Microorganism Control System and Method of Using the Same

Abstract

The present invention relates to microorganism control field in process for treatment of pulp and/or water in paper-making process. More specifically, the present invention provides a microorganism control system, which comprises a first component and a second component which are separately provided, the first component comprises a stabilized halogen-containing bactericidal agent (e.g., a stabilized hypochlorite), and the second component comprises an aminosulfonic acid reagent (e.g., aminosulfonic acid). The present invention further provides a method for controlling microorganism in process for treatment of pulp and/or water in papermaking process, which comprises using the microorganism control system of the present invention.

Claims

1. A microorganism control system comprising a first component and a second component which are separated, wherein the first component comprises a halogen-containing bactericide, and the second component comprises an aminosulfonic acid reagent.

2. The microorganism control system of claim 1, wherein the halogen-containing bactericide is selected from an oxide, an oxygen-containing acid of fluorine, chlorine, bromine, or iodine, and salts or esters thereof.

3. The microorganism control system of claim 2, wherein the halogen-containing bactericide is a hypohalous acid or salt thereof.

4. The microorganism control system of claim 1, wherein the aminosulfonic acid reagent is selected from aminosulfonic acid (NH.sub.2—SO.sub.2—OH) and/or substituted aminosulfonic acid.

5. The microorganism control system of claim 4, wherein the aminosulfonic acid reagent is aminosulfonic acid (NH.sub.2—SO.sub.2—OH).

6. A method of controlling microorganism in process of treatment of pulp and/or water of a pulp and/or papermaking system comprising: applying a halogen-containing bactericide to a pulp and/or water to control microorganisms therein, and applying an aminosulfonic acid reagent to maintain pH of the pulp and/or water to be treated.

7. The method of claim 6, wherein the halogen-containing bactericide is selected from an oxide, an oxygen-containing acid of fluorine, chlorine, bromine, or iodine, and salts or esters thereof.

8. The method of claim 7, wherein the halogen-containing bactericide is a hypohalous acid or salt thereof.

9. The method of claim 6, wherein the aminosulfonic acid reagent is selected from aminosulfonic acid (NH.sub.2—SO.sub.2—OH) and/or substituted aminosulfonic acid.

10. The method of claim 9, wherein the aminosulfonic acid reagent is aminosulfonic acid (NH.sub.2—SO.sub.2—OH).

11. (canceled)

12. The microorganism control system of claim 1, wherein the halogen-containing bactericide is stabilized with a stabilizing agent.

13. The method of claim 6, wherein the halogen-containing bactericide is stabilized with a stabilizing agent.

14. The microorganism control system of claim 12, wherein the stabilizing agent is a nitrogen-containing stabilizing agent.

15. The method of claim 13, wherein the stabilizing agent is a nitrogen-containing stabilizing agent.

16. The microorganism control system of claim 14, wherein the nitrogen-containing stabilizing agent is selected from ammonium sulfate, urea, aminosulfonic acid, an aminosulfonate salt, dimethylhydrazine, or a combination thereof.

17. The method of claim 15, wherein the nitrogen-containing stabilizing agent is selected from ammonium sulfate, urea, aminosulfonic acid, an aminosulfonate salt, dimethylhydrazine, or a combination thereof.

18. The microorganism control system of claim 16, wherein the stabilizing agent is ammonium sulfate, urea and/or dimethylhydrazine.

