Bai Bao Ve Su Dung NF RO Part 2

A NANO FILTRATION (NF) MEMBRANE PRETREATMENT OF SWRO FEED AND MSF MAKE-UP

(PART - II)1 A. NF SWRO demonstration plant using commercial size modules, and B. NF system optimization.

A. M. Hassan, M. AK. Al-Sofi, A. M. Farooque, A. G. I. Dalvi, A. T. M. Jamaluddin, N. M. Kither, A. S. Al-Amoudi, and I. A. R. Al-Tisan

Saline Water Conversion Corporation

P.O.Box 8328, Al-Jubail -31951, Saudi Arabia Tel: + 966-3-343 0012, Fax: + 966-3-343 1615

Email: [email protected]

SUMMARY

Earlier pioneering work done at SWCC RDC demonstrated that the NF

pretreatment of seawater feed to seawater desalination plants: (1) prevented

SWRO membrane fouling by the removal of turbidity and bacteria, (2) prevented

plants scaling (in both SWRO and MSF) by removal of scale forming hardness

ions, e.g., SO=4 by up to 98%, total hardness by up to 93%, and (3) lowered

required pressure to operate SWRO plant by reducing TDS of seawater feed by

better than 50%. The net effect of this NF pretreatment was to increase SWRO

potable water yield by up to 100% and recovery from 35% without NF

pretreatment to 70% with NF feed pretreatment. Likewise, it increased MSF

distillate recovery from 35% up to 80% without and with NF pretreatment,

respectively. Moreover, it allowed for the operation of SWRO and MSF without the

addition of antiscalant. It also allowed for the operation of the latter also without

antifoaming agent and without scale formation at MSF top brine temperature of

120 oC. This work was covered under Part I of the project on “A Nanofiltration (NF)

Membrane Pretreatment of SWRO feed and MSF make-up”. Part II, which is a

continuation of the above project, deals with two main tasks: (1) Optimization of

the NF pretreatment process, and (2) Construction and the Evaluation of a

Commercial-like NF-SWRO Demonstration Plants. This report describes the

results obtained under Part II of the project

All the previous work (Part I) was done employing only one type of NF membrane

Filmtec NF-70. Although, the NF permeate quality was excellent, nonetheless, the

1 Issued as Technical Report No. (TR-3807/APP96008-II) in December 1999, also Desalination 118 (1998) 35-51.

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NF permeate water recovery ratio was modest about 50%, at an applied pressure

of 30 bar. To optimize the NF pretreatment of seawater feed to seawater

desalination plants, the performance behavior of a total of 13 different NF

membranes, made by different membrane manufacturers, size 4" x 40" and some

in 8" x 40", were investigated along with the influence on SWRO membrane

performance when using NF permeate as feed. Although all NF membranes

examined showed excellent rejection of SO=4, from 3200 to less than 70 ppm, for a

rejection of 98% or better, nevertheless, each membrane was found to differ from

other membranes in performance behavior, which is measured by NF permeate

flow, permeate recovery ratio and hardness ions concentration (SO=4, HCO-

3, Ca++

and Mg++) as well as TDS rejection. From the study, it is shown that NF

membranes can be divided, more or less, into three groups : Group “A” with high

ion rejection and low permeate flow in contrast to Group “C” of high flow and

modest ions rejection particularly TDS, while Group “B” has a good balanced

performance of permeate flow and ionic rejection.

In view of the positive and encouraging results obtained on a pilot plant scale in

Part-I of the project, triasl on a commercial-like NF-SWRO demonstration unit was

not only logical but essential to determine the operating conditions as well as to

establish plant performance parameters. The demonstration unit built for this

purpose consisted of 6 NF spiral wound membrane elements, size 8"x40" followed

by a SWRO unit comprising 3 HFF SWRO elements 8"x40" or 9"x40", where in

both cases the membranes are arranged in series in a brine staging process. The

report describes the NF-SWRO demonstration unit along with the experimental

approach used in this investigation and the results obtained thereof from both the

NF optimization process and the demonstration plant. The results obtained from

the demonstration unit confirm the earlier results, which were obtained from the

pilot plant study. 1. INTRODUCTION The application of nanofiltration (NF) membrane pretreatment of seawater feed to seawater

desalination plants (Project APP 3807/96008, Part-I) was started on 22.3.1997. The three

main tasks of the project dealing with the establishment and evaluation of this new approach in

NF-SWRO, NF-MSF and NF-SWROreject-MSF seawater dual and triple hybrid desalination

processes along with technoeconomic evaluation of the NF-SWRO seawater desalination

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process were completed on time as specified in the project and results obtained thereof were

published in a series of papers in international Journals on desalination or conference

proceedings and also presented in a series of lectures to SWCC management and technical

staff [1-6]. All the previous work, however, was done utilizing one type of NF (Filmtec NF-

70) membrane.

In view of the positive and encouraging results obtained in Part-I, the project was continued

under Part-II which covers the following tasks:

(1) NF process optimization by increasing recovery and improving quality of NF

products;

(2) Scaling-up of the NF and NF-SWRO processes from pilot plant to demonstration

plant scale, utilizing large NF and SWRO of 8" x 40" or 9 " x 40" membrane elements;

(3) Supply of NF product or SWRO reject from an NF-SWRO unit as make-up to an

MSF unit, and also,

(4) To perform various tasks on chemical, biological and technoeconomical analyses.

In order to optimize the process by increasing water recovery to 60 -70% level and improving

water quality by increasing the hardness ions rejection and minimizing the TDS level in NF

permeate, the effect of changing NF membrane process operation parameters, on NF

permeate recovery and quality was investigated for thirteen different NF membranes, which

are produced commercially by various NF membrane makers. These membranes differ vastly

in their performance, water yield and recovery ratios.

Operation of the proposed demonstration plant (Task 2) should allow for the determination of

the operating conditions and the performance parameters of large scale NF-SWRO plants as

well as the technoeconomic evaluation of the process itself. Although, the task of evaluating

the NF product or SWRO reject from an NF-SWRO hybrid as make-up to the MSF pilot

plant were completed as defined in Part-I, nevertheless, more work on this task was done

under this investigation (Part-II). The NF permeate or the reject from SWRO in an NF-

SWRO hybrid was supplied, for a period of 3 months, as make-up to MSF pilot plant.

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Results of this work will be reported under Part-III (NF-MSF and NF-SWROreject-MSF),

which deals with the upgrading and operation of MSF pilot plant at top brine temperature

(TBT) ≥ 120 oC.

This progress report describes the results obtained from the execution of the above tests from

the start of the project May 30, 1998 to present. The report also covers the work done on

modification of the present NF pilot plant, which utilizes 4" x 40" NF membrane elements, to

allow for testing and performance evaluation of two different sets of NF membranes

simultaneously within a series of pressure vessels and also, to allow for the performance

evaluation of each NF membrane module separately. It also covers the conversion of existing

SWRO units to an NF and NF-SWRO demonstration units in which commercial size 8" x 40"

NF and 8" x 40" or 9"x40" SWRO membranes elements were utilized, respectively (see

Section 2, where the 9" x 40" elements were utilized only part of the time). The experimental

work is covered under Section 3 of this report, while results obtained from Tasks 1 & 2 are

described in Sections 4 and 5, respectively. As mentioned earlier, results obtained under

Task 3 shall be described separately under Part III of the proposed NF R&D project.

2. NF AND NF-SWRO SYSTEM MODIFICATION Luckily, there are three SWRO pilot plants available at RDC. The first unit, with its own

pretreatment system (capacity 3-4 m3/hr), utilizes 4" x 40" NF or ultrafiltration (UF)

membrane fully integrated with 2.5 " x 40" SWRO membrane unit, and as required can be also

integrated with an existing 8" x 40" SWRO unit. The second and third SWRO units are

based on spiral wound (SW) and hollow fine fiber (HFF) SWRO membranes and with both

units fed from one common pretreatment (capacity 5 - 7 m3/hr). The pretreatment for both

systems consists of dual media followed by fine sand filters. A good deal of work which is

discussed in the following sections, was done to convert or to upgrade the three pilot plants to

allow, as mentioned earlier, for (i) NF process optimization and (ii) Evaluation of commercial

size 8" x 40" NF or 9" x 40" SWRO membranes in an NF-SWRO demonstration unit.

2.1 Upgrading of Pretreatment Units

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In all the pretreatment units, the sand filter and anthracite media were in service for several

years and contained within their layers various contaminants. First task was to replace these

old media with fresh new media. The thickness and particle size of the old and new media are

as shown in Table 1. To allow for finer filtration, both the thickness of the various replaced

media and their particle size were changed as shown in the same table. In both pilot and

demonstration plants, one type of fine sand was used in filter #2. For example, the fine sand

thickness and particle size in pilot plant filter #2 are 640 and 0.55 mm compared to media

thickness of 800 mm and particle size of 0.25 to 0.45 mm for the same filter #2 in

Demonstration plant.

2.2 Modification of NF-SWRO Pilot Plant ( 4" x 40" Membrane Elements) In Part I of this investigation using Filmtec NF-70 Membranes, the product recovery ratio was

maintained at 50% or less while maintaining good quality product having very low content of

hardness ions and relatively low TDS [1-6]. For economical and cost effectiveness of water

production, the recovery ratio is expected to be raised to 60 to 70% or better, while

maintaining good quality product. The optimization of the NF process was accomplished by

examining the effect of operation conditions, i.e., feed pressure, temperature, feed flow and

pH, on the performance and recovery ratio of numerous NF membranes produced

commercially by various NF membrane makers.

To perform the above optimization process, certain modifications were introduced in the NF

part of the NF-SWRO pilot plant. The five pressure vessels, each contains two NF

elements, were arranged as shown in Figure 1. This arrangement allowed for the

measurement of permeate flow for each module separately as well as the determination of the

permeate quality and consequently the evaluation of NF membranes performance within each

pressure vessel separately. This way the permeate quality and flow from each module can be

accurately established. The arrangement also allowed for the evaluation of one or more of

same or different NF membranes simultaneously. Also, due to this flexibility in membrane

arrangement, the effect of membrane staging on their performance and the overall

performance of the system can be established. The present flexibility in module layout also

allows for the determination of best and most efficient mode for membrane staging in

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commercial plants. As was done in earlier work, the full integration of the NF pilot plant with

SWRO or MSF pilot plant or SWRO Demonstration plant was maintained (Figs. 1 to 3).

2.3 Conversion of Present Two 8" × 40" SWRO Plants to an NF-SWRO

Demonstration Unit According to their use in the past, the two SW and HFF SWRO plants, which were described

earlier, received their feed from the 7 m3/hr pretreatment unit, where the feed is split equally

between them. To convert the two SWRO units into a fully integrated NF-SWRO

demonstration plant, the spiral wound SWRO unit was converted to serve as a SW NF unit

and with all the feed from the pretreatment unit (7-8 m3/h) was channeled to it, while its NF

product was made feed to the HFF SWRO unit or used as a make-up to the MSF pilot plant,

to form a dual hybrid of an NF-SWRO in the former case, and to form an NF-MSF in the

latter case (Figure 2). Alternatively, the NF-SWRO dual hybrid system was integrated with

MSF to form a trihybrid NF-SWROreject _MSF desalination system, where the SWRO reject

from the NF-SWRO unit serves as make-up to the MSF unit (Figure 3). For a greater degree

of integration, especially during the cold season, the seawater from the MSF heat rejection

section was made feed (by blending it with seawater) to the NF pretreatment unit to raise the

feed temperature to 30 - 33 oC (Figure 3).

The above forms of NF integration with SWRO and MSF and the conversion of the SW

SWRO to a SW NF unit required changes in piping systems connecting the various units and

the addition of a high pressure pump, capacity 7 m3/h at pressure of 28 bar, to provide

sufficient feed to the SW NF unit. Figure 2 illustrates the new NF-SWRO set up. The NF

membrane arrangement, which is similar to that in commercial plants, consists of three 8"

pressure vessels, each contains two 8"x40" SW NF membrane elements. The HFF SWRO

membrane arrangement is made of two pressure vessels the first is fitted with two 8"x40"

Toyobo HM 8255 HFF membrane elements followed by a second pressure vessel fitted with

one 8"x 40" Toyobo HM 8355 NF membrane element. In all cases, the NF and SWRO

membranes are arranged in series, as it is done in commercial large size NF and SWRO plants

with reject staging, i.e., reject from first membrane element constituted the feed to the second

(following) membrane element and so on. Such arrangement is necessary because the results

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obtained and plant performance will be close, if not similar, in values to those obtained from

the large size commercial NF & SWRO plants.

Towards the end of November, 1998, the two SWRO modules which were fitted with two 8"

x40" membrane elements in the first pressure vessel and one element in the second pressure

vessel, were replaced by two larger SWRO modules, each contains two of the same Toyobo

HFF membrane elements, but of larger size 9"x40", i.e., HM 9255 instead of HM 8255

model. The above modifications and arrangements allowed, as illustrated in later sections of

this report, for the performance evaluation of various commercial size 8" x40" NF and SWRO

membranes.

