SA08290598B1 - Process and Apparatus for Reducing Biofouling on Membranes of Pressure-driven Membrane Separation Processes - Google Patents

Abstract

Abstract: The present invention relates to a process and apparatus for reducing biological contamination on membranes during the purification of an aqueous medium by means of pressure-driven membrane separation processes. Components causing biocontaminants are removed from the aqueous media for purification by attaching to sacrificial filters (3) placed in the feed line (2) of a pressure driven membrane separator (4), where the device includes a filter housing containing synthetic complexes as filter material The components of the aqueous media causing biocontamination for the synthetic complexes that are carried out have an affinity as high as their affinity for the membrane of the pressure-driven membrane separator. Figure 1.

Description

_Y_ A process and apparatus for reducing biological contamination on membranes of pressure-driven membrane separation processes

Process and apparatus for reducing biofouling on membranes of pressure-driven membrane separation processes FULL DESCRIPTION BACKGROUND The present invention relates to a process for reducing biofouling on membranes during purification of an aqueous medium by means of pressure-driven membrane separation processes; It also relates to a device to perform this operation. water purification; Ge Pressure-driven membrane separation processes are often used to isolate drinking water eg by desalination of sea or brine; or in the purification of waste water; or in the treatment of boiler feed water; Or in high-ell waterproofing or in the production of concentrated aqueous solutions in the pharmaceutical industry and in the food industry. due to adhesion of particulate organic or inorganic components and microorganisms contained in the aqueous medium to be purified to the membrane of the membrane separation process; Wd often forms outer layers on these components. Based on the density of the labs these outer layers; The permeability of the outer layer 0 system and the membrane may be reduced to the extent that it is necessary to increase the operating pressure ratings on the feed water side or it will not be possible to achieve the required volumetric productivity of the membrane separator; to maintain the required performance. This loss of performance is called pollution. Sel is not particularly favored; i.e. the loss of performance associated with the formation of a coating due to the adhesion and growth of microorganisms (GES) Jie microalgae, fungi or protozoa

animal or bacteria. This outer layer is called Aide. Partially adherent microorganisms may be used as nutrients or metabolize organic matter or adherent organic matter retained in the aqueous media. The metabolic products formed in this condition have a very low permeability and adhere firmly to the membrane; aps oo are hardly removed even by chemical cleaning; Or they are not removed at all from the surface of the membrane. The formation of the non-reversible outer layer results in a persistently low permeability of the membranes which makes replacement of the membranes necessary. Until now; Several security measures have been taken to avoid this irreversible outer layer or to minimize its consequences. So far, biocides or biostatics are often added to the water 0 to be treated; to avoid biological contamination; These substances are intended to kill or inhibit the growth of microorganisms. These additives are mostly effective only at higher concentrations; It may remove the existing outer layers only unsatisfactorily or not at all; It can destroy membranes and their performance. in addition to; It is known that when biocidal chemicals Jie are used to chlorinate water; The organic components are oxidized in the Al 1 media and as a result their overall bioavailability increases as a biofilm feeder and biocontamination occurs more frequently in areas where the biocide is used. Judy AT Standard for the avoidance of biocontamination in the pretreatment of water to be purified to remove organic matter that acts as a biofilm feeder and/or biofilm-forming microorganisms.

_ ¢ — therefore; In the water treatment process; Jie filtration processes are used with or without the use of pre-flocculation and pre-sedimentation; bioactive impurities or pre-filters. GENERAL DESCRIPTION OF THE INVENTION: The present invention provides a process and device by which biological contamination can be reduced on membranes of pressure-driven membrane separation processes in aqueous media purification.

The object of the invention is achieved through a process to reduce biological contamination on the membranes during purification of the aqueous media by means of pressure-driven membrane separation processes. This process is characterized by the removal of bio-contaminating components present in the aqueous media at least partially from the medium (A) in a first step; The removal process is accomplished by binding these components to a filter material as it flows

0 through one or more so-called sacrificial filters; (which are filters that include a filter housing containing permeable synthetic collectors as a filter material) where the components of the aqueous medium causing bio-contamination with respect to the permeable synthetic collectors have quite a high affinity for the membrane of a pressure-driven membrane separator” and accordingly are purified The filtrate is isolated in the first step by pressure-driven membrane separation processes.

