EP0888251A1 - Compositions et procedes destines a reduire la formation de depots sur des surfaces - Google Patents

Compositions et procedes destines a reduire la formation de depots sur des surfaces

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Publication number
EP0888251A1
EP0888251A1 EP97945310A EP97945310A EP0888251A1 EP 0888251 A1 EP0888251 A1 EP 0888251A1 EP 97945310 A EP97945310 A EP 97945310A EP 97945310 A EP97945310 A EP 97945310A EP 0888251 A1 EP0888251 A1 EP 0888251A1
Authority
EP
European Patent Office
Prior art keywords
whereb
water
systems
accordbg
surfactant
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP97945310A
Other languages
German (de)
English (en)
Inventor
Rodney M. Donlan
David L. Elliott
Nancy J. Kapp
Christopher L. Wiatr
Paul A. Rey
Jasbir S. Gill
Peter R. Ten Eyck
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Calgon Corp
Original Assignee
Calgon Corp
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
Priority claimed from US08/929,909 external-priority patent/US6039965A/en
Priority claimed from US08/929,980 external-priority patent/US6139830A/en
Application filed by Calgon Corp filed Critical Calgon Corp
Publication of EP0888251A1 publication Critical patent/EP0888251A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment

Definitions

  • the present invention relates, in part, to methods for inhibiting the formation of deposits on surfaces in contact with aqueous systems. More particularly, the present invention, in part, relates to methods of using compounds including repeating ethylene oxide units to reduce the adherence of microorganisms and the resultant formation of bilofilms on surfaces in contact with aqueous systems. The present invention also particularly relates to multi-component compositions and to methods of using those compositions to reduce the occurrence of deposits of water-bome matter, for example, silt and microorganisms, on surfaces in contact with aqueous systems.
  • compositions and methods of the present invention may be used in any system in which surfaces are subjected to static or flowing aqueous media.
  • examples of such systems include industrial water system applications, such as, for example, process or cooling water systems and paper mills and paper processing systems BACKGROUND OF THE INVENTION
  • Biofilms are considered indigenous to industrial water systems and may result in a number of serious problems, including fouling of heat exchangers and cooling tower fill materials, microbially-influenced corrosion, reseeding of the water system with biofilm organisms, plugging of orifices or piping, and final product or process stream complications.
  • biofilms are not merely comprised of monoiayers of bacterial cells embedded in a polysaccharide matrix, but rather are heterogeneous assemblages of cells, extracellular polymeric substances (EPS), and abiotic panicles
  • T1TUTE SH acid 40% 2-acrylamido-2-methylpropylsulfonic acid (AA/AMPS copolymer) to control the fouling onto PVC fill material in a seawater fed system.
  • AA/AMPS copolymer 2-acrylamido-2-methylpropylsulfonic acid
  • the present invention discloses compositions and methods of use for inhibiting the formation of deposits of microorganisms and other matter on surfaces in contact with aqueous systems.
  • the present invention provides a method for inhibiting the microbial colonization of a surface in contact with an aqueous system by adding to the aqueous system at least one compound that will inhibit adhesion of microorganisms.
  • the method more specifically includes adding to the system an effective amount of at least one compound having repeating ethylene oxide units.
  • Compounds useful in the method include, for example, an ethoxylated nonionic surfactant and, more particularly, may be selected from the following: block copolymers of repeating ethylene oxide and repeating propylene oxide units; polysiloxanes including pendent polyethylene oxide grafts; alcohol ethoxylates including hydrophilic head groups and hydrophobic tail groups; and sorbitan monooleates including about 20 ethylene oxide units.
  • block copolymers useful in the foregoing method of the present invention may be selected from, for example, block copolymers including first and second blocks of repeating ethylene oxide units and a block of propylene oxide units interposed between the first and second blocks of repeating ethylene oxide units.
  • block copolymers may have the general structure (I):
  • the block copolymers of the above structure (I) may include from 20% to 80% ethylene oxide (EO) units by weight and have a molecular weight in the range from 2000 to 20,000. Additional examples of block copolymers useful in the foregoing method of the present invention include those wherein the copolymers include first and second blocks of repeating propylene oxide units and a block of repeating ethylene oxide units interposed between the first and second blocks of repeating propylene oxide units. Such block copolymers may have the general structure (II):
  • the block copolymers of the above structure (II) may include from 20% to 80% ethylene oxide (EO) units by weight and have a molecular weight in the range from 2000 to 10,000.