3. EXPERIMENTAL WORK 3.1 NF Process Optimization

This step involved the operation of the 4" x 40" NF unit (Figure 1) to establish the optimum

membrane performance at different operating conditions of feed pressures (10 to 40 bars),

feed temperatures (25 to 40 oC), feed pH of 6.5 to 8.2, feed SDI 2.0 to 4.0 and also at

various rates of feed flow. Also, the operation of the NF unit with and without a secondary

ultrafiltration (UF) membrane pretreatment was tried by placing the SW UF membrane

modules ahead of the SW NF modules. The operation of both the UF and NF membranes

was made with the same pump and under nearly same pressure. Although this secondary UF

pretreatment removed all the very fine particles and bacteria, which was not removed by the

primary pretreatment, nevertheless, this arrangement failed to yield high flow of UF filtrate and

thus was discontinued after only a few days of operation. The UF membrane used in this trial

were Desal 50, with a molecular weight (mw) cut-off of 15,000. This experiment in which UF

is utilized in the pretreatment of feed to seawater desalination plants, shall be tried again , as

time allows, by using either hollow fine fiber UF membranes, pore size 0.05 µm, and/or SW

UF with larger MW cut-off > 100,000. Such cases of UF membrane proved to be effective

as a primary pretreatment of seawater feed, and it yields high quality pretreated feed with SDI

<1.0 [7]. The following 4"x 40" NF membranes were purchased and tried: Filmtec NF 90,

NF 70 and NF 45, Toray SU 610; Osmonics HL 4040F DK 4040F and DL4040, Trisep

TS40TSA and Trisep TS 80TSR; Hydranautics ESNA ; Fluid System 4721SR.

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3.2 Operation of NF SWRO Demonstration Unit The operation of the NF part of the demonstration 8" x 40" NF-SWRO plant (Figure 2) was

done at ambient seawater temperature, feed pH ≈ 6.6, feed flow of about 4 -6 m3/h and feed

pressure of 17.4 bar (250 psi), and for certain membranes was raised to reach 40 bar.

Operation of the SWRO unit, however, was done utilizing the NF product at ambient

seawater temperature and feed pressure of 25 - 60 bar. The 8" x 40" NF membranes which

were purchased and tried in this study are : Filmtec NF 70, Osmonics HL 8040FL, Fluid

System TFC NF 8921S, Toray SU620F and Hydranautics ESNA. The latter two

membranes were tried for a limited time and their results will not be discussed in this report.

Product of the 4"x 40" NF membrane elements of Filmtec NF 45, Toray SU 610, Osmonics

HL 4040F and Trisep TS 40TSA as well as DK 4040 and Trisep TS 80 TSA were also tried

for a limited period, separately or in combination of two as feed to the 8" x 40" SWRO part of

the demonstration plant.

For both the 4"x40" and 8"x40" NF units in the pilot and demonstration plants, the seawater

feed pretreatment consisted of minor coagulation (0.4 ppm of Fe+3 from FeCl3) without

chlorination followed by dual media, fine sand and cartridge filtration. The pH of pretreated

feed was adjusted to about 6.6. The pretreated feed was then passed under pressure to the

NF units and their products were passed as feed to SWRO units or made make-up to the

MSF unit. In one set of experiments, the SWRO reject from the NF-SWRO hybrid was fed

as make-up to the MSF unit (Figure 3).

Experiments were also carried out to determine the scaling tendency, i.e., scaling potential, for

various NF permeates. Two procedures were utilized: the first by threshold effect method and

second by evaporation method. The threshold effect for each of the NF permeate was

determined by adding 5 ml of 1 molar solution of sodium carbonate (Na2CO3) to an already

heated (to 95 oC) 500 ml sample of the permeate in a special experimental set up, details of

which are given elsewhere [8]. Five minutes after the addition of Na2CO3, a known amount

(25 ml) of the solution was withdrawn for M-Alkalinity measurement and the same was

repeated at an interval of 5 minutes. The experiment was carried out for a total of 30 minutes.

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Throughout the experiment the solution temperature was maintained at 95OC. For comparison,

the experiment was repeated also for seawater as well as brine with and without antiscalant.

As an alternative to the above threshold effect experiment, the scaling potential experiment

was conducted by the evaporation of a certain percentage of 250 ml permeate from different

NF membrane followed by cooling of the remaining portion to room temperature, after which

the solution turbidity was determined. The solution was also visually inspected for clarity and

for the observation of scalent precipitation. The same evaporation procedure was repeated

for several times until up to 90 to 92% of the sample was evaporated. For example, the first

evaporation experiment performed on permeate from Filmtec NF 45 reduced the initial

permeate volume from 250 down to 120 ml for 52% volume evaporation. Second, third and

fourth evaporation reduced the volume from 120 to 78, from 78 to 39 and from 39 to 20 ml

for percentage evaporation, as compared to initial volumes, of 69, 84 and 92%, respectively.

Chemical and biological analyses were made as required by skilled staff from Chemistry and

Biology Departments, according to established ASTM methods.

Performance parameters were measured daily, on a routine basis by staff working on the

project from SWRO and Pilot Plant Departments. No membrane cleaning were carried out,

only simple flushing of membrane with MSF distillate or SWRO permeate was done

occasionally.

4. RESULTS & DISCUSSION OF NF PROCESS OPTIMIZATION

4.1 Quality of Pretreated Feed With the replacement of sand filter media with high quality and finer particle size sand and in

some cases thicker sand media, the quality of the pretreated feed improved significantly and

was exceptionally good. This is in spite of feed non-chlorination and minimum use of

coagulant, i.e., 0.4 ppm Fe+3. Most of the time, the pretreated feed quality, as measured by

SDI, was less than 3, and for more than 50% of the time, SDI < 2.0. Occasionally the SDI<4

but it never exceeded the SDI <5, which is the SDI water quality limit required by the SW NF

membrane makers. These SDI values compare to SDI < 1.0 for the NF permeate. Thus, no

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SWRO membrane fouling was expected, as already was observed here and earlier, when the

SWRO feed consisted of NF permeate [1-6, 9].

4.2 Bacteriological Study of NF Process Obviously, and as is expected, the number of bacteria in colony forming unit/ml (CFU/ml)

should be at maximum and minimum values in raw seawater and in NF permeate, respectively.

Furthermore, the bacteria count in feed should decrease with feed pretreatment. This is

illustrated in Figure 4, which shows the bacteria count for feed samples taken at various stages

of the seawater pretreatment and the NF membrane process. The plotted data, also shown in

table form in the same figure, are the average bacteria count per month for the months of May

to mid December, 1998. The bacteria count is reported in CFU/ml before dual media filter

(BDMF), after dual media filter (ADMF), after micron cartridge filter (AMCF), in NF brine

(NFB) and in NF permeate (NFP). The results indicate that the pretreatment is very effective

in reducing number of bacteria, in pretreated feed after dual media filter and after micron

cartridge filters (AMCF). It is noticed that the monthly average of bacteria count in raw

seawater (BDMF), in pretreated feed and in NF product and brine are greater during the hot

months of June to September than they are during the months of October to December, yet

regardless of the season, they are the least in NFP. Theoretically, from size comparison of

about 1 µm for bacteria to less than 0.01 µm for NF pore size, no bacteria is expected to

pass through the NF membrane and, therefore, the bacteria count in NFP is expected also to

be near the zero count instead of the values showing in Figure 4. This hypothesis of near zero

bacteria count in NFP, however, can be supported by the observed differential pressure

across the SWRO membrane (∆P), which remained constant at 1 bar when the SWRO unit

was operated for a long period on feed consisting of NF product. Moreover, no decline in

SWRO membrane performance due to biofouling was observed. Even the NF membrane

itself, did not show any biofouling as evidenced by the steadiness of its ∆P and membrane

autopsy results[10]. Earlier studies showed also the same trend in constancy of ∆P ≤ 1.0 bar

[1-3].

4.3 Chemical Composition of NF Permeates

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Tables 2, 3 and 4 summarize the average concentration of the various ions in Gulf seawater,

Al-Jubail, before and after their NF treatment by the various NF membranes investigated in

this study. The three tables carry the same information except for membrane arrangement,

wherein Tables 2, 3 and 4 membranes are arranged serially according to their ability to lower

TDS, Ca++, and total hardness in NF permeate, respectively. A bar chart representation of

results selected for 7 NF membranes is given also in Figure 5. The results obtained from same

membranes wound in 4" x 40" or in 8" x 40" size are similar and, therefore, the data reported

in Tables 2, 3, 4, and Figure 5 applies for both membrane sizes.

At an applied feed pressure of 17.4 to 22 bar, the concentration of hardness ions in the NF

permeate of the various membranes examined differs from one NF membrane to another. In

all cases, the NF pretreatment of seawater feed reduced the SO=4 content from 3200 in

seawater to less than 70 ppm in NF permeate, for SO=4 rejection of better than 97%. For

some membranes, such as Osmonics DK4040 no sulfate could be detected in the permeate.

In other permeate from Filmtec NF-45, the SO=4 rejection is better than 99.7%, and still is

better than 98% for the NF membrane, Toray SU 610, Trisep TS40TSA and Osmonics HL

4040F. Likewise, at feed pH of 6.6 the M-alkalinity was reduced from 128 in seawater to

30 ppm in NF permeate of Filmtec NF 70 for about 77% rejection. This compared to 46

ppm or 63% when feed pH=8.2, i.e., nonacidified seawater (11). The rejection of M-

alkalinity differs from one NF membrane to another, and is pH dependent. Thus the M-

alkalinity concentration varied from 50 (rejection 61%) in NF permeate of Osmonics

HL4040F and Trisep TS40 TSA when feed pH = 6.8, down to 15 (rejection 88%) in

permeate of NF - 90 at feed pH = 6.17.

The reduction in concentration of hardness cations of Ca++ and Mg++ in seawater caused by

the NF pretreatment varied over a wide range from one NF membrane to another. This is

clearly illustrated in Figure 5 and Tables 2 and 3. For example, the Ca++ concentration in

permeate from Filmtec NF-90, NF-70 and NF-45 are 19, 84 and 108 ppm for a percentage

rejection of 96, 82.5 and 77.5%, respectively. By comparison, the Ca++ concentration in

permeates from Osmonics HL4040F and Trisep TS40TSA are 204 and 300 ppm,

respectively, for a percentage rejection by the former of 57.5% and by the latter membrane by

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only 37.5%. However Osmonics DK 4040F and Trisep TS80 have excellent Ca++ rejection.

The Ca++ concentration in the former permeate is only 44 ppm as compared to 99 ppm in the

latter permeate. The same trend is observed for the rejection of the Mg++ ions. The Mg++

content is again lowest in permeate of Filmtec membranes NF-90 (32 ppm) and with similar

values for Osmonics DK4040F permeate, for a rejection of better than 96%. These values

compare to Mg++ concentration of 260 and 425 ppm in NF permeate from Osmonics

HL4040F and Trisep TS40 TSA, respectively, for Mg++ rejection by the former membrane of

83.8% and only for 73.5% by the latter one. Concentration of Ca++ and Mg++ ions in the

permeate of other NF membranes is as shown in Tables 2, 3 and Figure 5. In general it can

be concluded that within the exception of the last three membranes in Table 3, the rest of the

NF membranes have good rejection of Ca++ ions and , more or less, Mg++ ions in their

permeate. Moreover, the NF membranes ionic rejection improves as the applied pressure is

increased.

Maximum reduction in seawater conductivity and TDS and, therefore, maximum total ions

rejection by the NF pretreatment, more or less, follows the same order as the NF membrane

arrangement in Table 2. This tends to be the case for rejection of Cl- ions and also as

expected for the Na+ and K+ (although concentrations of the latter two ions are not shown in

Table 2). These chemical analyses results are further discussed in latter Sections 4.3, 4.4 and

4.6, where in the latter section they are discussed with respect to their effect as feed on the

performance of SWRO membranes. According to their TDS rejection, the NF membranes

can be divided into three groups:

Group “A” with TDS < 25,000 ppm in permeate includes NF membranes of Filmtec NF-90,

Fluid Systems TFS 8921S and Hydranautics ESNA ;

Group “B” with TDS > 25,000 but < 33,000 ppm in permeate includes NF membranes of

Trisep TS80, Osmonics DK 4040F, Filmtec NF-70 Toray SU620F and NF 45; and

Group “C” includes the rest of the membranes in Table 2 with TDS > 33,000 ppm in

permeate.

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The relationship between NF permeate TDS and conductivity is shown in Figure 6 and can be defined by the following equation: TDS NF permeate = 317.16 x Conductivity 1.1512 (1) 4.4 Scaling Potential of NF Permeate Scaling in the desalination processes occurs when the concentration of scale forming ions

(hardness ions) reaches the saturation points (solubility limit) at which after a certain time,

scales nucleation starts, followed by the precipitation of scale matter. Antiscalants are

normally added to interfere with the nucleation process, therefore, preventing (delaying) up to

a certain concentration and temperature levels, the scale formation, and thus, allowing for the

operation of the seawater desalination plants at high saturation of hardness ions in seawater.

Methods initially developed to measure the efficiency of antiscalant in retarding scale formation

are the threshold effect and evaporation techniques.

The scaling threshold is considered to be the maximum permissible concentration factor of

hardness ions in water samples at fixed temperature prior to the start of the nucleation process.

Here in this investigation, both the threshold and evaporation techniques were utilized in

determining the effectiveness of NF pretreatment, which causes, among other changes in

seawater qualities, a high degree of hardness ions rejection, on retardation of scale formation

as compared to the antiscale additive approach. To re-emphasize, no antiscalant was added to

the NF permeate when used in both the threshold and evaporation experiments.

