United States
Environmental Protection
Agency
Water Engineering Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-86/007 May 1986
Project Summary
Computer Assisted Preliminary
Design for Drinking Water
Treatment Process Systems
Robert Smith
A computer program known as
WATE R MAI D was developed for use in
estimating the performance and costs
of existing and proposed drinking water
treatment systems. Design procedures
and cost-estimating relationships for
25 individual drinking water treatment
processes are contained within the com-
puter model. The unit processes were
selected on the basis of their applica-
bility to the removal of contaminants
included in the National Interim Primary
Drinking Water Regulations or to the
treatment and disposal of sludges and
brines produced by these treatment
processes.
This Project Summary was developed
by EPA's Water Engineering Research
Laboratory, Cincinnati. OH, to an-
nounce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Estimating the performance efficiency
and cost of water supply systems is of
considerable interest to Federal, State,
and local agencies, as well as to con-
sulting engineers and planners. The
computer program developed as part of
this project can be used to calculate the
expected contaminant removal perform-
ance and associated construction and
• operation/maintenance costs of drinking
water treatment systems consisting of
various unit treatment processes ar-
ranged in multiple configurations. The
technology used in sizing unit processes,
estimating removal efficiencies, and de-
termining treatment cost is the best that
is known to be currently available for
preliminary design. Since the technology
for each process is contained in individual
subroutines of the computer program,
improving and updating the technology
as it becomes available is easily accom-
plished. The structure of the program
allows the inclusion of additional unit
process models if desired. The final report
for this project also serves as a user's
guide for the computer program.
Scope
The program name is WATER MAID,
with MAID being an acronym for micro-
computer assisted interactive design.
WATER MAID consists of a number of
support subprograms and a design/cost
subprogram for each of 25 unit treatment
processes.
The user must provide the influent
concentrations or values for a list of 55
contaminants and other parameters that
characterize the raw water stream enter-
process is also displayed after each unit
processes to be used, which are arranged
in a specific flow diagram. The program
then computes one or more effluent
stream vectors and cost estimates for
each process based on design input
decisions supplied by the user. WATER
MAID is an interactive program, and
design decision parameters are entered
from the computer keyboard in response
to screen prompts.
The following unit processes are in-
cluded in WATER MAID:
1. Sludge drying beds
2. Basin air stripping
3. Sludge centrifugation
4. Filtration
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5. Flocculation
6. Sludge filter pressing
7. Finished water pumping
8. Granular carbon adsorption
9. Ion exchange
10. Disinfection with chlorine
11. Sludge lagoons
12. Land disposal of sludge
13. Lime softening
14. Stream mixer
15. Presedimentation
16. Lime sludge recalcination
17. Rapid mixing (chemical addition)
18. Reverse osmosis
19. Raw water pumping
20. Sedimentation
21. Stream splitter
22. Clearwell storage
23. Sludge gravity thickening
24. Tower air stripping
25. Sludge vacuum filtration
The following water parameters and
contaminants are included in the stream
vector (trihalomethane concentrations
are in units of fjg/L; all other concen-
trations are in mg/L unless otherwise
specified):
1. Design plant flow rate, mgd
2. Water temperature, °C
3. pH
4. Turbidity, ntu
5. Color, pcu
6. Coliform organisms, #/100 mL
7. Total dissolved solids
8. Total suspended solids
9. Volatile suspended solids
10. Carbonate alkalinity
11. Noncarbonate alkalinity
12. Calcium ion
13. Magnesium ion
14. Sodium ion
15. Copper
16. Ferrous ion
17. Ferric ion
18. Bivalent manganese
19. Quadravalent manganese
20. Chloride
21. Sulfate ion
22. Nitrate ion
23. Total organic carbon
24. Nonpurgeable organic carbon
25. Pentavalent arsenic
26. Trivalent arsenic
27. Barium
28. Cadmium
29. Hexavalent chromium
30. Trivalent chromium
31. Lead
32. Mercury
33. Organic mercury
34. Quadravalent selenium
35. Hexavalent selenium
36. Silver
37. Fluoride
38. Endrin
39. Lindane
40. Toxaphene
41. 2,4-D
42. Silvex
43. Methoxychlor
44. Gross alpha particle, pCi/L
45. Radium-226, pCi/L
46. Radium-228, pCi/L
47. THM formation precursors
48. CHCI3(THM)
49. CHBrClz(THM)
50. CHBr2CI (THM)
51. CHBr3(THM)
52. Aluminum hydroxide
53. Ferric hydroxide
54. Calcium carbonate
55. Magnesium hydroxide
Purposes and Objectives
WATER MAID was developed to provide
an efficient, interactive process design
tool for consulting engineers, students,
etc. The primary purpose is to evaluate
any proposed system of drinking water
treatment processes with respect to
treatment effectiveness and cost with a
minimum of engineering effort. Tech-
nology used in the development of indi-
vidual process models is consistent with
the state of the art. However, in many
cases, the need for additional research is
clear. Updating the technology when
improved performance, cost, and design
information becomes available can be
done by the user.
