110625 NEU Beschreibung LEGIO.module 2 EN

LEGIO WATER GmbH Schlattgrabenstraße 10 D-72141 Walddorfhäslach Telefon (+49) 0 71 27 – 89 05 47 Fax (+49) 0 71 27 – 89 05 48 e-mail: [email protected] www.legio.com

LEGIO LEGIO.module® with LEGIO.bore® (ultra filtration me mbranes)

The membranes of LEGIO.modules® provide significant advantages for the water filtration of drinking water and industrial recycling water.

These ultra filtration membranes are called LEGIO.bore®. They are designed with 7 capillaries in each single tubular hollow fibre membrane. This breakthrough technology of LEGIO.bore® eliminates the precious main cause of failure of hollow fibre membranes in the extremely challenging process of water treatment – the membrane rupture. The LEGIO.bore® inside the LEGIO.modules® has a superior quality and high performance in the process of water treatment. It is possible to implement and install the LEGIO.modules® into systems, which are originally designed for other types of membranes.

The LEGIO.bore® consists of 7 channels of 0,9 mm-inner-diameter inside one fiber. The membrane is a new generation of UF-hollow-fiber-membrane, which combines strength, high hydrophilic and very low energy consumption during operation. The membrane fiber is about 20 times stronger than the known and conventional polyether sulfone (PES) single bore fiber.

The LEGIO.modules® are unique elements with a distinctive ultra filtration technology. These LEGIO.modules® can make any water nearly free from microbiology without adding further disinfecting chemicals. Due to the extremely small filter pores inside the LEGIO.modules®, viruses and bacteria as well as chlorine-resistant germs can be removed. With the LEGIO.modules® a revolutionary drinking water purification starts. The membrane combines seven single capillaries in just one fiber, thus forming a compact support structure. The advantage of LEGIO.modules® compared to conventional single bore is, they can offer much more stability and fiber breakage can be avoided. This means maximum security in operation and substantial saving regarding repair and maintenance.

The LEGIO.modules® give customers several advantages such as: optimized flow distribution, effective cleaning performance capabilities and variable operation modes at very low pressure, which guarantees high quality treated water. Furthermore the LEGIO.module® concept requires less piping, valves and process technology and consequently less installation space, which leads to savings in investment costs and installation complexity. These factors make the LEGIO.modules® intriguing for private users, municipal water works and industrial customers.

Single-bore-membrane

LEGIO.bore®


LEGIO Broadly taking into account the known water treatment applications in industrial and municipal installations, LEGIO.modules® are normally selected with a pore size of approximately 0,02 microns (millionths of a meter), in aims of providing a complete barrier against particles larger than its pore size - whilst rejecting bacteria and viruses, which may be found in the feed water. Comparing this to micro filtration (dividing line between 1,0 – 0,1µm), which removes pathogens only to a small extent, the micro filtration is used for other applications aside from the drinking water treatment, because it is not an effective virus barrier. So the ultra filtration is the most effective barrier against bacteria and virus.

The separation scope of LEGIO.modules® and also of conventional treatment devices, such as granular media filters, is very different. Media filters have a significantly bigger nominal pore size and rely on a gravity filtration mechanism. In comparison with conventional filtration, LEGIO.modules® operate on a surface removal mechanism resembling a fine sieve with a high uniform pore size. Particles larger than the pore size are rejected and may not go through the membrane surface. That’s one of the main reasons, which makes LEGIO.modules® ideal for meeting stringent filtration quality requirements and, to some degree, independent from the provided feed water quality.

Besides its nominal removal efficiency and absolute removal rating, LEGIO.modules® allow the complete construction to be more compact by needing smaller plant-footprint, enabling higher automation and risk-free installation and parallel a lower or no chemical dosage is needed.

Separation layer with a pore size of 0,02µm


LEGIO The differences – What’s the essential?

1) LEGIO® – Single bore / LEGIO.bore®

UF membranes can be either produced as flat sheets or as hollow fibers. Flat sheet membranes are mainly installed in specific processes and difficult waste water applications; whereas hollow fiber membranes dominate water treatment applications.

Currently there are mostly conventional and commercial hollow fibers on the market with only one capillary per fiber, which are called single bore fiber. The capillaries inside each fibre may have an inner diameter of 0.8 mm or smaller. The fiber diameter presents an optimum of partly conflicting targets like high packing density, easy back-wash-ability, low fouling tendency, low operating costs, high permeability; and at the same time good mechanical strength ensures membrane integrity. One more issue, that still remains, is membrane integrity; directly compromised by broken fibers. Single bore fibers are particularly fragile due to their dimensions, which in turn makes them susceptible for breakage due to the stress they endure in the frequent backwashing cycles.

