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MXPA01008029A - Method of removing biofilms from surfaces submerged in a fouled water system - Google Patents

Method of removing biofilms from surfaces submerged in a fouled water system

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Publication number
MXPA01008029A
MXPA01008029A MXPA/A/2001/008029A MXPA01008029A MXPA01008029A MX PA01008029 A MXPA01008029 A MX PA01008029A MX PA01008029 A MXPA01008029 A MX PA01008029A MX PA01008029 A MXPA01008029 A MX PA01008029A
Authority
MX
Mexico
Prior art keywords
water system
ppm
biocide
pga
biofilms
Prior art date
Application number
MXPA/A/2001/008029A
Other languages
Spanish (es)
Inventor
F Philip Yu
Anthony W Dallmier
Original Assignee
Nalco Chemical Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nalco Chemical Company filed Critical Nalco Chemical Company
Publication of MXPA01008029A publication Critical patent/MXPA01008029A/en

Links

Abstract

A method is disclosed for removing biofilms from surfaces submerged in a fouled water system by adding to the water system an alkyl polyglycoside having chemical formula (I) wherein R is a C8-C16 alkyl chain and DP is from 0 to 3 carbohydrate units.

Description

METHOD FOR ELIMINATING BIQPELICULAS FROM SUBMERGED SURFACES IN A CONTAMINATED WATER SYSTEM FIELD OF THE INVENTION This invention relates generally to the field of water treatment technologies, and more particularly, to a method for removing biofilms from submerged surfaces in a contaminated water system. BACKGROUND OF THE INVENTION Biofilm has always been problematic in industrial water systems, such as cooling towers, heat exchangers and air scrubbers, since this can adversely affect the heat transfer efficiency and frictional resistance of the fluid, so that the production speeds are subsequently reduced. In addition, biofilm also plays an important role in microbiologically influenced corrosion. The presence of microorganisms in industrial waters can not be totally eliminated, even with the excessive use of chemical biocides. The most common way to control the biofilm is through the application of toxic chemical biocides such as chlorine, bromine, isothiazolones, glutaraldehyde or other antimicrobials. These biocides are added in an attempt to kill both the REF: 132027 planktonic and united microorganisms. Some microorganisms join the inert surfaces forming aggregates with a complex matrix consisting of extracellular polymeric substances (SPE). This consortium of bound microorganisms and the associated SPEs are commonly referred to as a biofilm. Biocides have difficulty penetrating biofilms and eliminating them from surfaces. Although doses of excessive biocides may be able to control the biofilm, the presence of biocides in effluent water is usually environmentally unacceptable. Mechanical treatments include scraper blades, sponge balls, or "pigs" are also commonly used to remove biofilms. The acids, chelants and dispersants are similarly considered to be effective in causing the release of deposited materials. In addition, sidestream filtration devices, which continuously process 1-5% of the system water, have received an increased interest lately. However, these procedures are both very labor-intensive and / or expensive. Dispersants are sometimes applied together with biocides to increase antimicrobial efficacy in industrial waters. The dispersants used in these applications will be referred to herein as "biodispersants". Most biodispersants currently available in the market, such as the block copolymer or terpolymer, have high molecular weights in the range of 1,000 to 15,000,000. These biodispersants attract fine contaminant particles onto the polymer chains and form fluffy particles that are more easily detached from contaminated surfaces. It is also believed that these surface active compounds can increase the diffusion of the biocide in the biofilm, and subsequently cause the release of the biofilm. To date, biodispersants have not been used effectively without complementation with the biocides. While the global regulations and concerns of the United States Environmental Protection Agency (EPA) become more prevalent, high resolution biodispersants that have low toxicity will be necessary to control the biofilm either with or without the addition of biocides chemical Accordingly, it may be desirable to provide a method for removing the biofilms from surfaces immersed in water using a bis-dispersant which is effective both alone and with the use of a biocide. It may also be desirable to use a biodispersant which is biodegradable and has a low toxicity. It may be additionally desirable to employ a biodispersant which does not affect the corrosion inhibition and oxide layer programs used in industrial water treatment. SUMMARY OF THE INVENTION The method of the invention relates to adding to an contaminated water system an alkyl polyglycoside having the chemical formula: It is 0 to 3 carbohydrate units. This method efficiently and effectively removes biofilms from submerged surfaces in the contaminated water system. The method is also environmentally acceptable and economically attractive since the