\o The aqueous medium to be purified can be; For example « is superficial ela; like sea water or salt water; or tank water, or river water, or np from industrial wastewater, or municipal water; Or service water and process water Jie boiler feed water or cooling water or emulsions. However; The water can be solvents or fruit juice. The membrane separation process can be operated by pressure; For example; Reverse osmosis (RO) process or filtration to size

(MF), ultrafiltration (UF) or ultrafiltration (NF) vy. In a first step of Sl the aqueous media components causing bio-pollution from the medium (Ally) are done

Because oo through its binding in the sacrificial filters. and then; The first-step filtrate is purified in a pressure-driven membrane separation process. and by the fact that the isolated filtrate contained in the first step contains trace components that cause biocontamination; or does not contain these ingredients at all; The purification process carried out by membrane separation processes is rarely hindered; or not at all impeded by biological pollution. As a result; 558 increases the survival of membranes for pressurized membrane separations© and unit performance can be maintained to implement the pressure controlled membrane separation process at the lowest cost. Aqueous media biocontaminant components are microorganisms that can lead to biofilm production; their metabolites; As well as organic materials that can be used by microorganisms as nutrients, such as carbohydrates, polysaccharides, proteins, or low molecular weight obligate substances.

Good structural conditions in the form of a glade prevail at least within proximity filters to bind bio-contaminant components present in the aqueous media as in the case of membranes for separating processes.

Subsequent pressure managed diaphragms. The limiting factors in the attachment of aqueous media constituents to the surface are the transport potential with which the constituents pass to the surface as well as the adhesion potential with which the constituents that have moved to the surface remain attached to the surface. Jil capability depends primarily on flow conditions. The adhesion potential depends primarily on the surface properties of the components and the surface properties and flow conditions determine the separation potential. Separation potential means the ability to separate a surface-bound particle from the surface by a flow. Binding to the sacrificial filter dng generally begins due to mechanical and/or specific adhesion.

Specifically, in the case of qualitative adhesion; The electrostatic forces, By Dargals, between the aqueous media component and the filter material play an important role. The development of hydrogen bonds causes bonding processes to occur. These mechanisms are determined by the surface properties of the aqueous media components and the surface properties of the sacrificial filter material.

0 A comparison of the affinity of the aqueous media components that cause biocontamination to the sacrificial filter and to the pressure-driven membrane separation process membrane can be made by; For example, Ja give the following surface properties of the sacrificial filter and the adhesion film:

- the insolubility in water or the wettability achieved by measuring the contact angle - the surface charge; which is obtained by measuring the zeta capacity.

Affinity in this context means the willingness of biocontaminants to bind to a surface. The values of these surface properties for the sacrificial filter should not differ from the corresponding value for the membrane by more than JE and preferably not more than AF and specifically preferably not more than JY and most preferably not more than + JV preferably Wad that the values of these surface properties for the proximity filter align exactly with the corresponding membrane properties of the pressure-driven membrane separator.

1 The affinity of the contaminant aqueous media components present in the sacrificial filter must match the affinity of the membrane components. It is preferable that the affinity of the biocontaminating components is higher for the sacrificial filter than for the membrane. in addition to; When the stream passes through the sacrificial filter; Flow conditions are bound to prevail so that

VY —_ — transport potential to the surface is at least high and separation potential is low at dle pressure-operated membrane separation” for biocontaminant metamedia components. Lave Components of biocontaminating aqueous media have an affinity for the sacrificial filter i

0 corresponds to or exceeds its affinity for the membrane and at the sacrificial filter more favorable flow conditions prevail for the binding than at the membrane of the membrane separating process; It is preferable that the components are attached to the sacrificial filter. The greater the surface area of the sacrificial filter available for binding; The bio-polluting components have been completely removed from the aqueous medium to be purified. The more positive the flow conditions of the link; slow flow The space in which the flow passes is narrowed.