LEGIO.bore® (ultra filtration membranes) eliminate the probability of fiber breakage by combining 7 capillaries, each with an inner diameter of 0.9 mm in one fibre, by strongly increased mechanical strength and integrity guarantee.

Cross-section of LEGIO.bore® under a scanning electrode microscope

d = 0,9mm


LEGIO 2) LEGIO® – Fiber chemistry

Common UF membranes span the range from fully hydrophilic to fully hydrophobic types, where the LEGIO.bore of polyether sulfone (PES) is positioned in-between both extremes. However, the characteristics of PES are ideal for being blended with other polymers to modify the membrane’s properties as needed - as well as its affinity with water being a major concern for its treatment performance and its feature of being cleaned easily.

While fusing hydrophilic polymers, the hydrophilic of PES is enhanced gaining one more advantage compared to cellulose acetate (CA) membranes; whilst avoiding the disadvantages, namely biodegradability and poor pH tolerance making cleanings difficult (membrane reversibility). LEGIO.bore®, respectively the membrane material PES, is tolerant to chlorine up to a certain extent never required in water treatment applications. It also can tolerate an extremely wide pH range from pH 1 to pH 13, resulting in a very good clean-ability under inorganic and organic contamination.

Organic fouling accumulation (deposition) caused by dissolved organics is by far the most common result of CA membranes, due to high pH level intolerance. Conversely to this inconvenience, LEGIO.bore®, respectively the membrane material PES, allows to remove this organic fouling very efficiently by using a pH of 12 or above in backwashes.


LEGIO 3) LEGIO® – Flow operation Inside-Out / Outside-In

Basically there are two different techniques of flow operation, which a membrane can be streamed and operated with. Either feed water will be introduced through the inside of the capillary lumen with the permeate being pushed to the outside walls (inside-out) - or it can be fed from the outside walls with permeate being forced into the inside of the capillary (outside-in). It is also important to highlight the fact, where the active surface area of the membrane lies within the fiber. Using inside-out, this active surface is within the capillary lumen, and it is the other way round for outside-in membranes.

The inside-out configuration has feed water entering the capillary during filtration mode with the flow direction being reversed during backwash. During backwash mode in inside-out membranes, the flow direction comes from the outside surface of the fiber; this ensures an even flow distribution along the entire length of the fiber. This is critical for the removal efficiency of the contaminants from the fiber lumen and the reversibility of the LEGIO.module® itself.

Inside-out membranes have a very low volume of contaminated feed water, because the feed water flows from the inside of the fibers, and its volume is much smaller than the volume outside the fibers. This makes the backwashes economical even at relative short intervals, avoiding a formation of a fouling layer from the very beginning. The results are low operating pressures and very rare off-line chemical membrane cleanings.

Moreover, the backwash effluent can be discharged completely through the capillary channels, making reversibility short and simple, and filterability periods longer and more efficient.

Method of a water treatment process in the case of Inside-Out membranes


LEGIO 4) LEGIO® – Pressurized / submerged operated membra nes

In a pressurized LEGIO.modul®, membranes are bundled in a tube, known as housing. In turn, the LEGIO.modul® can be operated by a feed water pump against a back pressure pump, if required.

In contrast, submerged systems normally operate with membranes being immersed in an open tank, where a vacuum is applied to the filtrate side to draw the permeate through the membrane. At the same time, submerged membranes are generally operated at lower flux rates, but pressurized membranes require less membrane area to reach higher fluxes - they can be preassembled to a large degree before being shipped to site.

In addition pressure operated membranes in LEGIO.modules® could be assembled into larger systems (LEGIO.filter) and delivered as such to the application site.

Maintenance, replacements and cleaning in place (CIP) is simpler in pressurized systems, because LEGIO.modules® are directly accessible; no cranes are necessary to take the submerged membranes out of the tanks.

Sample of pressure operated LEGIO.modules® with a horizontal installation


LEGIO 5) LEGIO® – Adjustment vertical /horizontal

When ultra filtration technology was first introduced into the market, the system’s design was developed in a way to imitate that of a nano filtration (NF) or a reverse osmosis (RO) system; hereby elements are fitted into a pressure vessel in a parallel display to operate horizontally. Each of these pressure vessels may contain up to four elements. As feed water enters both ends of the pressure vessels simultaneously, it creates a dead-end at the centre. However, the horizontal multi-element design suffers from a number of disadvantages.

The most important disadvantage is poor efficiency during backwash mode, since it is impossible to achieve an even flux distribution over the whole length of the vessel. In addition, there is no possibility to flush-through at the dead-end section in the centre of the vessel, where most of the debris are accumulated. In case of integrity problems, it is a labour intensive task to identify the affected element, because of having four membrane modules in one pressure vessel. O-rings used to seal the modules also pose a potential source for leakages between permeate and feed water, which is another one of the listed drawbacks.