19. The method of claim 17, wherein the stabilizing agent is ammonium sulfate, urea and/or dimethylhydrazine.

20. The microorganism control system of claim 18, wherein the stabilizing agent is ammonium sulfate and/or urea.

21. The method of claim 19, wherein the stabilizing agent is ammonium sulfate and/or urea.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0051] FIG. 1 shows the active component (monochloroamine) as contained in a halogen-containing bactericide (sodium hypochlorite), which was stabilized with ammonium sulfate, under different pH conditions, when sulfuric acid was used to regulate pH. The halogen-containing bactericide sodium hypochlorite stabilized with ammonium sulfate under different pH conditions (pH=9.08, 5.35 or 2.15, sulfuric acid was used for pH regulation) was subjected to all wavelength scanning with an ultraviolet spectrophotometer. The results showed that when pH=9.08, the sodium hypochlorite stabilized with ammonium sulfate had characteristically highest peak at 245 nm, which indicated that the desired active component, i.e., monochloroamine (having characteristic wavelength of 245 nm) was comprised therein. When pH=5.35 or 2.15, the sodium hypochlorite stabilized with ammonium sulfate had highest peaks at 206 nm or 295 nm (rather than 245 nm), respectively, which indicated that the undesired side product, i.e., dichloroamine, was generated, while the amount of the desired monochloroamine decreased significantly. These results showed that when sulfuric acid was used as pH regulating agent to down-regulate pH, the active component (monochloroamine) in a halogen-containing bactericide stabilized with ammonium sulfate would decrease significantly, and undesired side products would be generated, and stability of the product would decrease significantly.

[0052] FIG. 2 shows the active component (monochloroamine) as contained in a halogen-containing bactericide (sodium hypochlorite), which was stabilized with ammonium sulfate, under different pH conditions, when aminosulfonic acid was used to regulate pH. The halogen-containing bactericide sodium hypochlorite stabilized with ammonium sulfate under different pH conditions (pH=9.08, 4.68 or 2.72, aminosulfonic acid was used for pH regulation) was subjected to all wavelength scanning with an ultraviolet spectrophotometer. The results showed that, under all 3 pH conditions, the halogen-containing bactericide stabilized with ammonium sulfate had highest peak at 245 nm or nearby, and did not show peaks at 206 nm and 295 nm. These results showed that when aminosulfonic acid was used as pH regulating agent to down-regulate pH, the halogen-containing bactericide stabilized with ammonium sulfate would substantively remain stable, and the amount of active component (monochloroamine) therein did not change significantly, and undesired side products (for example, dichloroamine) would not be generated.

[0053] FIG. 3 shows the microorganism controllability (microbiocidal activity and biofilm removal capacity) of a halogen-containing bactericide (having concentrations of 2.5 ppm, 5 ppm and 10 ppm, respectively) stabilized with ammonium sulfate, under conditions of using or not using aminosulfonic acid to regulate pH, which was measured by total aerobic bacteria counting (TABC, cfu/ml), ATP fluorescence method (RLU) and spectrophotometric method (absorbance at 480 nm), in which sodium hypochlorite samples of 2.5 ppm, 5 ppm and 10 ppm were used as bactericide controls. The results showed that in presence of aminosulfonic acid, the halogen-containing bactericide stabilized with ammonium sulfate had a significantly enhanced biofilm removal capacity, as compared to the situation in absence of aminosulfonic acid. These results showed that in a microorganism control system using halogen-containing bactericide, aminosulfonic acid not only had function of regulating pH (i.e., avoiding pH value fluctuation, for example, being elevated), but also had synergistic effect on biofilm removal capacity of the halogen-containing bactericide.

SPECIFIC MODELS FOR CARRYING OUT THE INVENTION

[0054] The following examples are intended to illustrate the present invention (rather than to restrict the present invention). However, the scope of the present invention is not limited to the following examples. Those skilled in the art would understand that the present invention could be changed and modified in varioius ways without departing from the sprit and scope of the present invention.

[0055] The materials and test methods used in the examples are generally and/or specifically described in the present invention. Although many materials and operation methods used for fulfilling the objectives of the present invention are well known in the art, they are still described in details as much as possible. The chemicals of which sources are not explicitly described are all readily producible by those skilled in the art or commercially available.

Example 1

[0056] The present example demonstrated that: when a stabilized halogen-containing bactericide was added to a pulp (for example, broke pulp and white water pulp), the pH value of pulp would increase; and when sulfuric acid or citric acid was used to regulate pH value of halogen-containing bactericide, halogen-containing bactericide would become unstable, in which available chlorine content would decrease significantly. However, when aminosulfonic acid was used to regulate pH value of halogen-containing bactericide, the fluctuation of pH value of halogen-containing bactericide and pulp would be effectively avoided, and the halogen-containing bactericide would remain stable, in which available chlorine content would not change significantly (i.e., not decrease significantly), and thus the bactericidal effects of halogen-containing bactericide is effectively maintained.

