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h1. 

Tamara

...

Design

...

Report

...

Fall

...

2007

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Abstract

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 Abstract

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A

...

new

...

AguaClara

...

drinking

...

water

...

treatment

...

plant

...

has

...

been

...

designed

...

for

...

the

...

town

...

of

...

Támara,

...

Honduras.

...

The

...

plant

...

has

...

a

...

maximum

...

flow

...

rate

...

of

...

740

...

liters

...

per

...

minute

...

and

...

features

...

a

...

vertical

...

flocculation

...

tank

...

with

...

one

...

turn,

...

three

...

sedimentation

...

tanks,

...

and

...

a

...

new

...

plant

...

leveling

...

tank.

...

Keywords:

...

AguaClara,

...

Design,

...

Támara

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Introduction

...

and Objectives

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 Objectives

{cloak:id=Introduction and Objectives}

AguaClara

...

is

...

a

...

team

...

of

...

students

...

from

...

Cornell

...

University

...

who

...

work

...

to

...

design

...

sustainable

...

water

...

treatment

...

plants

...

in

...

Honduras.

...

The

...

goal

...

of

...

the

...

team

...

is

...

to

...

design

...

and

...

disseminate

...

water

...

treatment

...

plants

...

globally

...

that

...

are

...

easy

...

to

...

build

...

and

...

maintain,

...

that

...

are

...

economical

...

to

...

operate,

...

and

...

that

...

can

...

be

...

prepared

...

using

...

locally

...


available

...

materials.

...

To

...

date,

...

two

...

AguaClara

...

water

...

treatment

...

plants

...

have

...

been

...

built

...

in

...

Honduras.

...

The

...

first

...

was

...

built

...

under

...

the

...

supervision

...

of

...

Fred

...

Stottlemeyer

...

in

...

La

...

34,

...

Honduras

...

(Figure

...

1).

...

This

...

plant

...

featured

...

a

...

horizontal

...

hydraulic

...

flocculator.

...

The

...

second

...

AguaClara

...

plant

...

was

...

built

...

in

...

Ojojona

...

and

...

its

...

initial

...

construction

...

was

...

completed

...

in

...

Fall

...

2006.

...

The

...

Ojojona

...

plant

...

(Figure

...

2)

...

was

...

designed

...

by

...

the

...

AguaClara

...

team,

...

and

...

Ted

...

Segal

...

completed

...

the

...

structural

...

design.

...

This

...

was

...

an

...

experimental

...

plant

...

with

...

both

...

a

...

vertical

...

and

...

horizontal

...

flocculator.

...


Image Added
Figure 1. La 34 AguaClara Plant.

Image Added
Figure 2. Ojojona Plant.

The next AguaClara plant was planned to be built in the town of Moroceli, Honduras. However, due to transmission pipeline problems, design of this plant was delayed so that it would not sit idle as the transmission line is repaired. The next AguaClara plant will be built in Támara, Honduras.

The Támara design team was only responsible for the environmental engineering design consideration for this plant because Agua Para el Pueblo has hired a civil engineer to deal with all structural aspects.

The Támara plant was partially designed using programs created by the AguaClara team during previous semesters. In Fall 2006, Monroe Weber-Shirk's CEE 454 class created algorithms for the unit processes involved in the plant. In Spring 2007, these algorithms were combined into a Main Program that would begin to design a plant. The program is written in MathCAD, and accepts user inputs such as flow rate and tank width to calculate output design parameters such as tank length and baffle spacing. In Fall 2007, the CEE 454 class created new programs to design pipes and flow measurement structures. These programs were used by the Támara design team as well.

The team also made use of the automated drawing capabilities developed by the Fall 2007 automated design team. This allowed the team to produce AutoCAD commands for drawing of the sedimentation tank by inputting design constraints to a MathCAD program.

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{toggle-cloak:id=Design Flow Rate}

...

Design

...

Flow Rate

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 Rate

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The

...

Támara

...

plant

...

flow

...

rate

...

was

...

determined

...

using

...

an

...

initial

...

town

...

population

...

of

...

