HomeMy WebLinkAbout05/00/1990, 1 - DESALINATION EVALUATION �ytl�ll�l^�I�III � MEETING DATE:
CIoI" SSanlUIs OBIS� Mal,, 3 1990
COUNCIL AGENDA REPORT Imo"''NUMBER:
FROM: William T. Hetland Prepared by Allen Short
Utilities Director Water Division Manager
SUBJECT: Desalination Evaluation
RECOMMENDATION:
By motion, authorize staff to solicit Request for Proposal (RFP)
for professional engineering services for evaluating desalination
as a viable option to augmenting current water supplies.
BACKGROUND:
The City of San Luis Obispo is currently in the fourth year of a
water shortage. The City's surface water supplies are
approaching the critical level and the City Council has approved
the implementation of a thirty-five percent (35%) mandatory water
conservation program. Additionally, as the City began reaching
the maximum yields of its reservoir supplies, it began to look at
groundwater as an additional source. .
Staff began investigating several options to supplement existing
water supplies. One of those options under consideration is
desalination. At the February 26, 1990 City Council Meeting, an
agenda report and Request For Proposal (RFP) was prepared by
staff to further investigate desalination. Council at that time
did not feel they had sufficient information on desalination to
either approve or disapprove the request. Council requested that
staff schedule a study session to assist in the education process
and invite local individuals who have desalination experience.
Staff has scheduled the study session for May 8, 1990 and have
invited the following firms:
1. Mike Spangler H2O Organization
2. Mike Peterson PG&E (Diablo)
•3. Jay Hesby Black and Veatch
Each individual will make a brief 15-20 minute presentation on
desalination and answer any Council questions.
Attached for your review and action is the original staff report
and desalination RFP.
CONSEQUENCES OF NOT TAKING ACTION_
The ability to properly investigate the viability of desalination
as an alternative water supply will continue to be delayed and be
greatly impaired.
�I���► �IIIIIII�p� ���lU city of san tuis oBispo
i COUNCIL AGENDA REPORT
Desalination Evaluation
Page 2
RECOMMENDATION•
By motion, authorize staff to issue a Request for Proposal (RFP)
for professional engineering services for evaluating desalination
as a viable option to augmenting current water supplies.
i
i
Attachments: Desalination Staff Report dated February 26, 1990.
Request for Proposal.
RFP#2/B
I
. _ ME nNG GATE:
city Of San LL OBISpO Februa 26 1490
(TBM NUMBM-
j COUNCIL AGENDA REPORT r
ZOM: William T. Hetland Prepared by Allen Short
Utilities Director Water Division Manager
SUBJECT: Desalination Evaluation
RECOMMENDATION:
City Council consider retaining professional engineering services
for evaluating desalination as a viable option to augmenting
current water supplies.
BACKGROUND:
The City of San Luis Obispo is currently in the fourth year of a
water shortage. The City's surface water supplies are approaching
the critical level and the City has implemented a twenty percent
(20%) mandatory water conservation program. Additionally, as the
City began reaching the maximum yields of its reservoir supplies, it
began to look at groundwater as an additional source.
The groundwater development program was initiated and divided into
4-wo phases. Both phases of the groundwater development program are.
impleted. The wells identified in both phases, have been developed
and are operational. Additionally, to fully utilize groundwater to
its greatest benefit a zonal booster pump station was designed and
installed at the Edna Saddle Reservoir. This pump station allows the
city to move large amounts of groundwater from one area of the City
to another.
As the City's usable water supplies become depleted or contaminated
the conversion of saltwater to usable water for domestic consumption
becomes more attractive as an alternative for the augmentation of
water supplies. The technology for doing this currently exists. The
problem with implementing the technology on a widespread basis is
that it is limited by energy requirements, costs, and environmental
constraints. It is estimated that the cost per acre foot for
desalination ranges from a low of $1,500 to a high of $3,500
excluding transmission costs. Currently, the City's cost per acre
foot for water ranges from $250 to $350. The cost per acre foot for
proposed water projects such as State Water Project, Salinas Dam
Expansion or Coastal Streams, ranges from $400 to $600. The cost for
desalination is more expensive but it is not locally rain dependent.
To fully evaluate the effectiveness of desalination, staff needs up-
-to-date information and answers to the following questions:
/-3
l
city of san LUIS OBisp0
COUNCIL AGENDA REPORT
Desalination Evaluation
February 20, 1990
Page 2
1. A description, identification, and evaluation of all alternative
desalination processes.
2. A description, identification and evaluation of the costs of
production.
3. A description and identification of the permit process, cost, and
schedules. .
4. A description and evaluation of water quality standards.
5. A description, identification and evaluation of the delivery
method, pipe sizing, line pressures, plant size and location. '
6. A description, identification and evaluation of the methods of
financing.
7. A description, identification and evaluation of the costs
associated with decommissioning a plant.
8. An evaluation of desalination in comparison to other potential
City water supplies. --
9. Preparation of a report which identifies the best managerial
approach to utilization of desalinization as an alternative water
supply.
FINANCIAL IMPACT•
To conduct an evaluation of desalination is estimated not to exceed
$50, 000. This project was not originally identified in the 1989-91
Financial Plan and Approved budget. The money has been identified_ to
come from the water fund balances.
CONSEQUENCES OF NOT TAKING ACTION:.
The ability to properly investigate the viability of desalinization
as an alternative long term water supply will be greatly impaired.
ACTION RECOMMENDED:
Authorize staff to solicit Request for Proposal (RFP) for
professional engineering services for evaluating desalination as a
viable option to augmenting current water supplies.
Attachment: Draft Request for Proposal for Engineering Services for
Evaluating Desalination as a Viable Water Supply.
l'
� AI CTCy of San Lul.? OBISPO
COUNCIL AGENDA REPORT
Desalination Evaluation
February 20, 1990
Page 3
APPROVED:
City A inistrative Officer
`- tto ne
Finance Director
Wt
Utilities Director
r inn -2A�
Water Division' Manager
I
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CITY OF SAN LUIS OBISPO
REQUEST FOR PROPOSAL
FOR ENGINEERING SERVICES
FOR EVALUATING DESALINATION AS A
VIABLE WATER SUPPLY
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GENERAL NOTICE
`,The City of tan Luis Obispo invites your firm to submit a proposal to
provide engineering services for evaluation of desalination.
Sealed proposals for professional engineering services for the.
desalination evaluation will be received by the Clerks office, at
P.O. Box 8100 San Luis Obispo CA, 93403, on or before XXXXXXXXX
Proposals received after that date will not be accepted. Contacts
regarding the development of a proposal and the status of interviews
shall be made with Allen Short, Water Division Manager.
Please submit your proposal in six (6) copies to the attention of the
Water Division Manager. The proposals shall be submitted in
envelope(s) clearly marked indicating the project title.
BACKGROUND
The City of San Luis Obispo is located on the Central Coast
approximately at the half way point between San Francisco and Los
Angeles. Historically, the City has used its two surface water
supplies to provide domestic water to the citizens of San Luis
Obispo. With increasing water demands and limited rainfall over the
past four (4) years, the surface water supplies have not replenished
to adequate levels. As a result, the City has undertaken and
implemented a groundwater development program.
\ Currently, the City has developed a number of wells which range in
-- production from 80 gpm (134 acre feet) to 700 gpm (1100 acre feet) .
The City is in the process of developing additional wells. The wells
have been primarily developed in the Southwest section of the City
with a few low producers located in the in the Northern section of
the City.
As the City's water supplies become depleted or not suitable for
drinking, the conversion of saltwater to usable water becomes more
attractive as an alternative for the augmentation of water supplies.
The technology for doing this currently exists. The problems which .
have been identified and must .be evaluated with implementing this
technology on a widespread basis are: energy requirements, costs, and
environmental constraints.
In an effort to explore all water resources available to the City an
evaluation of desalination will be conducted which will provide the
City with the information necessary to properly decide if
desalination is a viable option.,
' 1
SCOPE OF WORK
The consultant(s) shall complete the studies, and evaluations of �.
desalination, to determine the feasibility, energy requirements,
costs and environmental constraints. The consultant(s) shall address
the following:
1. Describe, identify and evaluate all alternative
desalination processes.
2. Describe, identify and evaluate the costs of
production.
3. Describe and identify the permit process, cost, and
schedules.
4. Describe and evaluate water quality standards.
5. Describe, identify and evaluate the methods of
delivery, pipe sizing, line pressures, plant size and
location.
6. Describe, identify and evaluate methods of financing.
7. Describe, identify and evaluate costs associated with
decommissioning a plant.
8. Evaluate desalination in comparison to other potential
City water supplies.
9. Preparation of a report which identifies the best managerial
approach to utilization of desalinization as an alternative water
supply.
10. Assist City staff with presentations to the City Council
during the preparation of the preliminary and final
reports. Attendance at more than two meetings may be
considered as extra cost to the consultant.
SPECIAL REQUIREMENTS
1. Consultant selected will be required to enter into the City's
standard contract form. The city will also require proof of
Workers Compensation Insurance and Comprehensive General
Liability as a minimum of and Proof of Errors and Omissions
insurance in a minimum amounts of $500,000/$1,000,000.
2. Firms or individuals submitting a proposal and any associated
consultant or subcontractor must be legally qualified in the
State of California to practice the work required in this RFP and
must hold all licenses and/or registrations required by law. The
selected firm will have to obtain a City of San Luis Obispo
business license.
2 1
CONTENT OF PROPOSAL
'he proposal from the consultant should include the following:
1. Legal name, address and telephone number of firm
submitting proposal.
2. Name, address, and telephone number of the person to whom
correspondence should be directed.
3. Year the firm was established as it is currently operated.
4. Is the firm an individual, partnership, corporation, joint
venture, etc.
S. The maximum fee to do the work as outlined under the scope of
work.
6. A breakdown of the estimate for performing the work to
include the costs of hourly personnel charges, equipment,
materials, and travel.
7. Comments from the consultant regarding his approach to the
project and any recommended modifications to the scope of
work that consultant feels would be desirable.
8. The Consultant will submit a proposed schedule.
9. Complete list and description of previous projects of a
similar nature in which the firm .has been involved,
including the status of these projects and address of
contact persons employed by the project owner.
SELECTION CRITERIA
The initial selection of a consultant(s) will be based on the
following criteria:
1. It is the City of San Luis Obispo's desire to place the
responsibility for the success of the overall project with one
consultant, because of the need for continuity in coordination of
the various phases of the project. Continuation of consultant(s)
services beyond the preliminary study phases is solely at the
City's discretion.
2. Evaluation will be based not only upon the firms capabilities,
but also the abilities and accomplishments of individuals to be
assigned to the project. Proven experience with desalination
evaluation is required expertise of the firm.
3
� � 9
SELECTION PROCESS
The proposals submitted will be reviewed by a selection committee
consisting of City staff members. After evaluating the proposals the
City will select a minimum of three (3) candidates for an oral
interview. The committee will submit a recommendation to the City
Council for final determination.
Each consultant's proposal will be reviewed on the following
criteria:
1. Professional excellence and technical approach.
2. Demonstrated competence on similar projects, (Selected firm will
have been thoroughly involved in at least two successful
desalination projects that are completed, including control of
costs, quality of work, completion in timely manner
3. Education and experience of key personnel. Resumes should be
furnished for the proposed team members, team leader and
alternates designated.
4 . Financial capability, estimated fee schedule and method of
compensation.
5. Candidate's capacity to perform the work in a timely fashion. A
proposed work plan, organization chart, and man-weeks estimate
for each item in the plan should be included.
6. Candidate's familiarity with the type of problems applicable to
the project.
FINAL REPORT
1. Within thirty (30) days of project completion the consultant
shall furnish the City with a Final Report.