On the other hand, vertical configurations of LEGIO.modules®, comprising single or double element arrays, do not suffer from the constraints of the horizontal design for several reasons. One important advantage is, the feed water can be introduced either at bottom or top side of the LEGIO.module®, as well as the backwash effluent can be withdrawn at either end, simultaneously or alternating in sequence, giving the membrane element uniformity. Another advantage is, the LEGIO.module® can also easily be accessed and removed for maintenance, whenever needed. In fact, a rack in double array configuration matches a smaller footprint compared to that of a horizontal system. A further advantage is, an air based integrity test can be carried out easily, since the venting of vertical systems is easier and more thorough, avoiding mechanical stress caused by air and water hammers. In contrast, the proper venting of horizontal configurations is very difficult to achieve.

6) LEGIO® – Improved hydrophilicity

The latest development in the membrane production is the proprietary process for creating PES membranes with a greatly improved hydrophilic characteristic for an effective addressing the problem of “fouling,” which is a problem common to all other hollow fibre membranes.

Fouling occurs, as soon as pores begin to avoid water passage (permeate out of the membrane), decreasing a membrane’s effectiveness over time. Most PES membranes use PVP (polyvinyl pyrolidone) as a coating to increase the hydrophilic of the PES. Unfortunately, the PVP degrades over time, washing away during operation, and hence, decreasing the hydrophilic and permitting more rapid fouling.

To solve this problem, a proprietary additive would develop and bound it into the structure of the PES fibre. This new additive can not be washed away and therefore, fouling is significantly reduced. This, in turn, increases the membranes efficiency and the ease it can be cleaned with, further decreasing maintenance and operating costs.


LEGIO 7) LEGIO® – Open foam structure and outer surface

A new production technology ensures the outer surface of the hollow fibre membranes remaining open.

Hollow fibers membranes are manufactured by intrusion and extrusion process, also known as “spinning”. Generally, the production of membrane fibers closes the surface of the fiber during extrusion. For a single bore fiber this is useful, because it adds extra strength to its structure; although, there is a price to be paid for this added strength: the closed outer surface hinders the exit of fluid from the membrane, which decreases efficiency. However, for single bore membranes, an increased membrane structure is worthwhile to achieve a desirable lifetime in some degree.

On the other hand there are LEGIO.bore® membranes, which are 20-times stronger than typical single bore fibers. The added strength of the closed outer surface offers little benefit and decreases efficiency unnecessarily. Therefore, a method for producing hollow membrane fibers with an open outer surface was developed. The result is an increased flow through the membranes and, thus, an increased efficiency.

Open foam structure of the LEGIO.bore®

Uniform structure of the membrane surface on the inner surface of the LEGIO.bore®

Section 1 of the LEGIO.bore® uniform structure of the membrane surface 1

Section 2 of the LEGIO.bore®

uniform structure of the membrane surface 2


LEGIO 8) LEGIO® – Reduction of the SDI-value

One of the preconditions in evaluating water quality, particularly of sea water, the SDI index is taken into account. Since UF is becoming widely popular as the technology of choice for reverse osmosis (RO) pre-treatment, it is important to acknowledge, that generally the SDI value for RO feed water should be less than , although the SDI reduction value is depending on the constituents in the feed water prior to the LEGIO.module®. SDI value is directly influenced by particles, suspended solids, colloidal contaminants, as well as dissolved organic substances. Regardless of the fact LEGIO.modules® completely remove particles and colloidal substances, dissolved organic matter is totally dependent on the size of these molecules. To address this situation, the rejection of organics and reduction of the SDI value can be significantly improved by dosing coagulant into the feed water. The SDI value of the permeate ranges between 0,5 and 3,0, although it relies entirely on the feed water quality and operating conditions.

9) LEGIO® – Reduction of the TOC-value

Comprised by different types of organic carbons found in particles, colloidal substances and dissolved organic matter, the TOC is defined as the total organic carbon found. Regardless, the rejection of TOC by means of LEGIO.module® mainly depends on its molecular weight and shape. One of the ways to increase the overall rejection rate of TOC, particularly of low molecular weight organic matter, is by dosing coagulant in front of the LEGIO.modules®. At the same time, the rejection rate of the coagulant may be enhanced by optimizing the dosing parameters of the coagulant and the pH level of the feed water. Comparing it to conventional treatments, monitoring sedimentation or filterability of the flocks is not necessary, because the performance of the LEGIO.module® is independent on the geometry and/or specific weight of the flock. Reduction rate of TOC with UF can reach up to 60%.

10) LEGIO® – Reduction of bacteria and viruses

During extensive testing it was proven, that micro-pollutants such as E. coli (typical cell volume is 0.6 µm), Pseudomonas Aeruginosa and MS2 – bacteriophage (with a size ranging from 27 – 34 nm) were rejected by membranes of LEGIO.modules® to an extent of more than > 9 log for some bacteria, and > 5 log for virus.