Cost estimating data used in WATER
MAID came from technical literature,
equipment manufacturer's information,
previous EPA research projects, etc.
Treatment plant capacity limits for these
data have been set at 1 to 200 mgd. A
secondary purpose of WATER MAID is to
provide a more flexible, preliminary, cost-
estimating tool than that provided by
graphical or tabular cost data. Cost-esti-
mating procedures or data bases are
often presented at a number of specific
design parameter levels such as pumping
heads or hauling distances for sludge,
thus limiting their general applicability.
When a cost-estimating algorithm is
known, it can be used in WATER MAID in
place of mathematical representations of
tabular data, thus providing more accu-
rate cost estimates. Some of the design
procedures used in the program are
limited by the availability of cost infor-
mation.
Approach to Program
Development
WATER MAID was written in the BASI
computer language for use on the IBM P
microcomputer. Because of system men
ory requirements, it was necessary I
store the program on two floppy disks.
The general philosophy used in deve
oping WATER MAID wastoallowthe usi
to input every possible design decision, 1
display the results of each design con
putation as it is made, and to inform th
user when design decisions are made t
the program. The user is given th
opportunity to change the raw wati
stream vector or to change any of the co
variables or chemical prices when a ne
case is initiated. Recycling capability
provided. The raw water stream vect<
and process flow diagram are stored ar
can be used in the next case if desire
Stream vectors for influent and effluei
streams are displayed after each proces
computation. A cost report for eac
processs is also displayed after each ur
process computation. An overall cost ar
parameter summary report is display*
after each case. Design flow is used
compute construction cost and buildir
energy requirements, and operating flo
is used to calculate operation/maint
nance costs. The user may also delete
unit process from the flow diagram
replace any unit process with anoth
after each process computation. Th
allows the user to consider alternate
processes without rerunning the pr
gram.
Conclusions
WATER MAID represents a matherm
ical modeling effort that is a significa
improvement on the hand calculate
method of process design still commor
used today. The principal deterrents
better process design are usually tl
manual effort required in computing t
expected performance and cost of alt*
native designs and the labor required
accumulate and correlate the lar
amount of experimental process desi
performance data that is often availab
The computer model can minimize t
computational work required for exami
ing alternative designs, and assumi
that the model has been correctly dev
oped, it will reflect the best experimen
and scientific information obtainab
WATER MAID provides the process t
signer with a tool for quantitatively sele
ing the most cost-effective system of u
processes to achieve any drinking wa
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treatment goal. The use of computer
design techniques is a significant aid in
achieving better treatment at a minimum
cost.
The full report was submitted in fulfill-
ment of Cooperative Agreement No.
CR810267-01 between the University of
Central Florida and the U.S. Environ-
mental Protection Agency.
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Robert Smith is with the University of Central Florida. Orlando, FL 32816.
Richard G. Eilers is the EPA Project Officer (see below).
The complete report consists of two parts, entitled "Computer Assisted
Preliminary Design for Drinking Water Treatment Process Systems:"
Paper copy only (Order No. PB 86-181 112/AS; Cost: $22.95}
Software for Computer Program (2 diskettes) (Order No. PB 86-181 120'/AS;
Cost: $90.00, this price includes the paper copy as well)
The above will be available only from: (cost subject to change)
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S2-86/007
0000329 PS
U S ENVIR PROTECTION AGENCY
REGION 5 LIBRARY
230 S DEARBORN STREET
CHICAGO IL 60604
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