[0057] White water samples and broke samples were taken from a paper plant, 5 parts for each, 100 ml per part, and their pH values were measured (for white water samples, pH was 8.20; for broke samples, pH was 8.23). Sodium hypochlorite stabilized with urea was prepared and used as halogen-containing bactericide 1, in which the molar ratio of available chlorine in sodium hypochlorite to urea was 1:1; sodium hypochlorite stabilized with ammonium sulfate was prepared and used as halogen-containing bactericide 2, in which the molar ratio of available chlorine in sodium hypochlorite to ammonium sulfate was 1:1. The available chlorine content of sodium hypochlorite used in the example was 12.5%. The stabilized halogen-containing bactericide 1 (pH was 12.15, dosage was 1.25 ppm or 5 ppm, expressed in Cl.sub.2) and the stabilized halogen-containing bactericide 2 (pH was 10.0, dosage was 1.25 ppm or 5 ppm, expressed in Cl.sub.2) in different amounts were separately added to the white water samples and broke samples, and the pH values of the resultant mixtures were measured. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 Effects of the addition of stabilized halogen-containing bactericides on pH values of different pulps of paper machine system Dosage pH pH of Bactericide expressed of broke white water as added in Cl.sub.2 sample sample Blank (not adding any 0 8.23 8.20 bactericide) Halogen-containing 1.25 8.45 8.48 bactericide 1 5 8.87 8.84 pH was 12.15 Halogen-containing 1.25 8.30 8.24 bactericide 2 5 8.38 8.31 pH was 10.0

[0058] The results showed that when the stabilized halogen-containing bactericides were added to white water samples and broke samples, the pH values of pulps all increased, in which when the amount of urea-stabilized sodium hypochlorite was 5 ppm (expressed in Cl.sub.2), pH value increased from 8.23 to 8.87 (the highest) for the broke samples, and increased from 8.20 to 8.84 (the highest) for the white water samples. Thus, the addition of the halogen-containing bactericide resulted in an increase of pulp pH value.

[0059] In order to avoid fluctuation of pulp pH value (for example, avoiding an increase of pulp pH value), the pH of halogen-containing bactericide could be regulated so that it was similar to the pH value of paper machine system (i.e., pulp) before the halogen-containing bactericide was added to pulp.

[0060] In this connection, firstly, a urea-stabilized sodium hypochlorite was prepared in proportion that the molar ratio of available chlorine to urea was 1:1, and the sodium hypochlorite had available chlorine content of 12.5%. Then, 5 beakers were provided and separately added with 1 ml of the prepared urea-stabilized halogen-containing bactericide. After that, 29 ml of water was added to the first beaker for dilution (blank control), while the other 4 beakers were separately added with 20% sulfuric acid (0.5 ml or 1.0 ml) or 20% citric acid (1.0 ml or 2.0 ml), and added with water to reach a final volume of 30 ml. Finally, pH values and available chlorine contents (ppm) of solutions in the 5 beakers were measured. The results are shown in Table 2.

TABLE-US-00002 TABLE 2 Effects of addition of sulfuric acid or citric acid on urea-stabilized halogen-containing bactericide Acid Available volume as Solution chlorine, Acid as used added (ml) pH ppm Blank control 0 12.75 2550 20% sulfuric acid 0.5 7.35 750 1.0 2.15 455 20% citric acid 1.0 7.75 1250 2.0 3.65 725

[0061] The results showed that when an acid (for example, sulfuric acid or citric acid) was added to the urea-stabilized halogen-containing bactericide, its pH value was effectively regulated (i.e., significantly decreased). However, in comparison with the blank control (not adding acid to regulate pH), the addition of sulfuric or citric acid also resulted in a significant decrease of available chlorine in the solution. This indicated that the addition of sulfuric acid or citric acid would result in that a stabilized halogen-containing bactericide became unstable, effective component degraded, and available chlorine content decreased significantly.