5,500

...

people.

...

The

...

flow

...

rate

...

was

...

based

...

on

...

the

...

projected

...

population

...

and

...

associated

...

water

...

demand

...

in

...

20

...

years.

...

Population

...

was

...

calculated

...

using

...

a

...

linear

...

growth

...

model

...

with

...

a

...

3.5%

...

growth

...

rate.

...

Water

...

demand

...

was

...

estimated

...

as

...

114

...

Liters

...

per

...

person

...

per

...

day.

...

The

...

minimum

...

plant

...

flow

...

rate

...

was

...

initially

...

estimated

...

as

...

half

...

of

...

the

...

maximum

...

flow

...

rate.

...

However,

...

after

...

discussion

...

with

...

John

...

Erickson

...

and

...

Carol

...

Serna,

...

the

...

AguaClara

...

engineers

...

in

...

Honduras,

...

it

...

became

...

clear

...

that

...

the

...

town

...

did

...

not

...

currently

...

have

...

a

...

population

...

of

...

5,500.

...

At

...

the

...

time

...

of

...

design,

...

570

...

homes

...

were

...

hooked

...

up

...

to

...

the

...

transmission

...

line.

...

With

...

an

...

average

...

of

...

6

...

people

...

per

...

house,

...

this

...

population

...

was

...

3420

...

people.

...

This

...

would

...

result

...

in

...

a

...

water

...

demand

...

of

...

463

...

L/min

...

in

...

20

...

years.

...

The

...

potential

...

for

...

120

...

new

...

connections

...

in

...

the

...

near

...

future

...

exists.

...


However,

...

the

...

engineers

...

in

...

Honduras

...

believe

...

that

...

source

...

at

...

Támara

...

can

...

provide

...

at

...

least

...

740

...

L/min.

...

It

...

was

...

decided

...

that

...

740

...

L/min

...

should

...

remain

...

the

...

maximum

...

plant

...

flow

...

rate

...

because

...

the

...

actual

...

demand

...

for

...

water

...

is

...

uncertain,

...

and

...

the

...

extra

...

size

...

of

...

the

...

plant

...

would

...

not

...

be

...

too

...

costly.

...

Initial

...

baffle

...

spacing

...

in

...

the

...

flocculation

...

tank

...

will

...

be

...

designed

...

in

...

a

...

way

...

to

...

ensure

...

that

...

the

...

current

...

flow

...

rate,

...

possibly

...

as

...

low

...

as

...

270

...

L/

...

min

...

could

...

be

...

handled.

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h2. 

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...

Plant Layout

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 Layout

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The

...

Támara

...

plant

...

layout

...

has

...

a

...

few

...

major

...

changes

...

from

...

the

...

layout

...

of

...

the

...

previous

...

Ojojona

...

plant.

...

 
 

  1. The horizontal flocculator was removed.  Testing in Ojojona confirmed that the vertical flocculator worked well  The vertical flocculator is less costly to build because it does not need to be elevated, so the horizontal flocculator will no longer be used in AguaClara plants. 
  2. At the request of plant operators in Ojojona, a "bodega" was added to the plant.  This walled-in, roofed area is to be used for chemical storage, mixing of chemicals, and possibly a cot for night-time operators.   
  3. A plant leveling tank was added to replace the pipe elbow level control feature in Ojojona. 
  4. Chemical barrels were separated.  The alum and chlorine barrels will be located on different tables to allow for open walkways without tubes stretching across them, and to allow the tables to be at different heights as necessary. 
  5. Tanks will be built of brick.  APP is more familiar with brick, they believes it is less porous than concrete, and they can build more cheaply with brick. 
  6. The plant will be more protected.  There are two possible scenarios. The first is to have a fence around the plant with a roof over the platform. The second is to have open walls that start at the platform and stretch partway up to a roof. These walls would eliminate the need for a railing around the plant or extra sunlight protection for thetanks. Overall, this decision and design will be left to the plant operators and engineers inHonduras.  
  7. A catwalk may be added to span the flocculation and sedimentation tanks.  Because brick walls will be thin, a catwalk would allow for safer access to these tanks.  The AguaClara team envisions a sturdy, metal catwalk that could slide from one end of the tank to the other.  .The tank walls need to have a ledge inside the external walls of the building covering the plant so there is a place for the catwalk to rest.
    Image Added
    Figure 3. Támara Plant Layout