  • EO ethylene oxide
  • the hydrophilic-lipophilic balance (HLB) be in the inclusive range of from 7 to 24.
  • the foregoing method of the present invention preferably includes adding at least 0.25 ppm (parts per million, by weight) of at least one ethylene oxide-containing compound to the aqueous system containing the surface, and more preferably includes adding to the system at least 50 ppm. It is contemplated that the foregoing method may be used to inhibit adherence of microorganisms in any system wherein a surface is in contact with an aqueous system. Examples of specific applications of the method include use in process and cooling water systems, pulping systems, and papermaking systems.
  • the present invention also is directed to compositions and a method of using those compositions to reduce the formation of deposits of water-borne materials such as, for example, silt and microorganisms, on surfaces in contact with aqueous systems.
  • the method comprises applying to the particular surface an amount of a multi- component composition comprising at least a polyoxypropylene-polyoxyethylene block copolymer and a biocide.
  • a multi- component composition comprising at least a polyoxypropylene-polyoxyethylene block copolymer and a biocide.
  • examples of the possible biocide component of the composition include glutaraldehyde, quaternary ammonium compounds, isothiazo ⁇ ne, carbamates, dibromonitrilopropionamide. and dodecylguanidine hydrochloride.
  • the multi-component composition may also include a dispersant such as, for example, one of the anionic polyelectrolyte dispersents conventionaUy used to disperse minerals such as clay ("clay dispersants”), e.g., an acrylic acid/AMPS copolymer.
  • a dispersant such as, for example, one of the anionic polyelectrolyte dispersents conventionaUy used to disperse minerals such as clay (“clay dispersants”), e.g., an acrylic acid/AMPS copolymer.
  • FIGURE 1 is a schematic view of the apparatus used by the present inventors to perform the Recirculating Water System (RWS) experiments discussed below;
  • FIGURE 2 is a plot showing the effect of addition of Pluronic P103 surfactant on bacterial adherence on PVC exposed to treatment for 24 hours as measured by colony forming units per square centimeter (cfu/cnr), each bar showing results from a single RWS run, and standard errors shown by brackets;
  • RWS Recirculating Water System
  • FIGURE 3 is a plot showing reduction in bacterial adherence onto PVC in Lab RWS as measured by cfu/cnr, wherein bars represent the mean reduction for two Lab
  • FIGURE 4 is a plot showing the effect of presoaking PVC substrata in a 0.1% solution of Pluronic P103 surfactant and then placing in a Lab RWS treated with 10 mg/L Pluronic PI 03 for 24 hours, as measured by cfu/cnr, and wherein each bar represents the percent reduction in bacterial adherence, brackets are standard errors, and 50 mg/L clay was added for Lab RWS treated with clay;
  • FIGURE 5 is a plot showing the reduction in bacterial adherence onto PVC in Field RWS experiments as measured in cfu/cnr. and wherein bars represent the mean reduction in single Field RWS treated with 50 mg L Pluronic PI 03 surfactant, and brackets are standard errors;
  • FIGURE 6 is a plot showing the reduction in bacterial adherence onto PVC in
  • FIGURES 7 and 8 are graphs depicting the weight of deposit (mg deposit) per gram of PVC fill as a function of the experimental treatment of the invention used; and FIGURE 9 is a plot showing the linear regression of the relationship between
  • the 96 Well plate/urease assay system (designated screening assay) was used for preliminary screening of surfactants. Those surfactants which performed well in the initial screen were then evaluated under more complex, dynaimc conditions in recirculating water systems (Lab RWS). Finally, a select number of surfactants were evaluated under actual cooling systems conditions, with an apparatus similar to the Lab RWS (designated Field RWS). These field studies were performed at a fossil fuel power plant in Pennsylvania using plant recirculating cooling water (river water makeup). b. Laboratory Screening Assay
  • a culture ofKlebsiella aerogenes (wild type isolate) was restreaked on a fresh plate of Standard Methods Agar. This plate was incubated for 24 hours at 37° C. 150 ml of sterile Trypticase Soy Broth contained in a tissue culture flask was then inoculated with a swab which had been streaked across the plate. This flask was then placed into a 37° C water bath and shaken at 80 rpm overnight ( 17 hours). As a rule, the culture was inoculated around 4:30 P.M. and removed approximately 9:00 A.M. the next morning.