use of the biocides can be minimized or eliminated, and the biodispersant used in the practice of the invention is biodegradable and has a low toxicity. On the other hand, the method does not affect the corrosion inhibiting and oxide layer programs used in the industrial water treatment. DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method for removing biofilms from surfaces submerged in water. a contaminated water system. In accordance with this invention, an alkyl polyglycoside (PGA) having the chemical formula is added to the water system: wherein R is a C8-C6 alkyl chain and the degree of polymerization (DP) is from 0 to 3 carbohydrate units. Preferably, the alkyl chain is linear and the DP is from about 1.1 to 1.5. Glucopon® 225 and Bureo® NPS-225 (C8, Cio), Glucopon® 425 (C8-C16) and Glucopon® 600 and 625 (C? 2-C16) are commercially available PGA products which can be used in the practice of the invention. (Glucopon® products are available from Henkel Corporation of Ambler, PA and the Bureo® product is available from Burlington Chemical Co., Inc. of Burlington, NC). It is believed that other PGA products from other suppliers can also be used in the practice of the present invention. It is preferred that the amount of PGA which is added to the water system is in the range of about 0.1 ppm to about 10 ppm based on the active ingredient, with about 1 ppm to about 10 ppm being more preferred. The PGA can be added to the water system by any conventional method, that is, by cartridge, intermittently or continuously. A biocide can also optionally be added to the water system in accordance with the practice of this invention. The biocide can be added by any conventional method either separately or in combination with the PGA. Biocides that can be used in the practice of the present invention include oxidizing biocides such as chlorine-based biocides, bromine-based biocides, peracetic acid, hydrogen peroxide and ozone; and non-oxidizing biocides such as isothiazolone, glutaraldehyde and quaternary amine compounds. The amount of the biocide added to the water system is dependent on the particular water treatment application and is generally known to those skilled in the art. However, it should be noted that the required amount of the biocide is minimized when used in combination with the PGA. According to the method of this invention, biofilms are removed from all types of submerged surfaces, for example, glass, metals, wood and plastics. The method of the present invention can be used in an industrial water system or a recreational water system. The types of industrial water systems in which the PGA can be applied include, but are not limited to, cooling water systems, air scrubbers, evaporative condensers, pasteurizers, air scrubbers, sanitizing stream producers, water systems of fire protection 'and heat exchanger tubes. The types of recreational water systems in which the PGA can be used include, but are not limited to, decorative fountains and full-body immersion systems such as pools, spas and hot tubs. The present invention takes advantage of the PGA detergency and dispersity for use as a biodispersant. It is surprisingly discovered that when the PGA is added to a contaminated water system, the biofilms are effectively removed from the submerged surfaces. The PGA biodispersant described herein exhibits superior performance compared to other commercially available biodispersants, and the elimination of the biofilm is achieved both with and without the addition of chemical biocides. It should be noted that when PGA is used, smaller amounts of toxic biocides are needed to achieve the same level of control. In addition, the PGA offers a means of low toxicity or non-toxic to control biocontamination and the PGA is biodegradable, so that an environmentally acceptable procedure for the treatment of water is provided. On the other hand, the use of PGA does not affect the programs of inhibition of corrosion and the oxide layer used in the industrial water treatment. EXAMPLES The following examples are proposed to be illustrative of the present invention and to teach an ordinary expert how to make and use the invention. These examples are not proposed to limit the invention or its protection in any way. The biofilms used in the following Examples are generated from a mixed microbial consortium isolated from a cooling water reservoir. The devices used to house the test bacterial biofilms are continuous flow stirred tank bioreactors. Laminar and turbulent flow conditions are tested for product behavior. Synthetic cooling water [alkalinity 400 ppm of Ca, 200 ppm of Mg, 400 ppm of M (all based on CaC03] as make-up for the bioreactors is used. Bacterial biofilms are grown on glass and stainless steel surfaces by 96 hours at room temperature in order to achieve steady-state conditions.The thickness of the biofilms is approximately 500 μm.The biofilms are then treated by continuously applying the biodispersant for 24 hours in an attempt to remove the biofilms from the substrates The area densities of the bacterial biofilms are measured with a protein assay.The biomass is expressed as μg of protein per cm.sup.2 The efficiency of biofilm removal is determined by the loss of biomass during the treatment period. also use the conventional plate counts on tryptone extract and glucose (TGE) agar to measure the viability of the population bac The viable cell density of the biofilm bacteria is expressed as the colony forming units (UFO per cm2 of biofilm. Example 1 Several surfactants are tested in laboratory biofilm reactors to evaluate their biofilm removal activities. Biomass elimination activities of biodispersants against bacterial biofilms are measured after 24 hours of continuous treatment. The tested PGA is Glucopon® 425 (a mixture of C8 / Cio and C? 2-? 