The new plant layout will be ideal for scaling of future AguaClara plants.  As long as baffle materials remain available to allow for the same width of tanks, the width of the plant should not change.  When a new plant is designed, the only necessary change to the layout will be the length of the tanks.  This will allow for more rapid design, easier automated design, and more uniform future plants. Another important feature of the new layout is that many of the pipes will be under the platform.  While this may be somewhat more difficult to build, it allows for easier access with no obstructions to walkways. The area under the platform should be secured so that all of the valves and pipes are protected
 Although not shown in the above drawing, all four major tanks will have drains that leave from the entrance side of the tanks.  These pipes will go to a waste collection tank under the platform where the operator will be able to see the water that is leaving the plant.  In this way he may know when all the dirty water has been flushed out.  This will be especially useful when cleaning out the sludge from the bottom of the sedimentation tanks.
Image Added
Figure 4. Támara Plant Layout, modified from a drawing by APP engineer Ing Serrano. Magenta pipes in sedimentation tank represent sedimentation tank inlet pipes. Green Pipes are for the sludge drainage.

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...

Pipe Design

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 Design

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A

...

major

...

part

...

of

...

designing

...

an

...

AguaClara

...

plant

...

is

...

sizing

...

the

...

pipes

...

in

...

the

...

plant.

...

A

...

pipe

...

design

...

program

...

was

...

created

...

so

...

that

...

all

...

pipes

...

could

...

be

...

designed

...

quickly

...

and

...

correctly.

...

The

...

program

...

returns

...

a

...

pipe

...

diameter

...

given

...

a

...

length,

...

allowable

...

headloss,

...

and

...

number

...

of

...

elbows,

...

tees,

...

valves,

...

etc.

...

A

...

table

...

of

...

the

...

K

...

values

...

used

...

and

...

a

...

table

...

of

...

input

...

pipe

...

sizes

...

used

...

can

...

be

...

found

...

in

...

the

...

Appendix

...

as

...

Table

...

2

...

and

...

Table

...

3.

...

The

...

program

...

uses

...

functions

...

defined

...

in

...

the

...

Fluids

...

Functions

...

program

...

developed

...

in

...

the

...

Fall

...

2007

...

CEE

...

454

...

class.

...

In

...

order

...

to

...

find

...

the

...

proper

...

diameter

...

the

...

program

...

iteratively

...

solves

...

for

...

the

...

flow

...

that

...

can

...

fit

...

through

...

a

...

pipe

...

of

...

the

...

given

...

diameter

...

with

...

the

...

given

...

headloss

...

until

...

a

...

large

...

enough

...

diameter

...

is

...

found.

...

Headloss

...

values

...

are

...

calculated

...

using

...

the

...

following

...

set

...

of

...

equations.

...

Include Page
Re(Q)
Re(Q)

...

Re

...

=

...

Reynolds

...

Number,

...

to

...

determine

...

if

...

flow

...

is

...

turbulent

...

or

...

laminar

...


Q

...

=

...

Flow

...

Rate

...


D

...

=

...

Pipe

...

Diameter

...


¿  =

...

Kinematic

...

viscosity

...

of

...

water

...

Include Page
f Swamee-Jain
f Swamee-Jain

...

Include Page
laminar flow friction
laminar flow friction

f = Friction factor, equation for either turbulent or laminar flow
¿= Roughness factor of PVC

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Major Head loss
Major Head loss

hmajor = Major head loss
hminor = Minor head loss
Values for all constants used may be found in the Appendix

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...

Grit

...

Chamber

...

and

...

Rapid Mix

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 Mix

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A

...

simple

...

new

...

design

...

is

...

in

...

place

...

for

...

the

...

rapid

...

mix.