[0062] Further, 10% aminosulfonic acid (which was used to replace sulfuric acid or citric acid, which dosage was 1.1 ml or 1.24 ml) was used to repeat the above experiments. In particular, a urea-stabilized sodium hypochlorite was prepared in proportion that the molar ratio of available chlorine in sodium hypochlorite to urea was 1:1, and the sodium hypochlorite had an available chlorine content of 8.5%. In addition, after aminosulfonic acid was added, pH values and available chlorine contents (ppm) in solutions were measured, and after standing for 40 min, 120 min, and 240 min, available chlorine contents (ppm) of solutions were measured again. The results are shown in Table 3.

TABLE-US-00003 TABLE 3 Effects of the addition of aminosulfonic acid on urea-stabilized halogen-containing bactericide Acid Solution volume as pH added after Available chlorine after mixing, ppm Acid as used (ml) mixing 0 min 40 min 120 min 240 min Blank control 0 12.25 1425 1325 1375 1350 Aminosulfonic 1.1 8.46 1275 1275 1325 1400 acid 1.24 5.96 1300 1325 1475 1250

[0063] The results showed that in comparison with the blank control (not adding with acid to regulate pH), when the stabilized halogen-containing bactericide was added with aminosulfonic acid, its pH value was effectively regulated (i.e., significantly decreased), and its available chlorine content did not change significantly (even after standing for 240 min). This indicated that aminosulfonic acid could regulated pH of halogen-containing bactericide, would not render halogen-containing bactericide unstable, and could maintain available chlorine content of solution for a long time (at least 240 min). Thus, aminosulfonic acid used as pH regulating agent had effects superior to that of sulfuric acid or citric acid.

[0064] In order to further evaluate effects of aminosulfonic acid on a stabilized halogen-containing bactericide, we further analyzed the microbiocidal activity of halogen-containing bactericide after using aminosulfonic acid to regulate pH, and after pH regulation and standing for 40 min. In brief, as stated above, to 1 ml of urea-stabilized sodium hypochlorite (having available chlorine content of 8.5%), 0, 0.8, 1.1, 1.24, 1.3 or 1.55 ml of 10% aminosulfonic acid (for regulating pH) was separately added, then water was added until the final volume was 30 ml, and pH values of solutions after adding aminosulfonic acid were measured. Pulp was taken from a paper plant, which was divided in several parts, 100 ml for each part; to each part, the prepared bactericides of different pH values which were stabilized with urea, wherein pH were regulated with aminosulfonic acid, were added, so that the pulp samples had final available chlorine concentration of 5 ppm. The pulp samples without adding any halogen-containing bactericide were used as blank control. Then, all pulp samples were incubated in 37° C. thermostat for 2 h, and then were measured for the pulp pH, and for the microorganism activity in pulp by ATP activity (RLU) and total aerobic bacteria counting (TABC, cfu/ml), so as to determine the control effect of the stabilized halogen-containing bactericide (standing for 40 min, or without standing) which pH was regulated with aminosulfonic acid on microorganism activity. The results are shown in Tables 4-5.

TABLE-US-00004 TABLE 4 Bactericidal effects of stabilized halogen-containing bactericide (without standing) with pH regulated by aminosulfonic acid Volume pH of of bactericide acid as after used addition ATP, TABC, Pulp (ml) of acid RLU cfu/ml pH Blank control / / 4.85E+04 2.50E+07 7.95 Stabilized 0 12.25 3.21E+03 4.60E+05 8.43 halogen-containing 0.8 10.19 1.96E+04 4.80E+06 7.98 bactericide with 1.1 8.46 6.25E+03 5.60E+05 7.96 pH regulated by 1.24 5.96 3.68E+03 2.60E+05 7.94 aminosulfonic acid 1.3 3.95 3.22E+03 3.00E+05 7.92 1.55 2.61 4.83E+03 7.30E+05 7.90

