Demonstration project to prove the techno-economic feasibility of
using algae to treat saline wastewater from the food industry
Call identifier
Topic
Start date of project
Duration
Website
Email
Project Coordinator
H2020-WATER-2015-two-stage
WATER-1b-2015 Demonstration/pilot activities (Innovation
action)
01.06.2016
36 months
saltgae.eu
[email protected]
José Ignacio Lozano (Tecnologías Avanzadas Inspiralia S.L.)
[email protected]
WP3 Valorisation of HRAP Effluents
Deliverable D3.1 Design specifications and manufacture /
configuration development report
Lead Organization
Deliverable due date
Submission date
Version
Author(s)
DCU
M12
31/05/2017
0.8
Type of Deliverable
R (Document, Report)
Dissemination level
CO Confidential, only for members of the consortium
(including the Commission Services)
Yan Delauré (DCU), Lorna Fitzsimons (DCU), Philip Daly (DCU),
Micheal Cairns (DCU), Claudia Galinha (iBET), Joao Crespo (iBET),
Camille Viot (Extractis) Antonio Aparici (Bibo Aqua), Francesco
Colacino (OMS), Elin Lennartsson (RISE) and Björn Folkeson (RISE)
SaltGae project has received funding from the European Union’s Horizon 2020 research and innovation programme
under Grant Agreement No 689785
D3.1 Design specifications and manufacture/configuration
development report
Document Control Page
Title
Design specifications and manufacture/configuration development report
Creator
Yan Delauré (DCU)
Description
The effluent from the High Rate Algae Ponds will be treated to produce water with a salinity
level lower than 500mg/l. The water produced is to be used for dilution in the two-step
Anaerobic Digester of the Slovenian demonstration site and to develop a more sustainable
water cycle in the fish production and crop irrigation of the Israeli demonstration site. Three
alternative pre-treatment solutions are being benchmarked with a view to selecting the most
efficient and effective approach. This solution will be optimised to suit the standard
operating conditions at the two demonstration sites. Two alternative
desalination/demineralisation methods based on electrodialysis (ED) on the one hand and
reverse osmosis (RO) on the other hand are being designed and optimised for the two
demonstration sites. As part of Work Package 3, prototype pumps and pumps with energy
recovery are being built and tested and a control strategy for the overall RO system is being
developed to suit operating conditions at the two deployment sites. In parallel the ED pilot
is being specified and optimised to suit conditions at one of the two deployment sites. Testing
of representative HRAP samples from the two deployment sites will inform the selection of
the preferred site in this case. This deliverable D3.1 provides a preliminary definition of the
design specifications for both systems along with a report on the pre-treatment
characterisation, selection and optimisation.
Publisher
SaltGae Consortium
Contributors
Yan Delauré (DCU), Lorna Fitzsimons (DCU), Philip Daly (DCU), Micheal Cairns (DCU),
Claudia Galinha (iBET), Joao Crespo (iBET), Camille Viot (Extractis) Antonio Aparici
(Bibo Aqua), Francesco Colacino (OMS), Elin Lennartsson (RISE) and Björn Folkeson
(RISE)
Creation date
16 May 2017
Type
Text
Language
en-GB
Audience
internal
public
restricted
Review status
Draft
WP leader accepted
Technical Manager accepted
Coordinator accepted
Action requested
to be revised by Partners
for approval by the WP leader
for approval by the Technical Committee
for approval by the Project Coordinator
Requested deadline
saltgae.eu
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D3.1 Design specifications and manufacture/configuration
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Revision History
Version
Date
Modified by
Comments
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
16/05/2017
16/05/2017
16/05/2017
17/05/2017
17/05/2017
18/05/2017
22/05/2017
31/05/2017
Elin Lennartson (RISE)
Camille Viot (Extractis)
Claudia Galinha (iBET)
Yan Delaure (DCU)
Antonio Aparaci (BiboAqua)
Francesco Colacino (OMS)
Björn Folkeson (RISE)
José Ignacio Lozano (INSP)
Change to Section 3.2.3.2
Section 3.1
Change to Table 5
Editing Sections 2.1 and 2.2
Editing Section 3
Review and Editing Section 3.2.4
Revised Section 3.2.4.7
Review and editing
STATEMENT FOR OPEN DOCUMENTS <if applicable>
© SaltGae Consortium, 2016.
This deliverable contains original unpublished work except where clearly indicated otherwise. Acknowledgement of
previously published material and of the work of others has been made through appropriate citation, quotation or both.
SaltGae Consortium (saltage.eu) grants third parties the right to use and distribute all or parts of this document,
provided that the SaltGae project and the document are properly referenced.
Creative Commons licensing level.
The authors are solely responsible for the content of this publication. The opinions expressed, do not reflect the
opinions of the Executive Agency for Small and Medium-sized Enterprises (EASME) or the European Commission
(EC) and neither the EASME nor the EC are responsible for any use that may be made of the information contained
herein.
This deliverable results from the SaltGae project, which is supported by funding Framework Programme Horizon
2020 of the European Commission under Grant Agreement no.689785 .
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D3.1 Design specifications and manufacture/configuration
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Table of Contents
1 INTRODUCTION ................................................................................................................... 7
2 ASSESSMENT OF HRAP EFFLUENT PRE-TREATMENT (IBET) ................................... 8
2.1 Objectives ........................................................................................................................... 8
2.2 Solutions ............................................................................................................................. 8
2.2.1 Direct ultrafiltration/nanofiltration of the supernatant .............................................. 8
2.2.2 Activated carbon adsorption and retention of its particles by micro/ultrafiltration ... 8
2.2.3 Direct photolysis ......................................................................................................... 8
2.3 Methodologies for processes optimisation .......................................................................... 9
2.3.1 Direct ultrafiltration/nanofiltration of the supernatant .............................................. 9
2.3.2 Activated carbon adsorption and retention of its particles by micro/ultrafiltration . 10
2.3.3 Direct photolysis ....................................................................................................... 10
2.4 Progress (Summary of Results)......................................................................................... 11
2.4.1 Direct nanofiltration of the supernatant: case study KOTO ..................................... 11
2.4.2 Activated carbon adsorption tests: case study KOTO............................................... 12
2.4.3 Direct Photolysis: case study KOTO ........................................................................ 12
2.5 Conclusions and Final Remarks ........................................................................................ 13
3 CHARACTERISATION OF DESALINATION SOLUTION .............................................. 14
3.1 Electrodialysis ................................................................................................................... 14
3.1.1 Objectives .................................................................................................................. 14
3.1.2 Solution ..................................................................................................................... 14
3.1.3 Description of methodologies.................................................................................... 15
3.1.4 Summary of current results ....................................................................................... 15
3.2 Reverse Osmosis ............................................................................................................... 16
3.2.1 Objectives .................................................................................................................. 16
3.2.2 Solution ..................................................................................................................... 16
3.2.3 Methodology of technology development .................................................................. 17
3.2.4 Progress .................................................................................................................... 20
3.3 Integration ......................................................................................................................... 33
4 CONCLUSIONS .................................................................................................................... 36
REFERENCES ............................................................................................................................ 37
ANNEXES .................................................................................................................................. 38
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Index of Figures
Figure 1. Permeate flux vs concentration factor (CF) during filtration with NF and DK membranes
at 10 and 20 bar. .......................................................................................................................... 11
Figure 2. Absorbance curves of samples from direct photolysis taken at times 0, 30, 60, 120 and
180 min. Colour of the sample in the beginning and at 180 min of light exposure. ................... 13
Figure 3. Principle of conventional electrodialysis (EURODIA®) ............................................ 14
Figure 4. Pump/ERD and RO design for testing, flow properties are indicative of expected
conditions .................................................................................................................................... 18
Figure 5. Quadruplex Pump version 1. ....................................................................................... 20
Figure 6. Quadruplex Pump version 2 ........................................................................................ 21
Figure 7. Simulink diagram of one pump chamber to study the effects of internal compliance. 22
Figure 8. Effect of pre-compression of seals on pressure values in one pump chamber (yellow
lines) and the outlet manifold (purple lines). Top, peak-to-peak pressure fluctuations ±0.7%;
Bottom, peak-to-peak pressure fluctuations ±4%. ...................................................................... 22
Figure 9 Quadruplex cross-section highlighting cooling lubricating channels ........................... 23
Figure 10. Intersection of bolt hole and cooling channel in pumping chamber. ......................... 24
Figure 11. Intersection of guide rod and securing bolts, identified using virtual prototyping. ... 24
Figure 12. Velocity vector plot of valve cross sections, from CFD simulation of the valve showing
vortex creation and force imbalance. .......................................................................................... 25
Figure 13. Seal support blocks highlighted in blue. .................................................................... 26
Figure 14 Overview of the triplex mechanism of the pump/ERD device ................................... 27
Figure 15 Schema of the pump/ERD device. Side view of the block comprising pump and ERD
chambers, piston, seals, manifolds, passive and active valves. Triplex actuation mechanisms (on
the left) not shown ....................................................................................................................... 27
Figure 16 Active valves timing and piston’s profiles.................................................................. 28
Figure 17. Determining the most suitable membrane quantity to be used in the RO test rig. ..... 29
Figure 18. Saltgae solution for Slovenia Demonstration Site ..................................................... 34
Figure 19. Saltgae solution for Israel Demonstration Site .......................................................... 35
Figure 20. Task 3.1 GANTT Chart. Green, Blue and Red indicate completed, started and pending
tasks. ............................................................................................................................................ 38
Figure 21. Task 3.2 GANTT Chart. Green, Blue and Red indicate completed, started and pending
tasks. ............................................................................................................................................ 38
Figure 22. Task 3.3 GANTT Chart. Green, Blue and Red indicate completed, started and pending
tasks. ............................................................................................................................................ 38
Index of Tables
Table 1: Abbreviations and Acronyms. ......................................................................................... 6
Table 2: Summary of results obtained during nanofiltration experiments. “Perm” is the final
permeate and “Conc” the concentrate. ........................................................................................ 12
Table 3: Results of pH, conductivity and total organic carbon of activated carbon batch tests. . 12
Table 4: Comparison between the quality of actual HRAP effluent and the effluent form
Methanogenic Reactors in study by NOVA. ............................................................................... 13
Table 5: RO input stream characteristics (to be updated with test results from task 3.1) ........... 17
Table 6: Membrane characteristics ............................................................................................. 29
Table 7: Reverse Osmosis Control Optimisation & Testing ....................................................... 30
Table 8: References ..................................................................................................................... 37
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Glossary
The glossary of terms used in this deliverable can be found in the public document
“SaltGae_Glossary.pdf” available at: http://saltgae.eu/downloads-public/
Abbreviations and Acronyms
Abbreviation /
Acronym
Description
TDS
Total Dissolved Solids
TOC
Total Organic Carbon
CAE
Computer Aided Engineering
ED
Electrodialysis
BOD
Biochemical Oxygen Demand
HRAP
High Rate Algae Pond
RO
Reverse Osmosis
CFD
Computational Fluid Dynamics
FEA
Finite Element Analysis
Table 1: Abbreviations and Acronyms.
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D3.1 Design specifications and manufacture/configuration
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1 Introduction
The aim of this deliverable is to provide preliminary definition of the design specifications of
an economically viable solution for the valorisation of effluents from the High Rate Algae Ponds
(HRAPs) after extraction of the algae biomass. The objective is to produce water with a salinity
level lower than 500𝑚𝑔/𝑙 while optimising the systems’ efficiency and efficacy. The fresh water
produced is to be used to:
i.
offset the need for an external supply of fresh water for dilution in the two-step Anaerobic
Digester pre-treatment and conditioning of High Biochemical Oxygen Demand (BOD)
Waste Water at the Slovenian demonstration site, and to
ii.
develop a more sustainable water cycle in the fish production and crop irrigation of the
Israeli demonstration site.
Two alternative desalination solutions are being developed in separate and parallel Tasks.
i.
Task 3.2: Optimal operating conditions of an electrodialysis demineralisation process are
to be identified. The system is being optimised for effluent from the Israeli demonstration
site and is to achieve a demineralisation yield of at least 50%. A decision making tool
will also be developed to support the assessment of the solution viability for other type
wastewater originating from the agroindustry.
ii.
Task 3.3: A Reverse Osmosis (RO) desalination solution is being developed along with
a new positive displacement pump and an innovative pump with energy recovery. The
target mechanical to hydraulic efficiencies are 95% and 98% for the pump and pump with
energy recovery respectively. The RO system is designed to suit the Slovenian and Israeli
sites.
The HRAP Effluent requires pre-treatment to avoid excessive fouling and guarantee high
efficiency treatment by the ED and RO processes. This is the purpose of Task 3.1. Three
alternative pre-treatment solutions are being tested with a view to optimising the removal of mass
foulants and extending the service life. The best solution will be identified with a target of 99%
removal rate. The three alternatives considered are:
i.
Direct ultrafiltration/nanofiltration,
ii.
Activated carbon adsorption and retention by micro/ultrafiltration
iii.
Direct photolysis.
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2 Assessment of HRAP effluent pre-treatment (iBET)
2.1 Objectives
The HRAP Effluent requires pre-treatment to avoid excessive fouling and guarantee high
efficiency treatment by the ED and RO processes. The main objective of Task 3.1 is the selection
and optimisation of the processes to be used for the pre-treatment of the HRAP effluent. This
optimisation will consider each of the pre-treatment solutions proposed (direct
ultrafiltration/nanofiltration of the supernatant; activated carbon adsorption and retention of its
particles by micro/ultrafiltration; direct photolysis) from a technical, environmental and economic
perspective.
The technology selected should maximise the removal of organic compounds (responsible for
fouling on subsequent ED and RO processes) as well as the recovery of water. It should also allow
the use of the equipment for extended periods with minimal energy consumption and without
requiring cleaning, addition and/or regeneration of reagents/components.
Finally, the best solution will be tested and validated at pilot scale, assuring its techno-economic
viability and environmental sustainability.
2.2 Solutions
2.2.1 Direct ultrafiltration/nanofiltration of the supernatant
The use of ultrafiltration/nanofiltration guarantees the retention of organic compounds, according
to the membranes’ pore sizes. The process however, requires periodic cleaning of the membranes.
Therefore, the approach will be studied in order to optimise the membrane characteristics as well
as the most relevant operating conditions (fluid dynamics in the feed circuit and transmembrane
pressure). The percentage of water recovered and the need for chemical cleaning will be also
evaluated. The main advantages and disadvantages of this pre-treatment are summarised below:


Advantages: Complete retention of suspended particles and organic compounds (based
on molecular size).
Disadvantages: Membrane cleaning; limited recovery of water (osmotic pressure).
2.2.2 Activated carbon adsorption and retention of its particles by micro/ultrafiltration
Activated carbon capacity for adsorption will depend on the compounds present in the HRAP
effluents. The adsorption kinetics and the loading capacity of the activated carbon will be
evaluated as well as the impact of activated carbon particles’ retention by the micro/ultrafiltration
membranes. The need for particles addition / disposal will be assessed from a techno-economic
and environmental perspective. The main advantages and disadvantages of this pre-treatment are
summarised below:


Advantages: Potentially high absorbance capacity; traditional method with a large
acceptance by industry.
Disadvantages: Activated carbon addition/disposal; organics are adsorbed depending on
their affinity to the activated carbon.
2.2.3 Direct photolysis
Direct photolysis allows for a complete mineralisation of the organic compounds present in the
effluents. Ultraviolet radiation can be used without any addition of chemicals, avoiding the
presence of free radicals, which can have a detrimental impact on the lifetime of the membranes
used in subsequent steps. The optimal operating conditions will be identified, namely in terms of
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residence time (exposure time) to the photolysis system. Potential formation of degradation byproducts will be also assessed. The main advantages and disadvantages of this pre-treatment are
summarised below:


Advantages: Total recovery of water;
Disadvantages: Light delivery in dark samples is hindered (low performance); Potential
formation of degradation by-products;
2.3 Methodologies for processes optimisation
The process optimisation of Task 3.1 considers two demonstration sites: KOTO in Slovenia and
ARAVA in Israel. The same methodologies for process assessment and optimisation are followed
for the two sites but the specificities of the two effluents are taken into account.
For processes assessment at iBET, samples of the algal ponds have been received directly from
both demonstration sites. These samples are harvested by membrane filtration at iBET (preconcentration of microalgae by membrane filtration). The permeates from this process are already
free of solids so that, the performance of the pre-treatment processes is assessed based on the
removal of dissolved organic compounds. Initial results obtained by iBET from harvesting from
KOTO effluent samples, the water recovery rate achieved with the initial step of membrane
filtration is higher than 90%. This indicates that most of the water from the algal ponds will be
recovered in the pre-concentration step. It is this recovered part of the effluents which will be
studied for further treatment.
The characterisation of the effluents produced by the pre-treatment processes under study is done
by measuring the electrical conductivity, pH, total organic carbon, chemical oxygen demand and
absorbance spectroscopy.
2.3.1 Direct ultrafiltration/nanofiltration of the supernatant
In order to study and optimise the removal of organic compounds by ultrafiltration/nanofiltration,
different operating conditions were selected and tested. Since the effluent has already been
processed by microfiltration or ultrafiltration, only nanofiltration is being assessed for dissolved
compounds removal. Nanofiltration rejects compounds with lower molecular weight than
ultrafiltration and, thus, may produce an effluent with higher quality (lower concentration of
organic compounds). Nevertheless, in the presence of suspended solids in low concentrations,
nanofiltration membranes should be able to maintain good performance. Two different
membranes were assessed. DOW FILMTECH NF270 membrane is made of Polyamide with a
molecular exclusion of 200-400 Da, while the GE Osmonics DK membrane is also made of
Polyamide, but has a molecular exclusion of 150-300 Da. Although these membranes have similar
characteristics, they result in different performances dependent on the feed characteristics (mainly
due to significant differences in organic and salt loads).
Additionally, the process performance at two different operating transmembrane pressures (10
and 20 bar) are also assessed for each membrane. These tests aim at understanding how the
increase of pressure (and the costs associated to higher pressures) affects the performance of the
process.
In filtration systems, the performance of a process can be assessed through the rejection of
membranes to specific compounds (through chemical characterisation of process streams),
membrane permeability during process operation and fouling formation. The characterisation of
membrane fouling and the requirements for membrane cleaning are tested in the present work by
measuring the loss of permeability (to water) after processing a sample and rinsing the system
with clean water.
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The selection of the membrane and operating transmembrane pressure is being done at small lab
scale using a METcell unit, in a dead-end configuration. METcell is a stainless steel high-pressure
stirred cell that can process a wide range of membrane separation processes. The METcell unit is
operated at dead-end configuration using high-pressure nitrogen from a gas cylinder to provide
the operating transmembrane pressure. A magnetic stirrer plate is used to generate the stirring
required in the cell to minimise concentration the polarisation effect. In such system is possible
to assess the rejections and infer about the impact of different organic and salt concentrations.
The operating conditions selected at this small scale are, then, validated at larger scale, using a
GE Omonics flat-sheet membrane unit system. The GE Osmonics system is a crossflow filtration
unit that is designed to evaluate flat sheet membranes in a variety of applications. It simulates the
flow dynamics of larger, commercially available membrane elements such as industrial spiral
wound membrane elements.
In the presence of higher salinity, the effect of osmotic pressure during nanofiltration may also
affect the performance of the system. Therefore, the maximum concentration factor achieved by
each membrane at different operating conditions will also be taken in account for process
optimisation and selection.
2.3.2 Activated carbon adsorption and retention of its particles by micro/ultrafiltration
Since activated carbon capacity for adsorption is dependent of the compounds present in the
effluent to be treated, the adsorption kinetics and the loading capacity of the activated carbon
needs to be evaluated.
The first study consists in evaluating the adsorption capacity of granular activated carbon for the
compounds present in the effluent. Such study is done by measuring the removal of compounds
(through TOC measurements) using different concentrations of activated carbon. The samples are
put in contact with different amounts of granular activated carbon (0.5, 1, 2, 3 g of activated
carbon per L of effluent to treat) in batch mode until reaching the equilibrium. The samples are
then filtered to remove the activated carbon and the remaining TOC of each sample is measured.
The second study evaluates the ability of the granular activated carbon to be used continuously in
a fixed bed, through breakthrough curves of TOC adsorption. In this study, the sample is
continuously feed to a column of granular activated carbon and samples collected at regular times
to assess the remaining organic carbon. The results obtained with these tests will allow the design
and feasibility of this process at larger scale.
After the establishment of the breakthrough curves, activated carbon adsorption and retention of
its particles by ultrafiltration will be tested, using the amount of activated carbon estimated with
the previous tests.
2.3.3 Direct photolysis
Ultraviolet radiation can be used for degradation of organic compounds in water without any
addition of chemicals, avoiding the presence of free radicals. Therefore, for direct photolysis
assessment, a collimated beam reactor is used with a medium pressure UV lamp. The total
irradiance is of 20 mW/cm2, at 20°C. The optimisation of photolysis will, then, focus on exposure
time. The degradation of organic compounds is measured through TOC, and the potential
formation of degradation by-products will be also assessed (at optimised conditions).
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2.4 Progress (Summary of Results)
2.4.1 Direct nanofiltration of the supernatant: case study KOTO
Two membranes (DK and NF270) were tested at two transmembrane pressures (10 and 20 bar).
The permeate fluxes obtained are shown in Figure 1. For the effluent tested, the NF270 membrane
has better performance at both pressures. Furthermore, the average permeabilities during effluent
filtration were 4.3 and 3.5 𝐿/(𝑚2 ℎ 𝑏𝑎𝑟) for the DK membrane at 10 and 20 bar, respectively,
while for the NF270 membrane the average permeabilities were 8.4 and 6.9 𝐿/(𝑚2 ℎ 𝑏𝑎𝑟),
respectively for 10 and 20 bar.
Figure 1. Permeate flux vs concentration factor (CF) during filtration with NF and DK membranes
at 10 and 20 bar.
The concentration factor is calculated as:
𝐶𝐹 = 𝑉𝑖 /(𝑉𝑖 − 𝑉𝑝 )
𝑉𝑖 is the initial volume of sample, 𝑉𝑝 is the volume of permeate collected. Rejection percentage
is calculated as:
𝑅 = (𝐶 − 𝑃)/𝐶 ∗ 100
𝐶 is the concentration (TOC) in the concentrate and 𝑃 is the concentration (TOC) in the permeate.
In the four experiments the water recovered in the permeate was higher than 80% of the initial
sample, corresponding to a concentration factor (𝐶𝐹) higher than 5. This value was achieved in
lab-scale tests and will be further optimised to 90%.
In Table 2 is shown the quality of the effluent before and after the filtrations performed, for both
concentrate and permeate streams. These results indicate that the removal of organic carbon is
slightly better when using the NF270 membrane.
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pH
Perm
Initial
DK_10 bar
DK_20 bar
NF270_10 bar
NF270_20 bar
Conc
6.68
5.64
5.91
6.18
6.29
6.50
6.60
6.65
6.69
Cond. (mS/cm)
Perm
Conc
8.01
7.35
12.73
7.52
14.35
8.48
12.36
8.28
11.93
TOC (ppm)
Perm
Conc
156.6
19.01
662.6
14.39
754.8
10.56
769.6
12.97
744.2
R=(C-P)/C*100 Recovery of water
permeability
%TOC
97.1
96%
98.1
89%
98.6
99%
98.3
100%
Table 2: Summary of results obtained during nanofiltration experiments. “Perm” is the final permeate
and “Conc” the concentrate.
Along with the performance of the filtrations, the recovery of water permeability was assessed.
Recovery of water permeability was calculated as the percentage of membrane permeability to
water at the end of the experiment compared to the permeability before the experiment. Final
permeability was measured after rinsing the module only with clean water. Once more, the results
obtained for NF270 membrane (Table 2) were better.
2.4.2 Activated carbon adsorption tests: case study KOTO
In preliminary batch studies, powder and granular activated carbon were tested at two different
concentrations of 1 and 4 g activated carbon / L effluent sample. The samples were left overnight
with the activated carbon and then decanted and filtered using a 0.45 micra disposable filter.
The results are shown in Table 3 (pH, conductivity and TOC). The results obtained so far show
that the granular activated carbon used has higher capacity of adsorption than the powder, and
therefore, the granular activated carbon will be used in further experiments. Furthermore,
activated carbon does not affect significantly the pH and conductivity.
Table 3: Results of pH, conductivity and total organic carbon of activated carbon batch tests.
To determine the adsorption capacity of granular activated carbon, additional tests were
performed using different concentrations of activated carbon.
2.4.3 Direct Photolysis: case study KOTO
The effluent sample to be treated was brownish (as shown in Figure 2), which may interfere in
the performance of the treatment by direct photolysis.
The effluent sample was exposed to the light and sample were taken at different times, 0, 30, 60,
120, 180min. In Figure 2, the Absorbance of samples are shown at the different times. At the end
of 180 min test period, the samples were analysed in terms of pH, conductivity and TOC (data
not shown). However, the comparison between initial (time 0) and final (180 min) samples
revealed that no significant changes occur in term of these parameters. Additionally, even if the
sample colour changed significantly in 180 min of light, the organic carbon was not removed.
Therefore, further tests are going to be performed in order to analyse the potential formation of
other organic compounds during photolysis.
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Figure 2. Absorbance curves of samples from direct photolysis taken at times 0, 30, 60, 120
and 180 min. Colour of the sample in the beginning and at 180 min of light exposure.
2.5 Conclusions and Final Remarks
Considering the results obtained for the treatment of HRAP effluent form KOTO, with the
different processes, the treatment that removes the highest percentage of organic compounds
(measured as TOC) was the nanofiltration process using the NF270 membrane. Since the
permeate flux is significantly higher at 20 bar (although with lower permeability), the pressure to
be used for nanofiltration may be further assessed in an economical/processual perspective for
use at larger scale.
However, the samples processed to date are not completely representative of the final system that
will be implemented at the KOTO demonstration site in the scope of the SaltGae project. In fact,
the salinity of the sample tested is still lower than the salinity expected at the end of the project.
The characteristics of the HRAP effluent will depend on the effluent from Methanogenic Reactor
being optimised by NOVA partner. This effluent will be the influent of algal ponds, therefore,
although differences will be present due to microalgae activity, the salinity expected in the HRAP
effluent will be similar to the methanogenic effluent. Table 4 shows the actual differences between
the HRAP effluent and the effluent from the methanogenic reactor.
Table 4: Comparison between the quality of actual HRAP effluent and the effluent form
Methanogenic Reactors in study by NOVA.
In view of the results obtained so far and the characteristics of the methanogenic reactor effluent,
the methodologies described in this document will be further applied to the effluent from ARAVA
demonstration site and to a new effluent sample from KOTO supplemented with salt (to achieve
a conductivity of approximately 90 mS/cm).
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3 Characterisation of Desalination Solution
3.1
Electrodialysis
3.1.1 Objectives
After the pre-treatment realized by IBET in task3.1, the objective of task 3.2 is to go further in
the treatment of the effluents by removing the residual salts. The first solution investigated for the
desalination of the HRAP effluent relies on electrodialysis in order to produce a permeate which
could be released in the natural media or recycled by the demonstration sites studied in the
SALTGAE project and more particularly by ARAVA and KOTO demo sites.
3.1.2 Solution
Conventional electrodialysis (ED) is an electrochemical separation process in which ions are
transferred from a product to a brine solution. Ions are transferring through selective ion exchange
membranes (cation- and anion- exchange membranes which are respectively selective to cations
transport and anions transport) under the influence of an applied electric field. These membranes
(grafted with sulfonate for the cationic ones and alkyl ammonium for the anionic ones) are
impermeable to liquids. A large number of alternating cation and anion-exchange membranes are
assembled to form diluate and concentrate compartments in what is known as an electrodialysis
stack.
Concentra te s trea m
CEM
+
Na
AEM
+
CEM
+
AEM
+
CEM
+
AEM
+
CEM
+
Na
Na
Na
Na
Na
Na
Cl -
Cl -
Cl -
Cl -
Cl -
Cl -