...

  It

...

was

...

decided

...

that

...

the

...

mixing

...

elements

...

used

...

in

...

past

...

designs

...

were

...

not

...

necessary,

...

and

...

that

...

if

...

the

...

rapid

...

mix

...

pipe

...

from

...

the

...

grit

...

chamber

...

to

...

the

...

flocculation

...

tank

...

has

...

at

...

least

...

2

...

90°

...

elbows

...

enough

...

mixing

...

would

...

occur.

...

  This

...

was

...

determined

...

using

...

the

...

rapid

...

mix

...

pipe

...

parameters

...

and

...

determining

...

the

...

G¿

...

value

...

for

...

the

...

rapid

...

mix.

...

  A

...

G¿

...

value

...

of

...

at

...

least

...

600

...

was

...

desired.

...

  The G¿ and G values were determined using the following set of equations.

Include Page
Relationship between G and Head loss
Relationship between G and Head loss


hl = headloss in pipe
Assuming that major losses may be neglected:

Include Page
Roughness Factor
Roughness Factor

V = Velocity in pipe = Q / (¿D2/4)
L = Length of pipe

Include Page
Relationship Between G and Headloss (neglecting major losses)
Relationship Between G and Headloss (neglecting major losses)



Include Page
G¿ and head loss (neglecting major losses)
G¿ and head loss (neglecting major losses)



This two 90° elbow minimum after alum addition is easily met.  The current design has three 90° elbows: the turn from vertical to horizontal along the underside of the platform (1), the turn down along the side of the flocculation tank (2), and the turn back to horizontal to release the water into the flocculation tank(3).  See figure number 5 for a depiction of these turns.  The first baffle in the flocculation tank will be resting on the bottom of the tank and will direct water upwards.  The pipe from the grit chamber will enter the flocculation tank near the bottom  The first baffle will be a bottom baffle so the flow must turn over it.  This means the pipe should enter near the bottom of the floc tank so the water will have further to travel.
 
Image Added
Figure 5. Turns in Rapid Mix after alum addition. Alum addition occurs through the white pipe outside of Grit Chamber.
Image Added
Figure 6. Grit Chamber with one riser pipe leading to the rapid mix. Picture from CEE 454 Homework 4, Plant Measurement written by Monroe Weber-Shirk, Fall 2007.
The pipes for the grit chamber and rapid mix were designed using a program developed by the CEE 454 class in Fall 2007. This flow measurement program designed a grit chamber with two riser pipes that have orifices to allow for flow measurement.
The two riser pipes in the grit chamber contain orifices that will cause the water level to build up above them. This means that the plant flow rate may be determined based on the height of water above these orifices. Then water will free fall for a space and go down through the rapid mix. The open air pipe above the rapid mix, with alum flow holes, will allow for alum addition.
For the rapid mix pipe a maximum headloss, ¿horifice, of 20 cm was set for a pipe with 4 total turns, including 2 turns after alum addition and two turns before alum addition. The diameter of the pipe was determined using methods discussed in the "Pipe Design" section of this paper.
The riser pipe design algorithm set the height of water above the orifices at the design flow rate to be 20 cm. The diameter of the orifices in the risers was set to 1.5 inches, the same value as in Ojojona, and the area of the orifices was limited to 0.3 times the area of the pipe to ensure that orifice flows did not interfere.
The total area of orifices needed was determined using the above constraints and the orifice equation below. The Korifice is 0.63.


Include Page
Orifice flowrate
Orifice flowrate

\\\\

The number of riser pipes needed was determined from the total orifice area needed, the area of the pipe, and the ratio of pipe to orifice area. Finally, the total number of orifices was determined by dividing the total area of orifices by the area of one orifice and rounding up.
The footprint of the grit chamber was set to the same size of the plant leveling tank. The height of the walls was set to the depth of water in the grit chamber, as detailed in the "Water Levels" section of this paper, plus 10 cm of freeboard. This grit chamber tank will sit on the platform of the plant. The final parameters for the grit chamber are below.