4 ��
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e 9EE ING �4PITEM
AGENDA
DACE 1 #
F"2%p
RCANIZAT'ION
WATER ANALYSIS
EXISTING COST PER AC. FT. $650.00 $800.00 $800.00 $1,200.00 $1,500.00
TOTAL USAGE IN AC. FT. 5400 5400 5400 5400 540(
TOTAL REVENUE $3,510,000 $4,320,000 $4,320,000 $6,480,000 $8,100,000
PERCENT CONSERVATION 30.00% 30.00% 30.00% 30.00% 30.009@
USAGE WITHOUT CONSEP.VATION 7,714 7,714 7,714 7,714 7,71 z
TOTAL WATER SAY NGS 2,314 2,314 2,314 2,314 2,31
DESAL COST PER AC. FT_ $1 ,100.00 $2,000.00 $3,000.00 $3,000.00 $3,000.00
SHORTFALL IN AC. FT. 2,314 2,314 2,314 2,314 2,314
COST TO PROVIDE SHORTFALL $2,545,714 $4,628,571 $6,942,857 $6,942,857 $6,942,857
COST WITHOUT CONSERVATION $5,014,286 $6,171 ,429 $61171,429 $9,257,143 $11,571,429
USING DESAL FOR SHORTFALL $6,055,714 $8,948,571 $11,262,857 $13,422,857 $150042,857
INCREASE USING DESAL FOR SHORTFALL 20.77% 45.00% 82.50% 45.00% 30.0091
NEW AVE. COST PER AC. FT. $785 $12160 $10460 $10740 $10950
AVE. RES. BILL WITHOUT DESAL $18.42 $22.67 $22.67 $34.00 $42.50
AVE. RES. BILL WITH DESAL $22.24 $32.87 $41.37 $49.30 $55:25
TOTAL INCREASE $3.82 $10.20 $18.70 $15.30 $12.75
COST PER GAL. BEFOR DESAL $.002 $.002 $.002 $.004 $.00!
COST PER GAL.AFTER DESAL $.002 $.004 $.004 $.005 $.00
QST PER UNIT BEFOR DESAL $1.49 $1.84 $1.84 $2.75 $3.4�
COST PER UNIT AFTER DESAL $1 .80 $2.66 $3.35 $3.99 $4.4E
*Denotes action by Lead Person
Res nd by:-�
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ity Atty.
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RECEIYEK)
MAY 1990
r`U
ary
bbl Wisoejeao c6
664 MARSH ST. SAN LUIS OBISPO, CA 93401 805.543762
- r
Interim Report No. 01 (Rev. 0)
Robert Blevitt
H2Organization
664 Marsh St.
San Luis Obispo, GA 93401
®RGANIZATION
MIKE SPANGLER
GENERALL"GER
664 MARSH ST. SAN LUIS OBISPO.CA 09x01 80S•54>782C
Table of Contents
1.0 Summary
2.0 Process Review and Discussion
2.1 Reverse Osmosis System Designs
2.2 Distillation System Designs
2.3 Process Comparisons and Recommendations
3.0 Water Quality Requirements
4.0 Site Selection
5.0 Plant Capital and Operating Cost Estimates
6.0 Future Study Scope for Plant Construction
7.0 Appendix
J
.0 Summary
H20rgan&Won has made an initial evaluation of the feasibility of constructing a seawater desalting system to famish
:Water for potable and other domestic The capacity of the system has been
defined as approximately 179 acre-feettyear,enough for 716 dwelling units.Actual plard size would be 224 acre-feet per
year in order to meet plant demand factors.
There are three main processes available for the desalting seawater in commerclal quantities available at this tine.They
are steam driven distillation, vapor compression driven distillation (electric driven, and reverse osmosis. Cther mkwr
processes are available and there are several Interesting combinations of power and water cycles which may be,of
interest
At the current time, it appears for the small plant envisioned for the project,about 179 acre-feet year(160,000 GPD),that
a single reverse osmosis (RO) package plant with pretreatment, energy recovery turbine and post-treatment package Is
the most attractive system.A strong runnerup, but at a higher capital cost is vapor compression distillation(VCD).
If more water were to be produced, other processes may be more efficient and will be more costly capitaal-wwise although
less costly from an operating standpoint.
For the larger plants, the steam driven distillation system Is very economical but would be Wri ted to planus over about
250,000 GPD. These types of plants when operated in combined cycles with Diesel engines or gas turbines, both wkh
heat recovery systems, and both generating electricity, can be very efficient energy-wise but Impose a heavy capital
burden for the initial investor. Much large plants In the .75 to 1.0 million GPD are better candidates for these combined
cycle processes.
-The quality of water produced by the desalting system exceeds the requirements mandated by State laws(ntie 22 of the
;afdornia Administrative Code). The upper limit of dissolved solids is 1000 PPM, while the preferred lower limit Is 600
PPM. Permits are expected to require furnishing a water bearing less than 1000 PPM but not mandating the 600 PPM
limit. The design limit for water quality has been set at 750 PPM TDS which permits staying under the maximum
comtaminartt level of 500 PPM for Chloride ion specified In the Code.All other constraints for water quality including those
specified In the Code and limits for corrosivity for standard plumbing systems would be met by the system discussed
herein.
Existing seawater wells have not been tested but appear to be ideal as a source of raw water to feed the desaking plant.
Use of an existing outfall will facilitate installation and construction of the plant and will be able to meet regulatory)
constrairus for discharge into the ocean.
Permits for the project would be required from various agencies,but this activity Is not discussed in this interim report.
The estimated cost of the plant completely engineered and Installed ranges from$1,791,000 to$2.099,000 tu.tnd ng the
cost of storage tanks for 2 days storage time. Costs are not included for hooking up to existing municipal water mutts.
The estimate unit capital cost allocated per dwelling would be$2500.00 to$2930.00/dwelling unit.
The production cost of water at a 80% plant load factor without allowances for initial capital charges nor insurance but
including allowances for refurbishing the plant (sinking fund) Is estimated to be $4.03/1000 gaL($1314.00/me400t).
These values equate to about$27.38/month for the average dwelling using 1/4 acre#oot/annum.
Completion of the project would require additional studies which would Include preliminary engineering work for a
selected site, acquisition of basic permits, preparation of submittal drawings, reports and tables for the permitting
agencies and preparation of final designs and drawings.
H20RGANIZATiON INTERIM REPORT#01 REV 0: PAGE 3
Ao Process Review and Discussion
The basic desalting processes to be discussed include the following:
1.0 Reverse osmosis with energy recovery turbine,pretreatment,and post-treatment subsystems.
2.0 Vapor compression distillation without waste heat supply and with post-treatment system.
2.1 As above but with waste heat supply in a combined cycle process.
3.0 Multi-effect low temperature distillation without waste heat supply and with post-treatment
system.
3.1 As above but with waste heat supply In a combined cycle process.
The process selection is impacted partially by the design capacity selected for the project We have defined the capacity
at approximately 179 acre4eet/year which, for 716 homes will furnish about 160,000 GPD or 220 GPD/household for
uses. Additional surplus capacity may be desireable or be mandated by permitting agencies during the review of this
project to the extent that more than 20% excess capacity may be specified as a condition for permitting.The Mal plant
capacity selection remains to be negotiated. Therefore, this study may have to be altered to reflect such conditions
which may result in selecting a modified or different process.
In all of the cases discussed below, a standard seawater at a temperature of 12oC (53.60F.) and bearing the
composition listed in Table 2.1 has been selected for comparison and calculation purposes. '
Table 2.1 Reference Seawater Analysis
Cations Anions
(DOM) Spm
Ca 380. HCO3 160.
Mg 1320. SO4 2500.
Na 10,600. Cl 19,280.
K 385. Si02 2.0
NH4 0.. NO3 0.0
Turbidity: <5.0 NTU
An additional constraint on the processes selected is the final product water quality. fl the permitting agency desires„ it
could mandate a 500 PPM TDS limit in accordance with the recommended levels shown In Title 22 of the California
Ave Code. The upper mineralization level, 1 oo0 PPM, is the upper limit permitted by the law if no other source
Is available. Since it is possible to make 500 PPM water with both RO and/or distillation, the permitting agency Could
request the lower UmiL However, these limits are negotiable and should be determined as early as possible since these
limits affect the designs of RO systems especially. The upper omit is relatively easy to attain for most membrane
suppliers,while the lower limit can be attained in a single stage high recovery rate RO system by only one supplier at this
time(FlmTec Corp.).
2.1 Reverse Osmosis System Designs
The reverse osmosis system is a relatively energy efficient producer of potable water providing the raw seawater
supplied to it is reasonably free of objectionable materials or contaminants such as excess turbidity, oil, grease,biota,or
agressive chemicals entering from chemical processing systems waste discharges.
In order to ensure trouble-free operation, it is good practice to coagulate and filler raw seawater before admission to the
40 membrane system. Additionally, the typical RO system system at the design temperature of 12oC would operate at
"about 9W PSI;the waste brine from the RO system ranges from 55-65%of the feedwater and has a pressure of about 15
PSI less, or about 885 PSI.This brine stream contains a great deal of energy which can be recovered easily by the use of
H2ORGANizAnoN KrEalM REPoRr#01 REv 0: PAGE 4
•vater turbine whose shaft is coupled to the RO system high pressure pump crankshaft.
The product water from an RO unit is typically low in solids and very low In hardness. Its pH is relatively low which leads
to the aggressive nature of this type of water. In order to avoid excsss corrosion In typical piping systems, ft Is good
practice to stabilize the RO product water by elevating its pH slightly and adding small amounts of Calcium Carbamate
and zinc Phosphate to retard corrosion in both copper and steel piping.
The final process elements for this system would be:
1. Flocculation and coagulation with Ferric Chloride and organic polymer(coagulant aid).
2 Filtration on multimedia filters loaded with anthracite,sand and garnet media.
3. Scale inhibition with polyacrylic acid polymer(such as Flocon-100,Pfizer Corp.)
4. Oxygen scavenging and corrosion inhibition of RO system piping with sodium bisulfita
S. Fine filtration on cartridge filters to remove 5-10 micron particles and larger.
6. Pumping to 900 PSI and separation in the RO subsystem into two streams, a product water stream and a
waste brine stream.
7. Discharge of the brine through an energy recovery hydraulic turbine to recover approximately 80% of
available energy in the brine stream.
6. Post-treatment of the product water by filtration on calcite, elevation of pH with soda ash solution (NaCO3),
and finally addition of Zinc phosphate corrosion inhibitor for domestic piping systems.
9. Disinfection with sodium hypochlorite to maintain a Chlorine residual In the distribution and storage
subsystem.
10. Flushing of the RO membrane system with product water during shutdown periods to retard fouling by
precipitation of sparingly soluble substances present in the concentrated seawater.
11. Intermittent cleaning of the RO membranes as required to maintain specifications for product quality and
system operation.
Additional commentary on the process elements described above is offered in the following paragraphs.
COMMENTARY ON RO PROCESS UNIT OPERATIONS
Flocculation and coagulation using inline feed of Ferric chloride and polymer aid for removal of particulate matter,
colloidal material, marine biota, and similar contributors to turbidity Is ordinarily required to maintain longterm trouble4m
operation of RO systems. However, there are some situations where it Is not necessary to use chemical additions of
coagulants and coagulant aids: High purity filtered seawater obtained from carefully constructed vertical or horizontal.
wells is usually free of the marine biota which is a severe foularrt for RO systems. In the event that the seawater source Is
of very high quality (not supplied by an ordinary submerged or floating intake structure)k would be possible to dispense
with chemical feed and use only the media filtration without Iron or polymer feed This would be advantageous because
of the problem of disposal of the filter backwash waste which would contain all of the chemical precipitarm This
backwash waste would have to be decanted and the sludge at the bottom separately disposed of if there was no kx:W
sewer system capable of accepting this waste which would have a volume of about 300 GPD. The final selection of
retreatment filtration will depend on the feedwater system design. If possible, seawater wells vertical or horizontal
(Ranney well) would be best from a process standpoint and possibly would be more advantageous from a cost
standpoirtas well if all factors including permitting,construction and time to commission are considered
H2ORGANIZATION INTERIM REPORT#01 REV 0: PAGES
_ .�ltimedia filtration would be used in all cases no matter what seawater supply was furnished.Typically,these f bm ere -
-assembled with three media, anthracite, sand and garnet, for very sharp filtration. Other variations are available which
have been used including multimedia filters with 5 media, some of them synthetic and some from natural sources.We
.believe that the 3-media filter described above would be adequate to do the job of protecting the RO system
The addition of scale Inhibitor is necessary to avoid fouling by the sparingly soluble materials present in the seawater.