TABLE-US-00005 TABLE 5 Bactericidal effects of stabilized halogen-containing bactericide (standing for 40 min) with pH regulated by aminosulfonic acid pH of Volume of bactericide acid as after used addition of ATP, TABC, Pulp (ml) acid RLU cfu/ml pH Blank control / / 7.19E+04 2.50E+07 7.95 Stabilized 0 12.25 3.41E+03 1.34E+05 8.48 halogen-containing 0.8 10.19 2.50E+04 4.90E+05 8.05 bactericide with 1.1 8.46 8.71E+03 2.80E+05 7.99 pH regulated by 1.24 5.96 3.32E+03 3.20E+05 7.97 aminosulfonic acid 1.3 3.95 5.19E+03 2.42E+05 7.97 1.55 2.61 5.32E+03 1.95E+05 7.96

[0065] The results showed that in comparison with blank control, both the urea-stabilized halogen-containing bactericide without being regulated with acid and the stabilized halogen-containing bactericide with pH regulated by aminosulfonic acid had bactericidal effects in pulp, and they could reduce total aerobic bacteria number (TABC, cfu/ml) by about 2 log. At the same time, in comparison with the stabilized halogen-containing bactericide without being regulated with acid, the use of the stabilized halogen-containing bactericide with pH regulated by aminosulfonic acid did not result in significant increase of pulp pH. These results showed that aminosulfonic acid not only avoided pH fluctuation (i.e., increase) of halogen-containing bactericide and pulp, but also effectively remained bactericidal effects (i.e., capability of inhibiting growth of bacteria) of halogen-containing bactericide.

Example 2

[0066] The present example demonstrated that: when sulfuric acid was used to regulate pH value of ammonium sulfate-stabilized halogen-containing bactericide (sodium hypochlorite), halogen-containing bactericide would become unstable, in which active component (monochloroamine) content decreased significantly, and undesired side products, for example, dichloroamine, were generated. However, when aminosulfonic acid was used to regulate pH value of ammonium sulfate-stabilized halogen-containing bactericide, the halogen-containing bactericide remained stable, in which active component (monochloroamine) content did not change significantly, and undesired side products, for example, dichloroamine, were not generated.

[0067] As stated above, an ammonium sulfate-stabilized sodium hypochlorite was prepared in proportion that the molar ratio of available chlorine in sodium hypochlorite to ammonium sulfate was 1:1, and the used sodium hypochlorite had available chlorine content of 12.5%. To 3 beakers, 1 ml of the prepared halogen-containing bactericide was added separately, then 29 ml of water was added to one of the beakers for dilution (solution pH was measured as 9.08); the other 2 beakers were regulated with sulfuric acid to reach pH of 5.35 and 2.15, respectively, and their volume was adjusted with water to reach 30 ml. After measurement, the 3 solutions had available chlorine content of 2550 ppm, 750 ppm and 455 ppm, respectively.

[0068] The 3 solutions were subjected to all wavelength scanning with an ultraviolet spectrophotometer. The results were shown in FIG. 1. The results of FIG. 1 showed that when pH=9.08, the ammonium sulfate-stabilized halogen-containing bactericide, sodium hypochlorite, had characteristically highest peak at 245 nm, which indicated that the desired active component, i.e., monochloroamine (having characteristic wavelength of 245 nm) was comprised therein. When pH=5.35 or 2.15, the ammonium sulfate-stabilized halogen-containing bactericide had highest peaks at 206 nm or 295 nm (rather than 245 nm), respectively, which indicated that the undesired side product, i.e., dichloroamine, was generated, while the amount of the desired monochloroamine decreased significantly. These results show that when sulfuric acid is used as pH regulating agent to regulate pH, the active component (monochloroamine) in a halogen-containing bactericide stabilized with ammonium sulfate would decrease significantly, and undesired side products would be generated, and stability of the product would decrease significantly.

[0069] As stated above, an ammonium sulfate-stabilized halogen-containing bactericide was prepared. To 3 beakers, 1 ml of the prepared halogen-containing bactericide was added, respectively, then 29 ml of water was added to one of the beakers for dilution (solution pH was measured as 9.08); the other 2 beakers were regulated with aminosulfonic acid to reach pH of 4.68 and 2.72, respectively, and their volume was adjusted with water to reach 30 ml. After measurement, the 3 solutions had available chlorine content of 2550 ppm, 2315 ppm and 2195 ppm, respectively.