0 eg (JU) Organic nutrients required to create a biofilm such as carbohydrates or polysaccharides; Jie alginate; are removed from the aqueous medium by the wafer filter before reaching and binding to the membrane. After that, they cannot form Biofilm on Membrane Due to its lack of nutrients or Bhai very low supply of nutrients, biofilm will form very slowly.

ve based on (Bae) in the process presented in | of the invention; it is impossible or difficult for biocontamination to occur on the membranes from a pressure-driven membrane separation process in which the filtrate of the sacrificial filter is purified.

m - as a result of preventing or reducing the binding of aqueous media components causing bio-contamination to the membrane surface; No increase in operating pressure occurs; Or, a slow increase in the operating pressure may be required to ensure a specified performance level of the pressure driven membrane separation process is achieved. in addition to; Wasted labor times cleaning the pressure driven membrane separator can be avoided; Or oo can reduce the number of times this operation occurs. As a result of the small number of chemical cleaning operations needed; The expected period of survival of the membranes increases. to avoid slipping of bio-contaminant aqueous media components through the sacrificial filter; 508 dimensions must be specified for the surface area available for bonding operations. In terms of (AY) the size of the sacrificial filter should be as small as possible to reduce capital costs. The choice of the surface area size of the 0 - sacrificial filter used to shal the cleaning process falls within the context of these preconditions. For the kinship candidate; A filter material is used in the form of permeable synthetic complexes (0565). Permeable synthetic aggregates consist of a porous polymer foam that has a large number of internal droplets and thus has a large internal surface area. These pools can be made of different materials and in different shapes; It can be made, for example, from polyurethane or polyamide. And on the sea 1 Tvlidi; A single PSC particle was generated in a cylindrical shape having a size of eg 7 * © mm. PSCs have been described in references; For example: “Lehr- und Handbuch Wasserversorgung, Band 6, Wasserautbereitung - Grundlagen und Verfahren” [Water Supply Textbook and Handbook, volume 6, Water Treatment - Fundamentals and Processes], pp. 174-183, Oldenburg Industrieverlag GmbH, Munich, Vienna; DVGW (publishers) (2004). 0 70.1

In the filter bed made of a collection of single PSC particles; The flow does not pass around so that it is withdrawn; Rather, it also passes through it in a way in which the components of the aqueous medium to be purified are not only attached to the outer surface, but also to the inner surface. Since the internal space between individual PSC particles acts as a bypass of the pore space of individual PSCs; Inside the filter bed made of PSCs oo only a small pressure drop occurs when the flow passes through the filter bed. As a result of the bypass; The flow velocity within alae PSCs is significantly lower in the internal space between individual PSCs; As a result; In the Jala pores of PSCs, optimal conditions are provided for the binding of biocontaminant components. in the sacrificial candidate himself; Biopollution occurs due to the binding of components of aqueous media causing -0 biopollution. and in areas of the sacrificial filter where there is a thin biofilm; Components of aqueous media suitable as nutrients for the biofilm can be directly adsorbed from the aqueous medium or into the biofilm and then trophically Lelia. As a result of the growth of biofilms, filtration and association of particles and dissolved components present in the aqueous medium; With the increase in operating time; at the sacrificial candidate; The operating pressure required to achieve a specified level of performance increases and the sacrificial filter's 10 filtrate flow quality decreases. The effluent quality of the isolated filtrate in the first step of the process according to the invention indicates the activity of All) the biocontaminating components from the aqueous media in the first step. The quality of the flowing current can be measured in several ways; such as turbidity as defined by ISO 1707; Jie dissolved organic carbon (DOC) for aqueous media as specified in 84 14 (DIN EN) or Jia Specific Absorption Coefficient © at 754 (SAK254) jie ili as specified in 38404-3 ( DIN or Jie density indicator

- 1.

Silt (SDI) as specified at 1-4189 85711. Preferably specified as 5816254 and turbidity on line

operating in this case.

As a result of the removal of bio-contaminant aqueous media components as they pass with the flow through the filter

sacrificial Their concentration is reduced in the filtrate released in the first step of the process according to the invention. With the increase in the use of the sacrificial filter; The effectiveness of the AY operation decreases since - as a result of the completion of an operation

Binding - The surface area available for the binding process is constantly decreasing. Accordingly; Streaming quality decreases

filter product. The proportion of bio-contaminant aqueous media components bound to the filter material is dependent

Qurbani on the type of ingredients and their concentration.

And based on the water to be treated; The minimum requirements needed to achieve the desired 0 quality of current flow can vary. When the quality of the filtrate flow released in the first step of the

process according to the invention with the desired minimum requirements; Some sacrificial filters are replaced

Or all with new sacrificial filters. relating to minimum requirements; For example; downwardly

Initial performance of the removal and turbidity process.