  •  Height of Water Above Orifices: 20 cm
  •  Head Loss through Rapid Mix Pipe = 20 cm
  • Total Number of Rapid Mix Elbows: 4
  •  Number of Rapid Mix Elbows After Alum Addition: 2
  •  Length of Rapid Mix Pipe: 3 m
  •  Rapid Mix G¿ Value: 1662
  •  Rapid Mix Average G Value: 375 /sec
  •  Diameter of Orifices: 1.5"
  •  Area of Orifices/ Area of Pipe ratio: 0.3
  •  Diameter of Riser Pipes and Rapid Mix: 6"
  •  Number of riser pipes: 2
  •  Total Number of Orifices: 9 => 4 on one pipe and 5 on the other
  •  Footprint of Grit Chamber: 1m x 0.70 m
  •  Height of Grit Chamber Walls: 1.25 m
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...

Flocculation Tank

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 Tank

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The initial flocculation tank design was completed using the "Main Program" developed by the Spring 2007 design team.  However, due to changes in the lamella design and length of the sedimentation tanks, it had to be revised.  The current total flocculation tank length is twice the length of the sedimentation tanks.
 The flocculation tank is 21 inches wide, half the width of the sedimentation tank and doubles back to form a u-shape.  This means that the polycarbonate plastic roofing material sheets will need to be cut in half in order to make baffles.  The reason for the shape of the flocculation tank is that increasing the length of the tank and decreasing the width causes the tank to need less baffle material.  This is ideal because in the past baffles have bent and broken.  Additionally, smaller baffles will be more stable, and the design will require the baffles to be spaced farther apart. 
 Baffle spacing will be determined in Spring 2008 when a better understanding of baffles and flocculation has been achieved An assessment of the actual water demand for Tamara should be made early next year and if possible  the flocculator should be designed to handle the range of flow from the current demand to the plant design.. 
 Two drainage pipes have been added to the flocculation tank for emptying the tank.  These pipes are located at the very beginning and very end of the tank and will flow into the waste collection tank under the platform.  Due to the nature of the baffles in the flocculation tank, water will not be able to freely flow out of the tank.  A system will need to be set up to raise these baffles while the tank is draining.  One suggestion is tying string to the PVC pipes that attach the baffles to each other.  The string would be tied on each side of each baffle.  This string could loop over a long pole spanning the length of each tank.  When the tank was being emptied, a brick could be placed under each end of this pole to keep the baffles raised off the bottom of the tank and allow water to flow out.
 
Sizing of the flocculation drainage pipes was based on a time to drain tank of 30 min.  The initial flow rate was found as two times the average flow rate.  This means that:
\\

Equation 12
\\
Where _L{_}{_}{~}tank{~}_ is the length of one-half of the tank, and the average depth is found as 2 m plus half the expected headloss, or 2.1 m.  The drain size was determined using the pipe sizing program with a headloss of 200 cm and flow rate of _Q{_}{_}{~}initial{~}_.
 
The wall heights of the flocculation tank are based on the assumption that there will be 20 cm of headloss in the flocculation tank.  The wall heights were set to approximately 10 cm above the water level in the tanks.  The first half of the tank will have walls 20 cm higher than the second half of the tank because the majority of the headloss comes from the first half of the flocculation tank where the baffles are closer together 
The turn in the flocculation tank was modeled as one baffle. The opening in this turn was calculated to have the same area as the opening left by a baffle at the end of the flocculation tank with a G value of 15/sec.  This baffle opening area was determined the Fall 2007 CEE 454 flocculation solution.  The program iterates to solve the following equations.
\\

Equation 13
\\
_R{_}{_}{~}h{~}_ = Hydraulic Radius
_w_ = Width
_b_ = Baffle spacing
Equation 14
 In this equation it is assumed that dissipation occurs over approximately the length of baffle spacing, b.
 