These Include such compounds as CaCO3 (Calcium Carbonate), CaSO4 (Calcium SuUate), Barium salts and similar
materials.The Inhibitor Is usually added so as to produce a 3.5 PPM residual In the brine waste.This organic material
greatly retards the formation of crystals of the compounds described above. Hoer,the Inhibitor
Is then
viro�und n the
the
brine which Is dumped back into the ocean As part of the permitting process protection it
composition of the waste brine must be described and would include this Inhibitor.The most frequently used trtttibit0r of
this type Is probably Pfizer Corp. NFlocon-100•, a proprietary version of polyacryUc acid which Is furnished as a liquid
solution which is metered Into the filtered feedwater stream. The material has all necessary certifications showing its
biodegradability and non-toxic characteristics and has been used safety throughout the world in marry types of
desalination operations.It is the material of choice for this application
Seawater is a very corrosive material over extended periods.A typical material of construction for the high pressure side
of the RO system Is 316 SS which will corrode it steps are not taken to retard attack.A safe appy has p��add
small amounts of Sodium Bisutfite for scavenging Oxygen from the seawater,this retards corrosion of the in stem
An added advantage of this approach, especially with the thin film composite membranes made by Filrmtsc Corp., is the
marked extension of the membrane life when using small amounts of this chemical in the filtered seawater. Agalm-the
brine now will contain the bisulfite added upstream and will have to be identified as one of the components in the waste
brine entering the ocean outfall.The bisuifto concentration would be about 50-60 PPM. If this level of blsulfite Is rejected
by the permitting agencies, we could chlorinate the bisuUde to oxidize it to sulfate Ion which would be more benign.
Bisulfites also ant as a bacterial growth inhibitor and would have some minor effect on the flora and fauna near the ocean
tfall. If necessary, we can dispense with bisulfite feed and live with the longterm problems of corrosion and bacterial
growth.The latter can be controlled by periodic disinfection of the RO system In lieu of continuous feed
Filtration on cartridge filters has always been used to reduce the amount of particulate matter permitted to enter the RO
system The bane of good RO operation has been entrance of particulates of very fine size into the membranes where
they Impede brine flow and product flow as well.Typical particle size removals are In the range of 5.10 microns.Although
5 micron filters are more costly because they have to be replaced more frequently, they are recommended since they
offer greater protection to the heart of the system,the RO membrane elements.
Depending on the temperature of the seawater, the operating pressure of the RO system would be about 8504W PSI.
Typically, the pumps selected for this operation are multiplunger piston pump rated for 1000 PSI at higher service.
Because of the inherently higher efficiency of these pumps, they are preferred over centrifugal pumps which are
dWncdy inferior to the positive displacement pumps. For very large seawater systems, it might be possible to use high
efficiency vertical turbine pumps which can, in certain sizes, reach efficiencies around 8396. Because plunger pumps
require a higher level of maintenance, they could be preferred in very large systems. However,we recommend that only
plunger pumps be used for this smallsize RO system
The high pressure brine from the RO system contains a great deal of energy that is easily recovered by an hydraulic
turbine.There are two basic types of turbines used One is the socalled Pelton wheal which has small buckets our It
arranged in a radial manner on a wheel attached to an output shaft,and the other is the traditional Francis-t)►pe turbine
which looks similar to a centrifugal pump(run backwards). Either type can get up to about 80%recovery of energy from
the brine waste. For example, the 200,000 GPD system selected for this project would produce about 208 GPM of brine
waste at about 850 PSI and a recovery rate of 40%.The power available from this stream Is:
208*(85011714)*.8= 83.5 HP,or about 61.5 kW.
The power consumed by the main high pressure pump which would be pumping about 347 GPM at about 900 PSI Is:
H2ORGANizATi0N INTERIM REPORT#01 REV 0: PAGE 6
347*900/1714/0.9= 202 HP,or about 151 kW.
Thus,the net power consumption can be reduced from 151 kW to 89.5 kW.This equates to a unit energy consumption of
about:
89.5*24/200 = 11 kWh/1001}gallons of product
To this energy consumption must be added the energy for transferring seawater to the RO plant plus the energy for
distribution Into the user's system..
Because of the potential savings of about$36;000/annum (at 80% load),we recommend that this unit operador4 energy
recovery,be incorporated into the final process.
RO product water is low in hardness and dissolved solids.Also, Its pH is relatively low(usually less than 8.0)because Of
the low alkalinity of the water. Without correction of these values, the water Is very corrosive to typical plumbing and
piping materials such as copper, brass,steel and cast iron.Therefore, it is necessary to stabUus the water by addition of
some Calcium and elevating the pH of the product to attain a corrosion index that is acceptable.Typically,this would
mean attaining a Langelier Index of about + 0.5 or higher. Additionally, corrosion can be inhibited by the addition of
small amounts of Zinc in the foam of Zinc Orthophosphate can greatly retard corrosiorL Typically, levels of about 0.5 PPM
of Zn at a pH of about 7.5 to 8.5 are successful in controlling corrosion.
The addition of some Calcium as described above Is most easily accomplished by the pumping the product water
through a Calcite filter which is loaded with fine(20-40 mesh)Calcium Carbonate(calcite or Ca003).This action tends to
stabilize the water by bringing it into equilibrium with the calcite which results In adding about 30 PPM of Calcium
hardness to the finished water.The pH may be slightly too tow even after Calcite flltratlor,,this Is corrected upward by the
addition of a small amounts of soda ash solution which increases the alkalinity and increases the stabUiry of the water
.less corrosive).
The product water is now ready for storage and distribution except for disinfection.This is most easily accomplished by
the addition of small amounts of Sodium Hypochlorite ('Bleach') to the product stream. Typically, about 1.2 PPM of
chlorine are added.This would amount to less than about 1.0 GPD of commercial pool bleach.
During the shutdown phase of plant operation, the concentrated brine In the RO system tends to continue precipitation
of foula=, process that is only inhibited partially but not stopped during operation. On shutdown, these materials wID
start to drop out materials on the membrane surface.To avoid this, especially during longer shutdowns,flushing of the
RO membranes with product water (free of chlorine d thin film composite elements are used) prevents the deposition of
precipitates and actually redissohres material that has already accumulated This flushing operation can be done
automatically and results in the loss of only minor amounts of finished product The procedure is recommended for all
RO systems.
From time to time, the small amounts of foulants accumulate on the RO membane surfaces and impede the flow of water,
increase the pressure drop across the brine path and elevate the permeation of salts into the product water. These
foulants require removal. This is accomplished by the circulating of chemical cleaning solutions through the membrane
system. Typically, materials used for cleaning include , citric acid, ethylenediamine tetra-acetic acid, detergents and
ammonia.The waste products from this cleaning operation must be kept separate from the brine waste and disposed'of
separately because of the potential.effect on the marine environment
The calculation of the amount of membrane required to produce the rated amount of product water depends On the
following factors
FeedwaIer analysis
temperature
Percent recovery of product
Final water quality desired
Final cost of RO subsystem
Cost of power
1-12OacuwizanON wrEaim REPoaT#01 REv 0. Pace 7
i
most important of these factors are the first three while the fourth factor, water quality, Is a negotiable factor .
.depencRng on local arrangements.
A typical computer design printout appears in the following Table 3.1
Table 3.1 RO UNIT PERFORMANCE PROJECTION
PROJECT' DATE:1/15/90
The and has 96 Model 2021 SS elements which are 3 yrs.old.
The Array Is 16 with 6 element tubes
Permeate Flow= 200000.gpd ( 139 gpm) at 40.0%recovery.
Feed Temp. = 120 C (53.6 F) Avg.annual unit Temp. = 120 C(53.6 F)
Feed Press =888.9 psi Brine Press = 879.1 psi
Feed Osmotic Press =346.5 psi Brine Osmotic Press =SM3 psi
The ratio of the concentration in the brine to the saturation level for
CaSO4 is .43 SiO2 is .04
The Stiff-Davis saturation index of the concentrate stream is plus .5
BANK FEED CONCENTRATE AVERAGE TUBE FINAL ELEMENT
TOTAL TUBE TOTAL TUBE ELEMENT DELTA P BETA %RECOVERY
(gpm) (gpm) (gpm) (gpm) (9pd) 0*
1 347. 21.7 208.7 13. 2078.5 9.3 1.053 7.7
RAW PRETREATED
FEED FEED CONCENTRATE PERMEATE
mg/L mg1L mg/L mg/L
Ca 380. 380. 689. .5
Mg 1320. 1320. 2392 1.7
Na 10600. 10600. 19083. 171.4
K 385. 38& 692 &1
NH4 0. 0. 0. 0.
CO3 0. 0. 0. 0.
HCO3 160. 160. 28& 1.0
SO4 2500. 2500. 4533. .4
CI 19280. 19280. 34738 276.6
NO3 0.0 0.0 0.0 0.0
F 0. 0. 0.0 .0
SiO2 2 2• & .1
SUM 34627. 34627. 62419. 459.8
TDS 34547. 34547. 62274. 459.3
CO2 & 3. & &
pH &1 &1 8.4 &9
pHs 8.1 7.8
This projection Is the anticipated performance and Is based on nominal properties of the elements. No allowance was made for fouling or for pressure
'•uses in the manifolds.
his computer printout should not be considered a guarantee of system performance unless accompanied by a statement to that effect
Not shown in the above analysis is the trace additions of chemicals such as Sodium Bis;ulfde or Flown-100 which would
appear in the brine stream A complete projected analysis would have to be made for submission during the.permitting
1-12ORGANIZATION NTFFIIM RfaKxTr#01 REv 0 PAGE 8
P
The system described above is a single stage system that can yield 500 PPM product water, thereby meeting EPA
standards for recommended total solids. Because of minor leaks, membrane degradation and the addition of stabilizing
and anti-corroslon agents, the product water TDS can rise significantly above that value. An option, available B
necessary, is to install a two-stage RO system In which a portion of the first stage product is reprocessed In a low
pressure brackish water RO system.The re-processed water and the first stage product are Uteri blended to produce the
desired end analysis. This approach can meet the lower limit of 500 PPM but the cost in,equipment and operating
expense is significantly higher than a single stage unit. Discussions of water quality and standards are carried out In
Section 3.0.
The Filmtec Corp. has a membrane, the HR8040, an 8' diameter high rejection element which can produce a 220 FPM
product when operating at about 1000 PSI. Since this level is less than half of the recommended State standard,thele
would be no problem in meeting the standard even N some degradation did occur.
Other companies, including Fluid Systems Div. of UOP, Desafination Systems, Ina, Hydranautics and DuPont
Permasep modules) have not been successful in being able to reliably produce membrane that can yield less than 500
PPM product in a single stage at high recovery rates for extended periods of time. Although this scene will change as
time passes, currently, Filmtec is the only reliable supplier of single stage membrane that can make much less than 500
PPM TDS with some margin at 40-45%recovery rates.
2.2 Distillation System Designs
Two basic types of distillation systems are to be considered The fust, vapor compression distillation(VCD),uses avapor
(steam) compressor to compress the water vapor which elevates its temperature and pfor evaporating
_ incoming cooler seawater.Depending on the size of the system, these type units
can
li made either
larger sizes(e or
over
multistage.The multistage design is much more energy efficient but is generally manufactured only lar9
250,000 GPD).Therefore,it is expected that only single effect units will be applicable In the San We Bay application.