Organism Feed concentration Permeate concentration Reduction (%) Reduction (log)

E- Coli 1.4 x 1010 cfu/l <10 cfu/l >99,9999999 >9,15

Pseudomonas Aeruginosa 1.5 x 108 cfu/l <0 cfu/l >99,999999 >8,18

MS2-Bacteriaphagen 2.2 x 107 pfu/l <100 pfu/l >99,999 >5,34

11) LEGIO® – Reduction of turbidity

In terms of turbidity, the most important trait is, turbidity in the permeate side of the membranes of LEGIO.modules® is completely independent from the turbidity level found in the feed water side. The LEGIO.modules® can provide superior product water, even during turbidity peaks in the feed water. Normally, the turbidity level given by LEGIO.modules® is lower than 0,1 NTU.

Constituent Rejection rate approx.

TOC without coagulant 0 – 25%

TOC with coagulant 25 – 60%

cfu/l = colony forming units per litre pfu/l = plaque forming units per litre


LEGIO 12) LEGIO® – Treatment and rinsing processes

Depending on the application of LEGIO.modules® and water type to be treated, different inflow directions during the treatment and/or the rinsing processes could result. The regular inflow directions are applied as follows:

I highly contaminated water additional inflow directions can push up the effectiveness. These are the following:

Filtration bottom up Forward flush bottom up Backwash to t he top

Filtration top down Forwardflush top down Backwash to the bottom


LEGIO Summary of LEGIO.modul® and LEGIO.bore®

1) Membrane

Fibre breakage is avoided due to its superior mechanical strength of the membrane, combined into one fibre. The result is:

• 7 capillaries in one membrane with a honeycombed-shaped cross-section - a huge strength is achieved.

• Protection against viruses and bacteria, resulting in increased protection of subsequent treatment steps and furthermore avoiding the use of chemical dosage.

• Increased productivity and reduced maintenance because a fibre breakage or repairing is improbable.

• Enormous hydrophilic membrane material consisting of modified PES.

• Minimized membrane pollution by:

• increased inner diameter (0,9 mm) - leading to a better tolerance against high particle loads, lower pressure drop and improved feed water distribution along the fibre.

• high backwash pressures possibilities and high backwash velocities due to mechanical fibre strength.

2) Design of the LEGIO.modules®

Hydro-dynamically optimized design. Through an annular gap between housing and distribution pipe, filtrate is collected, and backwash is introduced into the LEGIO.modul®, respectively. This results in a nearly constant radial velocity across the module diameter leading to a minimized fouling due to very efficient backwash impulse over the total cross-section of the module. A high integrity at the LEGIO.modul® is guaranteed, since no o-rings are used to separate the feed from the filtrate side. Furthermore the lifetime is maximized by reducing mechanical stress of the hollow fibre membrane.


LEGIO

Basic data of LEGIO.modules®:

Method of filtration: Ultra filtration

Membrane material: Polyether sulfone (PES)

Housing material: PVC

Type of filtration: dead-end

Art of filtration „purification process“: Inside-Out

Membrane diameter: 4,0 mm

Numbers of capillaries per LEGIO.bore®: 7

Diameter per capillary: 0,9 mm

Pore size: 20nm = 0,02 µm

Dividing line (MWCO): 100 -150 kDa

Performance (coliform germs, E-Coli): 99,9999999 % / LOG 9,15

Performance (Pseudomonas aeruginosa): 99,999999 % / LOG 8,18

Performance (MS2-bacteriaphagen): 99,999 % / LOG 5,34

Membrane surface / LEGIO.modul®: 0,25 up to 60m²

Max. trans membrane pressure (TPM): 2 – 2,5 bar / 29 – 36,25

Resistance hypochlorite (NaOCl): 50 – 200 ppm (per cleaning process) at 40°C – 104°F

Resistance hydrogen peroxide (H2O2): 100 – 200 ppm (per cleaning process) till max. 40°C – 104°F

Possible cleaning detergents: Sodium hydroxide (NaOH - max. pH 13), hydrogen peroxide (H2O2), hypochlorite (NaOCl), hydrochloric acid (HCl), sulphuric acid (H2SO4), citron acid (mind. pH1)

Max. life time (chlorine resistance): 200 000 ppmh

Min. - Max. water temperature: 2° / 35°F - 40°C / 104°F (bis 80°C / 176°F at special types)

pH- value: 3 – 10 (per cleaning process)

pH- value: 1 – 10 (per cleaning process)

Permeability: depending on the water quality

Flux: depending on the water quality

All images, texts and diagrams are protected by copyright. A use requires a written approval by LEGIO-WATER GmbH.

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110625 NEU Beschreibung LEGIO.module 2 EN