_V{_}{_}{~}max{~}_ = Maximum velocity needed to produce proper G
 _f_ = Friction factor, new equation for _f{_}{_}{~}turbulent{~}_ because not using pipes
 Equation 15

Equation 16

Equation 17

Equation 18
\\
= Distance between baffle and floor for top baffle
Equation 19
 _Area_ = Area left by a bottom baffle
 
The opening will be left at the bottom of the wall separating the two halves of the tank.  This will allow water to drain out of the tank more easily.  The width of this opening was set to be the space between two baffles with G = 15/sec, the same as b calculated above.  Because the opening is at the bottom, the top baffle next to the opening must be removed
\\ !Tamara Report Photos^Flocculation Tank Figure 7.jpg!
Figure 7. Drawing of second half of Flocculation Tank. Notice the opening in the dividing wall on the right. Drainage pipes will leave from the bottom left side of the tank in this view.

Design parameters for the flocculation tank are below.
¿ Initial Inside Dimensions: 4.2 m long, 21" wide on each side
¿ Updated Inside Length (based on sed tank length): 4.6 m
¿ Maximum Head Loss: set at 20 cm
¿ Depth at End of Tank: 2 m
¿ Gap for Baffle at end of tank: 0.445 m
¿ Area Left by Baffle at end of: 0.445 m * 21 in = 0.238429m2
¿ Tank Turn Opening Dimensions: 0.30 m x 0.80 m
¿ Wall Height: 2.1 m in second half and 2.3 m in first half
¿ Initial Drainage Flow Rate: 343.3 L/min
¿ Drainage pipes: 2 inches
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Tank Dimensions

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The initial flocculation tank design was completed using the "Main Program" developed by the Spring 2007 design team.  However, due to changes in the lamella design and length of the sedimentation tanks, it had to be revised.  The current total flocculation tank length is twice the length of the sedimentation tanks.
 The flocculation tank is 21 inches wide, half the width of the sedimentation tank and doubles back to form a u-shape.  This means that the polycarbonate plastic roofing material sheets will need to be cut in half in order to make baffles.  The reason for the shape of the flocculation tank is that increasing the length of the tank and decreasing the width causes the tank to need less baffle material.  This is ideal because in the past baffles have bent and broken.  Additionally, smaller baffles will be more stable, and the design will require the baffles to be spaced farther apart. 

 Baffle spacing will be determined in Spring 2008 when a better understanding of baffles and flocculation has been achieved An assessment of the actual water demand for Tamara should be made early next year and if possible  the flocculator should be designed to handle the range of flow from the current demand to the plant design.. 
 Two drainage pipes have been added to the flocculation tank for emptying the tank.  These pipes are located at the very beginning and very end of the tank and will flow into the waste collection tank under the platform.  Due to the nature of the baffles in the flocculation tank, water will not be able to freely flow out of the tank.  A system will need to be set up to raise these baffles while the tank is draining.  One suggestion is tying string to the PVC pipes that attach the baffles to each other.  The string would be tied on each side of each baffle.  This string could loop over a long pole spanning the length of each tank.  When the tank was being emptied, a brick could be placed under each end of this pole to keep the baffles raised off the bottom of the tank and allow water to flow out.
 
Sizing of the flocculation drainage pipes was based on a time to drain tank of 30 min.  The initial flow rate was found as two times the average flow rate.  This means that:

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initial flowrate (tamara)
initial flowrate (tamara)


Where Ltank is the length of one-half of the tank, and the average depth is found as 2 m plus half the expected headloss, or 2.1 m.  The drain size was determined using the pipe sizing program with a headloss of 200 cm and flow rate of Qinitial.
 
The wall heights of the flocculation tank are based on the assumption that there will be 20 cm of headloss in the flocculation tank.  The wall heights were set to approximately 10 cm above the water level in the tanks.  The first half of the tank will have walls 20 cm higher than the second half of the tank because the majority of the headloss comes from the first half of the flocculation tank where the baffles are closer together 
The turn in the flocculation tank was modeled as one baffle. The opening in this turn was calculated to have the same area as the opening left by a baffle at the end of the flocculation tank with a G value of 15/sec.  This baffle opening area was determined the Fall 2007 CEE 454 flocculation solution.  The program iterates to solve the following equations.