⊝
Di l ua te s trea m
Figure 3. Principle of conventional electrodialysis (EURODIA®)
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Compared to resins:
 Demineralization with ED goes fast,
 There is no high pH variation,
 High recovery with no dilution
 Waste correspond to salts coming from product –There is no extra salts added.
Electrodialysis requires a non-viscous product exempt of suspended matters. Moreover, below a
1-2 mS/cm conductivity, electrodialysis is no more relevant (it would involve a too important
electric consumption for a very low salts content).
3.1.3 Description of methodologies
3.1.3.1 Characterisation
Before processing electrodialysis, it is necessary to characterize the samples which have to be
desalted in order to know:




The dry matter
The mineral content
The salts content which means determinate the detail of monovalent and divalent ions.
The pH and the conductivity.
The analyses on initial and final products will permit to draw the ion balance and so, to estimate
the efficiency of desalinisation by ED.
EXTRACTIS will directly work with the samples pretreated by IBET.
3.1.3.2 Demineralisation
Electrodialysis tests will be performed on a EUR2B-10 pilot (EURODIA company) in a
conventional configuration. Each experiment will be achieved four times with 2 l of solution at
each time, the first run to pack the equipment and the three others to confirm the results
reproducibility. Electrodialysis trials will be realized at constant voltage while the current will be
suffered.
Along the runs, conductivity, temperature and pH will be measured. Initial and final products will
also be characterized by measuring dry matter and minerals contents. Anion and cation contents
will be measured by HPLC.
3.1.4 Summary of current results
Several samples were received by iBET from the Slovenian demonstration site and indicated that
non-negligible variability could be expected due to changes in operating conditions. Conditions
were however identified that produced samples that would be representative of the expected
Saltgae conditions in terms of ph, TOC and TSS. As the higher conductivity levels expected from
the demonstration sites would not be available until later on during WP6, it was proposed by WP3
partners and agreed by the consortium that pre-treated samples would be supplemented with NaCl
in order to achieve the conductivity desired for the project. EXTRACTIS received the first sample
on the last week of Month 12 and will start the electrodialysis tests during the first week of Month
13 with a viewing to completing these by the end of Month 14 to start the design of the pilot scale
reactor on Month 14.
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3.2 Reverse Osmosis
3.2.1 Objectives
The second solution investigated for the desalination of the HRAP effluent relies on a Reverse
Osmosis (RO) process and will be tested at the Israel and Slovenia demonstration sites. Task 3.3
is focussed on the design optimisation, testing and manufacture of a newly developed High
Pressure Pump (HP Pump) and of a new coupled Pump and Energy Recovery Device
(Pump/ERD). The two devices are to be combined to provide the hydraulic power needed to
operate the RO system. The testing will consider the stand-alone hydraulic performance of the
devices on the one hand and their operation as an integral part of the RO process on the other
hand. The objective for the latter set of tests is to determine the optimal control procedure for the
pumps taking account of the standard operating conditions at the two demonstration sites. This
means that although the final design and integration of the RO process including the HP Pump
and Pump/ERD and their sensorisations is scheduled to start after delivery of the HP Pump and
the Pump/ERD and completion of Work Package 3 in Work Package5, the RO process will be
tested and optimised as part the current Work Package. The target operational performances at
steady state are:




Mechanical efficiency of new pump of 95%
Mechanical efficiency of energy recovery of 98%
Reverse Osmosis recovery rate of 50% or higher in steady
Permeate salinity measured as the mass of Total Dissolved Solids of 500mg/l or less.
The current status of development of the two pumping devices and of the test platforms and test
plans are presented in this section.
3.2.2 Solution
3.2.2.1 Reverse Osmosis System
Reverse Osmosis (RO) is a membrane based water purification process. Flow through a semipermeable membrane separating two saline solutions is used to reduce the concentration of
dissolved solids feed water. The process involves three fluid streams:



The Feed Water is the saline solution supplied to the RO for treatment. In the Saltgae
project it is the HRAP effluent after pre-treatment.
The Permeate Stream is the liquid stream that flows through the RO membrane(s). In
the Saltgae project it will provide the desalinated water for use in the two-stage
Anaerobic Digester or irrigation.
The Brine (or Concentrate) Stream by-passes the membranes and emerges with higher
concentration of dissolves solids.
Separating two saline solutions by a semi-permeable membrane gives rise to osmotic pressure as
the solvent molecules cross the membrane in the direction of increased solute concentration. The
flow of molecule and the resulting pressure occurs naturally as the process attempts to equalize
solute concentration in the two solutions. In a RO process the solvent flow must be against
decreasing concentration gradients and the feed water must be pressurized above the osmotic
pressure. High pressure levels are typically needed and increase with salinity and recovery and
salt rejection rates. In the case of sea water, pressure in the range of 40 to 80 bar is typical.
Associated pumping requirements contribute most of the operating and energy costs of an RO
installation.
The Saltgae project aims to optimize the process in terms of its energy efficiency by developing
an innovative high efficiency positive displacement pump to provide 50% of the feed water flow.
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This will be combined with a pump coupled to an Energy Recovery Device (Pump/ERD) to
provide for the remaining 50% feed water flow. This Pump/ERD is one of the key innovations of
the project and its design and optimization is one of the project deliverables. The schematic
diagram of the RO system integrating the Pump and Pump-ERD connected in parallel and planned
for integration in the overall Saltgae system for demonstration is shown in Figure 4. The solution
will be based on a single stage system with no concentrate recycling.
3.2.2.2
Pump and Pump/ERD
The Pump and the Pump/ERD are based on two distinct dynamic systems:
1. The pump is a high pressure positive displacement Quadruplex pump. It is designed with
two banks of horizontally opposed cylinders/pistons driven by a single shaft. A cam fitted
directly on the shaft transform the shaft rotation in linear motion for the piston. Details of
the design are provided in Section 3.2.4.1.
2. The Pump/ERD based is on a six cylinders/piston system with a similar layout to the HP
pump. Whereas the two opposite chambers are used in the Quadruplex system to
contribute to pumping, one of the chamber is used here to extract the hydraulic power
from the brine stream and drive the pistons on the opposite side dedicated to pumping.
3.2.3 Methodology of technology development
3.2.3.1 Reverse Osmosis Design and Membrane Specification
The RO is being designed to meet the specific requirements of the two sites: Israel and Slovenia.
These sites pose different challenges both in terms of water characteristics, but also in relation to
the quantities of wastewater for treatment. The typical site wastewater characteristics and
flowrates are shown in Table 5. Suitable membranes were identified according to flowrates, water
characteristics, recovery, rejection capabilities, and energy requirements using membranespecific design software, ROSA [1]. Details of the approach to select these membranes are
discussed further in Section 0. Based on the flowrates, two modes of operation will be tested and
optimized: batch for Solvenia and continuous for Israel.
Parameters
Slovenia - Tannery
Israel - aquaculture
Units
Feed salinity
5120
2880
mg/L
Feed pH
6.68
6.6
Feed flowrate
0.1
2.1
m3/h
RO recovery
50
50
%
Concentrate flowrate
0.5
1.05
m3/h
TOC
156.6
ppm
COD
399
mg/l
Temperature range
25 to 30 °C
30 to 35 °C
°C
Brine flowrate
0.02 to 0.17
2
m3/h
Table 5: RO input stream characteristics (to be updated with test results from task 3.1)
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Figure 4. Pump/ERD and RO design for testing, flow properties are indicative of expected conditions
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3.2.3.2 Pump and Pump/ERD Design
The Pump and the Pump/ERD are currently at Technology Readiness Level 5 having been tested
in a fresh water irrigation system. Both technologies will be demonstrated in operational
environment relevant to the Saltgae project with a view to achieving TRL6/7 as defined in the EU
H2020 Work Programme 2014-2015 [2].
The target efficiency of 95% and 98% for the Pump and the Pump/ERD respectively imply
significant advances in a number of key parts requiring a full review of all components from the
pre-existing technology. The two devices are being developed based on the following 3-step
sequential process:
1. Virtual design
2. Production planning
3. Design verification
Following on from this design phase, the Saltgae project structure will allow for a design
assessment during the demonstration in operational environment (Work Package 6). This will
include a performance and wear assessment and will led to a design review. The wear assessment
was originally scheduled to take place during the 18 Month duration of Work Package 3.
Postponing analysis to include a period of demonstration was agreed to achieve more meaningful
and realistic wear cycles.
The first virtual design step is performed and completed using a suit of virtual tools covering
System Dynamics Modelling, 2D and 3D CAD and CAE in three distinct steps:
1. System dynamic modelling to specify and dimension all key driving components. The
initial design variables considered in this step are the pump drive shaft, cam shape and
piston configuration while the design criteria are flow and pressure fluctuations and pump
hydraulic performance. The deliverable from this initial design step is the full set of two
dimensional (2D) technical drawings.
2. 3D CAD modelling from 2D specification to assess functionality and to verify
dimensioning and part interferences.
3.
Computer Aided Engineering and virtual prototyping including Finite Element Analysis
(FEA) and Computational Fluid Dynamics (CFD) to confirm design or suggest changes
with a view to optimising efficiency and operation.
Steps 1 to 2 are performed iteratively. The current version of the HP Pump has undergone three
design cycles and key components are being assessed using CAE tools. The Pump/ERD
development is at step 1 of design iteration 1. In addition to the virtual design, an assessment of
manufacturing constraints and selection of commercially available equipment such as bearings,
seals and rollers. OMS and DCU are collaborating closely on this design phase.
The selection/assessment of materials, surface treatment and manufacturing tools is part of the
follow-on production planning stage which again involves a collaboration between OMS and
DCU. This production stage requires prototype assembly and some initial testing to confirm
functionality and detect any potential defect or design issue.
The initial design verification will be done in controlled environments in the laboratory. Two
series of parallel tests have been planned to take place at DCU and RISE with distinct objectives:
1. Performance tests to consider the two devices independently will be conducted by RISE.
Where suitable, the ANSI HI 3.6-2016 “Rotary PumpTests” standard will be adopted.
This will not be strictly applicable to the Pump/ERD but a test plan based on the
standard’s testing procedure and methodology will be adapted. These test will be
performed with saline water with a salinity corresponding to realistic operation.
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2. The two devices will be integrated in the RO process and tested under realistic operational
conditions. This series of tests will have two objectives, which are (i) to characterise
performance with RO and saline water and (ii) to test and develop the optimal control
strategy for the pumps in the RO system. The first objective will inform the design
assessment and its review as part of the follow on monitoring and assessment during
deployment. The second will form part of the WP3 deliverable D3.2.
3.2.3.3 Reverse Osmosis system control
The RO combined with the pump and Pump/ERD will be integrated, instrumented (pressure, flow,
conductivity, temperature), controlled (using VFDs and several valves) and tested following some
of the procedures defined in the ANSI HI 3.6-2016 rotary pump test standard. Various control
strategies for operation will be identified and optimised for each of the two sites: batch and
continuous modes. These strategies will be assessed from a life-cycle system perspective and the
operational trade-offs, if any, will be identified, for example, treated water quality versus energy
consumption and energy consumption versus membrane cleaning.
3.2.4 Progress
The current state of development of the RO solution is discussed in this section. The HP Pump,
the Pump/ERD and RO system are reviewed in terms of their design and testing.
3.2.4.1 Pump design and Optimisation
Three successive versions of the High Pressure pump have been developed since the start of WP
3. The first version was based on the pre-existing pump and is not discussed in this report. It did
undergo a series of significant design changes intended to facilitate manufacture/assembly and to
improve the mechanical operation to the pump. Exploded views of the 3D CAD assemblies of the
two follow-on design iterations (versions 1 and 2) are shown in Figure 5 and Figure 6.
Figure 5. Quadruplex Pump version 1.
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Changes to the original design have focussed on three components:
1. The crankcase was re-designed to facilitate assembly while preserving very tight
tolerance sought to minimize leaks. The main update involved splitting the pump block
into a number of parts.
2. The cam shape was changed to minimize flow fluctuations and the cam assembly was
reviewed to minimize friction losses by incorporating rollers.
3. Piston assembly and connection to the actuators was re-designed to minimize wear on
seals while limiting compression and associated pressure fluctuations at higher pressures.
This was achieved by incorporating multi-axis joints to improve correct alignment with
the seal supports.
Figure 6. Quadruplex Pump version 2
These changes were driven by a dynamic models of the entire high pressure quadruplex pump
implemented in MATLAB Simulink. Each pumping chamber, with their internal compliance, was
modelled along with the coupled piston whose motion followed the prescribed profile dictated by
the cams.
Figure 7 shows an excerpt from the Simulink model of the mechanisms regulating precompression of the high pressure seals as well as cooling and lubrication of the same.
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Figure 7. Simulink diagram of one pump chamber to study the effects of internal compliance.
Figure 8 shows the influence of compliance, determined by the presence of elastic components
such as the sealing pack, within a pumping chamber. The higher this value, the higher are the
pressure fluctuations within each pumping chamber as well as within the outlet manifold.
This is an example of how the dynamic analysis of the components of the pump, most importantly
when components interact with one another, has guided the choices made for the final design of
the device.
Figure 8. Effect of pre-compression of seals on pressure values in one pump chamber (yellow lines)
and the outlet manifold (purple lines). Top, peak-to-peak pressure fluctuations ±0.7%; Bottom, peakto-peak pressure fluctuations ±4%.
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Valve spring stiffness and pre-load have also been carefully designed as valves’ dynamics play a
crucial role in obtaining the desired continuous-flow volumetric behaviour. Correct timing for
aperture has been determined by an appropriate value of the pre-compression resistance (0.3 𝑏𝑎𝑟 ∙
𝑠/𝑐𝑚3 ) which induces an isochoric pressure increase inside the pumping chambers necessary to
equate the pressure of the outlet manifold before any ejection occurs.
Additionally, in order to increase the lifespan of high pressure seals in each pumping chamber,
particular attention has been paid to cooling and lubrication. To this aim, a series of channels to
convey working fluid to the sealing area have been designed in such a way that the right amount
of lubricating fluid is provided. This has been obtained by proper design of their cross-section
area and a fine-tuning throttle (Figure 9).
Figure 9 Quadruplex cross-section highlighting cooling lubricating channels
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CAE virtual prototyping was again applied to version 2 of the HP pump, this revealed further
interference and potential design issues. The information regarding the issues and potential
solutions were discussed by DCU and OMS, examples include:



Intersection of cooling channels and bolt holes as illustrated in Figure 10 and Figure 11
below.
Other issues identified included sealing and profile uncertainties
Virtual prototyping was used to highlight the contact areas between dissimilar metals at
risk of galvanic corrosion.
Figure 10. Intersection of bolt hole
and cooling channel in pumping
chamber.
Figure 11. Intersection of guide rod and
securing bolts, identified using virtual
prototyping.
The optimisation of the high pressure pump design has included a fluid-structure interaction
analysis around the outlet valve and outflow channels and a structural assessment of the pump
block with the following key objectives

A static CFD analysis has been used to provide information on hydrodynamic losses
linked to vortex shedding and on force imbalance which can cause valve flutter and
reduced performance of the valve system. This information, in turn, has been used for the
optimisation of the valve seat and support frame design and of the chamber geometry.

The CFD model has also been used to provide boundary conditions (fluid pressure and
valve closing speed) needed by an FEA model to determine if the valve contact speed
may cause excessive stresses and to review structural implications of a redesign of the
valve frame.

A solid model has been used to determine how the overall mass of the seal support block
could be reduced without impacting the structural strength of the block when the material
is changed to super duplex from aluminium. Results indicated that the weight reduction
would not be justified given the resulting complications in machining.
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D3.1 Design specifications and manufacture/configuration
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Figure 12. Velocity vector plot of valve cross sections, from CFD simulation of the valve showing
vortex creation and force imbalance.
In summary, the structural analysis has been used to assess the design suitability in terms of the
strength and weight of the seal support block and of the valve support frame while the fluid
simulations informed a redesign of the following parts:



Pumping chamber to minimize hydrodynamic losses linked to vortex shedding.
The valves to minimize the asymmetry of fluid loads
The valve cover to reduce losses by reducing the blockage effect.
The final part of the design work concerns the material selection. Materials considered for the
manufacture include:

Super Duplex and Duplex Grade Steels for all components which will be subjected to
cyclic wear and/or in contact with salty water

Aluminium with surface treatment have been considered for parts with minimal exposure
to salty water. The surface treatment considered transforms the surface from metallic
aluminium to oxide Al2O3 over a thickness specified to achieve pre-determined levels of
corrosion and abrasion resistance.
A review of material properties led to the following conclusions:

The life span of the Al2O3 protective layer is insufficient for the current application.

The Super Duplex grade will provide several benefits compared to Duplex in terms of its
corrosion resistance. In particular
saltgae.eu
o
The Critical Pitting Temperature (CPT) and Critical Crevice Temperature (CTT)
provide a measure of delay in onset of corrosion. Specifically, if the CPT is
exceeded, pitting initiates and propagates to a visible level within 24 hours.
Significantly higher CTT and CPT are achieved with Super Duplex [3].
o
Immersion tests in sea water indicate that pitting Corrosion is unlikely with Super
Duplex but can occur in regions where evaporation led to high chloride
concentration solutes or salt deposits on surfaces. The higher corrosion resistance
provided by Super Duplex is important over all surfaces including with parts
exposed intermittently to salty water [4].
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D3.1 Design specifications and manufacture/configuration
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SAF 2507 supplied by Sandvik Material Technology is the Super Duplex Steel selected for all
metallic parts of the Quadruplex pumps except parts that will be immersed in oil. The steel
characteristics are (note that the maximum temperature of the HRAP is expected to reach
approximately (45℃):


𝐶𝑃𝑇 > 80℃ and 𝐶𝑇𝑇 > 60℃ (in 6% FeCl3)
Yield Strength 0.2%: < 480 MPa at temperature lower than 100℃
It remains to be determined whether the central mobile unit which encases the cams and is fully
immersed in the lubricating oil will be made of Aluminium with surface treatment or Super
Duplex Steel. This will be determined before the end of Month 13.
The final design of the Quadruplex pump which incorporates modifications arising from the CFD
and solid model simulations was completed at the end of Month 12. The design outline is shown
in Figure 13 with an exploded view of the assembly. The manufacturing of its components by
OMS has commenced and is due to be completed by the end of Month 13.
Figure 13. Seal support blocks highlighted in blue. T
The CFD analysis of valve seat will continue as part of the Pump/ERD optimisation. This work
will extend the static analysis with a dynamic analysis to simulate both the responses of the pump
valves to the piston driven flow through the pumping chamber. The use of a dynamic model will
allow the closing speed and impact forces between the valve and the seat to be investigated and
used to inform a further optimisation of the cam profile by OMS.
3.2.4.2
Pump/ERD design and optimisation
The pump/ERD device comprises a triplex-type actuation system with three cam-pistons
mechanisms each 120° out-of-phase (Figure 14).
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The design of the pump/ERD actuation system has been conceived to guarantee that the same
continuous geometric flowrate exists between the pump side and the ERD side of the device.
Figure 14. Overview of the triplex mechanism of the pump/ERD device
Pumping chambers and hydraulic motor chambers (i.e. ERD side) are separated by a 40mm
diameter piston. While the passive valves of the pump side have been designed using the same
principles as those reported in 3.2.4.1, the motor side uses active valves, actuated by additional
cams for the timing of intake and discharge (Figure 15) and whose motion is determined by a gear
mechanism connected to the shaft actuating the triplex mechanism (Figure 14).
Figure 15 Schema of the pump/ERD device. Side view of the block comprising pump and ERD
chambers, piston, seals, manifolds, passive and active valves. Triplex actuation mechanisms (on the
left) not shown
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Figure 16 shows the timing of the valves in relation to the piston’s position and velocity profiles
for one of the three cylinders of the device.
Figure 16. Active valves timing and piston’s profiles
Dimensions will be optimised using modified form of the dynamic model presented in Section
3.2.4.1. The CFD and FEA simulations will carried out to confirm suitability of the design
optimisations applied to the Quadruplex Pump.
3.2.4.3 Reverse Osmosis Test Rig Design and Optimisation
Before the wastewater can be treated using the RO process, it requires pretreatment to reduce
membrane fouling which increases membrane cleaning/membrane replacement and subsequently
increases system lifecycle costs. The specific RO pretreatment processes are being designed and
optimized by iBET. It is expected that the pretreatment will produce water with suitable Silt
Density Index (SDI) and total organic carbon (TOC) levels for RO, i.e. SDI < 5 and TOC < 3
ppm. These parameters help to determine the propensity for membrane fouling, and thus the
effectiveness and cost of the treatment process. Initial tests, carried out by iBET, to determine the
choice of pretreatment, using samples from the Slovenia site, identified a combination of
ultrafiltration and nanofiltration as the potentially most effective pretreatment option. In a series
of tests this combined approach yielded the lowest TOC values of 10.56 ppm and conductivity
values of 8.48 mS/cm (approximately equivalent to 5,430 mg/L Total Dissolved Solids (TDS)).
It is important to note that the TOC values are above the threshold of 3 ppm TOC recommended
by RO membrane manufacturers. As a result, it is expected that specific, low fouling membranes
may be required for the RO system in Slovenia. However, this will depend on further testing of
wastewater samples.
The feedwater flowrates vary between the sites: 2 m3/h in Israel to an average value of 0.1 m3/h
in Slovenia. Due to the low flowrates in Slovenia, it is planned to operate the Pump/ERD system
as a batch process, as opposed to a continuous process in Israel. Batch mode is necessary to ensure
adequate hydraulic power to the Pump/ERD for the Slovenian site. To test the pump/ERD system
under applicable conditions for both sites, the system will be tested in both batch and continuous
modes. Process start-up is very important to prime the pumps and to avoid hydraulic shock loads
to the RO membranes; operating in batch mode effectively means that start-up occurs frequently,
potentially complicating operations, increasing transient energy consumption and leading to wear
and tear of system components. Consequently, the integration of the Pump/ERD and RO system,
and its subsequent testing under various modes of operation is very pertinent prior to on-site pilot
testing.
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Membranes are usually designed for 1) low salinity, medium to high organics or 2) high salinity,
low organics. The wastewaters characteristics in this project straddle the two and the division that
typically exists between membranes suitable for brackish water and seawater applications. There
are a number of operating constraints to satisfy in membrane selection; these can be characterized
as membrane physical limitations (feed pressure, pH, pressure drop) and operating constraints
(design to reduce cleaning frequency, membrane replacement, capacity loss). A number of
membranes were considered, including seawater and brackish water membranes. Membrane
selection was assessed according to a number of parameters: pH, temperature, permeate flux,
operating pressures, salt rejection capabilities, and fouling mitigation. The options considered are
presented in Table 6.
Dow membrane
models
NF90-4040
NF270-4040
TW30-4040
BW30-4040
LP-4040
SW30-4040
SW30-HRLE4040
LCHR-4040
LCLE-4040
XLE-4040
RO-4040-FF
Low fouling