The second type of distillation system is the low temperature muittleffect distillation system (LTMED). In this type of
system low pressure steam at a temperature of about 1500E is used to drive the distillation of seawater. Multiple effects,
or evaporating/condensing compartments are used to attain high ratios of water to energy consumed.Typically,these
systems easily yield 8-12 lbs of water per pound of motive steam used in the process. However,the use of such systems
is usually justified only in larger installations well over 150 to 200 thousand GPD of product This Is due to the fact that
they are steam driven and require an auxiliary boiler or other heat source capable of furnishing the 150 9 heat
necessary to drive the system.Such waste heat systems can be used but only in larger systems.The installation of these
units would always need a boiler of some kind to supply the motive steam or waste heat from a Diesel generator or gas
turbine.
Unless it becomes possible to augment the potable water demand to about 250,000 GPD, the low temperature muBi-
effect distillation systems are not particularly attractive economically.These systems typically sell for about$6.00/GPO of
capacity plus additional costs of boilers or heat recovery systems can easily increase the cost to more thani$8.00/GPD of
product Therefore, in the Interests of economy,we are eliminating the LTMED systems from further consideration unless
Me system capacity can be expanded and if a dual power-water system that makes both electricity and water by means
of gas turbine driven generators(or Diesels) coupled with waste heat boilers or heat exchangers and the LTMED system
are to be installed
The VCD units, on the other hand are available in much smaller sizes down to about 10,000 GPD.Again, larger capacity
systems are considerable more cost effective because of the decrease in unit cost with an Increase In size.There are
several types of VCD units available in the market place but we have focussed on the unit using the lowest possUle
temperature which avoids scaling and fouling of the heat exchange surfaces. Typically, these units use about 40.50
kWh/1000 gal. of product and operate with electric power only which drives the vapor compressor. Higher temperaWM
units may use double the specific energy.
H2ORGANizA'noN INTERIM RE PoFrr#01 REV 0: PAGE 9
The typical performance of a vapor compressor unit to produce 54,0.00 GPD of high quality distillate bearing less than 8.
PPM TDS Is shown in Table 221 below.
Table 2.21 Typical Low Temperature VCD SpecNicatlona,200,000 GPD
Energy consumption, kWh/1000 Gal. 43.5*
Connected load, kW 16550
Scale inhibitor, lbs/day 18.5
Percent recovery of seawater 41.6
Feedwater rate,GPM "'
Product water composition,PPM 5 0
Number of effects 1
Time to startup, minutes 75,0
*Note: Energy use does not include seawater transfer to the plant.Typically, this will require about 35
kWh/1000 additional energy to bring water to the system.
Feedwater for the VCD system typically would have to free of fouling material such as grease, all and marine biota.To
prevent the intrusion of such materials, feedwater may be taken from seawalls,vertical or horizontal as described above
under RO plants. No additional treatment would be required unless the water was uncommonly dirty or cordarninaoxi
Thus, no prefift8M special chemical feed for coagulation or corrosion Inhibition would be needed The only chemical
used would be a scale inhibitor such as Flocon-100 or similar.
Periodically, about once to twice/year depending on specific operating conditions at the site, the VCD plant would have
to stopped for chemical cleaning with mild acidic reagents to remove accumulated scale on the heat transfer surfacers.
The volume of waste produced by this maintenance procedure is small.No special cleaning system is needed since the
VCD pumps are used to circulate the cleaning solution.
The product produced by the VCD system is very low In solids and would have to be stabilized in the same manner as
the product from an RO system. Thus, calcite filtration, soda ash addition and Zinc Phosphate addition would be
required as before with the RO product water.
In summary,the VCD total process train v�ould include the following procedures or equipment:
VCD PROCESS STEPS
1. Intake of seawater either from vertical or horizontal seawalls and transfer by pump to the plant intake
point.
2 Assuming there Is no detritus or heavy load of turbidity present In the feedwater, a small amount at.'..
inhibitor is added to retard fouling.
3.The cold seawater flows into the VCD unit where it is distilled at low temperature.Approximately 42%
of the feedwater is converted to product The balance Is discharged back Into the ocean. The p induct
contains about 5 PPM of MS.
4. Occasionally, the VCD plant is stopped and chemically cleaned to remove scale deposits and restore
operating conditions to specification levels.
5. The product water is then filtered in a calcite filter to add small amounts of Calcium Carbonate for
stabilization purposes. Additionally, a small amount of soda ash Is added to elevate the pH, a small
amount of Zinc Orthophosphate is added to retard pipeline or fixture corrosion.
H20RGANIZAI ION INTERIM REPORT#01 REv 0: AGE 10
6. Finally,the post-treated product is chlorinated with a small amount of Sodium Hypochlorlte to disinfect
C. the product for storage and distribution.
This plant is essentially simpler than any of the other plants because of Its lack of special pretreatment equipment
Maintenance procedures for this type of plant are relatively simple and these plants can be fumished (as they usually
are) with full automatic features which greatly limits operator intervention. The distlllate from this plant Is much lower in
TDS than any of the other processes. Consequently, blending with other supplies inline may present a problem because
of the large drop in solids concentration which may cause changes in the piping system;this factor is not of Importance
in the event that the water produced from this project is used solely for the a single dedicated project.
The high temperature VCD units such as those built by Aqua-Chem or MECO have a higher energy consumption.These
units typically have to be descaled on a relatively frequent basis because of their high operating temperature which is in
the region of Gypsum (CaSO4) precipitation. Additionally, their energy consumption is very high when compared to
other processes.Typically, about 90 kWh/1000 gallons of distillate Is required to operate these units. Based on energy
alone,the cost per 1000 gallons would be about$9.00 solely for energy.Therefore,these units are being eliminated from
further consideration unless there is a waste heat source available at the project site which would permit preheating of
the feed by a substantial amount.
2.3 Process Comparisons
There are three processes being considered:
1. Reverse Osmosis(RO)
2.1-ow Temperature Vapor Compression Distillation(VCD)
3. Multi-effect low temperature distillation(LIMED)
'he last process, LTMED, is being eliminated from consideration at this time because of the small size of the plant.An
--excessively small plant drives up the unit capital cost as well as operating costs to point where It becomes greatly
uneconomical to own and operate such a plant.
This leaves the first two processes for comparison.Table 2.31 lists the positive and negative aspects of these two
processes. '
Table 2.31 Procese Comparisons
D RO
Energy use,kWh/1000** 43 11.
Chemical useage low high
Recovery rate,% 41.6 45
Product quality,TDS <5.0 <450
Membrane replacement None 3.4 years
Overall height,feet 19 7
length, • 25 24
Manpower,hours/day 23 3.4
Brine composition Clean Contains chemicals
Fitter backwash waste None 4000 CTPD
Filter disposal sludge None 600 GPD
Chemical cleaning 1-2 time/annum 3-4 times/annum
Process complexity Low High
Startup time 75 minutes 5 minutes
Connected load, kW* 98 60
;ote:* VCD is low temperature design such as Ambient Technology Co.
**No allowance made for raw seawater transfer pump power.
H2ORGANIZATION INTERIM REPORT#01 REV 0: PAGE 11
Abe most obvious differences between these two processes is the low energy consumption of the RO process. If we
- Ssume about$0.08/kwh energy cost,then in one year at 80%capacity,the RO process would save about$150,0006 a
sizeable amount. On the other hand, the VCD process uses no pretreatment system to speak of and does hot produce
any filter backwash waste to dispose of nor does it add any Sodium bisulfite to the brine. Control of particulates using
coagulation with multimedia filters can be tricky even for the most experienced operator, especially during an upset
condition.The VCD system on the other hand is much simpler and requires less general attention and maintenance nor
does it require membrane replacement
Although the VCD plant has many good features, especially Its simplicity and lack of requirement for extensive
pretreatment and planned membrane replacements, its higher capital cost and expensive energy consumption make it
difficult to select as a first choice at this time.
Therefore, we conclude that single stage RO with Filrntec, or equal membranes are very likely the best choice for the
favored process at a San Luis Bay site.
At this point in our evaluation activities, we believe that only single stage RO Is a viable candidate despite the need for
extensive pretreatment (depending partly on the type of intake used for collecting the feed seawater) and membrane
replacement We have heard reports about some of the F.ilmtec plants, large ones, using membranes such as those that
would be used =that are very favorable with respect to longevity of membrane, stability, 0f
performance, ease of cleaning without loss of properties and excellent product water quality well funder 400 PPM.
Therefore, we recommend that the process of choice for the project be single stage reverse osmosis with energy
recovery and pretreatment as described above.
3.0 Water Quality Requirements
The general water quality requirements are spelled out in detail in Title 22 of the California Administrative Code.
)erivattve specifications and rules are issued by the County which essentially adheres to the composition and maximum
contaminant levels(MCL)shown in the Tide 22 rules.
Under these regulations,the final water quality must meet the following basic criteria shown in Table 31 below.
Table 3.1 Potable Water Quality Selected Criteria
Constituent Maximum ContaminarrtLevel
Recommended Uaaer
Chloride ion 250•mg/I 500•
Sulfate ion 250 500.
Copper 1.0
Iron 0.3
Manganese 0.05
Zinc 5.0
Specific Conductance 900 micromho 1600•
Total Dissolved Solids 500. mgll 1000.
Review of the above table shows that there is a range over which the water supply may be acceptable to County officials.
UnderTNe 22,the community water supply is administered by the local health officers.They can accept or deny speciSa
water conditions depending on local circumstances and needs. Generally, we do not expect any problems with this
since most of the water supplies in the area will be far worse in composition than that produced by an San Luis Bay
desalting system
typical composition of the finished product RO water would be as shown In the following Table 3.2
Ii20MANIZAnoN wrEpann REPOFrr#01 REV 0:OM IIIIIIIIIIIPPAaE 12
C Table 3.2 RO PRODUCT QUALITY PROJECTION AFTER POST-TREATMENT
CA .5 mgp
MG 1.7
Na 181.4
K 8.1
NH4 0.
CO3 0.
HCO3 20.0
SO4 .4
Cl 290.6
NO3 0.
F 0.
Si02 2.1
TDS 495.
CO2 2
pH 8.2
Zn inhibitor 0.5
Depending on the final plant design selected, this final water quality could be lower or higher than the typical values
shown above. A key factor would be the type of membrane finally used and the type of process.Typically, a r1h2u amn
process such as VCD will produce a very low TDS product which would have to be chemically treated to make it useable
In the traditional(or existing)piping systems normally used in this country.
The effluent brine from the desalting plant must meet governmental regulations before being discharged into the ocean,
The quality of this waste stream is essentially the same as what was taken in except that it contains a few PPM d
polymeric organic inhibitor and Is concentrated by about 35%above normal seawater.This stream Is not toxic and many
projects In sensitive areas have received approval based on Installation of appropriate waste discharge outfall Qrm
-rhe organic inhibitor (usually Pfizer Corp.'s 'Flocon-100n is an EPA approved material and is biodegradable. No other
wastes would be discharged into the ocean. Cleaning wastes and similar fluids would have to be hauled offsite for
proper disposal.
In summary,the plant can be designed to meet all of the constraints imposed by the rules of T"22 of the Code.
4.0 Site Selection
Selection of the site will be determined predominantly by the existing configuration of the land being developed
SITE SELECTION VARIABLES
1. Easy access to the shoreline
Z Ability to drill productive seawells
3. Ocean floor sloping gradually and relatively free of rocks
4. Simple installation of outfall line
S. Absence of local structures or residents which would impact the design of the plant causing it to be
more costly.
6. Area not part of sensitive zone,e.g.,wetlands,etc.
7. Capable of supporting heavy truck transport for installation and medium truck transport for future
delivery of goods and chemicals to the site.
8. If possible, the outfall site should be naturally protected from heavy storm conditions by harbors,
jetties, natural shape of the land or other condition,especially in the surf zone of the outfall line.