4.4.1 Threshold Effect of NF Permeate The threshold effect at 95 oC for each sample of NF permeate or seawater or brine with and

without antiscalant was determined here in terms of changes in the M-alkalinity, which is

measured in ppm as CaCO3, versus time, i.e., 0 to 30 minutes. The scaling threshold effect

curves for various permeates of Trisep 4040 TS40TSA, Osmonics HL8040F and Filmtec NF

70(8" x 40") are shown in Figure 7. For comparison, the scaling threshold effect curves for

seawater, MSF recycled seawater brine with and without the antiscalant poly phosponate

(PPN) are shown in the same figure. The brine consisted of seawater concentrated by 1.5

folds. Chemical composition of the seawater and permeate examined in this investigation are

shown in Table 5 with emphasis on their hardness (Ca++, Mg++, SO=4, HCO3

- and total

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hardness) content. The TDS, conductivity, Cl- and pH values of each sample are also shown

in the same table. As can be seen in Figure 7, the NF permeate threshold curves are quite

different in shape from those for seawater, brine and brine with PPN antiscalant. Moreover,

differences are also noticed among the NF permeate curves themselves. From the loss in their

M-alkalinity as shown in Figure 7, the NF-permeate scaling tendency ranking will be as

follows:

TrisepTS40TS > Osmonics HL 4040F > Permeate NF 70 (2)

Moreover, both the NF-70 and NF Osmonics permeate threshold curves are characterized

by having a slow gradual decline in their M-alkalinity values within the time scale region 5 to

30 minutes. This is also true for Trisep NF permeates but with some deviations from this

generalization within the first 5 to 10 minutes time scale region, where the loss in M-alkalinity is

more pronounced for the Trisep TS40TS NF permeates than it is observed for the Filmtec

NF-70 and Osmonics HL4040F permeates.

By contrast to NF permeates, the brine sample without antiscalant addition showed no

threshold range, while seawater sample had only a 5 minute threshold range. For both

samples, however, a drastic drop in M-alkalinity is noticed at very early stages of the test,

within the first 10 to 15 minutes. The addition to brine of 2 ppm PPN, which is considered to

be one of the best antiscalant at 95 oC, delays the onset of decline in the threshold curve by

maintaining high degree of supersaturation of hardness ions (CaCO3) in brine and, therefore,

extends the threshold range to 20 minutes.

From this discussion and from the threshold curves in Figure 7, it can be concluded that within

the time region of 5 to 20 minutes, the scaling tendency of the various samples follow the

following scaling tendency ranking:

Brine > Seawater > Trisep > Osmonics 8" > Brine -PPN > Filmtec NF-70 (3)

where Trisep is NF TS40TS, Osmonics is NF HL4040F and Osmonics -8" indicates use of

8" HL8040F membranes. This means that within this time region, the scaling tendency is

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maximum for brine followed by seawater and is minimum for Filmtec NF-70. Scaling

tendency for the other membranes falls in between the values for seawater and NF-70.

The scaling threshold tendency is also a function of Ca++ concentration and as evidenced in

Figure 7 (bearing in mind that samples used in these analyses are not the same as in tabulation

because they were from different runs at somewhat different conditions), it increases as the

Ca++ concentration in the sample is increased (see Figure 7 and Table 5). An exception to this

generalization is the brine -PPN curve. As mentioned earlier, the addition of the antiscalant

delays the scale nucleation process, allowing for operation at high degree of supersaturation

for an extended period. But, unlike the NF permeate threshold curves, which can be

characterized by having a slow, gradually declining curves with no steep drop in M-alkalinity

even at 30 minutes, the brine-PPN threshold curve exhibited a steep drop in M-alkalinity after

20 minutes, where it drops rapidly to threshold values less than those for Trisep TS40TS

permeate. From this, the above scaling tendency ranking as under 3 is valid only for the first

20 minutes.

4.4.2 Evaporation Measurements of NF Permeates

The evaporation measurements were made in four consecutive steps for permeates from

Filmtec NF70, and NF45, Osmonics HL8040F and Toray SU 610. Composition of the

samples were as shown in Table 6. Figure 8 shows the scaling potential of their NF product

as compared to the scaling potential of seawater and seawater treated with antiscalant.

Although as shown in same table, differences are noticed in chemical composition of the

samples, especially in their Ca++ and Mg++, content (also TDS), the permeate solution turbidity

remained zero up to 92 and 94% without scale matter precipitation for HL4040F and NF-70,

respectively, and up to 92 for both NF 45 and SU 610 permeates. For the latter two NF

permeates, however, white crystalline precipitates appeared at 92%. From samples chemical

composition consideration and by comparison to evaporation performance of NF 70 and

HL4040F, this situation of precipitate formation at 92oC is not expected to occur at least in

the case of NF 45. Nevertheless, the results points out that at 95oC, it should be safe to

evaporate up to 90% of the NF permeate without scale formation. This means that at least

up to 90% distillate recovery can be realized without scale formation. Actually, this was

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observed at least for the NF-70 permeate at the MSF pilot plant level. The MSF unit was

operated on NF-70 permeate as make-up at 120 oC and distillate recovery of over 80%

without scale formation [1-5]. Unlike the NF permeate, which showed no scaling tendency ,

up to 90% or better, both the seawater sample with and without antiscalant showed scaling

tendency at about 30% and 20% of product evaporation, respectively (see Table 6 and Figure

8).

4.5 Performance of Various NF Membranes The 4" x 40" membranes performance, as measured by their product (1) flow (2) recovery

(3) conductivity are shown vs operation time in Figures 9 to 19 for Filmtec NF-70, NF 45

and NF-90; Toray SU 610, Osmonics HL 4040F, DK 4040F and DL4040F; Trisep

TS40TS and TS80TS; Hydranautics ESNA and Fluid System NF-4721SR. In each figure the

operation conditions (temperature, pressure and feed SDI) are also indicated. For each NF

membrane two pressure vessels (V-1 and V-2), which were arranged in series in a brine

staging operation, were utilized in its performance evaluation. For each NF membrane case,

the individual performance of each module (a module consists of one pressure vessel

containing two membrane elements) is plotted separately vs operation time along with the

overall performance of the two modules (V-1 + V-2) combined. Figure 20 shows a

performance comparison of the same above nine membranes (using two vessels) vs operation

time.

The composition of the NF permeate from the NF membranes shown in Figures 9-29 are

given in a previous section and are listed in Table 2, which also shows the flow characteristics

and recovery ratios for the same NF membranes. From Figures 7 to 20, Table 2 and the

scaling tendency studies (Section 4.4) the following conclusions can be drawn:

(1) Permeate flow and recovery ratio increase as the feed temperature or applied pressure

is increased.

(2) As mentioned earlier, the SO=4 rejection of all NF membranes examined here is

considered to be excellent. For the one module case, the SO=4 rejection by the NF

membrane is better than 98% (Table 2).

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(3) The rejection of the hardness cation of Ca++ and Mg++ differ from one membrane to

another and in general is inferior in percentage value to same NF membrane rejection

of SO=4. This variation especially in NF membrane rejection of Ca++, causes the

variation in scaling potential as measured by the threshold effect (Figure7). This is also

supported by earlier work done at RDC [1].

(4) The Ca++ ion rejection by NF membranes follows the following order:

Group “A” & “B” > “C” (4)

(5) Mg++ ion rejection by the various NF membranes tends to follow their same order of

rejection of Ca++.

By contrast to the rejection order of Ca++ and Mg++ by NF membranes, the flow and

recovery rates are as follows :

Group “C” > “B”> “A” (5)

For example, at 17.4 bar and 34.8 l/min feed flow, the permeate and recovery ratios for

Osmonics HL4040 (Group “C”) are 25.2 l/min and 64.6%, respectively, as compared to only

6.3 l/min. and recovery ratio of 43% for the NF-70 membrane (Group “A”), even at the

higher applied pressure of 22 bar (see Table 2). Group “B” membranes tends to have

balanced properties of permeate flow and ions rejection.

The observed differences in salt rejection and permeate flow and, therefore, permeate

recovery ratio among the various NF membranes examined here, can be explained in terms of

the membranes physical structure. Membranes with tight structure, thus small size pores, are

likely to have high salt rejection but low permeate flow, while the reverse tends to be the case

for membranes with less of a tight structure and larger size pores. The former tight structure

membrane resembles RO membrane in behavior, while the latter membrane with more of an

open structure resembles UF membranes in behavior. Rejection of SO=4 which as seen in

Table 2 and Figure 5 is more than 98% for all membranes, is not governed by the physical

structure of the NF membranes but rather by the membrane surface composition, which is

negatively charged. Evidently, all the NF membranes shown in Table 2 have sufficient negative

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charge to perform the observed excellent SO=4 rejection, but not a high rejection for Ca++ and

Mg++ cations.

4.6 Effect of NF Permeate Feed Quality on SWRO Membrane Performance This is discussed in some detail in earlier reference [1-3 and 5-6]. Here, it suffices to discuss

the effect of variation in NF permeates TDS and hardness ions concentration on SWRO

membrane performance.

The SWRO performance measured by permeate: a. flow, b. recovery and c. conductivity is

plotted vs. feed applied pressure in Figure 21. Feed to the SWRO unit consisted of the NF

permeate from Filmtec NF70 & NF45; Osmonics DK4040F & HL 4040F; Toray SU 610

and Ttrisep TS80NF membranes or conventionally pretreated seawater but without NF

pretreatment. In all cases, both the yield and SWRO permeate recovery increased as the

applied feed pressure is increased. The SWRO permeates yield and their recovery, however,

are much greater when using NF permeate as SWRO feed than when using seawater as feed.

Moreover, the rate of increase in both values (yield and recovery) is inversely related to feed

TDS. Thus, at pressure of 60 bar, the SWRO permeate yield and recovery are at maximum

values of 7.1 l/min and 70.7%, respectively, when the feed consisted of NF-70 permeate,

(TDS = 13,700 ppm), and dropped to minimum values of 3.6 l/min and 36% when the

SWRO feed consisted of seawater (TDS 44,000 ppm). The SWRO permeate yield and

recovery when using the other NF permeates (shown in Figure 21) as feed to SWRO, fall in-

between the above two ranges. This dependence of SWRO yield and recovery on feed TDS

is very well established through the equation :

Pnet = ∆Pappl - ∆ π (6)

where Pnet equals the effective pressure, ∆Pappl and ∆π are the differential applied pressure

and osmotic pressure across the membrane, respectively. Obviously, as the feed TDS is

increased the Pnet, which drives the permeate through the membrane, will decrease and

consequently the quantity of permeate is also decreased. The permeate starts to flow from

SWRO membrane as the applied feed pressure exceeds the osmotic pressure, which is for

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permeate of FilmTec NF-70 equals 9.6 as compared to 17.7, 22.6, and 25.5 bar for Trisep

TS80, Osmonics DK 4040F, Filmtec NF 45 and Osmonics HL 4040F, respectively, and 31

bar for seawater.

A linear relationship (straight line) is noticed between permeate flow and pressure (Figure

21a). This same relationship should also apply to percent permeate recovery, which follows

the permeate flow, provided all the tests of feeding SWRO with different NF permeate are

conducted under standard, same operating conditions of pressure, temperature and feed flow.

The noticed deviation of same recovery data in Figure 21b, especially in the high pressure

region above 65 bar, is mostly due to seasonal variation in operating temperature and/or

variation in the feed quantity.

Figure 22 illustrates the dependence of SWRO permeate flow on SWRO feed TDS at

different pressure of 40 to 70 bar, where the feed consisted of permeate derived from NF

Trisep TS 80 (TDS 25,000 ppm) NF Osmonics DK 4040 (TDS 29,000), Filmtec NF 45

(TDS 30,200), NF Toray SU610 (TDS 32500), NF Osmonics ýHL4040 (TDS 33,500) and

Seawater (TDS 44,000). For each feed the SWRO permeate flow increases as the feed

pressure increased. At the same pressure, however, the permeate flow increases inversely

with the decrease in TDS of feed. Moreover, the rate of increase is 0.176 l/bar at feed TDS

of 25,000 ppm for Trisep TS80 permeate as compared to only 0.103 l/bar at the larger feed

TDS of 44,000 ppm for seawater feed i. e., for the ratio of former : later of 1.7:1.

Major differences are noticed in SWRO product quality as measured by conductivity, which

at 60 bar pressure equals less than 800 µs/cm when the feed consists of NF permeate and

about 2200 µs/cm when it consists of seawater, requiring in the latter case further treatment to

reduce its conductivity to drinking water standards.

5. RESULTS & DISCUSSION OF NF-SWRO DEMONSTRATION PLANT

TRIALS Work done under this section involved the following tasks which were completed on time

according to schedule: (1) Basic design of the NF-SWRO demonstration plant, (2)

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Conversion and upgrading of existing SWRO pilot plants to an NF-SWRO demonstration

plant utilizing commercial large size 8" x 40" and 8" x 40" or 9" x 40" NF and SWRO

membrane elements respectively, (3) Modification and upgrading of SWRO pretreatment to

provide sufficient good quality feed to the NF unit of the NF-SWRO demonstration plant, (4)

Operation and optimization of the NF-SWRO demonstration plant and (5) Supply to MSF

pilot plant of make-up, which consisted of NF permeates or reject from SWRO unit in the

NF-SWRO dual hybrid plant.

Work done on the first three tasks and results obtained on modification and upgrading of

pretreatment pilot plant (Task-3 above) were described in earlier sections 2.1 and 2.3. The

NF permeate and the SWRO reject from an NF-SWRO unit were supplied as make-up to

MSF. As mentioned earlier the results of this work are to be reported in Part-III of this

program in the project titled "MSF Operation at TBT of 120-160 oC in the hybrid NF-MSF

and NF-SWROreject-MSF". This section covers only the results obtained under Section (4) the

"operation and optimization of the NF-SWRO demonstration plant" and more specifically,

deals with the operation and determination of its operating and performance parameters which

are essential for the operation of commercial plants utilizing same size NF and SWRO

modules.