And as a criterion to start the replacement process” the initial level of removal is reduced by 7460 preferred by ve by 7700 most preferred by 7710 and most preferred by all by AY

The decrease in the initial performance level of the removal process is measured as a corresponding reduction in current quality

gusher. And therefore; For example; A decrease of 701 of the value corresponds to DOC or

SAK 254 with a 7101% reduction in removal performance.

the

_ 1 \ —

in addition to; The turbidity rate must be kept below a specified value; Since the sacrificial candidate;

In addition to the components of aqueous media causing bio-pollution; Retains particulate matter that is sequestered

in aqueous media. Characteristically, the specific value for turbidity is 1 unit of concentration

Formazine suspensions (FNU) preferably FNU 1.5 and most preferred). + FNU and in Ala the turbidity in the filter product exceeds the specified value; Tan the process of replacing filters

sacrificial.

It is preferable to monitor the quality of the filtrate flow of each sacrificial filter.” Jie monitors the turbidity rate and the rate of decline

in performing the removal process.

when the quality of the filtrate stream from the first step of the process according to the invention does not meet the 0 minimum requirements; All sacrificial filters can be replaced; Or the filters can be replaced

dl files only.

When only one sacrificial filter is used in the process; The quality of the filtered product stream must comply with the limit

The minimum requirements for the effluent stream quality of the first step of the process according to the invention.

When using a set of sacrificial filters; It is accepted that the filtration output of the pre-sacrificial ve filters has an inrush stream quality that is less than the minimum requirements for stream quality

flowing in the first step; As long as the following dimensional sacrificial filters contribute to fulfilling the limit

Minimum requirements for the quality of the current flowing in the first step. Based on the number of filters

the sacrament and its place; The minimum requirements for the quality of the current flowing at

different levels; However, it is preferable to meet the minimum requirements for the first step

l

- 11 -

of the process according to the invention. In each case; The filtration output of the dimensional sacrificial filter must match

The latter with minimum first step requirements.

Wad can specify a limit value for the rate of pressure drop at the proximity filters which is;

when it is exceeded; It leads to the replacement of the sacrificial filter of interest. The determination of the oo rate of unacceptable pressure drop depends on the particular operating conditions. Preferably low

in pressure at a sacrificial filter is less than 1 bar and it is particularly preferred that it be

less than 000 mbar.

The present invention Wad relates to a device for carrying out the process By of the invention; Includes mid feed line

SW to be purified.” This feed line leads to a pressure driven film separator; The device 0 is characterized by the fact that at least one sacrificial filter flows ope the aqueous medium to be purified in a line

nutrition; Each sacrificial filter can be pulled from the feed line; There are at least two devices to set

The sacrificial filter is within the ddl line where the sacrificial filter comprises a full filter housing

with permeable synthetic complex particles; Where the affinity of the components of the aqueous medium causing bio-pollution

For the permeabilized synthetic complexes is quite high as is their affinity for the membrane of the pressure-operated ve membrane separator. The sacrificial filter includes a filter housing that is filled with filter material PSC comprising the housing charge

the candidate; It is also called a filter layer; In this case it is a collection of particles

individual PSC.

Sacrificial filters are placed in the feed line in such a way as to allow the flow of all the aqueous medium to be purified

through it on its way to a pressure-driven membrane separator.

AR

SJ - At least one sacrificial filter must be placed in the feed line; although alternatively two, three, four or more sacrificial candidates may be placed in succession or in parallel. axe supports sacrificial filters; For example; Depending on the loading of the medium to be purified with the biocontaminants or the performance required for the following pressure managed membrane separation process.

0 Each sacrificial filter can be removed in a simple way from the feed line. when it is necessary to replace the sacrificial filter; It is removed from the feed line and a new sacrificial filter is inserted into the feed line. The new sacrificial filter can be filled with new, previously unused PSC filter material. Alternatively, it may be filled with the filter material PSC produced from the sacrificial filter already removed and cleaned previously. inside the feed line; There are at least two devices for placing the sacrificial filter in the feed line. ally at

A 0 at least one sacrificial candidate; It is ensured that there is at least one sacrificial filter inside the feed line through which all the aqueous medium to be purified flows. The removal process can be completed while the pressure driven membrane separator is in operation or after the unit is closed. It is preferable to perform removal during operation to avoid loss of production rate due to waste of time. PSCs are the filter material contained within the sacrificial filter. The material and structure of PSCs are of such a nature as to allow compatibility of flow conditions and the possibility of

ve adhesion to the sacrificial filter with properties at least corresponding to that of a pressure-driven post-membrane unit membrane. Preferably, PSCs should be composed of the same type of material; Preferably from the same Bole membrane as the pressure driven membrane separator. According to another embodiment, PSCs consist of a support material coated with one or more of these materials. The supporting material is; For example JB in polyurethane; Law The outer layer consists of; For example; of polyamide, polyethersulfone, polyvinylidene fluoride or

0 - Polysulfone.