9. Relatively flat so as to permit simple construction.
10 Not exposed to heavy ocean storms.
H20RGANIZATION INTERIM REPORT#01 REv 0: PAGE 13
CThe plant site for a 200,000 GPD capacity system, whether it be an RO or a VCD unit would occupy a it of about
45X60 feet. To this must be added space for storage tankage which is estimated to be about 300,000 gallorm If two
150,000 gallon tanks are used each 16 feet high,they would occupy a space of about 45X90 fest total;these tanks need
not be sited adjacent to the plant since they could be located In any appropriate area However, the farther away they
are from the plant,the more the piping cost.
Permitting for the plant will depend on a number of factors which are not being considered In this interim report
5.0 Plant Capital and Operating Cost Estimates
We have concluded that the best plant for the site would be a single stage Reverse Osmosis plant because of the Iotm
operating costs; therefore, this report will not explore the costs associated with plants that will not be candidates MMMW
Typically,the costs of the plant include elements of cost which are not exact in the conceptual stage of the project.Typicauy,
the cost distribution for the plant would appear as follows:
Estimated Cost Range of Seawater Desalting System
Item No. Description Cost
1.0 Permit acquisition Not included
2.0 Seawater Well Not included
2.1 Outfall,submerged Not included
3.0 Reverse Osmosis System + pretreatment 900.-1,035,000
4.0 Civil works for RO,eta 200.-250,000
5.0 Installation of all equipment 210.-260,000
6.0 Engineering,drawings and startup IMAM=
7.0 Tankage for potable storage(150000.GaL) 195.-2259000
Subtotal $1690.-180,000
8.0 Contingency at 6% 1OL-119,000
Estimated Grand Total $179L-2,099,000
The unit cost per dwelling based on 716 hooses would be S25OLOO to$2932.00.
Table 5.1 below shows the major elements of costs associated with the plant Note that the capital charges taken are the
worst case condition based on the highest cost estimates for all categories.We believe that a very marked reduction In
these charges can be attained but,at this time,we felt that it would be wise to be more pessimistic.
H2ORGANIZAIION INTERIM REPORT#01 REv 0: PAGE 14
1
Table 5.1 Estimated Operating Costs for a 200,000 GPD Seawater RO Facfifty
C (80%Load Factor)
COST ELEMENT AMOUNT
Percent recovery rate 45.00
interest rate, Van. 8.00
Plant life,years 20.00
Replacement cost,$ 820,000.00
Depreciation,$/1000 gal** 1.54
Membrane life,years &0
Escalation factor, Van. 0.00
Chemical cost,$/lb:
Sodium Hypochlorite,125%sol'n 0.10
Ferric Sutfate,50%sol'n 0.15
Flocculant,20%sol'n 0.70
Flocon 100,35%sol'n 1.10
Soda Ash, 99.8% 0.20
Intake pump power,kW 10.00
H/P pump pressure 900.00
Feed flow,GPM 347.00
H/P pump net power, kW 89.50
O&M Costs:
Chemicals,$/1000 Gal. 0.34
Membrane replace.4/1000 gal. 0.35
Cartridge fills.,$/1000 0.02
Power charges/kWh,$ 0.085
Transfer&backwash pumps, kWh/day 240.00
Misc.power, kWh 40.00
H/P pumps, kWh 214&00
Electric power use,kWh/1000 gal. 1210
Power cost,$/1000 gal. 1.03
Labor costs:
No.of workers 025
Supervision personnel 025
Cost/hour,labor 20.00
Supervision,$/hour 40.00
Labor charge,$/1000gal 0.75
Subtotal,deprec.,$/1000 1.54
Subtotal,0&M,$/1000 gal 230
Subtotal,$/1000 gal. 4.03
Subtotal,$/Acre-foot, 1314.00
Note: Costs for insurance,capital investment or waste disposal are not included in this table.
RECAPITULATION OF UNIT COSTS/1000 GAL PRODUCT
WITH DEPRECIATION CHARGES $4.03/1000 GAL($1314./AC.-FT.)
Depending on the method of financing the water system and acquisition of sinking funds for plant refurbishment in the future„
the cost of the final product stream can vary.As is seen in the above table,inclusion of costs for the sinking fund would raise
the price of the water to an average value of$1314/acre-foot which equates to aboutat $27.30/month for each of the 716
assumed dwellings. The costs of capital for these small plants includes all of the elements found in large plants. 7bb
superstructure burdens the small plant with high unit costs.Any action that results in a larger plant that can operate at full load
most of the time will result in a significantly lower cost to the end unser.
The cost elements discussed above show that there is a penalty for constructing a small plant. Practically all the
permitting, engineering, planning and other administrative costs could easily be spent on a plant 5 or 10 times as large
--pith the result of much lower unit capital charges.Thus,if the unit cost of water for the small plant in the expected sewng
roject is perceived as a problem, one method for solving that problem would be to design and build
a much larger plant with the excess capacity being sold to any and all buyers at a rate that the traffic would bear.
H2ORGANIZATION INTERIM REPORT#01 REv 0: PAGE 15
SSA Future Study Scope for Plant Construction
Completion of the project would require additional studies which would Include preliminary engineering work toy
selected site, acquisition of basic permits, preparation of submittal drawings, reports and tables for the
agencies and preparation of final designs and drawings.
The H20anizadon along with its associates is fully le and prepared to p V . '
r9 9 ly�P� P par cant'out the nerd'phase of such 8
Typical study elements that should be addressed in the Phase 2 portion of the project are shown below..• , A
Proposed Study Elements.Phase 2 �� 3
1. Preparation of permit program. Definition of fees. e
2, Prepare proforma specifications for the desalting facility.
* Evaluate Intake and supply options for the plant.
4. Define the exact production capacity of the plant and submit requests for bids to qualified suppliers,
5. Identify best site(s) for the plant and prepare preliminary plot plans showing basic plant layout, tankage,
piping runs,power supply,chemical storage,distribution facilkles,etc.
,•fir ,i
6. Evaluate costs associated with plant design, acquisition and construction. Construct models for pricing.Up
final product including upfront capital by developer, sinking fund arrangements, subsidized costs,joint
with municipalities or other buyers(expanded pians versions),Impact of inflation,power costs,etc.
10,Assess risks associated with project and quantify In monetary terms as.return on Investm o(as`
.- losses.
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H2ORGANIZATION Wnnm REPORT#01 REv 0: PAGE 16 �]TTT y
. i
RGANIZATION oA ' GTE
"20
WATER ANALYSIS
EXISTING COST PER AC. FT. $650.00 $800.00 5800.00 $1,200.00 $1,500.00
TOTAL USAGE IN AC. FT. 5400 5400 5400 5400 5400
TOTAL REVENUE $3,510,000 $4,320,000 $4,320,000 $6,480,000 $8,100,000
PERCENT CONSERVATION 30.00% 30.00% 30.00% 30.00% 30.00%
USAGE WITHOUT CONSERVATION 7,714 7,714 7,714 7,714 7,714
TOTAL WATER SAVINGS 2,314 2,314 2,314 2,314 2,314
DESAL COST PER AC. FT. $1 ,100.00 $2,000.00 $3,000.60 $3,000-00 $3,000-00
SHORTFALL IN AC. FT. 2,314 20314 2,314 2,314 20314
COST TO PROVIDE SHORTFALL $2,545,714 $4,628,571 $6,942,857 $6,942,857 $6,942,857
COST WITHOUT CONSERVATION $5,014,286 $6,171,429 $6,171,429 $9,257,143 $11,571,429
USING DESAL FOR SHORTFALL $6,055,714 $8,948,571 $11,262,857 $13,422,857 $15,042,857
INCREASE USING DESAL FOR SHORTFALL 20.77% 45.00% 82.50% 45.00% 30.00%
NEW AYE. COST PER AC. FT. $785 $1,160 $10460 $10740 51,950
AYE. RES. BILL WITHOUT DESAL $18.42 $22.67 $22.67 $34.00 $42.50
AYE. RES. BILL WITH DESAL $22.24 $32.87 $41.37 -$49.30 $55.25
TOTAL INCREASE $3.82 $10.20 $18.70 $15.30 $12-75
COST PER GAL. BEFOR DESAL $.002 $.002 $.002 $.004 $.005
'OST PER GAL.AFTER DESAL $.002 $.004 $.004 $.005 $.006
--OST PER UNIT BEFOR DESAL $1.49 $1.84 $1.84 $2.75 $3.44
COST PER UNIT AFTER DESAL $1.80 $2.66 $3.35 $3.99 $4.48
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cc. k1 AOCIJ eT SAN I I IIS ORISPO. CA 93401 805.543.762(
Interim Report No. 01 (Rev. 0)
Robert BleviU
H2Organization
664 Marsh St.
San Luis Obispo, CA 93401
0RGANIZATION
MIKE SPANGLER
GENERAL MANAGE R
664 MARSH ST. SAN LUIS OBISPO.CA 93401 80Y5637620
� I \
Table of Contents
1.0 Summary
2.0 Process Review and Discussion
2.1 Reverse Osmosis System Designs
2.2 Distillation System Designs
2.3 Process Comparisons and Recommendations
3.0 Water Quality Requirements
4.0 Site Selection
5.0 Plant Capital and Operating Cost Estimates
6.0 Future Study Scope for Plant Construction
7.0 Appendix
n
J
1.0 Summary
H2Organlzadon has made an initial evaluation of the feasibility of constructing a seawater desalting system to furnish
water for potable and other domestic ==wMR The capacity of the system has been
defined as approximately 179 ac re4eet/year,enough for 716 dwelling units.,Actual plant size would be 224 acre-feet per
year in order to meet plant demand factors.
There are three main processes available for the desalting seawater in commercial quantities available at this time.They
are steam driven distillation, vapor compression driven distillation (electric driver), and reverse.osmosis. Other minor
processes are available and there are several interesting combinations of power and water cycles which may be,of
Interest
At the current time, it appears for the small plant envisioned for the project about 179 acre-feet/year(160,000 GPD),that
a single reverse osmosis (RO) package plant with pretreatment, energy recovery turbine and post-treatment package is
the most attractive system.A strong runnerup,but at a higher capital cost is vapor compression distillation(VCD).
If more water were to be produced, other processes may be more efficient and will be more costly capkaal-wise although
less costly from an operating standpoint.
For the larger plants, the steam driven distillation system is very economical but would be limited to plants over about
250,000 GPD. These types of plants when operated in combined cycles with Diesel engines or gas turbines, both with
heat recovery systems, and both generating electricity, can be very efficient energy-wise but Impose a heavy capital
burden for the initial investor. Much large plants In the.75 to 1.0 million GPD are better candidates for these combined
---ycle processes.
The quality of water produced by the desalting system exceeds the requirements mandated by State laws 011ie 22 of the
California Administrative Code). The upper limit of dissolved solids Is 1000 PPM, wke the preferred lower limit Is 500
PPM. Permits are expected to require furnishing a water bearing less than 1000 PPM but not mandating the 500 PPM
limit.. The design limit for water quality has been set at 750 PPM TDS which permits staying under the maximum
contaminant level of 500 PPM for Chloride Ion specified In the Code.All other constraints for water quality Including those
specified in the Code and limits for corrosivity for standard plumbing systems would be met by the system discussed
herein.
Existing seawater wells have not been tested but appear to be ideal as a source of raw water to feed the desaWng plant.
Use of an existing outfall will facilitate installation and construction of the plant and will be able to meet regulatory
constraints for discharge into the ocean.
Permits for the project would be required from various agencies,but this activity Is not discussed In this Interim report.
The estimated cost of the plant completely engineered and installed ranges from$1,791,000 to$2,099,000 Including the
cost of storage tanks for 2 days storage time. Costs are not included for hooking up to existing municipal wafer mains.
The estimate unit capital cost allocated per dwelling would be$2500.00 to$29.30.00/dwelling unit.
The production cost of water at a 80% plant load factor without allowances for initial capital charges nor insurance but
including allowances for refurbishing the plant (sinking fund) Is estimated to be $4.03/1000 gaL($1314.00/acre400t).