5.1 NF 8″ x 40″ membrane elements Trials Operating Conditions To establish the operating parameters, first work was done by the operation of the NF unit,

which is shown in Figure 2, as part of the NF-SWRO demonstration plant, at different

operating conditions of feed flow, temperature and applied pressure. The NF unit consists, as

mentioned above, of three brine staged 8" modules connected in series, where each module

consists of a pressure vessel fitted with two 8" x 40" NF membranes, which are, again, brine

staged.

Figure 23 shows the effect of applied pressure on permeates from Filmtec NF-70: flow,

recovery and conductivity at a feed flow rate of 4m3/h and feed temperature of 33 oC. Both

the permeates flow and their recovery ratios increased as the applied pressure was increased,

while only the permeates conductivity from first module decreased with applied pressure. The

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permeate conductivity from module #2, however showed, more or less, a steady value with an

increase in applied pressure, while the conductivity of permeate from module #3 showed an

increase in permeate conductivity with the applied pressure. Reason for this increase is the

high salinity of feed to this third module combined with the reduction in quantity of feed it

received. By comparison to modules # 1 and #2 which at P = 35 bar, received 4 m3/h at

TDS of about 44,000 ppm and 3.2 m3/h at TDS about 60,500 ppm, respectively, module #3

received only 2.7 m3/h feed with high TDS of about 71,700 ppm. The net effect of the

changes in feed flow and salinity of the various modules on conductivity of their combined

product is as shown in Figure 23, where the conductivity of the combined product decreased

with some sort of leveling - off towards the end of the conductivity - pressure curve. For the

total permeate at pressure of 38 bar , the conductivity was about 18,000 µs/cm ( TDS≅

10,000 ppm) as compared to 44,000 ppm in gulf seawater , for reduction in TDS of about

77%.

The effect of feed flow rate at different applied pressure on performance of NF-70 membrane

(8") is shown in Figure 24. The decrease in the combined permeates conductivity with increase

in feed flow is accompanied by an increase in both permeate flow and recovery up to a feed

flow of about 6.5 m3/h, thereafter the recovery started to decline. This indicates that the

optimum feed flow for this three module series arrangement is about 6.5 m3/h. This optimum

feed flow case prevails under the present operation conditions, however, it is expected to

change with operation time and operation conditions. As shown in Figure 24c, a sharp drop in

conductivity of the combined permeates from about 30,000 µs/cm to about 22,000 µs/cm is

noticed when the applied pressure was increased from 20 to 30 bar, respectively, and it

continued to drop but at a slow rate up to 35 bar, thereafter it tended to level-off when the

feed flow ≤ 5.5 m3/h, but permeate conductivity continued to drop when the feed flow ≥ 6

m3/h.

Both the permeate flow and recovery increased as the feed temperature was increased. This

is shown in Figure 25, which shows the performance of the 4" NF-70 membrane at various

temperatures. The changes in permeate flow with temperature is about 3% per one degree oC. Permeate conductivity, however, tends to increase slightly with an increase in feed

temperature.

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The composition, percentage salt and individual hardness ions rejection in Filmtec NF-70-

8040 permeate, from the first module (2 NF elements) and the combined product from three

modules, are shown in Table 7. At an applied feed pressure of 28 bar, the total ions rejection,

as represented by TDS rejection, is quite significant and equals 73.2% and 65.9% for

permeate from the first module and the combined product from the three modules,

respectively. By comparison to TDS rejection, superior ion rejection of 98.4, 99.6, 94 and

87.5% were obtained from the first module permeate for the hardness ions SO=4, Mg++, Ca++

and M-alkalinity, respectively.

Similar but slightly lower hardness ions rejection values were obtained for the combined

product from the three module units (Table 7). What is impressive also is that the NF-70

rejection of the monovalent ions, e.g., Cl- by about 68.8 and 61.2% for permeate from the

first module and the combined product from the three modules, respectively. Some changes

in ionic rejection values, however, are noticed with passage in operation time and also with the

applied feed pressure, e.g., compare ion rejection for NF-70 at 28 bar in Table 7 to its ion

rejection at 22 bar in Table 2.

5.2. Performance Evaluation of 8" x 40" NF Membranes Performance evaluation studies were made for the following 8" x 40" NF membranes utilizing

the NF part of the demonstration plant shown in Figure 2: Filmtec NF-70, Osmonics HL

8040F, Toray SU 620F, Fluid System NF 8921S and Hydranautics 8040 UHY ESNA.

The latter two membranes were screen tested only for a short period, and since they gave very

little flow their results will not be discussed in this report. Figure 26 shows the Filmtec NF-70

permeate : b. Flow, c. Recovery and d. Conductivity vs operation time at the a. operation

conditions shown also in the same figure. The V1, V2 and V3, as usual are pressure vessels

#1, #2 and #3, respectively, where pressure vessel with its two membrane elements

constitutes a module. As expected, the permeates flow and their recovery are greatest for

module #1 followed by these for module #2 and least yield was obtained from module #3.

At an applied pressure of 28 bar and feed flow of about 6 m3/h, the total permeate flow of

over 2 m3/h at the start of the experiment dropped to about 1.5 and 1.2 m3/h in about 500 and

1450 operation hours, respectively. For the same period, the product conductivity from first

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module decreased from about 20,000 to about 15,000 µs/cm, while the conductivity of the

combined product from the three modules decreased from 35,000 to about 23,000 µs/cm.

The case that both the differential pressure (∆P) across the membranes and feed SDI were

steady, with ∆P ≤ 1 bar and SDI ≤ 3.5, could suggest no membrane fouling or very little of it.

Perhaps, the more than expected loss in permeate flow and their recovery as well as improved

salt rejection within the 0 to 500 hour operational time scale (Figures 26) could be attributed

partially to a higher than expected membrane compaction and/or to the settling of the very fine

particle on NF-70 membrane surface. The high compaction, however, was not observed

earlier for the same NF-70 membrane, when using size 4" x 40" (Figure 9). Other than this

difference in membrane size, the only other difference in operating conditions between the

earlier (using 4" x 40" ) and the present (using 8" x 40" ) evaluation of NF-70 membranes was

in the applied pressure, where 22 and 28-40 bar were used in earlier and present evaluation

test, respectively (Figures 9 and 26). Perhaps, this difference in working pressure could

account for the observed greater than normally expected compaction of NF-70 membrane in

the latter evaluation test. Raising the pressure to about 42 bar, while reducing the feed flow

rate to about 3.5 m3/h (which is the maximum flow that can be obtained from the pump at this

pressure) increased both the permeate flow and recovery to about 1.8 m3/h and to about 45

± 2 %, respectively (Figure 26). Moreover, the permeate flow, more or less, remained

steady over the operation time scale of 1440 to 2850 hours, which means that within this time

scale region not only the membrane compaction is occurring at the normally expected rate but

also suggests that no membrane fouling, is occurring, otherwise the membrane yield should

have dropped. This case is further discussed in Section 5.5, which deals with the restoration of

NF -70 membrane performance. It is interesting to note that this type of behavior, i.e., decline

in permeate flow with operation time, has not been noticed with many other membranes (see

Figures 10 to 19).

Figure 27 shows the performance of NF membranes in a mixed arrangement of Osmonics NF

HL 8040 membrane elements placed in first vessel (V1) and Filmtec NF-70 8040 membrane

elements placed in second and third vessels (V2 and V3) of the NF unit shown in Figure 2.

Figure 28 shows also the performance of the same NF membranes in a mixed arrangement but

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with same Osmonics membrane elements placed in V3, while the same Filmtec NF-70

membrane elements were placed in V1 and V2. Again each of the 8" pressure vessels

contained two NF membrane elements of 8" x 40".

Initially, for the first 450 hours of operation, at an applied pressure of 18 bar (250 psi) and

feed temperature of 35 oC, the permeate flow from the Osmonics membrane of 1.8 m3/h

constituted about 80% of the combined permeate flow from V1+V2+V3. The permeate flow

rose to about 2.3 m3/h when the pressure raised to 25 bars (Figure 27) The same

generalization can be made for the NF membranes recovery ratios. The 80% ratio of

permeate flow and their recovery ratio from Osmonics membranes to the total permeate flow

and total recovery ratio of the three vessels (V1+V2+V3) were, more or less, maintained during

the extended operation period, even when changing the membrane arrangement as shown in

Figures 28 and 29. Of course, as usual, an increase in applied pressure and/or feed

temperature resulted in an increase in both permeates feed flow and their recovery ratio and

vice versa (Figures 23 to 25).

Contrary to the case of permeates feed flow and recovery ratios, which for Osmonics HL

8040F are much superior to those of Filmtec NF-70, the latter yields permeate with a much

lower conductivity and TDS values than those observed for the former NF membranes. One

remarkable aspect of the Osmonics NF HL 8040FL membrane is that, in addition to its high

permeate flow and recovery performance, it practically maintained a normal compaction

behavior with, more or less, a steady performance from 0 to 1400 hours of operation. Its salt

and hardness ions rejections are as shown in Table 2 and Figure 5.

Comparison of permeate yield of Osmonics DK, HL and DL (Figures 14, 13 and 15) shows

that at a pressure of 25 bar, the yield from 4 of 4”x40” elements, arranged in series in a brine

staging operation, were in the ratio of 20 : 25 : 50 l/min or the permeate yield from the DL is

twice, or more than, the permeate quantity produced by the same number of DK or HL NF

membrane elements. Stated differently, twice the number of DK or HL membrane elements

are required to produce the same quantity of permeate from NF DL membrane elements. The

ionic rejection of the Osmonic NF membrane, however, is reversed, i.e., DK > HL > DL (see

Table 2). Thus, a trade off in properties of flow and rejection of those membranes is to be

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made when selecting one membrane type or another. Utilization of 4 DL elements of 8”x40”

in series is expected to give yield of over 6 m3/h. This very high flow characteristic is quite

interesting and an economic consideration of its use in an NF-SWRO plants worth further

investigation, which shall be carried out under a new project dealing with the technoeconomic

evaluation of using NF groups “B” and “C” membranes (Table 2) in the pretreatment of feed

to seawater desalination plants.

Figure 29 shows the performance vs operation time of NF 8”x40” Toray SU 620F in pressure

vessel 1, Filmtec NF 70 in pressure vessel 2 and Osmonic HL in pressure vessel 3. Operating

conditions were as shown in same Figure 29a. At a pressure of 17.4 bar, the Toray SU 620F

produced about 3 m3/h from the first two elements in the six elements modules, which was

maintained over the entire operation time and it accounts for ~70% of the module total yield of

4.2 m3/h from a feed of about 6.5 m3/h, for a total recovery of about 60%. The 6.5 m3/h is

approaching the maximum flow limit for the present pump at this pressure. Higher feed flow

definitely will not only increase the permeate flow from SU 620F and other membranes, as

well as the total flow, but also should improve the permeate quality. This matter deserves

further investigation, which shall be carried out in the near future. Even when placing SU 620F

in second module, after over 1000 hours of operation while in first module it continued to

produce over 3.2 m3/h, thus maintaining a steady flow. The productivity of the 8 ″ x 4″ Toray

SU 620F is the highest among all the 8 ″ x 4″ NF membrane tested so far. Moreover,

product TDS is about 30460 ppm for a TDS rejection of 31%. Hardness rejection is as

shown in Table 2.

5.3 Operating Conditions of SWRO in an NF-SWRO Hybrid The effect of feed pressure on the performance of SWRO membrane, Toyobo HFF HM

8255, fed NF-70 permeate is shown in Figure 30. Permeate flow and recovery ratio were

increased as the feed pressure was increased. For example, the total permeate flow at 30 bar

was 1.2 m3/h as compared to 2.1 m3/h at an applied feed pressure of 55 bar or greater by

75%. This represents an increase in permeate flow with pressure (∆ flow/∆P) of 0.036

m3/bar or about 3%/bar. Likewise, under same operating conditions, the recovery increased

with pressure in the same manner as SWRO permeate flow (see Figure 30b).

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As expected, among the three membrane elements, the first element has the highest yield

followed respectively by the flow from second and third elements. Conductivity is best for

permeate from second element, although it should have been best for permeate from first

element and is considerably much higher than expected for the third element which was

malfunctioning since its initial operation. The high conductivity of permeate from the third

element has a significant influence on the average conductivity of the total product, which at a

pressure of 50 bar is about 750 µs/cm. Without mixing of permeate from element #3 with

permeate from elements #1 and #2, the average permeate conductivity of the mixture (from

the latter two elements) at a pressure of 50 bar is about 300 µs/cm (Figure 30).

The influence of feed flow rate on SWRO membrane performance in an NF-SWRO

demonstration plant is shown in Figure 31. Increasing the flow rate of feed (consisting of NF-

70 permeate) to SWRO membrane increased its permeate flow rate but not the recovery ratio

and in this case has a hardly detectable increase in permeate conductivity. For comparison,

Figure 31 shows also the performance of the same SWRO membrane when operated on feed

consisting of seawater without the NF pretreatment. At 3.0 m3/h feed and at an applied

pressure of 50 bar, the recovery from the conventionally operated plant (SWRO curve) is only

26% compared to 70% when operated on feed consisting of NF-70 permeate, or in the ratio

of 1:2.69 by the latter case over the former case by, i.e., an increase by 2.7 folds. This is in

addition to the improvement in permeate quality when the SWRO plant is operated on NF

permeate.