[0070] The 3 solutions were subjected to all wavelength scanning with an ultraviolet spectrophotometer. The results were shown in FIG. 2. The results of FIG. 2 showed that under 3 pH conditions, the ammonium sulfate-stabilized halogen-containing bactericide always had the highest peak (i.e., containing active component monochloroamine) at 245 nm or nearby, and did not show peaks at 206 nm and 295 nm (i.e., not generating side product dichloroamine). These results show that when aminosulfonic acid was used as pH regulating agent to regulate pH, the halogen-containing bactericide stabilized with ammonium sulfate would substantively remain stable, and the amount of active component (monochloroamine) therein did not change significantly, and undesired side products (for example, dichloroamine) would not be generated. Thus, when aminosulfonic acid was used as a pH regulating agent, it could regulate pH of halogen-containing bactericide, and did not render the halogen-containing bactericide unstable (i.e., not resulting in a significant decrease of active component monochloroamine, and avoiding generation of undesired side product, for example, dichloroamine), which effects were significantly superior to those of other acids, for example, sulfuric acid.

Example 3

[0071] The present example demonstrated that: when aminosulfonic acid was used to regulate pH value of halogen-containing bactericide, the biofilm removal capability of halogen-containing bactericide was enhanced, i.e., aminosulfonic acid had synergistic effect on biofilm removal capacity of the stabilized halogen-containing bactericide.

[0072] White water was taken in acid papermaking process in a paper plant, filtrated, and measured for its pH (its pH was 5.10). The filtrated white water sample was added with casein broth culture medium, and loaded on a 24-well plate, then subjected to shaking culture for 48 h at 37° C. and 150 rpm, until biofilm was formed. After that, the biofilm was washed gently with phosphate buffer solution, and moved out for standby use.

[0073] As stated in Example 2, an ammonium sulfate-stabilized halogen-containing bactericide sodium hypochlorite was prepared. The prepared ammonium sulfate-stabilized halogen-containing bactericide was divided into 2 parts, one part was added with aminosulfonic acid to regulate pH as 5.12, while the other part was not subjected to pH regulation (i.e., not adding aminosulfonic acid, which pH was 9.08). The 2 halogen-containing bactericides were separately added to white water, at a dosage of 2.5 ppm, 5 ppm or 10 ppm (expressed in available chlorine), respectively. In addition, sodium hypochlorite was used as bactericide control and added to white water, at a dosage of 2.5 ppm, 5 ppm and 10 ppm (expressed in available chlorine). Then, the white water samples added with bactericides (i.e., aminosulfonic acid-containing ammonium sulfate-stabilized halogen-containing bactericide, aminosulfonic acid-free ammonium sulfate-stabilized halogen-containing bactericide, or sodium hypochlorite) were separately added to the above 24-well plate with formed biofilm, and subjected to shaking for 12 h at 37° C. and 150 rpm. Then, white water was removed, without damaging the biofilm, and the 24-well plate was washed with phosphate buffering solution. Then, the 24-well plate was added with biological dye, iodonitrotetrazolium chloride, and absorbance at 480 nm was read. The absorbance was in positive correlation with microorganism activity. The lower the absorbance, the lower the microorganism activity, the higher the inhibition effect on microorganism, and the more potent the biofilm removal capability of the bactericide was. In addition, the ATP activity (RLU) and total aerobic bacteria count (TABC, cfu/ml) in white water as removed were measured as well, to determine microorganism activity in white water. The results are shown in FIG. 3. The results of FIG. 3 showed that as compared to the situation in absence of aminosulfonic acid, in presence of aminosulfonic acid, the ammonium sulfate-stabilized halogen-containing bactericide had a significantly enhanced biofilm removal capacity. These results indicated that in a microorganism control system using halogen-containing bactericide, aminosulfonic acid not only has function of regulating pH (i.e., avoiding pH value fluctuation, for example, increase), but also has synergistic effect on biofilm removal capacity of halogen-containing bactericide.

[0074] Although the specific models for carrying out the invention are described in details, those skilled in the art would understand that the details could be modified and changed according to the above teachings, and all these modifications and changes fall in the protection scope of the present invention. The whole scope of the present invention is given by the appended claims and any equivalents thereof.