These values equate to about$27.38/month for the average dwelling using 1/4 acre-fool/annum.
Completion of the project would require additional studies which would Include. preliminary engineering work for a
Cilected site, acquisition of basic permits, preparation of submittal drawings, reports and tables for the permitting
__jencies and preparation of final designs and drawings.
Lo Process Review and Discussion
The basic desalting processes to be discussed include the following:
1.0 Reverse osmosis with energy recovery turbine, pretreatment,and post-treatment subsystems.
20 Vapor compression distillation without waste heat supply and with post-treatment system.
21 As above but with waste heat supply in a combined cycle process.
3.0 Multi-effect low temperature distillation without waste heat supply and with post-Veatrnent
System.
3.1 As above but with waste heat supply In a combined cycle process,
The process selection is impacted partially by the design capacity selected for the projecL We have defined the capacity
at approximately 179 acre-feettyear which,for 716 homes will furnish about 160,000 GPD or 220 GPD/household for all
uses Additional surplus capacity may be desireable or be mandated by permitting agencies during the review of this
project to the extent that more than 20% excess capacity may be specified as a condition for permitting.The final plant
capacity selection remains to be negotiated. Therefore, this study may have to be altered to reflect such conditions
which may result in selecting a modified or different process.
In all of the cases discussed below, a standard seawater at a temperature of 120C (53.60F.) and bearing the
composition listed in Table 2.1 has been selected for comparison and calcurlation purposes. '
Table 2.1 Reference Seawater Analysis
Cations Anions
(nom) (nom)
Ca 380. H003 160.
Mg 1320. SO4 2500.
Na 10,600. Cl 19,280.
K 385. SiO2 2.0
NH4 0.. NO3 0.0
Turbidity: <5.0 NTU
An additional constraint on the processes selected is the final product water quality. If the pemlitting agency desires, It
could mandate a 500 PPM TDS limit in accordance with the recommended levels shown In Title 22 of the California
Administrative Code. The upper mineralization level, 1000 PPM, Is the upper limit permitted by the law if no other source
is available. Since it is possible to make Soo PPM water with both RO and/or distillation, the Permitting agency could
request the lower limit. However, these limits are negotiable and should be determined as early as possible since these
limits affect the designs of RO systems especially. The upper limit is relatively easy to attain for most membrane
suppliers,while the lower limit can be attained in a single stage high recovery rate RO system by only one supplier at this
time(FilmTec Corp.).
2.1 Reverse Osmosis System Designs
The reverse osmosis system is a relatively energy efficient producer of potable water providing the raw seawater
supplied to it is reasonably free of objectionable materials or contaminants such as excess turbidity, oil, grease, biota, or
egressive chemicals entering from chemical processing systems waste discharges.
—.,r order to ensure trouble-free operation, it is good practice to coagulate and filter raw seawater before admission to the
RO membrane system. Additionally, the typical RO system system at the design temperature of 120C would operate at
about 900 PSI;the waste brine from the RO system ranges from 55-65%of the feedwater and has a pressure of about 15
PSI less, or about 885 PSI.This brine stream contains a great deal of energy which can be recovered easily by the use of
`-oaaterturbine whose shaft is coupled to the RO system high pressure pump crankshaft.
The product water from an RO unit is typically low in solids and very low In hardness.Its pH Is relatively low which leads
to the aggressive nature of this type of water. In order to avoid excess corrosion In typical piping systems, it is good
practice to stabilize the RO product water by elevating its pH slightly and adding small amounts of Calcium Carbonate
and Zinc Phosphate to retard corrosion in both copper and steel piping.
The final process elements for this system would be
1. Flocculation and coagulation with Ferric Chloride and organic polymer(ooagulm aid).
2. Filtration on multimedia filters loaded with anthracite,sand and gamet media
3. Scale inhibition with polyacrylic acid polymer(such as Flocon-100,Pfizer Corp.)
4. Oxygen scavenging and corrosion inhibition of RO system piping with sodium bisulfite.
5. Fine filtration on cartridge filters to remove 5-10 micron particles and larger.
6. Pumping to 900 PSI and separation in the RO subsystem Into two streams, a product water stream and a
waste brine stream
7. Discharge of the brine through an energy recovery hydraulic turbine to recover approximately 80% of
available energy in the brine stream
^\' 8. Post-treatment of the product water by filtration on calcite, elevation of pH with soda ash solution (NaCOS),
and finally addition of Zinc phosphate corrosion inhibitor for domestic piping systems.
9. Disinfection with sodium hypochlorite to maintain a Chlorine residual In the distribution and storage
subsystem.
10. Flushing of the RO membrane system with product water during shutdown periods to retard fouling by
precipitation of sparingly soluble substances present in the concentrated seawater.
11. Intermittent cleaning of the RO membranes as required to maintain specifications for product quality and
system operation.
Additional commentary on the process elements described above is offered in the following paragraphs.
COMMENTARY ON RO PROCESS UNIT OPERATIONS
Flocculation and coagulation using inline feed of Ferric chloride and polymer aid for removal of particulate matter,
colloidal material, marine biota, and similar contributors to turbidity is ordinarily required to maintain longterm trouble-free
operation of RO systems. However, there are some situations where it is not necessary to use chemical additions of
coagulants and coagulant aids: High purity filtered seawater obtained from carefully constructed vertical or horizontal.
wells is usually free of the marine biota which is a severe foulant for RO systems. In the event that the seawater source is
of very high quality (not supplied by an ordinary submerged or floating Intake structure)it would be possible to dispense
with chemical feed and use only the media filtration without Iron or polymer feed This would be advantageous because
of the problem of disposal of the filter backwash waste which would contain all of the chemical precipitants This
i 'ckwash waste would have to be decanted and the sludge at the bottom separately disposed of If there was no local
`�jwer system capable of accepting this waste which would have a volume of about 300 GPD. The final selection of
pretreatment filtration will depend on the feedwater system design. If possible, seawater wells vertical or horizontal
(Raney well) would be best from a process standpoint and possibly would be more advantageous from a cost
standpoint as well 6 all factors including permitting, construction and time to commission are considered.
H2ORGANLZATION iNTERiM REPORT#01 REvO:P PAGES
Multimedia filtration would be used in all cases no matter what seawater supply was furnished.Typically,these filters are
assembled with three meanthracite, sand and gamet, for very sharp filtration. Other variations are available which
dia,
have been used including multimedia filters with 5 media, some of them synthetic and some from sierra*sources.We
believe that the 3-media filter described above would be adequate to do the job of protecting the RO system.
The addition of scale inhibitor is necessary to avoid fouling by the sparingly soluble ma'teriais present In the seawater.
These include such compounds as CaCO3 (Calcium Carbonate), CaSO4 (Calcium Sulfate), Barium salts and similar
materials.The inhibitor is usually added so as to produce a 3-5 PPM residual In the brine waste. This organic material
greatly retards the formation of crystals of the compounds described above. However,the inhibitor is then found in the
brine which is dumped back into the ocean. As part of the permitting process and protection of our environment, the
composition of the waste brine must be described and would include this inhibitor.The most frequently used Inl*Aor of
this type Is probably Pfizer Corp. 'Flocon-100•, a proprietary version of polyacryk acid which is furnished as a liquid
solution which Is metered into the filtered feedwater stream. The material has all necessary CerWIC8111ons showing its
biodegradability and non-toxic characteristics and has been used safely throughout the world In many types of
desalination operations.It is the material of choice for this application.
Seawater is a very corrosive material over extended periods.A typical material of construction for the high pressure side
of the RO system is 316 SS which will corrode if steps are not taken to retard attack.A safe approach has been to add
small amounts of Sodium Bisutfite for scavenging Oxygen from the seawater,this retards corrosion of the piping system
An added advantage of this approach, especially with the thin film composite membranes made by FWTdw Corp, is the
marked extension of the membrane life when using small amounts of this chemical in the filtered seawater. Agaln,•the
brine now will contain the bisutfite added upstream and will have to be identified as one of the components in the waste
brine entering the ocean outfall The b1suifite concentration would be about 50-0 PPM. If this level of btsulfite iS rejected
,.the permitting agencies, we could chlorinate the bisulfle to oxidize fl to sulfate ion which would be more benign.
utfites also act as abacterial growth inhibitor and would have some minor effect on the flora and fauna near the ocean
outfall. if necessary,we can dispense with bisuffte feed and Uve with the longterm problems of corrasion and bacterial
growth.The latter can be controlled by periodic disinfection of the RO system in lieu of Continuous feed
Filtration on cartridge filters has always been used to reduce the amount of partIculate matter permitted to enter the RO
system.The bane of good RO operation has been entrance of particulates of very fine size into the membranes where
they impede brine flow and product flow as well Typical particle size removals are In the range of 5-10 microns.Although
5 micron filters are more costly because they have to be replaced more frequently,they are recommended since they
offer greater protection to the heart of the system,the RO membrane elements.
Depending on the temperature of the seawater, the operating pressure of the RO system would be about 850-900 PSL
Typically, the pumps selected for this operation are muldplunger piston pump rated for 1000 PSI or higher service.
Because of the inherently higher efficiency of these pumps, they are preferred over centrifugal pumps which are
distinctly inferior to the positive displacement pumps. For very large seawater systems, it might be possible to use high
efficiency vertical turbine pumps which can, in certain sizes, reach.efficiencies around 83%. Because plunger pumps
require a higher level of maintenance, they could be preferred in very large systems. However,we recommend that only
plunger pumps be used for thissmalisize RO system.
The high pressure brine from the RO system contains a great deal of energy that is easily recovered by an hydraulic
turbine. There are two basic types of turbines used. One Is the socalled Pelton wheel which has small buckets on it
arranged in a radial manner on a wheel attached to an output shaft, and the other Is the traditional Francis-type turbine
which looks similar to a centrifugal pump (run backwards). Either type can get up to about 80%recovery of energy from
the brine waste. For example, the 200,000 GPD system selected for this project would produce about 208 GPM of brine
waste at about 850 PSI and a recovery rate of 40%.The power available from this stream is:
' 208*(850/1714)*.8 = 83.5 HP,or about 61.5 W.
The power consumed by the main high pressure pump which would be pumping about 347 GPM at about 900 PSI is:
H2ORGANIZanON iNTERim REPORT#01 REV 0: PAGE 6
347 900/1714/0.9 =202 HP,or about 151 kW.
Thus,the net power consumption can be reduced from 151 kW to 89.5 kW.This equates to a unit energy consumption of
about:
89.5.24/200 = 11 kWh/1000 gallons of product.
To this energy consumption must be added the energy for transferring seawater to the RO plant plus the energy for
distribution into the user's system.
Because of the potential savings of about$36,000/annum (at 80% load),we recommend that this unit operation, energy
recovery, be incorporated into the final process.
RO product water is low in hardness and dissolved solids.Also, Its pH Is relatively low(usually less)ttian 6.0) because of
the low alkalinity of the water. Without correction of these values, the water Is very corrosive to typical plumbing and
piping materials such as copper,brass,steel and cast Iron.Therefore, it Is necessary to stabilize the water by addition of
some Calcium and elevating the pH of the product to attain a corrosion Index that Is acceptable. Typically, this would
mean attaining a Langelier Index of about + 0.5 or higher. Additionally, corrosion can be Inhibited by the addition of
small amounts of Zinc in the form of Zinc Orthophosphate can greatly retard corrosion.Typically,levels of about 0.5 PPM
of Zn at a pH of about 7.5 to 8.5 are successful in controlling corrosion.
The addition of some Calcium as described above is most easily accomplished by the pumping the product water
through a Calcite finer which Is loaded with fine(20.40 mesh)Calcium Carbonate(calcite or CaCO3).This action tends to
stabilize the water by bringing it into equilibrium with the cal which results In adding about 30 PPM of Calcium
hardness to the finished water.The pH may be slightly too low even after Calcite filtration;this Is corrected upward by the
_dMon of a small amounts of soda ash solution which Increases the all a Inity and increases the stability of the water
�-As corrosive).