5.4 Performance evaluation of SWRO membrane in an NF-SWRO hybrid

Figures 32 shows the performance of SWRO Toyobo HFF HM 8255 SWRO membrane

operated on NF-70 permeate as feed under the operating conditions as shown under (a) in

same figure. Membrane performance is measured by permeate flow, recovery and

conductivities, as shown respectively by curves (b), ( c ) and (d) of the same figure. Because

of the low TDS of NF permeate which constituted the SWRO feed, recovery of 50% was

obtained at a very low pressure of 35 bar or less. Upon increasing the applied feed pressure,

permeate recovery and permeate flow are expected to rise significantly. This has been

discussed in an earlier section, and as shown in Figure 30 recovery of 75% can be obtained at

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an applied pressure of 60 bar. In spite of the high TDS of permeate of over 1000 ppm from

element #3, nevertheless, the average conductivity of total permeate from the three SWRO

elements ranged between 600 to 700 µs/cm.

Figure 33 shows the performance for over 1700 hours of operation of Toyobo HM9255

(9”x40”) HFF SWRO membranes on feed consisting of :

(1) for the first 900 hours of a mixed permeate in the ratio of 50 : 50 of Filmtec NF45 and

Toray SU610, and

(2) for the remaining 800 hours of , again, a mixed permeate in the ratio of 30:70 of Filmtec

NF70 to Osmonic HL8040, and with the Osmonic membrane placed in vessel 3, while

Filmtec NF membrane was placed in vessel 1 and 2 of the 8 inch NF unit. In both cases

a SWRO permeate recovery of about 50% was obtained at pressure of 50 bar. This

ratio is expected to increase as the feed, which was low about 2.8 to 3.0 m3/h and less

than the normal feed requirement of over 4 m3/h, and applied pressure are increased.

Figure 34 shows the permeate of Toyobo HM9255 HFFF SWRO membrane fed on mixed

permeate from Toray SU620F, Filmtec NF70 8040 and Osmonics HL8040, in the ratio 67 :

6 : 27, respectively (for detail of permeate flow and ratio see Figure 29). As in the previous

case, permeate recovery of 42% was obtained at an applied pressure of 50 bar. Higher

SWRO permeate recovery is expected by increasing the pressure and the feed flow, where

the feed flow in the latter case (Figure 34) was not sufficient. Same discussion applies to the

case shown in Figure 35, where feed to SWRO unit was shown in same figure. By lowering

the TDS of feed, the overall permeate recovery at operating pressure of 50 bar was 50%

(Figure 35) as compared to 42% (Figure 34) where in the latter case the TDS of the feed to

SWRO unit from NF product was higher than that in the former case.

5.5 The NF 70 Membrane Performance Restoration In Section 5.2, the larger than expected decline in NF70 performance (Figure 26) was

discussed, and the assumption was made that this case could be attributed (or partially) to a

high degree of membrane compaction at high pressure of up to 40 bar or to membrane fouling.

To rule out fouling an investigation was started by cleaning the membrane. Detail of this

experiment is discussed in a special report to be issued on a later date. Here, it suffices to

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summarize the results obtained by using an effective cleaning method consisting of cleaning the

membrane by a special cleaning solution containing 1,000 ppm Cl2 with or without H2O2 at

0.5% concentration in the solution. The solution pH was maintained at 11, otherwise it will

damage the membrane. In this trial H2O2 was used as part of the cleaning solution. Six NF70,

4”x40” membrane elements were arranged in series with brine staging, utilizing the NF part of

the pilot plant shown in Figure 1. At feed flow of 60 l/min , and pressure of 25 bar, the total

permeate flow before membrane cleaning was 4.5 l/min. Under same operating conditions, but

after cleaning, the flow rose to an amazing value of 30 l/min or by about 6.66 folds, and in the

expected ratio of 12 : 10 : 8 l/min for the first, second and third vessel, respectively. Before

cleaning the membrane, the permeate conductivity was 20,000 µs/cm and rose after cleaning

to about 42,500 µs/cm, which compares to its value (42,450 µs/cm) at the start of operation

of the new NF-70 membrane (see Fig. 9). The conductivity, however, was 38,500, 44,200

and 47,000 µs/cm in permeate from the three consecutive vessels, respectively, for the

average conductivity of 42,466 µs/cm, which corresponds to a TDS value of 28,000 ppm.

Thus, the TDS rejection after cleaning were 36%, which again is equal to the original rejection

value for the new NF70 (see Fig. 9). Extended operation after cleaning of the membrane,

however, showed a decline in permeate flow, presumably by catching on the surface of this

particular membrane of very fine particulates, which were not removed by the feed

pretreatment.

6. CONCLUSIONS (1) The study covers two main areas of investigation: the optimization of NF pretreatment of

feed to 4 or 8 inch seawater plants and the construction and evaluation of an NF-

SWRO Demonstration Plant, utilizing large size 8”x40” or 9”x40” NF and SWRO

membranes.

(2) Both the 4 and 8 inch pilot plants were modified to allow for the performance evaluation

(permeate flow, recovery and ionic rejection) of each of the various NF and SWRO

membranes.

I ?

(3) Part of the work was concerned with providing make-up to MSF pilot plant, consisted

of NF permeate or seawater reject from a hybrid NF-SWRO. The part will be

reported separately under Part III of the NF work.

(4) A total of 13 NF membranes, size 4”x40” and/or 8”x40” were investigated: Filmtec

NF90, NF70 and NF45; Osmonics HL, DK and DL; Toray SU610 and SU 620F ;

Trisep TS40 and TS80 ; Fluid Systems 8921S and 4921SR as well as Hydraunatics

ESNA.

(5) In general, for all the NF membranes, the permeate flow and recovery ratio increased as

the feed temperature or applied pressure was increased.

(6) The SO=4 rejection of all NF membranes examined here is considered to be excellent.

For the one module case, the SO=4 rejection by any of the NF membrane is better than

98%.

(7) The rejection of the hardness cation of Ca++ differs from one membrane to another and,

in general, is less than the rejection of SO=4.

(8) The Mg++ ion rejection by the various NF membranes tends to follow the same order as

that Ca++ rejection.

(9) The observed variation in NF permeate scaling potential, as measured by the threshold

effect (Figure 7) follows their Ca++ content.

(10) At the same applied pressure, NF membranes with high rejection of Ca++ and Mg++

tend to have low flow and recovery, while the reverse is true, i.e., membranes with low

rejection of Ca++ and Mg++ tend to have high flow and high permeate recovery.

(11) From their permeate flow and ion rejection characteristics the various membranes

examined were grouped into:

n Group “A” characterized by high ion rejection (more than 45%) and low permeate flow.

n Group “B” characterized by balanced properties of good ion rejection (25 to 45%) and

good permeate flow,

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n Group “C” characterized by high permeate flow but moderate ion rejection (20 to

25%).

(12) At feed SDI <4 nearly all membranes maintained a steady permeate flow with operation

time, with exception of one NF membrane. A membrane cleaning study was undertaken

and membrane performance was restored by cleaning at pH of 11 with special Cl2

and/or Cl2 with H2O2 solution. However, a decline in permeate flow was noticed on an

extended operation.

(13) This report serves as a detailed documentation for all the R&D work done under this

part of the project.

7. RECOMMENDATIONS (1) Initially, Group “B” of NF membranes can be recommended for use in an NF-SWRO

commercial plants. However, because of their high flow and other characteristics, there

are great merits in considering membranes in Group “C” for the same purpose.

Preference of using of either membranes of Group “B” or “C” in an NF-SWRO plant,

however, can be established through a recommended technoechonomic study, which

should be added to the list of the 8 projects already recommended in Reference 1, and

thus it shall constitute Project Part IX.

(2) There could be a room for the development by the RO membrane industry of an NF

seawater membrane combining some of excellent ionic and hardness rejection

properties of the “A” type membranes with good permeate flow and permeation

characteristic of “B” or “C” type membranes. Joint work on this idea by the maker and

users of NF membrane, is recommended and is encouraged.

(3) Work is to be continued on evaluation of new NF, also on hollow fiber NF membranes

under Part IX of this NF project.

? I

Table 1 : Media thickness and particle size before and after media replacement

Media Thickness (mm)

Media Type Particle size (mm) Filter #1 Filter #2

Before media After media Before media After media replacement replacement replacement replacement

(a) Pilot Plant

Anthracite 1.2-3 203 320 - -

Coarse sand 0.7-1.3 152 - 152 -

Fine sand #1 0.6-0.8 406 - - -

Fine sand #2 0.55 - 460 - 460

Very fine sand 0.3-0.5 - - 533 -

(b) Demonstration Plant

Anthracite 0.8 400 300 400 -

Fine sand 0.55 400 300 400 -

Very fine sand 0.25-0425 - 200 - 800

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Table 2 : Comparison of 4″ Nanofiltration ( NF) Membrane2 Performance at Feed Pressure of 17.2 bar (250 psi) (Two modules in series, each pressure vessels contains two

elements) (Membranes are arranged serially according to their ability to lower TDS in permeate)

Membrane

Seawater NF-90* TFS 8921S

ESNA ANM TS80

NF-70** DK 4040F

SU - 620F***

NF - 45 SU - 610 HL 4040 F I550

DL 4040F

ANM TS40

NF-4721SR

Date 17/02/99 29/07/98 30/08/98 23/05/99 28/06/97 23/05/99 12/07/99 28/07/98 29/07/98 21/09/98 12/07/99 21/09/98 15/06/99 Temp. oC 23.0 37 38 28.7 34 28.7 34.8 37.2 37 33.5 34.0 33.5 33.8 Flow Rates (l/min) Feed 14.1 18.27 20.4 28.5 30.52 31.03 117 33.7 35.95 39.31 63.6 37.69 40 Product 2.17 0.56 2.85 8.52 13.19 11.03 45 16.73 21.57 25.39 32.2 22.25 29.6 Reject 11.9 17.7 17.53 20 17.23 20 72 16.96 14.38 14.92 31.4 15.44 10.4 Recovery %

15.4 3.01 14 29.9 43.2 35.6 38.6 49.6 60.01 64.6 50.6 59 74

Conductivity (µs/cm)

60000 21900 32600 36900 39900 43200 46300 46600 48600 48800 49200 51000 49900 52600

TDS (ppm) 44000 12900 21700 24026 25400 28270 29640 30460 32420 33080 33680 34250 35680 35920 pH 6.6 8.2 6.17 6.52 6.21 6.35 7.65 6.48 6.61 6.59 6.43 6.89 6.76 7.06 6.64 Hardness Total Hardness

7800 185 840 946 553 930 241 800 680 1600 1580 1318 3500 1810

SO4=(ppm) 3240 3200 41 99 107 20 52 ND <2 31 33 33 33 112 70

HCO3-

(ppm) 101 176 19 56 37 35 54 46 50 68 71 67 68 73 87

M. Alkalinity

83 128 15 46 30 28 44 38 41 56 58 55 56 60 71

Ca++ (ppm) 480 19 92 82 79 88 44 112 108 164 204 163 300 174 Mg++ (ppm) 1610 32 150 180 86 173 32 126 112 245 260 222 425 334 Cl- (ppm) 22780 8250 13490 14503 15290 17140 17770 18192 19500 20280 19446 20090 20074 20860 Group A B C * At feed pressure of 24.1 kg/cm2

** From 10 elements at feed pressure 19.3 kg/cm2

*** Deduced from 8 inch membrane element data

2 NF 90, NF 70 and NF 45 FilmTec ; DK 4040, DL 4040 and HL 4040 Osmonics ; TS 80 and TS 40 Trisep ; TFS 8921S and NF 4721 SR Fluid System ; SU 610 and SU 620F Toray and ESNA Hydranautics

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Table 3 : Comparison of 4″ Nanofiltration ( NF) Membrane3 Performance at Feed Pressure of 17.2 bar (250 psi) (Two modules in series, each pressure vessels contains two elements) (Membranes are arranged serially according to Ca++ concentration in their permeate)

Membrane

Seawater NF-90* DK 4040F

ANM TS80

ESNA NF-70** TFS 8921S

NF - 45 SU - 620F***

DL 4040F

SU - 610 NF-4721SR

HL 4040 F I550

ANM TS40

Date 17/02/99 23/05/99 23/05/99 30/08/98 28/06/97 29/07/98 28/07/98 12/07/99 12/07/99 29/07/98 15/06/99 21/09/98 21/09/98 Temp. oC 23.0 28.7 28.7 38 34 37 37.2 34.8 34.0 37 33.8 33.5 33.5 Flow Rates (l/min) Feed 14.1 31.03 28.5 20.4 30.52 18.27 33.7 117 63.6 35.95 40 39.31 37.69 Product 2.17 11.03 8.52 2.85 13.19 0.56 16.73 45 32.2 21.57 29.6 25.39 22.25 Reject 11.9 20 20 17.53 17.23 17.7 16.96 72 31.4 14.38 10.4 14.92 15.44 Recovery %

15.4 35.6 29.9 14 43.2 3.01 49.6 38.6 50.6 60.01 74 64.6 59

Conductivity (µs/cm)

60000 21900 46300 39900 36900 43200 32600 48600 46600 51000 48800 52600 49200 49900


7800 185 241 553 946 930 840 680 800 1318 1600 1810 1580 3500

SO4=(ppm) 3240 3200 41 ND 20 107 52 99 31 <2 33 33 70 33 112

HCO3-

(ppm) 101 176 19 46 35 37 54 56 68 50 68 71 87 67 73

M. Alkalinity

83 128 15 38 28 30 44 46 56 41 56 58 71 55 60

Ca++ (ppm) 480 19 44 79 82 88 92 108 112 163 164 174 204 300 Mg++ (ppm) 1610 32 32 86 180 173 150 112 126 222 245 334 260 425 Cl- (ppm) 22780 8250 17770 15290 14503 17140 13490 19500 18192 20090 20280 20860 19446 20074 * At feed pressure of 24.1 kg/cm2