Low energy











Organic rejection
Element durability






















Table 6: Membrane characteristics
The tabulated membranes are all suitable in terms of size; however, some are specifically designed
to be low fouling, high rejection, and/or low energy. Once the range of membrane options had
been reduced, according to their functionality, membrane-specific design software (ROSA) was
used to simulate the membrane performance and to determine the RO configuration, i.e. the
number of elements per pressure vessel, and to predict membrane performance. The results are
presented in Figure 17.
Figure 17. Determining the most suitable membrane quantity to be used in the RO test rig.
A six element pressure vessel was selected, which ensured that the recommended element
recovery and permeate flow rates were not exceeded during operation. In addition, the choice of
six elements also facilitates testing of the novel Pump/ERD over a wider pressure range while
maintaining the requisite permeate water quality and flowrates. Based on the ROSA simulations,
the two most suitable membranes were chosen to be the Dow LCLE-4040 and Dow SW30HRLE4040. The design to incorporate and test the Pump/ERD and the RO system is shown in Figure
17. The design facilitates testing of the system under various conditions applicable to the
demonstration site locations.
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3.2.4.4 Control Strategy (DCU)
The control variables and initial control strategy for the integrated pump, Pump/ERD and RO
system have been identified. The integrated system has been designed, the instrumentation and
monitoring equipment has been specified and ordered.
Table 7: Reverse Osmosis Control Optimisation & Testing
Reverse Osmosis Control Optimisation & Testing
Objectives
Monitored Variables






HP pump inlet & outlet
pressures
HP pump inlet flow rate
ERD pump inlet & outlet
pressures
ERD outlet flow rate
Feed tank level
Feed water temperature
Shaft angular position
Shaft rotational speed
Shaft torque
Instantaneous current & voltage
Frequency of variable speed
drive
Instantaneous pressure at ERD
inlet.
HP pump carter block vibration
HP pump cam vibration
ERD vibration




Membrane fouling rate
Level of maintenance required
Cost justification of HP pump
Cost justification of ERD pump




Hydraulic
performance of
the pump and
Pump/ERD









Overall
functionality
and feasibility of
the HP Pump +
ERD
Control Variables










Feed water salinity
Feed water temperature
HP pump steady state
rotational speed
HP pump ramp-up/down
rotational speed
ERD steady state rotational
speed
ERD ramp-up/down
rotational speed
Inlet flow rate from feed
tank
HP pump inlet flow rate
ERD LP inlet flow rate
ERD HP inlet flow from RO
concentrate line
Initialization loop inlet flow
Initialization loop outlet
flow
Initialization feed pump
rotational speed
Recirculation pump
rotational speed
Note:

All pressure measurements being monitored are taken to be at gauge pressure.

All instruments used are within the acceptable deviation of independent test
quantities, See section 3.6.4.4/5 and 3.6.4.6.1 of the ANSI HI 3.6-2016 rotary pump
test standard.

Each of the objectives above will be compared with respect to current market
benchmark alternatives available constantly throughout.
This testing will require that the hydraulic performance of the pump and Pump/ERD be
characterised. This part of the test will conform to the ANSI HI 3.6-2016 rotary pump test
standard and the assessment will account for both transient and steady state phases of the pump
and Pump/ERD operation. Data Acquisition, at high sampling rates, will be used to monitor,
assess and optimise performance. To assess the overall function of the pump and Pump/ERD
during both transient and steady state phases of operation will be studied. Table 7 shows the
variables that will be monitored and controlled.
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3.2.4.5 Pump performance evaluation
RISE will perform hydraulic tests of the pump where the RO is not covered. The pump will be
tested according to the standard ANSI/HI 3.6-2016 Rotary Pump Tests. The standard defines the
test method to measure and calculate the performance of the pump.
The results of the pump performance evaluation will be presented in graphs versus differential
pressure at constant speed (or versus speed at constant differential pressure) for:
 Rate of flow
 Pump efficiency
 Pump power
The following quantities will be measured for the pump performance evaluation:
 Temperature
 Static gauge pressure at pump inlet
 Differential pressure over the pump
 Rate of flow
 Speed of rotation
 Motor power input
 Pump shaft torque
The pump power input is determined by measuring the torque and speed of rotation of the pump
shaft. The measurement equipment for this purpose has not yet been purchased.
The test liquid will be a solution of NaCl in water in concentration similar to the effluent. The
exact specification of the liquid is not yet determined.
The standard ANSI/HI 3.6-2016 also comprises two optional tests: a hydrostatic test and a NPIPR
test (net positive inlet pressure requirement). These tests will be carried out in addition to the
mandatory tests stipulated in the standard. The hydrostatic test identifies leaks or structural failure
when subjected to hydrostatic pressure 1.5 times maximum allowable working pressure. The
NPIPR test results in the net positive inlet pressure required for the pump.
The hydraulic performance test of pump is planned to take place during M15.
3.2.4.6 Pump/ERD performance evaluation
The pump/ERD system features the same pump as in the pump only system, but also includes the
ERD. In order to evaluate the performance of the Pump/ERD system, the performance test
according to ANSI/HI 3.6-2016 will be repeated. As opposed to the pump performance evaluation
previously carried out, the Pump/ERD performance evaluation will be based on measurements on
the pump/ERD system. This will result in data on the Pump/ERD system efficiency.
The results of the Pump/ERD performance evaluation will be presented in graphs versus
differential pressure at constant speed (or versus speed at constant differential pressure) for:



Rate of flow
Pump/ERD efficiency
Pump/ERD power versus differential pressure at constant speed
The following quantities will be measured for the Pump/ERD performance evaluation:
 Temperature
 Static gauge pressure at pump inlet
 Differential pressure over the pump
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D3.1 Design specifications and manufacture/configuration
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



Rate of flow
Speed of rotation
ERD motor power input
Pump power input
The Pump/ERD test will also include the optional hydrostatic test and the optional NPIPR test.
As the RO is not covered by the Pump/ERD performance test it should be noted that the salinity
of the test liquid that reaches the ERD will not completely resemble the real conditions the system
will encounter in field operation. In field operation the salinity of the liquid that reaches the ERD
will be higher than the salinity of the liquid that reaches the pump. This is due to that the RO will
increase the salt concentration in the liquid as it allows only pure water to pass through. As a
result, the salt concentration that reaches the ERD will be higher during field operation. In the test
rig the salinity of the fluid is constant. However, the difference in salinity is not deemed to have
any large impact on the performance evaluation.
The hydraulic performance test of Pump/ERD is planned to take place during M17.
3.2.4.7 Wear testing
An assessment of the system is being conducted by RISE to identify components that will be
subjected to the most critical levels of stress during operation and will require wear testing. This
assessment is on-going and requires a review of all components and their interactions taking into
account the material choices and the operating conditions. To date, the pump seals have been
identified as the most important components to analyse in terms of wear. The wear tests will be
split into two subtests: accelerated wear test and post-field operation wear measurement.
The wear that the seals will be subjected to in field operation is expected to fall under the
following categories:



Chemical wear. Corrosion
Physical wear. Structural change, leaching of additives
Mechanical wear. Macroscopic change in surface properties, abrasion
Accelerated aging test
During this test the seals will be subjected to accelerated aging in order to predict possible
weaknesses that might influence the maintenance intervals. The chemical as well as physical wear
will be determined. A number of seals will be immersed in a NaCl solution of higher concentration
and temperature than the field operation conditions. In order to facilitate the prediction of seal
service life the seals will be subjected to the accelerated aging test for different lengths of time.
The following will be measured:




Seal weight
Seal surface roughness
Seal thickness
Seal material composition (determined through thermogravimetric analysis)
The measurement results of the seals prior to the accelerated aging test will be used to form a
reference point. Since a set of seals will form this reference point the measurement results will
reduce the risk of drawing conclusions based on variation in manufacturing tolerance. In
comparison to this reference point the seals subjected to the accelerated wear test will be used to
determine the relative wear.
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D3.1 Design specifications and manufacture/configuration
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The expected outputs of the measurement of wear after the accelerated aging test are:





Change in seal weight
Change in seal surface roughness
Change in seal thickness
Change in seal material composition
Prediction of seal service life
The accelerated aging test is planned to start during M14.
Measurement of wear after field operation
After the Pump/ERD system has been in field operation (for about 12 months, exact schedule to
be determined) the actual wear on the seals will be determined. The chemical, physical and
mechanical wear will be determined. These seals will be analysed in the same manner as the seals
that underwent the accelerated aging test. The results will be compared to the data collected during
measurement of the reference seals prior to the accelerated aging test.
The expected outputs of the measurement of wear after field operation are:





Change in seal weight
Change in seal surface roughness
Change in seal thickness
Change in seal material composition
Prediction of remaining seal service life
The measurement of wear after field operation is planned to take place after the pumps have been
in field operation, but the exact time schedule is to be determined.
3.3 Integration
The key objectives of Work Package 3 can be summarized as follows:



Design and test three alternative pretreatments to condition the HRAP effluent before the
desalination phase and select the optimal solution.
Design an RO solution for desalination to include:
o Design, build and test two pilot prototype pump and Pump/ERD systems to be
integrated in the RO desalination system.
o Determine the optimal control strategy for the RO processes to suit the two
deployment sites
Design and optimize ED as an alternative desalination solution.
Once the overall RO solution with pre-treatment has been optimized, it will be integrated into the
overall Saltgae solutions outlined in
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D3.1 Design specifications and manufacture/configuration
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Figure
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D3.1 Design specifications and manufacture/configuration
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Figure 19 as part of Work Package 5. The optimized ED solution will be tested at Extractis
facilities using samples from the demonstration site deemed most suitable for ED treatment again
as part of Work Package 5.
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D3.1 Design specifications and manufacture/configuration
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Figure 18. Saltgae solution for Slovenia Demonstration Site
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D3.1 Design specifications and manufacture/configuration
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Figure 19. Saltgae solution for Israel Demonstration Site
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D3.1 Design specifications and manufacture/configuration
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4
Conclusions and Future plan
Significant progress has been made and work completed is summarised below:

Pre-treatment tests have been performed on HRAP effluent from the Slovenian demonstration
site with effluent representative of the TOC and TDS levels expected from the final HRAP
effluent. These tests indicate that the nanofiltration process using the NF270 membrane
achieve the highest organic compound removal. Further tests will be required to assess the
required pressure conditions to achieve optimal techno-economic performance. Tests will
also be needed to account for higher salt content expected in the final KOTO operations and
will need to be extended to include effluent from the Israeli demonstration site.

iBET has supplied EXTRACTIS with the first representative pre-treated samples on the 29th
May 2017. These samples have been supplemented with NaCl to better represent the expected
conditions at the Slovenian demonstration site and are ready for the electrodialysis tests.

The design of the Quadruplex pump for the RO solution was completed at the end of Month
12. Work completed include the selection of materials for manufacturing, selection of seals,
springs and other commercially available components and the design of all parts. Further
design optimisation and system analysis focussing on the valve support frame which can
easily be replaced will continue in parallel with the Pump/ERD design optimisation which
started at the start of Month 13. This analysis work will continue beyond Work Package 3 as
part of Work Packages 5 and 6 to integrate operational observations from the demonstration
phase. The manufacture of the pump parts and their assembly including initial tests will be
performed by OMS for delivery to RISE and DCU on Month 16. Two separate devices will
be built.

The testing programme has been finalised for both the Pump and Pump/ERD and will involve
two separate experimental investigations. On the one hand the devices’ performance
characteristics will be assessed by RISE. The Quadruplex pump will be tested according to
ANSI-HI 3.6-2016 standard. The innovative Pump/ERD will be tested following the same
procedure adapted to account for the specific nature of the ERD. The other test will
incorporate both devices within a RO test rig. The purpose of this experimental assessment is
to determine the optimal control to suit the two test sites and their respective operating
conditions. This RO test rig has been designed and is being built to suit the specific conditions
expected at the two demonstration sites.

Wear tests to be conducted by RISE are planned and it is proposed that this will be delayed
until the end of the demonstration phase (Work Package 6).

The two pump prototypes and design specification for the selected optimal pre-treatment
solution, the optimised ED solutions and the optimised RE solution (including control
strategies to suit the two deployment sites) will be provided to Bibo Aqua for integration in
the overall solutions.
Work planned for the remaining 6 months of the Work Package include:

The design of the Pump/ERD is at its initial design phase and its optimisation will be
completed at the end of Month 14. The methodology for this design optimisation is the same
as that developed for the pump and a number of component will rely on the same designs.
The manufacture of the Pump/ERD parts and their assembly including initial tests will be
performed by OMS for delivery to RISE and DCU on Month 16. Two separate devices will
be built. Further details on the Work Package plan and timelines can be found in the Annex.

Tests are planned by Extractis to characterise the samples produced by the pre-treatment at
iBET and to evaluate the effectiveness of electrodialysis as a desalination solution by will
commence during the first week of Month 13. Results will be available at the end of M 14.
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References
References
01
Dow chemical. ROSA software [on line]. http://www.dow.com/en-us/water-and-processsolutions/resources/design-software/rosa-software. Accessed 04/05/2017
02
European Commission;, “G. Technology readiness levels (TRL), HORIZON 2020 – WORK
PROGRAMME 2014-2015 General Annexes, Extract from Part 19 - Commission Decision C(2014)4995,”
European Commission, 2014.
03
International Molybdenum Association (IMOA), “Practical guidelines for the fabrication of Duplex
stainless steel,” International Molybdenum Association (IMOA), London, 2014.
04
B. Wallén, “Corrosion of Duplex stainless steels in seawater,” Acom : Avesta corrosion management,
Vols. 1-98.
Table 8: References
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D3.1 Design specifications and manufacture/configuration
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Annexes
Task
Who
Activated carbon
adsorption and iBET
retention
iBET
Direct Photolysis iBET
iBET
Direct filtration of
iBET
supernatant
iBET
Selection and
characterisation iBET
iBET
Outline
Month
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Design of technical solution and optimisation of operating
conditions
Cost Anslysis and Environmental assessment
Design of technical solution and optimisation of operating
conditions
Cost Anslysis and Environmental assessment
Design of technical solution and optimisation of operating
conditions
Cost Anslysis and Environmental assessment
Selection based on techno-economic and environmental analysis.
Criteria: 99% removal of mass foulant and 5 fold increase life in
service
Design and built of pilot scale test rig
Figure 20. Task 3.1 GANTT Chart. Green, Blue and Red indicate completed, started and pending
tasks.
Task
Who
Desalination by
Electrodialysis
Outline
Month
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Extractis Characterisation
Demineralisation tests: Evaluate efficiency of ED reactors for
Extractis demineralisation
Extractis Design pilot scale reactor
Figure 21. Task 3.2 GANTT Chart. Green, Blue and Red indicate completed, started and pending
tasks.
Task
Who
OMS
DCU
Pump
OMS
Design/Test/Build
DCU
RISE
RISE
OMS
DCU
Pump/ERD
OMS
Design/Test/Build DCU
RISE
Outline
Month
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Provide pump design specification as 2D Drawings and revise based
on reviews by DCU
Complete CAE Analysis and revised Design
Manufacture components, assembly and shipping
Design Test Rig and Test Pump and RO performance
Design Test and Test Pump Performance according to ANSI standard
Wear Test on pump components
Provide pump/ERD design specification as 2D Drawings and revise
based on reviews by DCU
Complete CAE Analysis and revised Design
Manufacture components, assembly and shipping
Test Pump/ERD and RO performance
Test Pump/ERD Performance according to ANSI standard
Figure 22. Task 3.3 GANTT Chart. Green, Blue and Red indicate completed, started and pending
tasks.
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