6), a non-ionic surfactant. NALCO® 7348, a block copolymer of nonionic ethylene oxide / propylene oxide (OE / OP) is also evaluated. The anionic surfactants used in this example are diphenyl disulfonate (Dowfax® available from the Dow Chemical Company of Midland, MI), a linear alkylbenzene sulfonate (SAL) and sodium octane sulfonate. A commercial biofilm cleaning product sold under the name Ultra-Kleen (available from Sterilex Corporation of Owing Mills, MD) is tested. Also included in this example is a cationic surfactant, dimethylamide polymer (DMAD), sold commercially by Buckman Laboratories, of Memphis, TN. As shown below in Table 1, the removal of biofilm by PGA is significantly higher than by any of the other products tested. Table 1 Note that a value of zero is assigned if the bound biomass or the levels of viable bacteria in the bioreactor are increased. This phenomenon occurs if the biodispersant is ineffective.
Example 2 The effects of PGA in the corrosion ratios are carried out with 4.5 ppm of sodium tolyltriazole, 20 ppm of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and 18 ppm of acrylic acid terpolymer. acrylamide / sulfomethylacrylamide. The chemistry and alkalinity of the test water are maintained at 360 ppm of CaCl2, 200 ppm of MgSO4 and 220 ppm of NaHCO3. The pH is maintained at 8.7 and the temperature is set at 55 ° C. The concentration of the PGA is 10 ppm. The tests are run in duplicate for 40 hours, and the proportions of corrosion are determined by electrochemical parameters. The addition of the PGA does not adversely affect corrosion control, as indicated by the low rates of corrosion shown below in Table 2.
Table 2 Example 3 The effects of PGA on the formation of the oxide layer are evaluated. The formation of the oxide layer is determined by a solubility pressure test which is run at 50 ° C. The oxide layer inhibitors used in this study are 1-hydroxyethylidene-1, diphosphonic acid (HEDP) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC). The formation of the oxide layer, indicated by the low percentage of recovery of soluble Ca2 + after two hours, is slightly higher in 400 ppm of CaCO3 or Ca2 + / HC03 with 10 ppm of PGA in the system. PGA does not affect the formation of the oxide layer when calcium levels are increased to 600 ppm. After all, as shown in Table 3, there is no significant difference in the formation of the oxide layer with or without the PGA applied at 10 ppm.
Table 3 EXAMPLE 4 The synergism between the PGA and a bromo-based oxidizing biocide stabilized with the calculation described by F.C. Kull, P.C. Eximan, H.D. Sylwestrowicz and R.L. Mayer, Applied Microbiology, vol. 9, pages 538-541, (1961) using the relationship: + = synergy index Where: Qa = amount of PGA, which acts alone, which produces a final point. Qb = quantity of biocide, which acts alone, which produces a final point. QA = amount of PGA in mixture, which produces an end point. QB = quantity of biocide in mixture, which produces a final point. If the synergy index is < 1, indicates synergy = 1, indicates additivity > 1, indicates antagonism Instead of using the conventional plate numbering method, a bacterial luminescent test is used to calculate the endpoints. A decrease in light emission depends on the concentration of the toxic in the test and is used to calculate the unit of relative toxicity (UTR). This test gives rapid and sensitive detection of toxic substances compared with conventional minimum inhibitory concentration (MIC) tests. Table 4 lists the synergy indices of various combinations of PGA and stabilized bromine-based biocide (STB) tested in the laboratory. The concentrations expressed are mg / L for PGA as an active ingredient and mg / L as total chlorine for STS. The results shown in Table 4 demonstrate that all tested PGA / STB combinations are synergistic. It should be noted that the PGA itself did not show significant toxicity to reduce the bioluminescence readings. However, when combined with biocides, the PGA dramatically improves antimicrobial activity. Table 4 * TRO = total residual oxidant (with reference to chlorine in the present) While the present invention is described above in connection with preferred or illustrative embodiments, these embodiments are not intended to be exhaustive or limiting of the invention. Rather, the invention is intended to cover all alternatives, modifications and equivalents included within its spirit and scope, as defined by the appended claims. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (19)