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Table 4 : Comparison of 4″ Nanofiltration ( NF) Membrane4 Performance at Feed Pressure of 17.2 bar (250 psi) (Two modules in series, each pressure vessels contains two elements) (Membranes are arranged serially according to total hardness concentration in their permeate)

Membrane

Seawater NF-90* DK 4040F

ANM TS80

NF - 45 SU - 620F***

TFS 8921S

NF-70** ESNA DL 4040F

HL 4040 F I550

SU - 610 NF-4721SR

ANM TS40

Date 17/02/99 23/05/99 23/05/99 28/07/98 12/07/99 29/07/98 28/06/97 30/08/98 12/07/99 21/09/98 29/07/98 15/06/99 21/09/98 Temp. oC 23.0 28.7 28.7 37.2 34.8 37 34 38 34.0 33.5 37 33.8 33.5 Flow Rates (l/min) Feed 14.1 31.03 28.5 33.7 117 18.27 30.52 20.4 63.6 39.31 35.95 40 37.69 Product 2.17 11.03 8.52 16.73 45 0.56 13.19 2.85 32.2 25.39 21.57 29.6 22.25 Reject 11.9 20 20 16.96 72 17.7 17.23 17.53 31.4 14.92 14.38 10.4 15.44 Recovery % 15.4 35.6 29.9 49.6 38.6 3.01 43.2 14 50.6 64.6 60.01 74 59 Conductivity (µs/cm)

60000 21900 46300 39900 48600 46600 32600 43200 36900 51000 49200 48800 52600 49900


7800 185 241 553 680 800 840 930 946 1318 1580 1600 1810 3500

SO4=(ppm) 3240 3200 41 ND 20 31 <2 99 52 107 33 33 33 70 112

HCO3- (ppm) 101 176 19 46 35 68 50 56 54 37 68 67 71 87 73

M. Alkalinity

83 128 15 38 28 56 41 46 44 30 56 55 58 71 60

Ca++ (ppm) 480 19 44 79 108 112 92 88 82 163 204 164 174 300 Mg++ (ppm) 1610 32 32 86 112 126 150 173 180 222 260 245 334 425 Cl- (ppm) 22780 8250 17770 15290 19500 18192 13490 17140 14503 20090 19446 20280 20860 20074 * At feed pressure of 24.1 kg/cm2



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Table 5: Composition of NF permeate and seawater (Scaling potential and threshold effect) Parameter Unit Filmtec Trisep TSA 4040 Osmonics Seawater

NF-70 4" 2 elements HL8040F 2 element

Ca++ mg/L 32 280 176 480 Mg++ mg/L 75 511 195 1610 SO4

= mg/L 125 48 39 3200

M.Alkalinity- as CaCO3

mg/L 22 49 50 128

Total Hardness

mg/L 390 2800 1240 7800

Cl- mg/L 7070 18670 19293 22500 Conductivity-

mS/cm 18000 39900 41500 60000

TDS mg/L 11000 32360 33120 44000 pH 6.23 6.74 6.86 8.2

Table 6 : Composition of NF permeates and results of scaling potential measurement using evaporation

method Parameter Unit FilmTec Osmonics Toray Seawater

NF-70 (8") #1 NF-70 (8") #2 NF-45 (4") HL4040F (8") SU610 (4") Ca++ mg/L 40 104 72 160 361 480 Mg++ mg/L 117 175 68 209 579 1610 SO4

= mg/L 196 189 10 180 20 3200

M.Alkalinity- as CaCO3

mg/L 18 33 39 50 44 128

Total Hardness

mg/L 580 980 460 1260 3280 7800

Cl- mg/L 6400 13160 16360 18490 17600 22500 Conductivity-

mS/cm 16300 32800 40400 44800 42800 60000

TDS mg/L 10250 21960 27300 31380 30560 44000 pH 6.3 6.3 6.4 6.34 6.46 8.2 Percentage of evaporation at which turbidity appeared

%

> 92

> 94

92

> 90

92

20

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Table 7: Seawater composition and ion rejection of FilmTec NF-70 8040 membrane (Pressure 28 bar).

Parameter Unit Seawater Permeate from single* module Combined permeate from three modules

Ionic concentration Ion Rejection(%) Ionic concentration Ion Rejection(%)

A. Hardness

Calcium mg/L 481 30 94 64 87

Magnesium mg/L 1608 7 99.6 54 96.6

Total hardness mg/L 7800 202 97.4 283 96.4

Sulfate mg/L 3200 50 98.4 85 97.4

M.Alkalinity as CaCO3 mg/L 128 16 87.5 18 85.9

B. Other Ions

Chloride mg/L 22780 7111 68.8 8846 61.2

Sodium mg/L (12860) (4014) 68.8 (5022) 61.2

Total dissolved solids mg/L 44046 11798 73.2 15031 65.9

pH mg/L 8.2 6.1 - 6.1

Conductivity mS/cm 60000 16900 72.0 21100 *Results obtained at 28 bar

?O

Fig. 1. Schematic Flow Diagram of NF-SWRO Desalination Pilot Plant Utilizing Existing SWRO Mini moduleTest Unit ( 4" x 40" NF and 2.5" x 40" SWRO membrane elements)

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Fig. 2. Schematic Flow Diagram of Demonstration NF-SWRO Desalination Plant Utilizing Existing Facilities with Commercial (8x40 inch) NF and SWRO Membrane Elements.

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Seawater

CF FEEDTANK

Duel Media Fine Sand Media

HIGH PRESSUREPUMP

Reject to MSF

PERMEATE

SWRO UNIT

A/A

MSF UNIT

4 H.R.C Stages

Brine heater

BOOSTER PUMPFEED TANK

H. RJ

SW

D

B.B

B.R

NF Unit

PRODUCT

NF REJECT

Pump

Seawater from MSF Heat Rejection SectionSWRO Unit

Figure 3. Schematic Flow Diagram of NF, SWRO and MSF Pilot Plant

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BD

MF

AD

MF

AM

CF

NFB

NFP

MAY

JUN.

JUL.

AUG.

SEPT.

OCT.

Nov

DEC

1.00E+01

5.01E+03

1.00E+04

1.50E+04

2.00E+04

Fig.4: Monthly AVG Bacteria Count in Colony Forming Unit /ml (CFU) from Different Sampling Points in NF Pilot Plant at 0 hrs (BDMF& ADMF, Before and After Dual Media Filter,AMCF After Micron Cartridge Filter, NFB& NFP, Nanofiltration Brine and Permeate)

Mon BDMF ADMF AMCF NFB NFPMAY 1.0E+3 2.8E+3 2.8E+3 6.2E+ 3 6.2E+1JUN 2.6E+3 2.4E+3 2.1E+3 4.3E+3 2.1E+2JUL 2.9E+3 8.5E+3 1.4E+3 2.4E+3 2.1E+2 AUG 1.2E+4 7.9E+3 7.9E+3 1.06E+4 3.1E+2SEP 1.7E+4 3.2E+3 7.2E+3 1.9E+3 1.5E+2OCT 1.1E+2 1.9E+2 6.0E+1 6.0E+2 3.0E+1 NOV 1.2E+3 9.5E+1 1.0E+2 8.5E+2 7.1E+1DEC 2.7E+3 9.5E+1 7.5E+1 1.2E+3 5.7E+1

? I

480

44

7988

108164

204300

1610

3286

173112

245206

425

3200

020

17831

3333

112

12838

2844

5658

5560

0

500

1000

1500

2000

2500

3000

3500

Con

cent

rati

on (

PP

M)

Ca++ Mg++ SO4= M-Alk.

seawaterOsmonics DK4040FTriSep TS 80-TSAFilmTec(NF70)FilmTec(NF45)Toray NF SU610Osmonics HL4040FTriSep TS 40-TSA

7800

241553 680

9301580

1600

3500

0

1000

2000

3000

4000

5000

6000

7000

8000

Con

cent

rati

on (

PP

M)

TH

2 2 . 5

1 5 . 3 1 7 . 1

1 7 . 7 1 9 . 5

2 0 . 3

1 9 . 42 0

4 4

2 5 . 42 8 . 3

2 9 . 6

3 2 . 4 3 3 . 1 3 3 . 73 5 . 7

0

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

4 5C

co

nc

en

tra

tio

n (

PP

M)

C l - T D S

Figure 5. Ionic Concentration of : a. Hardness Ions, b. Total Hardness and c. Cl- & TDS in Seawater and NF Permeates of Seven Different NF Membranes (Feed

to NF Membranes, Seawater, TDS 44,000 ppm)

a. Hardness ions (ppm)

b. Total Hardness (ppm) c. Cl- concentration and TDS (ppm)

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Conductivity ( ms/cm) 17.84 18.99 19.50 21.90 32.60 36.70 36.90 38.80 39.90 43.20 44.60 45.70 45.90 46.00 46.30 48.60 48.80 49.20 49.90 50.10 51.00 51.80 52.20 52.60 53.00 54.00 58.10

TDS (ppm) 10860 10300 11680 12900 21700 23130 24026 25110 25400 28270 28560 30420 30280 30340 29640 32420 33080 33680 35680 33060 34260 35580 35380 35920 36420 36240 41220

Calculated TDS (ppm) 10292 11059 11402 13032 20602 23612 23761 25174 25998 28488 29554 30394 30547 30624 30854 32625 32780 33089 33632 33787 34487 35110 35422 35735 36048 36832 40070

% Deviation -5.2 7.4 -2.4 1 -5.1 2.1 -1.1 0.3 2.4 0.8 3.5 -0.1 0.9 0.9 4.1 0.6 -0.9 -1.8 -5.7 2.2 0.7 -1.3 0.1 -0.5 -1 1.6 -2.8

Figure 6. TDS vs Conductivity of NF Permeate

y = 373.16x1.1512

R2 = 0.9947

0100020003000400050006000700080009000

100001100012000130001400015000160001700018000190002000021000220002300024000250002600027000280002900030000310003200033000340003500036000370003800039000400004100042000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

Conductivity (mS/cm)

TD

S (

pp

m)

? ?

0

100

200

300

400

500

600

700

0 5 10 15 20 25 30

Time, min.

M. A

lk. a

s pp

m (C

aCO

3)

NF-70 Brine + antiscalant PPNNF-Osmonics HL8040 NF-Trisep TS40Seawater Brine

52

720

136

481

264

720

Ca++(ppm)

Figure 7 : The Scaling Threshold of NF Membrane Permeates ( as ppm of Calcium Carbonate) without Scale Control Additives at 95oC for all Samples except for Brine where it was measured with and without Polyphosphonate (PPN) Antiscalant addition.

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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Raw Seawater

Treated Seawater

Toray SU610

NF 45 (Filmtech)

OsmonicsHL8040F

NF 70 (Filmtech)

Per

cent

Rec

over

y &

Its

Rel

atio

n to

Sca

le F

orm

atio

n

No Scaling Range Critical Range Scaling Range

Figure 8. Scaling Potenial of Various Types of Brine Solutions

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a.Operation Conditions

05

1015

202530

3540

0 200 400 600 800 1000 1200

P (b

ar),

T(0 C

),SD

I& F

eed

Flo

w

temperature(oC) pressure (bar) SDI Feed flow

b.Permeate Flow Rates

02468

10121416

0 200 400 600 800 1000 1200

Flo

w (l

/min

)

permeate flow (l/min)

c.Permeate Recovery

010203040506070

0 200 400 600 800 1000 1200

Rec

over

y(%

)

Recovery

d.Permeate Conductivity

32000

34000

36000

38000

40000

42000

44000

0 200 400 600 800 1000 1200Time(hrs)

Con

duct

ivity

( µs/

cm)

Product conductivity

Figure 9. Performance of 4"x40" Filmtec NF- 70 Membranes (10 elements) a. Operation Conditions, b. Permeate Flow Rates, c. Recovery and d. Conductivity vs

Operation Time

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0

5

10

15

20

25

30

35

0 200 400 600 800 1000 1200 1400 1600 1800 2000

P(b

ar),

T(o C

)& S

DI

50

55

60

65

70

75

80

85

90

95

100

Fee

d F

low

(l/m

in)

Pressure (bar) Temp.(0C) SDI Feed Flow (l/min)

0

5

10

15

20

25

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Flo

w (l

/min

)

V-1 V-2 (V-1 + V-2)

0

10

20

30

40

50

60

70

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Rec

over

y(%

)

V-1 V-2 (V-1 + V-2)

30000

35000

40000

45000

50000

55000

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Con

duct

ivit

y(µs/

cm)

V-1 V-2 (V-1 + V-2)

Figure 10: Performance of 4"x40" Filmtec NF-45 membranes a. Operation Conditions, b.Permeate Flow Rates, c.Recovery and d.Conductivity vs. Operation Time {Each Vessel(v) Contains 2 NF Elements}



c.Permeate Recovery


Time (hrs)

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0

5

10

15

20

25

30

0 50 100 150 200 250 300 350 400 450 500

Feed

Flo

w(l/

min

),Tem

p. (

o C)&

P.(

bar

)

Flow(l/min) Temp.(oC) Pressure(bar)

0

0.5

1

1.5

2

2.5

3

0 50 100 150 200 250 300 350 400 450 500

Flo

w(l

/min

)

V1 V2 (V1+V2)

0

5

10

15

20

25

0 50 100 150 200 250 300 350 400 450 500

Rec

ove

ry(%

)

V1 V2 (V1+V2)

d. Permeate Conductivity

15000

20000

25000

30000

35000

40000

0 100 200 300 400 500

Time(hrs)

Co

nd

uct

ivit

y(m

s/cm

)