  • a Corning 96- Well, round bottom, tissue culture treated polystyrene plate was used for the assay. While the culture was spinning down, individual treatments were prepared. Triplicate treatments for each dosage concentration were run. Treatments were added to each well prior to inoculation. After treatments were added, sterile phosphate buffered water (pH 7.2), followed by the bacterial culture were added to each well (except the negative control). Each well was then mixed, using the mix function on the automatic micropipettor (Matrix Technologies, Lowell, MA). Once mixed, the plate was incubated at 37° C for 24 horn's.
  • the Plate Reader (Dynatech MR5000 Automatic Microplate Reader, Dynatech, Chantilly, VA) was programmed for 51.7° C, equivalent to 37° C in the microwells. The plate was then removed from the incubator. The liquid was removed from each well by aspiration with a Pasteur pipette. After aspiration, sterile phosphate-buffered water was added to each well and aspirated again. This procedure was repeated thrice (a total of four washes). This step will remove any cells which are nonadherent on the well surface. The urease substrate reagent was then added to each well. The plate was then placed into the Dynatech Plate Reader and a colorimetric method developed to quantify presence of urease within bacterial cells was run. c. Lab and Field RWS Design
  • FIG. 1 The schematic of the apparatus used for both Lab and Field RWS is shown in Figure 1. It was comprised of a 20-liter volume polycarbonate tank (10) which contains a small polycarbonate tower (12). Water was pumped by recirculating pump (15) from the 8-liter volume sump (14) through a Biofilm Sampling Device (BSD) (16) at 1.5 gallons per minute (which equates to 2.5 linear feet per second) then back over the tower (12).
  • BSD Biofilm Sampling Device
  • the BSD ( 16) is shown enlarged in Figure 1 and was installed in water recirculating lines ( 18) in the position indicated.
  • the tank (10) also included
  • the tower ( 12) was constructed so that the water flows onto a "deck" (22) containing evenly spaced small holes, down through a fill pack of PVC fill material and down across slats (24), each of which contained one or more fill pieces (26).
  • a slat (24) and one fill piece (26) contained thereby is shown in a relative enlarged view in the circled portion of Figure 1.
  • the fill pieces (26) were made of PVC material (obtained from Munters Corporation, Fort Myers, Florida) and were attached to the slats (24) using stainless steel screws (28).
  • the Biofilm Sampling Device (16) contained multiple removable cylinders (30) (9/16 inch [14mm] I.D., 13/16 inch [20mm] O.D., 1/2 inch [13mm] long) constructed of CPVC material. Examination of the C-PVC material using Electron Spectroscopy for Chemical
  • R2A medium were purified, identified using the fatty acid profile analysis procedure, and frozen at -70° C. Each of these cultures was inoculated into R2A Broth, grown up at 30° C to turbidity, and then 1 ml from each was added to each LRWS.
  • the organisms identified were as follows: fia ⁇ Uus subtilis. Bacillus amyloliquefacians. Bacillus cereus. Pseudomonas saccharophila. with the remainder being unmatched gram negative organisms. Field RWS used indigenous microorganisms: therefore, they were not inoculated. d. Bulk Water Measurements
  • Table 1 Water chemistry measured in Lab RWS studies is shown in Table 1. This water was municipal tap water dechlorinated with 18 mg/l sodium thiosulfate. Table 2 shows water chemistry for Field RWS, made up with plant recirculating cooling water. Table 3 shows bulk water plate counts for both Lab and Field RWS.
  • the submersible recirculating water pump ( Figure 1 ) was turned off to stop flow through the BSD (16). .Alcohol sterilized pliers were then used to remove cylinders from the BSD. Each cylinder was first rinsed gently in sterile phosphate buffered water to remove reversibly attached cells prior to placing it into a sterile glass tube which contained homogenization solution and 3 mm glass beads.
  • This homogenization solution contained peptone-20 grams, Zwittergent-0.0067 grams (Calbiochem, La Jolla, CA), ethylenebis (oxyethylenentrilo) tetraacetic acid (EGTA)- 7.6 grams, tris (hydroxymethyl) aminomethane (Tris Buffer)-24.2 grams, and deionized water-200 ml, adjusted with 1:1 HC1 to pH 7 and autoclaved, after which it was diluted 1: 10 with sterile Butterfield Buffer, pH 7.2. The tube containing the cylinder was then vortexed at a speed of 10 on a Vortex Genie Mixer (Fisher Scientific, Pittsburgh, PA) for one minute. This "biofilm suspension” was then diluted and pour plated onto R2A medium (Difco Laboratories. Detroit, MI) and incubated for
  • This slurry was then pumped contbuously bto the LRWS sump at a rate of 2.0 ml per mbute which, when diluted with makeup water (bcludbg treatment) equated to a final clay concentration of approximately 50 mg/L.