The product water is now ready for storage and distribution except for disinfection.This Is most easily accomplished by
the addition of small amounts of Sodium Hypochlorite ('Bleach to the product stream. Typically, about 1.2 PPM of
chlorine are added This would amount to less than about 1.0 GPD of commercial pool bleach.
During the shutdown phase of plant operation,the concentrated brine in the RO system tends to continue precipitation
of foulants, process that is only Inhibited partially but not stopped during operation. On shutdown, these materials will
start to drop out materials on the membrane surface.To avoid this, especially during longer shutdowns, flushing of the
RO membranes with product water (free of chlorine If thin film composite elements are used) prevents the deposition of
precipitates and actually redissolves material that has already accumulated. This flushing operation can be done
automatically and results in the loss of only minor amounts of finished product The procedure is recommended for all
RO systems.
From time to time, the small amounts of foulants accumulate on the RO membane surfaces and Impede the flow of water,
increase the pressure drop across the brine path and elevate the permeation of salts into the product water. These
foulants require removal. This is accomplished by the circulating of chemical cleaning solutions through the membrane
system. Typically, materials used for cleaning include , citric acid, ethylenediamine tetra-acetic acid, detergents and
ammonia.The waste products from this cleaning operation must be kept separate from the brine waste and disposed of
separately because of the potential effect on the marine environment.
The calculation of the amount of membrane required to produce the rated amount of product water depends on the
following factors:
Feedwater analysis
temperature
Percent recovery of product
Final water quality desired
Final cost of RO subsystem
Cost of power
H20RGANLZATION INTERiM REPORT#01 REv 0: PAGE 7
The most important of these factors are the fust three while the fourth factor, water quality, is a negotiable factor
depending on local arrangements.
A typical computer design printout appears in the following Table 31
Table 3.1 RO UNIT PERFORMANCE PROJECTION
PROJECT: DATE: 1/15/90
The unit has 96 Model 2021 SS elements which are 3 yrs.old.
The Array is 16 with 6 element tubes
Permeate Flow= 200000.gpd ( 139 gpm)at 40.0%recovery.
Feed Temp. = 12.0 C(53.6 F) Avg.annual unit Temp. = 120 C(53.6 F)
Feed Press = 888.9 psi Brine Press =879.1 psi
Feed Osmotic Press =346.5 psi Brine Osmotic Press =5733 psi
The ratio of the concentration in the brine to the saturation level for
CaSO4 is .43 Si02 is .04
The Stiff-Davis saturation index of the concentrate stream is plus .5
BANK FEED CONCENTRATE AVERAGE TUBE FINAL ELEMENT
TOTAL TUBE TOTAL TUBE ELEMENT DELTA P BETA %RECOVERY
Win) (gpm) (gpm) (gpm) (gpd)
347. 21.7 208.7 13. 2078.5 9.3 1.053 7.7
RAW PRETREATED
FEED FEED CONCENTRATE PERMEATE
mg/L mg/L mg/L mg/L
Ca 380. 380• 689• .5
Mg 1320. 1320. 2392 1.7
Na 10600. 10600. 19083. 171.4
K 385. 385. 692• 8.1
NH4 0. 0. 0. 0.
CO3 0. 0. 0. 0.
HCO3 160. 160• 289• 1.0
SO4 2500. 2500. 4533. .4
Cl 19280. 19280. 34738 276.6
NO3 0.0 0.0 0.0 0.0
F 0. 0. 0.0 .0
Si02 2. 2 3 .1
SUM 34627. 34627. 62419. 459.8
TDS 34547. 34547. 62274. 459.3
CO2 3. 3. 3 3
pH 8.1 8.1 8.4 5.9
pHs 8.1 7.8
r is projection is the anticipated performance and is based on nominal properties of the elements. No allowance was made for fouling or for pressure
�cosses in the manifolds.
This computer printout should not be considered a guarantee of system performance unless accompanied by a statemerd to that effect.
Not shown in the above analysis is the trace additions of chemicals such as Sodium Bisulfta or Flocon-100 which would
appear in the brine stream. A complete projected analysis would have to be made for submission during the permitting
..17norAM17A7nkl tkrr=0ikA0 •Dncr dint Ca,n• pant= R
process.
The system described above is a single stage system that can yield 500 FFM product water, thereby meeting EPA
standards for recommended total solids. Because of minor leaks, membrane degradation and the addition of stabilizing
and and-corrosion agents, the product water MS can rise significantly above that value. An option. available If
a portion of the first stage product Is reprocessed In a low
necessary, is to install a two-stage RO system In which
pressure brackish water RO system.The re-processed water and the first stage product are then blended to produce the
desired end analysis. This approach can meet the lower limit of 500 PPM but the cost in.equipment and operating
expense is significantly higher than a single stage unit. Discussions of water quality and standards are carried out In
Section 3.0.
The Filmtec Corp. has a membrane, the HR8040, an W diameter high rejection element which can produce a 220 PPM
product when operating at about 1000 PSI. Since this level Is less than half of the recommended State standard.there
would be no problem in meeting the standard even if some degradation did occur. '
Other companies, including Fluid Systems Div. of UOP, Desalination Systems, Inc., Hydranautics and DuPont
Permasep modules) have not been successful in being able to reliably produce membrane that can yield less than 500
PPM product in a single stage at high recovery rates for extended periods of time. Although this scene will change as
time passes, currently, Filmtec is the only reliable supplier of single stage membrane that can make much less than 500
PPM TDS with some margin at 40-45%recovery rates.
2.2 Distillation System Designs
Two basic types of distillation systems are to be considered The first.vapor compression distillation(VCD),uses a vapor
_ (steam) compressor to compress the water vapor which elevates its temperature and supplies heat for evaporating
,morning cooler seawater.Depending on the size of the system, these type of units can be made either single or
multistage.The multistage design is much more energy efficient but is generally manufactured only ln larger sizes(over
250,000 GPD).Therefore,it is expected that only single effect units will be applicable In the San Luis Bay application.
The second type of distillation system is the low temperature mululeffect distillation system (LTMED). In this type of
system low pressure steam at a temperature of about 1500F Is used to drive the dcstiiation of seawater. Multiple effects,
or evaporating/condensing compartments are used to attain high ratios of water to energy consumed.Typlc�ally, these
systems easily yield 8-12 lbs of water per pound of motive steam used In the process. However,the use of such systems
is usually justified only in larger installations well over 150 to 200 thousand GPD of product This Is due to the fact that
they are steam driven and require an auxiliary boiler or other heat source capable of furnishing the 150 R heat
necessary to drive the system.Such waste heat systems can be used but only in larger systems.The installation of these
units would always need a boiler of some kind to supply the motive steam or waste heat from a Diesel generator or gas
turbine.
Unless it becomes possible to augment the potable water demand to about 250,000 GPD, the low temperature mu ltl-
effect distillation systems are not particularly attractive economically.These systems typically sell for about$8.00/GPD of
capacity plus additional costs of boilers or heat recovery systems can easily Increase the cost to more than$8.001GPD of
product Therefore, in the interests of economy,we are eliminating the LTMED systems from further consideration unless
the system capacity can be expanded and N a dual power-water system that makes both electricity and water by means
of gas turbine driven generators(or Diesels) coupled with waste heat boilers or heat exchangers and the LIMED system
are to be installed.
The VCD units, on the other hand are available in much smaller sizes down to about 10,000 GPD.Again, larger capacity
systems are considerable more cost effective because of the decrease in unit cost with an increase In size. There are
,several types of VCD units available in the market place but we have focussed on the unit using the lowest passible
temperature which avoids scaling and fouling of the heat exchange surfaces. Typically, these units use about 4050
kWh/1000 gal. of product and operate with electric power only which drives the vapor compressor. Higher temperature
units may use double the specific energy.
H2ORGANIZATI0N INTERIM REPORT#01 REV 0: PAGE 9
The typical performance of a vapor compressor unit to produce 54,000 GPD of high quality distillate bearing less than 5.
PPM TDS is shown in Table 221 below.
Table 2.21 Typical Low Temperature VCD Specifications,200,000 GPD
Energy consumption, kWh/1000 Gat. 43.5*
Connected load,kW % 0
Scale inhibitor, lbs/day 18.5
Percent recovery of seawater 41.6
Feadwaterrate,GPM
Product water composition,PPM 5.0
Number of effects 1
Time to startup, minutes 75.0
*Note: Energy use does not include seawater transfer to the plant.Typically, this will require about 3.5
WWI 000 additional energy to bring water to the system.
Feedwater for the VCD system typically would have to free of fouling material such as grease, oil and marine blots.To
prevent the intrusion of such materials, feedwater may be taken from seawalls,vertical or horizontal as described above
under RO plants. No additional treatment would be required unless the water was uncommonly dirty or contaminated.
Thus, no prefilters, special chemical feed for coagulation or corrosion inhibition would be needed The only chemical
used would be a scale inhibitor such as Flocon-100 or similar.
Periodically,about once to twice/year depending on specific operating conditions at the site, the VCD plant would have
"•o stopped for chemical cleaning with mild acidic reagents to remove accumulated sole on the heat transfer surfaces.
i`he volume of waste produced by this maintenance procedure is smaiL No special cleaning system is needed since the
VCD pumps are used to circulate the cleaning solution.
The product produced by the VCO system is very low in solids and would have to be stabilized In the same manner as
the product from an RO system Thus, calcite filtration, soda ash addition and Zinc Phosphate addition would be
required as before with the RO product water.
In summary,the VCD total process train would include the following procedures or equipment:
VCD PROCESS STEPS
1. Intake of seawater either from vertical or horizontal seawalls and transfer by pump to the plant intake
point
2 Assuming there is no detritus or heavy load of turbidity present In the feedwater, a small amount of
inhibitor is added to retard fouling.
3.The cold seawater flows into the VCD unit where it is distilled at low temperature. Approximately 42%
of the feedwater is converted to product. The balance is discharged back into the ocean. The product
contains about 5 PPM of TDS.
4. Occasionally, the VCD plant is stopped and chemically cleaned to remove scale deposits and restore
operating conditions to specification levels.
5. The product water is then tittered in a calcite filter to add small amounts of Calcium Carbonate for
stabilization purposes. Additionally, a small amount of soda ash is added to elevate the pH, a small
amount of Zinc Orthophosphate is added to retard pipeline or fixture corrosion.
H20RGANIZAT10N INTERIM REPORT#01 REV 0:. enc n
6.Finally,the post-treated product Is chlorinated with a small amount of Sodium Hypochlorite to disinfect
the product for storage and distribution.
This plant is essentially simpler than any of the other plants because of Its lack of special pretreatment equipment
Maintenance procedures for this type of plant are relatively simple and these plants can be furnished (as they usually
are)with full automatic features which greatly limits operator Intervention. The distillate from this plant Is much lower In
TDS than any of the other processes. Consequently, blending with other supplies Wine may present a problem because
of the large drop in solids concentration which may cause changes In the piping system;this factor is not of importance
in the event that the water produced from this project is used solely for the a single dedicated project.
The high temperature VCD units such as those built by Aqua-Chem or MECO have a higher energy consumption.These
units typically have to be descaled on a relatively frequent basis because of their high operating temperature which Is in
the region of Gypsum (CaSO4).precipitation. Additionally, their energy consumption Is very high when compared to
other processes. Typically, about 90 kWh/1000 gallons of distillate is required to operate these units. Based on energy
alone,the cost per 1000 gallons would be about$9.00 solely for energy.Therefore,these units are being eliminated from
further consideration unless there is a waste heat source available at the project site which would permit preheating of
the feed by a substantial amount
2.3 Process Comparisons
There are three processes being considered:
1.Reverse Osmosis(RO)
21-ow Temperature Vapor Compression Distillation(VCD)
3. Muld-effect low temperature distillation(LTMED)
The last process, LTMED, is being eliminated from consideration at this time because of the small size of the plant M
excessively small plant drives up the unit capital cost as well as operating costs to point where It becomes greatly
uneconomical to own and operate such a plant
This leaves the first two processes forcomparison.Table 2.31 lists the positive and negative aspects of these two
processes.
