14 continue fill for 15min then stop. After soak resin for 4-8h, using softening water to wash until pH is around 10. So far, pre-treatment of anion is finished, could process regeneration as usual. . (Use two times of normal volume regenerate agent to process the first regeneration)
2. Regenerate operation process
(1) cation resin operation process

Operation	Solution	Flow rate(BV/h)	Volume(BV)
sugar recovery	Softening water	2.0～4.0	1.5～2.0
backwash	Softening water	2.0～4.0	2.0～3.0
regenerate	4～5%HCl solution	1.0～1.5	2.0～3.0
replacement	Softening water	1.0～1.5	1.0～1.5
rinse	Softening water	10～15	3.0～5.0
flushing	Softening water	10～15	2.0～5.0
operating	Sugar liquor	2.0～4.0	30～60

(2) anion resin operation process

3.

Operation	Solution	Flow rate (BV/h)	Volume (BV)
sugar recovery	Softening water	2.0～4.0	2.0～3.0
backwash	Softening water	2.0～4.0	1.5～3.0
regenerate	4～5%NaOHs olution	1.5～2.0	2.5～4.0
replacement	DI water or output water from cation bed	1.5～2.0	1.5～2.0
rinse	DI water or output water from cation bed	10～15	4.0～6.0
flushing	output water from cation bed	10～15	4.0～6.0
operating	Sugar liquor	2.0～4.0	30～60

Causes of resin contamination and recovery method

(1) Causes of contamination

Because the treated solution contains organics, iron, silicon, microorganism, colloids etc., these substances cannot be removed completely during filtrating process by activate carbon, in the process of ion exchange, these substances will adsorb to the matrix of anion resin by the effects of hydrogen bond, ion bond, covalent bond, VDW, generally, after 15-30 operation cycles, accumulate organics will affect the exchange capacity of resins, cause the bad quality of sugar, cost more water to wash, this is so called organic contamination.

(2) Recovery method

(2.1) back wash contaminated resins until the output water is clean.

(2.2) cation resin usually with iron contamination, use 10-15% HCL that two times volume of resin to soak resin for 4-8h, then water washing to clean.

(2.3) anion resin usually with organic contamination, use 4-5% HCL that two time volume of resin soak for 2-4h, then water washing to clean; go through 10% NaCL + 3-4% NaOH mixing solution that three times volume of resin, temperature should be 40℃, flow rate 4m/h, after go through the last bed volume start to soak for 12h, then use DI water washing to clean, observe the water color to see if the water is clean enough and decide if need to be treated again.

(2.4) after double regenerate, it could start to operate.

4. Storage of the resin

Unused resins should be kept in sealed bag, do not expose resin to air, and keep it between the temperature of 0～40℃. If the resin stop operate for a while in the operation process, then should avoid condition as below:

(1) Prevent dehydration, should fill the equipment with full water, if you must discharge the water, then keep the equipment sealed to avoid resin’s inner moisture content lose.

(2) Prevent freezing, if the temperature is below 0℃, should fill salt solution to the equipment to soak resin.

(3) Prevent the growth of bacteria, if keep resin for long time in equipment it will grow microorganism like algae and bacteria, then cause the contamination of resin, preventive measure is completely back washing resin after resin lost its capacity to remove suspended impurities, then soak the resin after regenerate.

Notice: Before pre-treat resin for food industry, prepare softening water by use a set of cation bed resin and anion bed resin, keep the softening water in water container (when it’s not enough then make some again), softening water is prepared to use late to back washing resin during pre-treatment process, to prepare dilute acid and dilute alkali, and to avoid forming white deposit because the harness of water then affect the regenerate effect of resin at later operation period.