  • Zeta potential measurements were determbed usbg a Zeta Sizer 3 (Malvern Instruments Inc., Southborough, MA). Contact angle measurements were determbed usbg a Kruss Processor Tensiometer K-12 (Kruss Instruments. Charlotte. NC). In both cases, measurements were made according to manufacturer's bstructions. Electron Spectroscopy for Chemical Analysis (ESCA) was performed usbg a Physics Electronics Laboratories PH3-5600 ESCA spectrometer. ⁇ . Experimental esults a. Screening Assay Results
  • Cationic, anionic, nonionic and amphoteric surfactants were all evaluated b the screening assay. These surfactants were selected to cover the broadest range possible of chemical structures, type of head/tail groups, ionic charge, and water solubility. Ethoxylated surfactants were among the surfactants considered, as well as other possible bacterial adherence reduction mechanisms, bcludbg dispersion by anionic agents or partitionbg via hydrophobic (or poorly water soluble) agents. Tables 7 and 8 present results of these evaluations. Each product was tested at decreasbg concentrations of surfactant until a dosage was found which did not prevent at least 90% of bacteria from adhering to the substratum. At 0.25 ppm product, there were 11 of the origbal 32 surfactants which provided greater than 90% reduction b adherence.
  • Figure 3 presents data for reduction b adherence when treated with 10 mg/l P103 surfactant over a period of 40 days. The data shows that the surfactant was most effective over the first two weeks of exposure after which efficacy declbes.
  • Figure 4 shows results of experiments run to exambe the effect of both clay feed and presoakbg of the substrata b a 0.1% solution of the PI 03 surfactant for 18 hours prior to exposure.
  • Presoaked and non-soaked CPVC cylbders were bstaUed b Lab RWS and exposed to the test conditions for 24 hours.
  • PI 03 surfactant was also fed at a contbuous concentration of 10 mg/L.
  • the data shows that whether or not the test systems contabed added clay, presoakbg provided a significant advantage.
  • the effect of presoakbg was similar regardless of whether clay was present. However, when cylbders were not presoaked. the addition of clay resulted b greater bacterial adherence (less reduction).
  • Figure 5 shows percent reduction b adherence when PVC substrata were exposed to 50 mg/L P103 surfactant over an extended time bterval b a Field RWS made up with plant recirculatbg coolbg water. The surfactant reduced adherence up to 14 days after which the effect was diminished. This is a similar pattern to what was observed b lab studies ( Figure 3) and bdicates that the wbdow of greatest efficacy b terms of minimization is approximately 30 days.
  • Figure 6 shows a comparison between PI 03, Igepal CO-620, and Tween 80 surfactants. P103 outperformed the other two surfactants, both of which had minimal effect on reduction. d. Studies Investigat e Mechanisms of Surfactant Efficacy
  • Table 9 presents data showbg the effect of PI 03 surfactant treatment on Zeta Potential of planktonic ceUs.
  • Table 9 presents data showbg the effect of PI 03 surfactant treatment on Zeta Potential of planktonic ceUs.
  • four samples of water from a Lab RWS were collected. Two of these samples were further boculated with cultures of bacteria (from a streak across an R2A plate count plate) b order to bcrease the number of cells b the sample.
  • PI 03 surfactant at 10 mg L
  • Zeta Potential was determbed on each sample. Results show first of all that Zeta Potential was much greater (larger negative number) b samples that were boculated. Number of cells obviously had a significant effect on this measurement.
  • addition of P103 made no difference b Zeta Potential, whether or not the systems were boculated.
  • Table 10 shows the effect of P103 surfactant on contact angle of PVC material.
  • strips of PVC were placed bto contabers containing either deionized (DI) water or water coUected from a lab recirculatbg water system (LRWS).
  • DI deionized
  • LRWS lab recirculatbg water system
  • the Silwet sample is a polysiloxane with pendent PEO grafts. It is believed that both components, the PEO and the silicone, will lower surface tension and alter the nature of biobterfaces.