Table 2.31 Process Comparisons
D R
Energy use, kWh/1000** 43
Chemical useage low high
Recovery rate,% 41.6 45
Product quality,TDS <5.0 <450
Membrane replacement None 3-4 years
Overall height,feet 19 7
length, ' 25 24
Manpower,hours/day 2-3 3-4
Brine composition Clean Contains chemicals
Filter backwash waste None 4000 GPD
Fitter disposal sludge None 600 GPD
Chemical cleaning 1-2 time/annum 3-4 times/annum
�Process complexity Low High
ta
l rtup time 75 minutes 5 minutes
-connected load, kW* 98 60
Note:* VCD is low temperature design such as Ambient Technology Co.
**No allowance made for raw seawater transfer pump power.
W'DnDn AWIIvA +nr.i urrcOI&A Droner$n1 Oce n•
C
The most obvious differences between these two processes Is the low energy consumption of the RO process. If we
assume about$0.08/kWh energy cost,then in one year at 80%capacity,the RO process would save about$150,000,a
sizeable amours. On the other hand, the VCD process uses no pretreatment system to speak of and does not produce
any filter backwash waste to dispose of nor does it add any Sodium bisuifite to the brine. Control of particulates using
coagulation with multimedia fitters can be tricky even for the most experienced operator, espgc6* during an upset
condition.The VCD system on the other hand is much simpler and requires less general attention and maintenance nor
does it require membrane replacement
Although the VCD plant has many good features, especially its simplicity and lack of requirement for extensive
pretreatment and planned membrane replacements, its higher capital cost and expensive energy consumption make It
difficult to select as a first choice at this time.
Therefore, we conclude that single stage RO with Flmtec, or equal membranes are very likely the best choice for 1118
favored process at a San Luis Bay site.
At this point in our evaluation activities, we believe that only single stage RO Is a.viable candidate despite the need for
extensive pretreatment (depending partly on the type of Intake used for collecting the feed seawater) and membrane
replacement.We have heard reports about some of the Fimtec plants, large ones, using membranes such as those that
would be used that are very favorable with respect to longevity of membrane, stability d
performance, ease of cleaning without loss of properties and excellent product water quality well under 400 PPM.
Therefore, we recommend that the process of choice for the project be single stage reverse osmosis with energy
recovery and pretreatment as described above.
3.0 Water Ouallty Requirements
\-The general water quality requirements are spelled out In detall In Title 22 of the California AdrNnistrative Coda
Derivative specifications and rules are issued by the County which essentially adheres to the composition and maximum
contaminant levels(MCL)shown In the Title 22 rules.
Under these regulations,the final water quality must meet the following basic criteria shown in Table 3.1 below.
Table 3.1 Potable Water Quality Selected Criteria
Constituent Maxdmum Contaminant Level
Recommended Under
Chloride ion 25 •mgr sm
Sulfate ion 250 500.
Copper 1.0
Iron 0.3
Manganese 0•0s
Zinc 5.0
Specific Conductance 900 micromho 1600•
Total Dissolved Solids 500.mgli 1000.
Review of the above table shows that there is a range over which the water supply may be acceptable to County officials.
Under Title 22,the community water supply is administered by the local health officers.They can accept or derry specific
water conditions depending on local circumstances and needs. Generally, we do not expect any problems with this
-once most of the water supplies in the area will be far worse in composition than that produced by an San Luis Bay
_salting system.
Atypical composition of the finished product RO water would be as shown in the following Table 3.2.
Table 3.2 RO PRODUCT QUALITY PROJECTION AFTER POST-TREATMENT
CA .5 mg1l
MG 1.7
Na 181.4
K 8..1
NH4 0.
CO3 0.
HCO3 20.0
SO4 .4
CI 290.6
NO3 0.
F 0.
S102 2.1
TDS 495.
CO2 2.
pH 8.2
Zn inhibitor 0.5
Depending on the final plant design selected, this final water quality could be lower or higher than the typical values
shown above. A key factor would be the type of membrane finally used and the type of process.Typically,a distillation
process such as VCD will produce a very low TDS product which would have to be chemically treated to make k useable
In the traditional(or existing) piping systems normally used In this country. 1.
The effluent brine from the desalting plant must meet governmental regulations before being disduatged into time ocean.
The quality of this waste stream is essentially the same as what was taken In aimpt that It contains a few PPM of
polymeric organic inhibitor and Is concentrated by about 35%above normal seawater.This stream Is not toxic and marry
rojects In sensitive areas have received approval be on Installation of appropriate waste discharge outfall Ones.
The organic inhibitor (usually Pfizer Corp.'s Flocon-19M is an EPA approved material and is biodegradable. No other
wastes would be discharged into the ocean. Cleaning wastes and similar fluids would have to be hauled oflsits for
proper disposal.
In summary,the plant can be designed to meet all of the constraints imposed by the rules of Title 22 of the Code.
4.0 Site Selection
Selection of the site will be determined predominantly by the existing configuration of the land being developed
SITE SELECTION VARIABLES
1. Easy access to the shoreline
2. Ability to drill productive seawells
3. Ocean floor sloping gradually and relatively free of rocks
4. Simple installation of outfall line
5. Absence of local structures or residents which would impact the design of the plant causing It to be
more costly.
6. Area not part of sensitive zone,a g.,wetlands,etc.
7. Capable of supporting heavy truck transport for Installation and medium truck transport for future
delivery of goods and chemicals to the site.
8. If possible, the outfall site should be naturally protected from heavy storm conditions by harbors,
jetties, natural shape of the land or other condition,especially in the surf zone of the outfall line.
9. Relatively flat so as to permit simple construction.
10 Not exposed to heavy ocean storms.
H2ORGANIZATION INTERIM REPoFrr#01 REv 0: PAGE 13
The plant site for a 200,000 GPD capacity system, whether It be an RO or a VCD unit would occupy a space of about
45M feet To this must be added space for storage tankage which is estimated to be about 300,000 gallons. U two
150,000 gallon tanks are used each 16 feet high,they would occupy a space of about 45X90 feet total;time tanks need
not be sited adjacent to the plant since they could be located in any appropriate area However, the farther away Utes
are from the plant,the more the piping cost.
Permitting for the plant will depend on a number of factors which are not being considered In this interim report
5.0 Plant Capital and Operating Cost Estimates
We have concluded that the best plant for the site would be a single stage Reverse Osmosis plant because of the lower,
operating costs; therefore, this report will not explore the costs associated with plants that will not be candidates UMONMIW
Typically,the costs of the plant include elements of cost which are not exact in the.conceptual stage of the project.Typically,
the cost distribution for the plant would appear as follows:
Estimated Cost Range of Seawater Desalting System
Item No. Description Cost
1.0 Permit acquisition Not included
2.0 Seawater well Not included
2.1 Outfall,submerged Not included
3.0 Reverse Osmosis System+pretreatment 900.-1,035,000
4.0 Civil works for RO,etc 200.-250A00
5.0 Installation of all equipment 210.-260,000
6.0 Engineering,drawings and startup 185.210AW
7.0 Tankage for potable storage(150000.GaL) 195.-225A00
Subtotal 51690.4,980,000
8.0 Contingency at Wo 1OL-119AM
Estimated Grand Total $179L-2,099,000
The unit cost per dwelling based on 716 houses would be 5250L00 to 52932.00.
Table 5.1 below shows the major elements of costs associated with the plant Note that the capital charges taken are the
worst case condition based on the highest cost estimates for all categories. We believe that a very marked reduction In
these charges can be attained but, at this time,we felt that it would be wise to be more pessimistic.
M
Table 5.1 Estimated Operating Costs for a 200,000 GPD Seawater RO Facility
(80%Load Factor)
COST ELEMENT AMOUNT
Percent recovery rate 45.00
Interest rate,%/an. 8.00
Plant fife,years 20.00
Replacement cost,$ 820,000.00
Depreciation,$/1000 gal" 1.54
Membrane lite,years 3.0
Escalation factor, Van. 0.00
Chemical cost,$/Ib:
Sodium Hypochlorite,125%sol'n 0.10
Ferric Sulfate,50%sol'n 0..15
Flocculant,20%sol'n 0.70
Flocon 100,35%sol'n 1.10
Soda Ash,99.8% 020
Intake pump power,kW 10.00
H/P pump pressure 900.00
Feed flow,GPM 347.00
H/P pump net power, kW 89.50
O&M Costs:
Chemicals,$/1000 Gal. 0.34
Membrane replace.,$/1000 gal. 0.35
Cartridge flits.,$/1000 0.02
Power charges/kWh,$ 0.085
Transfer&backwash pumps, kWh/day 240.00
Misc.power, kWh 40.00
C- H/P pumps,kWh 2148.00
Electric power use,kWh/1000 gal. 12.10
Power cost,$/1000 gal. 1.03
Labor costs:
No.of workers 025
Supervision personnel 025
Cost/hour,labor 20.00
Supervision,$/hour 40.00
Labor charge,$/1000gal 0.75
Subtotal,deprec.,$/1000 1.54
Subtota1,0&M,$/1000 gal 230
Subtotal,$/1000 gal. 4.03
Subtotal,$/Acre-foot, 1314.00
Note:Costs for insurance,capital investment or waste disposal are not Included in this table.
RECAPITULATION OF UNIT COSTS/1000 GAL PRODUCT
WITH DEPRECIATION CHARGES $4.03/1000 GAL($1314./AC.-FT.)
Depending on the method of financing the water system and acquisition of sinking funds for plant refurbishment in the future,
the cost of the final product stream can vary.As is seen in the above table,inclusion of costs for the sinking fiord would raise
the price of the water to an average value of $1314/ acre-foot which equates to abouat S2730/mouth for each o1 the 716
assumed dwellings. The costs of capital for these small plants includes all of the elements found in large plants. Mils
superstructure burdens the small plant with high unit costs.Any action that results in a larger plant that can operate at full load
most of the time wW result in a significantly lower cost to the end user.
The cost elements discussed above show that there is a penalty for constructing a small plant Practically all the
�andting, engineering, planning and other administrative costs could easily be spent on a plant 5 or 10 times as large
,rRh the result of much lower unit capital charges.Thus, ff the unit cost of water for the small plant in the expected setting
at roject is perceived as a problem, one method for solving that problern would be to design and build
a much larger plant with the excess capacity being sold to any and all buyers at a rate that the traffic would bear.
H2ORGANLZATION INTERIM REPORT#01 REV 0: PAGE 15
6.0 Future Study Scope for Plant Construction
Completion of the project would require additional studies which would Include preliminary engineering work•fot.
selected site, acquisition of basic permits, preparation of submittal drawings, reports and tables for the
agencies and preparation of final designs and drawings.
The H2Organfradon along with its associates is fully capable and prepared to carry out the'next.phase of such a
Typical study elements that should be addressed in the Phase 2 portion of the project are shown below. `
Proposed Study Elements.Phase 2 i
1. Preparation of permit ram. Definition of fees. t `;
P� Pe Pro9
2 Prepare proforma specifications for the desalting facility. #
3. Evaluate intake and supply options for the plant "
4. Define the exact production capacity of the plant and submit requests for bids to qualified suppliers. "
S. Identify best site(s) for the plant and prepare preliminary plot plans showing basic plant layout. tankage,
piping runs, power supply, chemical storage,distribution facilities,etc.
6. Evaluate costs associated with plant design, acquisition and construction. Construct models for pdcing.ttp
final product including upfront capital by developer, sinking fund arrangements, subsidized costs,Joint.'
with municipalities or other buyers(expanded plant versions),Impact of Inflation,power costs.etc,
10.Assess risks associated with project and quantify In monetary terms as return on InvestrneM of as
}
i'
:41
.7 Ayl.
H20RGANIZATION INTERIM REPORT#01 REV 0: PAGE 16 _-` ••