V1 V2 (V1+V2)

a. Operation Conditions

b. Permeate Flow Rates

c.Permeate Recovery

Figure 11. Performance of 4" NF-90 Filmtec a. Operation Conditions, b. Permeate Flow Rates, c. Recovery and d. Conductivity vs Operation Time

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0

5

10

15

20

25

30

35

0 200 400 600 800 1000 1200 1400 1600 1800 2000

P (b

ar),

T(o C

) & S

DI

50

60

70

80

90

100

Fee

d F

low

(l/m

in)

Pressure (bar) Temp.(0C) SDI Feed Flow (l/min)

0

5

10

15

20

25

30

35

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Flo

w (l

/min

)

V-1 V-2 (V-1 + V-2)

0

10

20

30

40

50

60

70

80

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Rec

over

y (%

)

V-1 V-2 (V-1 + V-2)

30000

35000

40000

45000

50000

55000

60000

0 200 400 600 800 1000 1200 1400 1600 1800 2000Time (hrs)

Con

duct

ivit

y (µ

s/cm

)

V-1 V-2 (V-1 + V-2)

Figure 12. Performance of 4"x40" Toray NF-SU 610 membranes a. Operation Conditions, b.Permeate Flow Rates, c.Recovery and d.Conductivity vs. Operation Time

a.Operation Condition


c.Permeate Recovery


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05

10152025303540

0 50 100 150 200 250 300 350 400 450 500

Pre

ssur

e (b

ar) ,

Tem

p.(o C

) & S

DI

SDI Pressure (bar) Temp (oC)

Figure 13. Performance of 4" NF HL4040F Osmonics Membranes a.Operation Conditions, b.Permeate Flow Rates, c.Recovery and d. Conductivity vs.Operation

Time


05

101520253035

0 50 100 150 200 250 300 350 400 450 500

Flo

w (l

/min

)

V-1 V-2 (V1 + V-2)

c.Permeate Recovery

010203040506070

0 50 100 150 200 250 300 350 400 450 500

Rec

over

y (%

)

V-1 V-2 (V1 + V-2)


44000

46000

48000

50000

52000

54000

56000

0 50 100 150 200 250 300 350 400 450 500Time (hrs)

Con

duct

ivit

y ( µ

s/cm

)

V -1 V-2 (V 1 + V-2)

? ?


0

10

20

30

40

50

0 50 100 150 200 250 300 350 400 450 500

Tem

p.(

o C)

& P

ress

ure

(bar

)

010

2030405060708090

Fee

d F

low

(l/m

in)

Pres.(bar) Temp.(0C) F.Flow (l/min)

b.Permeate Flow Rate

0

5

10

15

20

25

0 50 100 150 200 250 300 350 400 450 500

Flo

w (l

/min

)

V-5 V- 7 (V-5 + V-7)

c.Permeate Recovery

0

10

20

30

40

50

60

0 50 100 150 200 250 300 350 400 450 500

Rec

ovry

(%)

V-5 V-7 (V-5+ V-7)

t


420004300044000450004600047000480004900050000

0 50 100 150 200 250 300 350 400 450 500Time (hrs)

Con

duct

ivit

y(µ

s/cm

)

V-5 V-7 (V-5 + V-7)

Figure 14. Performance of NF Osmonics-DK membrane a.Operation Conditions b. Permeate flow rates, c. Recovry and d. Conductivity vs. Operation time

? I

0

1020

30

4050

60

7080

90

100

0 50 100 150 200 250 300 350

F. F

low

(l/m

in.),

Tem

p.(0 C

)& P

(bar

)

Pressure Feed Flow Temp.(0C)

0

10

20

30

40

50

60

0 50 100 150 200 250 300 350

Flo

w (

l/min

)

V-5 V-7 (V-5 + V-7)

0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350

Rec

ove

ry(%

)

V-5 V-7 (V-5+ V-7)

47000

48000

49000

50000

51000

52000

53000

54000

0 50 100 150 200 250 300 350

Co

nd

uct

ivit

y(µs

/cm

)

V-5 V-7 (V-5 + V-7)

Figure 15. Performance of NF 4" Osmonics-DL a.Operation Conditions b. Permeate Flow Rates c.Permeate Recovery d. Permeate Conductivity vs. Operation Time



c. Permeate Recovery (%)


Time (hrs)

? I


05

10152025303540

0 50 100 150 200 250 300 350 400 450 500

P (b

ar),T

emp.

(o C) &

SDI

SDI Pressure (bar) Temp (oC)

Figure 16. Performance of 4" NF TS 4040 TSA Trisep Membranes a.Operation Conditions, b.Permeate Flow Rates, c. Recovery and d. Conductivity vs.Operation

Time


05

101520253035

0 50 100 150 200 250 300 350 400 450 500

Flo

w (l

/min

)

V-1 V-2 (V1 + V-2)

c.Permeate Recovery

0

102030

4050

6070

0 50 100 150 200 250 300 350 400 450 500

Rec

over

y (%

)

V-1 V-2 (V1 + V-2)


4400046000

4800050000

5200054000

56000

0 50 100 150 200 250 300 350 400 450 500

Time (hrs)

Con

duct

ivit

y (µ

s/cm

)

V-1 V-2 (V1 + V-2)

? ?


0

10

20

30

40

50

0 100 200 300 400 500 600

Tem

p.( o C

) & P

ress

ure

(bar

)

0102030405060708090

Feed

Flo

w(l/

min

)

Pres.(bar) Temp.(0C) F.Flow (l/min)

b. Permeate Flow Rate

0

5

10

15

20

0 100 200 300 400 500 600

Flow

(l/m

in)

V-6 V-8 (V-6 + V-8)

c. Permeate Recovery

0

10

20

30

40

50

0 100 200 300 400 500 600

Rec

over

y (%

)

V-6 V-8 (V-6 + V-8)


30000

34000

38000

42000

46000

50000

0 100 200 300 400 500 600Time (hrs)

Con

duct

ivty

(µs/

cm) V-6 V-8 (V-6+ V-8)

Figure 17. Performance of 4" NF TS-80 Trisep membrane a. Permeate flow rates, b. Recovery and c. Conductivity vs. Operation time

? ?


05

10152025303540

0 5 10 15 20 25 30 35 40 45 50

Pre

ssur

e (b

ar) &

Tem

p.(o C

)

0

1

2

3

4

5

6

SDI

Pressure (bar) Temp (oC) SDI

Figure 18. Performance of 4" ESNA Hydranautics Membranes .OperationConditions, b.Permeate Flow Rates, c.Recovery and d.Conductivity vs. Operation Time. (V = Pressure Vessel)


0

1

2

3

4

0 5 10 15 20 25 30 35 40 45 50

Flo

w (l

/min

)

V-1 V-2 (V1 + V-2)

c.Permeate Recovery

0

5

10

15

20

0 5 10 15 20 25 30 35 40 45 50

Rec

over

y (%

)

V-1 V-2 (V1 + V-2)


32000

34000

36000

38000

40000

0 5 10 15 20 25 30 35 40 45 50Time (hrs)

Con

duct

ivit

y ( µ

s/cm

)

V-1 V-2 (V1 + V-2)

? ?

0

10

20

30

40

50

60

70

80

0 100 200 300 400 500 600

P (

bar

), T

emp

. ( o

C)&

Fee

d F

low

(l

/min

.)

Feed Flow Pressure Temp.(0C)

0

5

10

15

20

25

30

35

40

45

0 100 200 300 400 500 600

Flow

(l/m

in)

V-6 V-8 (V-6 + V-8)

0

10

20

30

40

50

60

70

80

0 100 200 300 400 500 600

Rec

ove

ry (

%)

V-6 V-8 (V-6 + V-8)

48000

49000

50000

51000

52000

53000

54000

55000

56000

57000

0 100 200 300 400 500 600

Co

nd

uct

ivit

y ( µ

s/cm

)

V-6 V-8 (V-6+ V-8)

Figure 19. Performance of 4" NF-4721SR Fluid System membranes a.Operation Conditions b. Permeate Flow Rates c.Permeate Recovery d. Permeate Conductivity vs. Operation Time





Time (hrs)

Flushing

? ?

c. Avg. Permeate Conductivity

30000

35000

40000

45000

50000

55000

0 50 100 150 200 250 300 350 400 450 500Time (hrs)

Con

duct

ivit

y( µs/

cm)

HL-OS Toray Dk-OSTisep-TS-80 NF-45 Trisep-TS40NF-70 Fluid4721SR OS-DL

b. Total Permeate Recovery

30

35

40

45

50

55

60

65

70

0 50 100 150 200 250 300 350 400 450 500

Rec

over

y(%

)

Toray Dk-OS Tisep-TS-80NF-45 Trisep-TS40 NF70Fluid 4721SR OS-DL OS-Hl

a. Total Permeate Flow Rates

5101520253035404550

0 50 100 150 200 250 300 350 400 450 500

Flo

w(l

/min

)

Dk-OS Tisep-TS-80 NF-45Trisep-TS40 NF-70 OS-DLFluid 4721SR HL-OS Toray

Figure 20 : Performance of Filmtec NF- 45, NF70; NF-Trisep TS 40,TS80;NF-Osmonics-HL, DK, DL; NF-Toray SU 610 and NF-Fluid 4721SR; a. Total Permeate Flow Rates b. Total Recovery and c. Avg. Conductivity vs. Operatition Time

?O

-2

0

2

4

6

8

10

35 40 45 50 55 60 65 70 75

Flo

w (

l/min

)

SWRO Toray Osmonics-HL NF-45 Osmonics-DK Trisep-TS80 N F-70

0

10

20

30

40

50

60

70

80

90

35 40 45 50 55 60 65 70 75

Rec

ove

ry(%

)

SWRO Toray Osmonics-HL NF-45 Osmonics-DK Trisep-TS80 NF-70

0

500

1000

1500

2000

2500

3000

3500

35 40 45 50 55 60 65 70 75

Co

nd

uct

ivit

y(µs

/cm

)

SWRO Toray Osmonics-HL NF-45 Osmonics-DK Trisep-TS80 NF-70

a. Permeate Flow Rates

b. Permeate Recovery

c. Permeate Conductivity

Figure 21. SWRO Permeate a. Flow, b. Recovery, c. Conductivity From the NF-SWRO Process and the Conventional SWRO vs Applied Pressure in Pilot Plant (Feed to SWRO is : Permeate From NF Membranes or Seawater)

Feed Pressure (bar)

? ?

NF (4 elements)

SWRO PermeateNF

PermeateSeawater Feed

NF Reject

SWRO (6

Figure 22. SWRO Feed TDS vs SWRO Permeate Flow at Different Pressures (SWRO Feed Consists of Permeate from 4 Elements of Different NF Membranes or Seawater)

0

1

2

3

4

5

6

7

8

9

20000 25000 30000 35000 40000 45000 50000SWRO FEED TDS (ppm)

SWR

O P

erm

eate

Flo

w (L

/min

)

70

65

60

55

50

45

40

Pressure (bar)

NF-Osmonics DK 4040

Trisep TS80

Filmtec NF-45

NF-Toray SU 610NF-Osmonics-HL 4040

Seawater

? ?

a.Product Flow (m 3/h)

0

0.4

0.8

1.2

1.6

2

25 30 35 40

b. Recovery (%)

0

10

20

30

40

50

25 30 35 40

Module #1

Module #2

Module #3

Total

c. Conductivity ( µS/cm)

0

10000

20000

30000

40000

25 30 35 40Feed Pressure (bar)

Fig. 23 : Performance of 8" x 40" NF-A membrane as measured by permeate (a) Flow, (b) Recovery, and ( c) Conductivity for NF-SWRO Demonstration Plant vs. Applied Pressure (Feed Flow Rate = 4 m3/h, Temperature = 33oC)

? ?

a. Flow (m3/h)

0.0

1.0

2.0

3.0

4.0

0 10 20 30 40 50

b. Recovery (%)

0

10

20

30

40

50

60

0 10 20 30 40 50

5.0 m3/h

5.5 m3/h

6.5 m3/h

7.5 m3/h

c. Conductivity (µS/cm)

15000

20000

25000

30000

35000

0 5 10 15 20 25 30 35 40 45 50

Feed Pressure (bar)

Figure 24. Performance of NF-70 as Measured by Permeate a. Flow, b. Recovery and c. Conductivity vs Applied Pressure at Different Feed Flow rates (Demonstration Unit)

? I

4

6

8

10

12

14

16

20 25 30 35 40 45 50

a. Flow (L/m)

2224

28

31 bar

10

15

20

25

30

35

40

45

20 25 30 35 40 45 50

b. Recovery (%)

22

24

28

31 bar

Fig. 25. Filmtec NF-70 (4" x 40") permeate (a) Flow, (b) Recovery and (c) Conductivity Vs Feed Temperature at Different Applied Pressures (bar)

20000

24000

28000

32000

36000

40000

20 25 30 35 40 45 50Feed Temperature ( oC)

c. Conductivity ( µS/cm)

22 bar24

2831

? I

b. Permeate flow rates

0.0

1.0

2.0

3.0

0 500 1000 1500 2000 2500 3000

Flow

(m3 /h

r)

V1+V2+V3 V1 V2 V3

0

10

20

30

40

50

0 500 1000 1500 2000 2500 3000

Rec

over

y (%

)

V1+V2+V3 V1 V2 V3

c. Permeate recovery

5000

10000

15000

20000

25000

30000

0 500 1000 1500 2000 2500 3000Time (hours)

Con

duct

ivity

(µS/

cm)

Ave. Con. V1 V2

Figure. 26 : Performance of 8" NF-70 membranes a. operation conditions, b. permeate flow, c. recovery and d. conductivity vs. operation time (v = pressure vessel, contains 2 elements)

a. Operation conditions

0

10

20

30

40

0 500 1000 1500 2000 2500 3000

Pre

ssur

e (b

ar),

Tem

p.