  • the Neodol 25-12 surfactant is a linear alcohol ethoxylate having a hydrophilic head group of about 12 EO units, with a hydrophobic tail of 12- 15 carbons. The tail group, though considered linear, is sometimes branched with methyl groups. Apparently, higher EO levels are needed to give acceptable performance, notbg that Neodol 25-7, with an average of 7 EO, and Neodol 91-2.5, with a shorter tail and an average of only 2.5 EO, did not perform as well.
  • the Pluronics are block copolymers of ethylene oxide (EO) and propylene oxide (PO) segments having the general structure.
  • F68, F108, L62D, L64, and PI 03 are EO-PO-EO blocks.
  • the first type the higher HLB samples were slightly better, with the 25R2 (HLB 1-7) the poorest, though givbg acceptable performance at 94.4% reduction.
  • the second type of material (EO-PO-EO) seems to be better overall.
  • HLB seems to have a stronger effect, notbg that L62D does not work and has a very low HLB.
  • an HLB of 7 or greater seems to be desirable.
  • higher HLB values give greater water solubility. The results bdicate that higher HLB surfactants are more effective b reducbg bacterial adherence.
  • sorbitan monooleate surfactants which are modified with about 20 PEO units, also worked well. These types of materials have found use traditionaUy as dispersants and wettbg agents. This material has an bterestbg structure for this type of adherence assay due to the presence of its sugar or polyol component b combbation with its PEO component. Either of these or both may contribute to the observed performance.
  • the anionic and amphoteric surfactants showed no activity b this assay. These materials are not believed to contab EO or other functional groups which would readily deter adherence. Many of these are used as dispersbg agents, but it is apparent from the bventors' results that there is no dispersancy mechanism operable b this system. That is, the microorganisms are not deterred to any extent by the presence of anionic or amphoteric dispersbg agents.
  • the cationic surfactant Varine T showed good activity, but this may be due to some biocidal activity as well as adherence reduction properties. Both mechanisms are operable and cannot be partitioned from this study.
  • SUBST ⁇ UTE SHEET (RULE 26) Over an extended period of exposure, it was found that the surfactant was most effective initially, during the first two weeks of exposure. Between 3 and 4 weeks exposure, adherence reduction became bsignificant. The reduction b efficacy over time may be due to the surfactant film abrading off or biodegradbg, or due to some bacteria breaching the surfactant barrier and colonizbg the surface. Another explanation is that the surfactant bteracts with the surface, but does not fully cover and protect the entire surface - there are holes which aUow for bacterial adhesion to the surface. These cells then multiply and develop biofilms, unaffected by the surfactant.
  • VirtuaUy any process or coolbg water system subject to microbial fouling and biofilm formation could potentiaUy benefit from treatment with PI 03 surfactant.
  • Our findings have shown a clear benefit b reducbg bacterial adhesion onto pvc surfaces b recirculatbg coolbg water.
  • PI 03 would reduce or control microbial adhesion onto materials other than polyvbyl chloride.
  • treatment of recirculatbg coolbg water systems with PI 03 might be effective b reducbg microbial adhesion and biofilm formation onto heat exchanger and system pipbg surfaces, as well as aU coolbg tower fill material surfaces.
  • Pluronic surfactants are already used b spray washers used for metal cleanbg and surface finishing as antifoams. They may also provide an additional benefit by reducbg microbial adhesion.
  • clay and other inorganics are molded b a water-borne process, foUowed by heatbg and other final steps.
  • the PI 03 may assist b this process to prevent microbial adhesion.
  • the PI 03 may act both as an agent to reduce microbial adhesion and as an optical brightening agent.
  • P103 may be useful b mouthwashes. sbce the PEO surfactants are currently used for this application.
  • the PI 03 surfactants would provide the benefit of providing an effective product with less foam than other PEO surfactants.
  • the use of PI 03 also may inhibit the foulbg of water craft, ships, and other structures which reside b water, where it is necessary to prevent attachment of microorganisms.
  • the foregobg studies were initiated to bvestigate the effect of surfactants on bacterial adhesion.
  • the studies ' purpose was to determbe whether and to what extent surfactants might minimize bacterial adherence onto PVC material.
  • the ultimate btent was to provide the first component of a treatment scheme to minimize fiU foulbg by minimizing the microbial component.