  1. ÍS
  2. CLAIMS Having described the invention as above, it is claimed as property contained in the following claims: l.A method to remove biofilms from submerged surfaces in a contaminated water system, is characterized in that it comprises the step of adding to the system of water an effective amount of an alkyl polyglycoside having the following chemical formula:
  3. It is 0 to 3 carbohydrate units. 2. The method according to claim 1, characterized in that the alkyl chain is linear. 3. The method according to claim 1, characterized in that the DP is from about 1.1 to 1.5.
  4. 4. The method according to claim 1, characterized in that the alkyl polyglycoside is added to the water system in an amount of about 0.1 ppm to about 50 ppm.
  5. 5. The method of compliance with the claim 1, is characterized in that the alkyl polyglycoside is added to the water system in an amount of about 1 ppm to about 10 ppm.
  6. 6. The method according to claim 1, characterized in that the water system is an industrial water system.
  7. 7. The method according to claim 1, characterized in that the water system is a recreational water system.
  8. 8. The method of compliance with the claim 1, is characterized in that a biocide is also added to the water system.
  9. 9. The method according to claim 8, characterized in that the biocide is an oxidizing biocide.
  10. 10. The method according to claim 8, characterized in that the biocide is a non-oxidizing biocide.
  11. 11. A method for removing biofilms from submerged surfaces in a contaminated water system is characterized in that it comprises the step of adding to the water system an effective amount of a biocide and an alkyl polyglycoside having the chemical formula: wherein R is an alkyl chain of C8-C6 and DP is from 0 to 3 carbohydrate units.
  12. 12. The method according to claim 11, characterized in that the alkyl chain is linear.
  13. 13. The method according to claim 11, characterized in that the DP is from about 1.1 to 1.5.
  14. 14. The method according to the claim 11, is characterized in that the alkyl polyglycoside is added to the water system in an amount of about 0.1 ppm to about 50 ppm.
  15. 15. The method according to claim 11 is characterized in that the alkyl polyglycoside is added to the water system in an amount of about 1 ppm to about 10 ppm.
  16. 16. The method of compliance with the claim 11, is characterized in that the water system is an industrial water system.
  17. 17. The method according to claim 11, characterized in that the water system is a recreational water system.
  18. 18. The method according to claim 11, characterized in that the biocide is an oxidizing biocide.
  19. 19. The method according to claim 11, characterized in that the biocide is a non-oxidizing biocide. SUBMERGED SURFACES IN A CONTAMINATED WATER SYSTEM SUMMARY OF THE INVENTION A method is disclosed for removing biofilms from submerged surfaces in a contaminated water system by adding to the water system an alkyl polyglycoside having the chemical formula (I) wherein R is an alkyl chain of C8-C6 and DP is 0 to 3 carbohydrate units.
MXPA/A/2001/008029A 1999-02-17 2001-08-08 Method of removing biofilms from surfaces submerged in a fouled water system MXPA01008029A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US09251614 1999-02-17

Publications (1)

Publication Number Publication Date
MXPA01008029A true MXPA01008029A (en) 2002-03-05

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