(o C)

Pressure (bar) Temp (oC) Feed flow (m3/hr)


? ?

a.Operating Conditions

102030405060708090

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Pre

ssur

e (k

g/cm

2 ) & T

emp.

(o C)

Pressure (kg/cm2) Temp (oC) Feed (l/min)


05

101520253035404550

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Flow

(l/m

in)

V1 V2 V3 V1+V2+V3

c.Permeate Recovery

0

10

20

30

40

50

60

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Rec

over

y (%

)

V1 V2 V3 V1+V2+V3


20000

2500030000

35000

4000045000

5000055000

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500Time (hrs)

Con

duct

ivity

( µs/

cm)

V1 V2 V3 V1+V2+V3

Figure 27. Performance of NF-8" Osmonics membrane in V1 and NF-70 in V2, V3 , a.Operating Conditions, b.Flow Rates, c.Recovery and d.Conductivity vs. Operating Time.

? ?


15

20

25

30

35

0 500 1000 1500 2000 2500 3000 3500 4000 4500

Pre

ssur

e (k

g/cm

2 )

152535455565758595105115125135

F.F

low

(l/m

in) &

Tem

p.(o C

)



05

1015202530354045

0 500 1000 1500 2000 2500 3000 3500 4000 4500

Flow

(l/m

in)

V1 V2 V3 Total Product

c.Permeate Recovery

0

10

20

30

40

50

60

0 500 1000 1500 2000 2500 3000 3500 4000 4500

Rec

over

y (%

)

V1 V2 V3 V1+V 2+V3


0

10000

20000

30000

40000

50000

60000

0 500 1000 1500 2000 2500 3000 3500 4000 4500Time (hrs)

Con

duct

ivity

(µs

/cm

)

V1 V2 V3 Average Conductivity

Figure 28. Performance of NF-8" Osmonics (HL8040FL) in V3 and NF-70 in V2,V3 a.Operating Conditions, b.Flow Rates, c.Recovery and d.Conductivity vs. Operating Time.

? ?

a)Operating Conditions

020406080

100120140

0 100 200 300 400 500 600 700 800 900 1000 1100Pre

ssur

e (k

g/cm

2 ) & T

emp.

(o C)


b)Permeate Flow Rates

01020304050607080

0 100 200 300 400 500 600 700 800 900 1000 1100

Flo

w (l

/min

)

V1 V2 V3 Total

c)Permeate Recovery

010203040506070

0 100 200 300 400 500 600 700 800 900 1000 1100

Rec

over

y (%

)

V1 V2 V3 Total

d)Permeate Conductivity

3000035000400004500050000550006000065000

0 100 200 300 400 500 600 700 800 900 1000 1100

Time (hrs)

Con

duct

ivit

y ( µ

s/cm

)

V1 V2 V3 V1+V2+V3

Fig. 29: Performance of NF- 8" Toray SU 620F in V1, Filmtec NF- 70 in V2and Osmonics HL8040 in V3 a.Operating Conditions, b. Flow Rates, c. Recovery and

d.Conductivity vs. Operating Time.

Cleaning of NF-70 membranes only

? ?

a. Flow (m 3/h)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

20 30 40 50 60 70

Module #1

Module #2

Module #3

Total flow

b. Recovery

0

10

20

30

40

50

60

70

80

90

20 30 40 50 60 70

Module #1

Module #2

Module #3

Total recovery

c. Conductivity

0

100

200

300

400

500

600

700

800

20 30 40 50 60 70Feed Pressure (bar)

Module #1 Module #2 Average conductivity

Figure 30 : SWRO permeate (from Toyobo HM 8255 HFF) (a) flow, (b) recovery and (c) conductivity for the new NF-SWRO ( 8") process vs applied pressure (feed flow rate of 3 m3/h of NF- 70 permeate)

?O

a. Flow (m 3/h)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

20 30 40 50 60 70

SWRO - 3 m3/h

2 m3/h

3 m3/h

3.5 m3/h

4 m3/h

NF-SWRO

SWR

0

10

20

30

40

50

60

70

80

90

20 30 40 50 60 70

NF-SWRO

SWRO

b. Recovery

0

1000

2000

3000

4000

5000

6000

7000

20 30 40 50 60 70Feed Pressure (bar)

c. Conductivity (µS/cm)

Figure 31. SWRO permeate (From Toyobo HM 8255 HFF) a. Flow, b. Recovery and c. Conductivity for the New NF-SWRO Process at Different Flow Rates of Permeate Filmtec NF-70 and the Conventional SWRO vs. Applied Pressure- Demonstration Plant.

SWRO

NF-SWRO

Feed Flow

? ?

a. Operation conditions

20

25

30

35

40

45

0 200 400 600 800 1000 1200 1400

Pres

sure

(bar

), T

emp.

(o C

)

0

5000

10000

15000

20000

25000

30000

Con

duct

ivit

y ( µ

S/cm

)

Temp (oC)Pressure (bar)Conductivity

b. Permeate flow rates (l/min)

0

5

10

15

20

25

30

0 200 400 600 800 1000 1200 1400

V1 V2 V3 V1+V2+V3

d. Permeate conductivity ( µS/cm)

0

100

200

300

400

500

600

700

0 200 400 600 800 1000 1200 1400Operation time (hrs.)

V1 V2 Average conductivity

c. Permeate recovery (%)

0

10

20

30

40

50

60

0 200 400 600 800 1000 1200 1400

V1 V2 V3 V1+V2+V3

Fig. 32 : Performance of HFF Toyobo HM 8255 SWRO membranes a. Operation conditions, b. Permeate flow, c. Recovery and d. Conductivity Vs Operation Time (V = Pressure vessel, Feed is product of NF- 70 Membranes, Feed Flow 3m3/h)

O?


0

10

20

30

40

50

60

70

0 200 400 600 800 1000 1200 1400 1600 1800

P.(

bar)

, T

emp.

(o C)

& F

.Flo

w (

l/min

)

Pressure (bar) Temp (oC) Feed Flow (l/min)


0

5

10

15

20

25

30

35

0 200 400 600 800 1000 1200 1400 1600 1800

Flo

w (

l/min

)

V1 V2 V3 V1+V2+V3

c.Permeate Recovery

0

10

20

30

40

50

60

70

0 200 400 600 800 1000 1200 1400 1600 1800

Rec

over

y (%

)

V1 V2 V3 V1+V2+V3


0

500

1000

1500

2000

2500

0 200 400 600 800 1000 1200 1400 1600 1800

Con

duct

ivit

y (µ

s/cm

)

V1 V2 V3 V1+V2+V3

Figure 33. Performance of Toyobo HM 9255 HFF SWRO Membrane a. Operation Condition, b. Permeate Flow Rates, c. Recovery and d. Conductivity vs Operation Time (First 900 hrs Feed is Permeate of Filemtec NF- 45 and Toray SU 610 in the Ratio of 50:50 . Feed for the Last 800 hrs is Permeate of Filmtec NF- 70 in V 1 and V2 and Osmonics HL 8040 in V3 in the Ratio of 30:70 )

Time (hrs)

OI


30

35

40

45

50

55

0 25 50 75 100 125 150 175 200 225 250Pre

s.(k

g/cm

2 ), T

emp.

(o C) &

F.F

low

(l/m

in)

Pressure (kg/cm2) Temp (oC) Flow (l/min)


0

5

10

15

20

25

0 25 50 75 100 125 150 175 200 225 250

Flo

w (l

/min

)

V1 V2 V3 V1+V2+V3

c.Permeate Recovery

0

10

20

30

40

50

60

0 25 50 75 100 125 150 175 200 225 250

Rec

over

y (%

)

V1 V2 V3 V1+V 2+V3


0

500

1000

1500

2000

2500

3000

0 25 50 75 100 125 150 175 200 225 250Time (hrs)

Con

duct

ivity

(µS

/cm

)

V1 V2 V3 V1+V2+V 3

Figure 34. Performance of Toyobo HM 9255 Membranes a.Operating Conditions, b.Permeate flow rates, c.Recovery and d.Conductivity vs. Operating Time. (Feed from NF- 8" Unit: Toray SU 620F in V1, Filmtec NF 70 in V2 and Osmonics HL 8040F in V 3) .

OI


05

10

15

20

2530

0 50 100 150 200 250 300 350 400 450

Flo

w (l

/min

)

V1 V2 V3 V1+V2+V 3


0

1020

3040

5060

0 50 100 150 200 250 300 350 400 450

Rec

over

y (%

)

V1 V2 V3 V1+V2+V3


0

500

1000

1500

2000

2500

0 50 100 150 200 250 300 350 400 450Time (hrs)

Con

duct

ivit

y ( µ

s/cm

)

V1 V2 V3 V1+V2+V3

Figure 35. Performance of Toyobo HM 9255" Membranes a.Operating Conditions, b.Permeate flow rates, C.Recovery and d.Conductivity vs. Operation time. (Feed is from Both NF- 8" Unit NF- 70 in V1 & V2, Osmonics HL 8040 inV3 and NF- 4" Unit Osmonics DK 4040 F inV- 5&V7, Trisep TS 80 TSA in V- 6&V- 8 )

a. Operating Conditions

2025303540455055606570

0 50 100 150 200 250 300 350 400 450

Pre

ssur

e(kg

/cm

2 ), T

emp.

(o C)

202530354045505560

F.F

low

(l/m

in)

Pressure (bar) Temp (oC) Feed Flow (l/min)

O?

REFERENCES 1. Hassan, A.M., Al-Sofi M.Ak., Al-Amodi, A.S., Jamaluddin, A.T.M., Dalvi, A.G.I, Kither,N.M.,

Mustafa, G. and Al-Tissan, A.R, (1997), A Nanofiltration (NF) Membrane Pretratment of SWRO Feed and MSF Make-up, Paper presented at IDA, Madrid Oct.6-9.

2. Hassan, A.M., Al-Sofi M.Ak., Al-Amodi, A.S., Jamaluddin, A.T.M., Dalvi, A.G.I, Kither,N.M.,

Mustafa, G. and Al-Tissan, (1998), A two parts article, one published in Desalination and Water Reuse Quarterly, May-June Issue (1998), Vol. 8/1, 54-59, and Second part published in September-October issue, , Vol. 8/2, 35-45.

3. Hassan, A.M., Al-Sofi M.AK., Al-Amodi, A.S., Jamaluddin, A.T.M., Farooque A. M., Rowaili

A., Dalvi, A.G.I, Kither,N.M., Mustafa, G. and Al-Tissan, A.R. (1998), A New Approach to Membrane and Thermal seawater Desalination Process Using Nanofiltration Membranes, Part 1. Paper presented at EDS Conference, Amesterdam, Netherland, Sept. 21-26 and published in Desalination, 118, 35-51.

4. Al-Sofi M. AK., Hassan, A. M., Mustafa, G.M., Dalvi, A.G.I., and Kither, M.N.M., (1998),

Paper presented at EDS Conference, Amesterdam, Netherland, Sept. 21-26 and published in Desalination, 118, 35-51. Nanofiltration as means of Achieving Higher TBT of ≥ 120 oC, Desalination, 118, 123-129.

5. Hassan, A.M., Al-Sofi M.AK., Al-Amodi, A.S., Jamaluddin, A.T.M., Farooque A. M., Rowaili

A., Dalvi, A.G.I, Kither,N.M., Mustafa, G. and Al-Tissan, (1999), A New Approach to Membrane and Thermal seawater Desalination Process Using Nanofiltration Membranes, Part 2, Paper published in Water Science and Technology Association (WSTA) proceedings, WSTA Conference, Bahrain, Feb., Vol. II, 577-594.

6. Hassan, A.M., Al-Sofi M.Ak., Al-Amodi, A.S., Jamaluddin, A.T.M., Kither,N.M., Mustafa, G.

and Al-Tissan, A.R, (1999), A nanofiltration(NF) membrane pretreatment of SWRO feed and MSF make-up (Part-1), Report No. (TR 3807/APP 96008).

7. Hashim, Murbati, W. and Frickson, B. (1999), Process Investigation at the Addur SWRO

Desalination plant- the Cru to Pretreatment System Rehabititation, WSTA 4th Gulf Water Conference Proceeding Vol. 2 Feb. 13-17, State of Bahrain, Also provide visit to Al-Addur plant, 619 to 644.

8 Dalvi, A.G.I, Kither, M.N, Al-Sulami, S., Sahul, K. and Al-Rasheed, R., (1999), Effect of

various forms of Iron in Recycle Brine on Performance of Scale Control Additives in MSF Desalination, WSTA 4th Gulf Water Conference Proceeding Vol. 2, Feb. 13-17, State of Bahrain, p 663 to 677.

9 Hassan, A.M., Farooque A. M., Jamaluddin, A.T.M., Al-Amodi, A.S., Rowaili A., Al-Sofi

M.AK., Kither,N.M. and Al-Tisan, I.A.R., A Demonstration Plant Based on the New NF-SWRO, Process, Paper submitted for presentation at 1999-IDA World Congress in Desalination and Water Reuse in San Diego, California, U.S.A., 29/8 to 3/9, 1999 .

10 Hassan, A.M., Farooque A. M. and Al-Amodi, A.S., Autopsy and Characterization of NF

Membranes After Long Term Operation in an NF-SWRO Pilot plant, Paper submitted for presentation at 1999-IDA World Congress in Desalination and Water Reuse in San Diego, California, U.S.A., 29/8 to 3/9, 1999.

Bai Bao Ve Su Dung NF RO Part 2

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