  • the studies' results bdicate that nonionic surfactants of the EO PO configuration were effective b minimi ring adherence b both lab systems and under field conditions.
  • PVC high efficiency coolbg tower fiU material has been shown to foul rapidly with water-bome s ⁇ t and microorganisms.
  • the foulbg deposits formed are complex and difficult to either prevent or remove.
  • the clay dispersant used was an acrylic acid/AMPS copolymer.
  • the biocide used was glutaraldehyde.
  • an additional nonionic surfactant mixture b combbation with the clay dispersant was also tested.
  • the site chosen for the experimental work was a power plant located on the Monongahela River b Pennsylvania.
  • the plant uses the river as makeup water for its recirculatbg coolbg water. Because it is a surface water source, it would be expected to carry a variable silt load, dependbg upon season and weather related run-off events.
  • Exambation of many samples of fouled PVC fiU material from coolbg towers b the United States by Calgon laboratories revealed that those plants receivbg surface water makeup from fresh water rivers b the eastern/southeastern U.S. contabed a significant clay component.
  • Experiments were then designed to expose PVC material to a side stream of Monongahela River water during Summer and FaU months, when sUt loadbg and biofoulbg would be expected to peak.
  • the recirculatbg water system (RWS) apparatus used for aU experiments is shown b Figure 1 and is described above b connection with the bacterial adherence studies.
  • Recirculatbg water systems were bstaUed at the power plant site. Each system contabed 8 liters of Monongahela River water which was contbuously added to provide a retention time of 48 hours. Water temperatures b the RWS averaged about 30° C. The flow of recirculated water over the mini-tower b the RWS was controUed by a screw clamp so that each RWS had a similar flow over the exposed fiU pieces.
  • PVC fiU material was obtabed from Munters Corporation (Fort Myers, FL).
  • AU stock solutions were made up b deionized water and concentrations were based on a product weight, not on an active basis.
  • the biocide used b this case was
  • Acryhc Acid AMPS was a combbation of acrylic acid (60%) and 2-acrylamido-2-methylpropylsulfonic acid (40%). For this work, a 28% active solution was used.
  • the nonionic surfactant blend was comprised of the followbg components: 14.55% nonyl-phenoxy-polyethanol, 14.55% polyoxypropylene-polyoxyethylene block copolymer, 1.99% low molecular weight copolymer, and 0.49% 3-5 dimethyl-2H- 1.3,5-thiadiazbe-2-thione. 21% salt.
  • the EO PO surfactant was a polyoxypropylene-polyoxyethylene block copolymer obtabed from BASF Corporation, Parsippany, N.J.
  • a BASF Pluronic PI 03 EO/PO block co-polymer surfactant was used.
  • the Pluronic co- polymers are discussed in detail above b connection with the bacterial adherence studies.
  • Makeup to each recirculatbg water system was pumped contbuously usbg a Masterflex pump (Cole Partner. NUes, IL).
  • Surfactant and dispersant solutions were made up b 20 liter Nalgene carboys by addbg stock solutions to the makeup water.
  • the biocide was added directly bto the sump of each RWS at a concentration of 60 mg/L (product basis).
  • the EO/PO surfactant and the nonionic surfactant blend products were added at a concentration of 10 mg L (as product), and the acryhc acid/AMPS at a concentration of 30 mg/L (as the 28% product).
  • a chemical analysis of the water coUected from the sump of the RWS is shown b Table 11. Planktonic heterotrophic plate counts on water coUected from the RWS averaged 2 X 10 6 cfii/ml for the first eight week experiment and approximately 1 X 10 5 cfii ml for the second.
  • the untreated RWS tended to have somewhat lower plate counts than the treated systems though not significantly so. Otherwise, treatments had no obvious effect on the counts.
  • Results are for a single sample collected from the Recirculating Water System sump after 8 weeks exposure to the treatment. After the exposure btervaL 3 fill pieces, each taken from a different level b the mini- coolbg tower, were removed and processed.
  • fiU sample biofilms were analyzed for ATP by placbg fiU pieces bto sterile glass tubes containing a homogenization solution and vortexed on a Vortex Genie Mixer (Fisher Scientific, Pittsburgh, PA) at a settbg of 10 for 1 mbute.
  • Weights were calculated per gram of clean fiU weight.