_ $ \ _ Thanks to the porous structure of PSCs in sacrificial filters, the particulate components of the SL medium are largely removed through filtration. Consequently, particulate matter contamination is greatly reduced in a pressure-driven membrane separator. There is a possibility that pressure PSCs in sacrificial filters up to different limits and thus the flow conditions and the filtration process change.Devices can be provided between the filter (Jil) and the membrane separation units (lad) by pressure through which

Addition of biocides or biostatics to the penetrating material of the sacrificial filter for catia extermination or devices for the extermination of germs by ultraviolet light. Aida explanation of the drawings Figure (1): A schematic form of the Gay device of the current invention for water purification.

Detailed description Figure (1) shows the feeding of the medium (Sell) to be purified (0), which in this case is untreated water, via a feed line? Reverse osmosis unit (RO). The pure membrane window material 7 is removed from the pressure operated membrane separator; via an exit line

_ Membrane Penetrant © and the captive material A is removed via the exit line of the membrane retainer 1. The flow directions of the aqueous medium to be purified 1, the membrane permeable substance 1, and the membrane retainer A are indicated by arrows at Feed line oF, exit sald line) membrane window © and membrane retainer exit line 0.0

a

0

In the oF feed line there is a sacrificial filter © that is filled with permeable synthesis complexes preferably composed of the same membrane material as the membrane separator ;. All aqueous medium to be purified 10 flows on its way to a membrane separator; Via sacrificial filter ©. Heal mounts are provided for placing the sacrificial filter in the feed line. Sacrificial filter is installed? In the feed line ¥ by ela 4. At another point oo in the feed line oF there is a second holder 01 in the feed line oF into which another sacrificial filter © can be inserted as needed. Measuring systems for monitoring filter leachate turbidity (SLA) and rate of pressure drop at sacrificial filters; rate of pressure drop are not presented.

and permeability membrane separation unit.

Claims (1)

— = 3 __ protections 1-1 Process to reduce biological contamination on membranes during aqueous media purification by means of pressure-driven membrane separation processes; This process is characterized by the removal of the Y - components. ,- . £ Ally is present in the aqueous medium in at least part of the medium » - aqueous; in a first step; where the AY process is accomplished by coupling these components to a filter material: when it flows through one or more filters that have a filter housing containing On permeable synthetic complexes as a filter material and where the components of the aqueous media © that cause bio-pollution for the permeable synthetic complexes have a high affinity just like their affinity 4 for the membrane of the pressure-driven membrane separator 'and accordingly the filtrate product is purified isolated in the first step by pressure-driven membrane separation processes. For 1*?- the process according to claim (1); is characterized by the fact that the implemented synthetic complexes consist of Y of the same material; As a pressure-driven membrane separation process membrane. =F) operation under any of the preceding claims; It is characterized by holding the turbidity Y measured as specified in ISO 701717 of the first step isolated filtrate ¥ at a value below the cut-off value of FNU 1 preferably +0, for 1101; and more; In particular preference, + FNU 1 +- operation according to any of the foregoing claims; It features a filter replacement that does not include a filter housing that contains synthetic collectors implemented as filter material a - yy , which are replaced when the inrush current quality of the first step does not meet the minimum requirements. 1*- A device for carrying out the process in accordance with any of the claims from (1) to (;); comprising Y feed line (Y) of the aqueous medium to be purified of) and this feed line leads to the unit Pressure-driven membrane separation (8) The device is characterized by at least one filter being placed (3); oye flows the aqueous medium to be purified which includes a filter housing which is charged with synthetic collectors carried out as filter material placed in the feed line oY) Each filter (7) can be withdrawn from the oY feed line and there are at least two devices (5; and 10) 1" for placing the filter (©) into the oY feed line where the filter includes (3) on a filter housing A filled with permeable synthetic collector particles, whereby the affinity of the biopolluting components of the aqueous medium 4 for the permeable synthetic collectors is just as high as for the membrane of the pressure-driven membrane separator unit 0 (4). -1+1 The Gag of protection (0) is characterized by the pressure driven membrane separator Y (5) being a reverse osmosis unit.