Methods, compositions and systems for controlling fouling of a membrane

Inactive Publication Date: 2011-05-12
NOVOZYMES BIOLOGICALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0017]In one aspect, the present invention provides a method of improving permeability or flux of a membrane used in a process, comprising su

Problems solved by technology

Although membrane systems for water treatment and purification have been in use for decades, the employment of MBR systems as a widespread solution for water and wastewater treatment has generally been disregarded in favor of more conventional biotreatment plants.
One significant reason for such disregard is that MBR systems are often comparatively more expensive than conventional treatment systems.
One major drawback to membrane filtration processes is membranes tend to foul.
As the membranes foul, the permeability of the membranes decrease, and the effectiveness of the whole process is reduced.
However, air scouring significantly increases operating costs and is not completely effective at maintaining adequate critical flux rates.
These methods are energy-intensive and not applicable to all membrane types.
However, frequent chemical cleaning is costly due to the loss in system operation time, decreased life expectancy of the membranes, and large consumption of cleaning chemicals.
However, chemical cleaning cannot remove all permanent or irreversible fouling substances and residual resistance of the membrane remains.
This residual resistance or “irrecoverable” fouling is t

Method used

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  • Methods, compositions and systems for controlling fouling of a membrane
  • Methods, compositions and systems for controlling fouling of a membrane
  • Methods, compositions and systems for controlling fouling of a membrane

Examples

Experimental program
Comparison scheme
Effect test

example 1

Method for Screening Candidate Strains Capable of Reducing or Preventing Anti-Fouling in MBR Systems

[0145]Candidate strains were grown and cultured over an approximately 16 hour period subject to shaking at 25° C. in 1× Lysogeny Broth (10 g Tryptone; 5 g yeast extract; 1 g NaCl, and deionized water to 1 liter). Candidate strains were then counted using a hemocytometer and then serial diluted to a concentration of 1×103 cells / ml. Each well of a PVDF (poly(vinylidene fluoride))-bottomed 96-well plate (Millipore® no.: MSGVS2210) was filled with 100 microliters sterile 0.1× Lysogeny Broth. 100 microliters of the diluted candidate strains were added to the well. Those wells not including the addition of candidate strains were filled with 100 microliters sterile 1× Lysogeny broth. The 96-well plate was sealed with Breathe Easy® plate sealing film and placed on a plate shaker for approximately 16 hours at 25° C.

[0146]Pseudomonas aeruginosa PAO1 was selected as a biofilm-forming strain and ...

example 2

Lab Scale MBR Model (PVDF)

[0151]Lab-scale MBR systems were prepared using 0.5× Lysogeny Broth (5 g Tryptone; 2.5 g yeast extract; 0.5 g NaCl, and deionized water to 1 liter) flowing via gravity feed into an Amicon 8200 stirred cell ultrafiltration unit (Millipore, Billerica, Mass., USA) fitted with a 63.5 mm diameter (28.7 cm2 effective area) PVDF membrane that had been treated with 95% isopropanol prior to use followed by sterilization with 10% perchlorate. The filtration devices were inoculated with spores of strains of interest at a rate of 2×106 cfu / cm2 and incubated for 24 hours at 25° C. with constant stirring at approximately 125 rpm and a flow rate of 8.5 ml / hr / cm2. A control unit was prepared similarly but was not inoculated with a strain of interest. After 24 hours incubation, the units were inoculated with 2×104 cfu / cm2 Pseudomonas aeruginosa strain PAO1, a known biofilm forming organism and the flow-through rates of all concurrently running filter units were adjusted to ...

example 3

Lab Scale MBR Model (PES)

[0155]A lab-scale MBR experiment was constructed similar to that described in Example 2 utilizing a polyethersulfone (PES) membrane as opposed to the PVDF membrane. MBR units were inoculated as in Example 2 with either NRRL B-50141 or NRRL B-50136. A control unit was prepared similarly but was not inoculated with a strain of interest. Filter units were allowed to operate for 50 hours under the conditions specified in Example 2 and flow rates through the membrane were determined at regular intervals by measuring the volume of effluent discharge from each of the filter units over a 5 minute period. The measurement at the 48 hour timepoint (F48) was taken as the best indication point for flow comparison.

(F0−F48)*100 / F0=% decrease in flow

[0156]The efficacy of strains NRRL B-50141 and NRRL B-50136 at maintaining flow rates through a PES membrane was determined and is provided in Table 3.

TABLE 3Flow decrease% Pro-Strain (Genus, species)Numberat 48 hourstectionPseu...

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PUM

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Abstract

The present invention provides methods and compositions for improving permeability and flux in a membrane filtration system, especially in water or wastewater treatment processes.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit under 35 U.S.C. 119 of U.S. provisional application Nos. 61 / 259,936 and 61 / 369,801 filed Nov. 10, 2009 and Aug. 2, 2010, respectively, the contents of which are fully incorporated herein by reference.REFERENCE TO A SEQUENCE LISTING[0002]This application contains a Sequence Listing in computer readable form, which is incorporated herein by reference.FIELD OF THE INVENTION[0003]The present invention provides methods and compositions for improving permeability and flux in a membrane filtration system, especially in water or wastewater treatment processes.BACKGROUND OF THE INVENTION[0004]Membrane bioreactor (MBR) systems are becoming an increasingly popular solution for water and wastewater treatment. Although membrane systems for water treatment and purification have been in use for decades, the employment of MBR systems as a widespread solution for water and wastewater treatment has generally been disrega...

Claims

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Application Information

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IPC IPC(8): A01N63/00A01N63/04A01P1/00
CPCC02F3/1268C02F2303/20C02F3/34Y02W10/10C02F3/2853
Inventor DRAHOS, DAVIDPETERSEN, SVEND
Owner NOVOZYMES BIOLOGICALS
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