  • Figures 7 and 8 show the affect of treatments on deposit formation. Data shown b Figure 7 were coUected during an eight week exposure period b July and
  • Tables 12 and 13 below show the effect of treatments on biofilm ATP concentrations. As b Figures 7 and 8, these data represent results from two separate experiments. Data shown b Table 12 were coUected at the completion of an experiment run b July and August; data b Table 13 from an experiment performed b October and November. The data was highly variable and did not bdicate that any of the treatments provided a significant reduction b biofilm ATP levels.
  • Figure 9 shows the lbear regression of the relationship between ATP accumulation and deposit accumulation on fill material.
  • the EO/PO surfactant may be exhibitbg dispersant properties, sbce there was no measured reduction b microbial adhesion by the treatment.
  • the data presented here demonstrate that treatment with the surfactant does b fact reduce sUt accumulation onto the PVC surfaces.
  • the EO/PO surfactant dosage b this study (10 mg L) was below the level shown to be effective b eariier studies with surfactant alone for prevention of bacterial adhesion, which showed that between 30 and 50 mg/L were requires, and that this reduction b adhesion was beneficial for only the first approximately thirty days of exposure. Results of the present study support those conclusions. Biofilm ATP concentrations were unaffected by the treatment b the present bventors' studies, even with the supplemental biocide. It would appear that the effect of the EO/PO surfactant b reducbg deposit accumulation is not due primarily to an effect on bacterial adhesion but rather to the control of clay deposition, either by dispersbg that clay prior to association with the biofilms. or somehow reducbg the efficiency with which it sticks to the biofilm surface.
  • Spray washers used for metal cleanbg and surface finishing may have resultbg buildup of soU deposits and bacterial growth.
  • Household and bdustrial washers may have a similar buildup.
  • the surfactant-biocide combbation may help to control this problem b each of these systems.
  • clay and other borganics are molded b a water-borne process, foUowed by heatbg and other final steps.
  • Clay is also used as a fiUer b plastics or co ⁇ osites.
  • the use of the surfactant b combbation with the biocide may serve as a processbg aid to control deposition and microbial growth.
  • These surfactants combbed with appropriate biocides might be useful as dental antiplaque agents, where bacterial growth and borganic deposits form on dental surfaces.
  • these may be useful b denture adhesives, which are water-borne materials often containing borganic fiUers like clay. FbaUy, this technology may inhibit foulbg of water craft, ships, or other structures which reside b water, where it is necessary to prevent attachment of organisms.
  • biocides besides glutaraldehyde might work equaUy weU b these applications, when used at concentrations adequate to kill biofilm bacteria.
  • Such biocides might bclude quaternary ammonium compounds, isothiazolbe. carbamates, DBNPA (dibromonitrilopropionamide), or dodecylguanidbe hydrochloride (DGH).
  • DBNPA dibromonitrilopropionamide
  • DGH dodecylguanidbe hydrochloride
  • welL nonionic surfactants of the EO/PO configuration other than Pluronic PI 03 would be expected to act b similar fashion.

Abstract

L'invention concerne un procédé, destiné à inhiber une colonisation microbienne d'une surface en contact avec un système aqueux, ledit procédé comprenant l'adjonction à ce système d'une quantité d'au moins un composé comprenant des unités répétées d'oxyde d'éthylène. Une composition à plusieurs composants, comprenant un copolymère bloc polyoxypropylène-poloxyéthylène et un biocide, est également décrite, ainsi qu'un procédé comprenant l'application de cette composition sur une surface en contact avec un système aqueux, en vue de réduire la formation de dépôts sur cette surface.
EP97945310A 1996-09-27 1997-09-26 Compositions et procedes destines a reduire la formation de depots sur des surfaces Withdrawn EP0888251A1 (fr)

Applications Claiming Priority (9)

Application Number Priority Date Filing Date Title
US929980 1986-11-12
US2690996P 1996-09-27 1996-09-27
US2684496P 1996-09-27 1996-09-27
US26844P 1996-09-27
US26909P 1996-09-27
US890909 1997-09-15
US08/929,909 US6039965A (en) 1996-09-27 1997-09-15 Surfanctants for reducing bacterial adhesion onto surfaces
US08/929,980 US6139830A (en) 1996-09-27 1997-09-15 Methods for reducing deposit formation on surfaces
PCT/US1997/017355 WO1998013305A1 (fr) 1996-09-27 1997-09-26 Compositions et procedes destines a reduire la formation de depots sur des surfaces

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