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Hydraulic Radius (Floc Tank)
Hydraulic Radius (Floc Tank)


Rh = Hydraulic Radius
w = Width
b = Baffle spacing

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Sedimentation Tank Upwards Velocity
Sedimentation Tank Upwards Velocity

 In this equation it is assumed that dissipation occurs over approximately the length of baffle spacing, b.
 
Vmax = Maximum velocity needed to produce proper G
 f = Friction factor, new equation for fturbulent because not using pipes
 

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f Swamee-Jain
f Swamee-Jain



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Reynold's number (related to hydraulic radius)
Reynold's number (related to hydraulic radius)





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Baffle Spacing
Baffle Spacing



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Distance between baffle and floor for top baffle
Distance between baffle and floor for top baffle


gap= Distance between baffle and floor for top baffle

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Area left by a bottom baffle
Area left by a bottom baffle

 Area = Area left by a bottom baffle
 
The opening will be left at the bottom of the wall separating the two halves of the tank.  This will allow water to drain out of the tank more easily.  The width of this opening was set to be the space between two baffles with G = 15/sec, the same as b calculated above.  Because the opening is at the bottom, the top baffle next to the opening must be removed
Image Added
Figure 7. Drawing of second half of Flocculation Tank. Notice the opening in the dividing wall on the right. Drainage pipes will leave from the bottom left side of the tank in this view.

Design parameters for the flocculation tank are below.
 Initial Inside Dimensions: 4.2 m long, 21" wide on each side

  • Updated Inside Length (based on sed tank length): 4.6 m
  • Maximum Head Loss: set at 20 cm
  • Depth at End of Tank: 2 m
  • Gap for Baffle at end of tank: 0.445 m
  • Area Left by Baffle at end of: 0.445 m * 21 in = 0.238429m2
  • Tank Turn Opening Dimensions: 0.30 m x 0.80 m
  • Wall Height: 2.1 m in second half and 2.3 m in first half
  • Initial Drainage Flow Rate: 343.3 L/min
     *Drainage pipes: 2 inches
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Baffle Spacing

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Due to the team's limited knowledge of the mechanisms behind flocculation, the baffle spacing for Tamara was not designed at the same time as the rest of the plant. Since the tank dimensions were determined first, the baffle spacings and number of baffles were subject to certain constraints.

Design Parameters

  • Number of channels: 2
  • Flocculator Dimensions
    Length(per channel): 4.6 m
    Width (per channel): .52 m
    Depth of water at end of 2nd channel (determined by sedimentation tank): 2m
  • Dimensions of hole between first and second channels (the hole is located at the bottom of the wall between the tanks):
    Width: 0.3m
    Height: 1m
  • Design flow rate (max): 150 gal/min
  • Low flow rate: 75 gal/min
  • Ratio between high and low flow rate: 0.5
  • Slope of floor: 8cm/4.6m = 0.017 (each channel has the same slope with the heighest part where the water passes between the two channels)
  • First baffle spacing: 0.355 m

Using the flocculation algorithm developed during spring '08 the baffle spacing was determined. For further information into how this file was developed, see the flocculation sections of both the Automated Design Final Report and the Automated Design Final Algorithm report.

Baffle Spacing

Number of Baffles

Gtheta

11 cm

7

1158

16 cm

7

1158

33 cm

18

2971

sum

32

5287

Attached is an excel file with the coordinates and lengths for each baffle. Polyarbonated is purchased in sheets that are 12 ft by 42 in. These sheets are cut in half to create baffles with a width of 21in (.52m). Two baffles are cut from each 12 ft sheet. The spreadsheet also contains information on how each sheet should be cut since some baffles are longer than 6 ft. Each baffle is a different length due to the slope of the floor.

The tank was built with walls 2.42m tall. Upper baffles, baffles with water runnning under them, should not be installed at this height because they will be too long and 8 polycarbonates sheets will not be enough. Instead upper baffle should be installed at a height of 2.38 m. This includes 5 cm of headloss and 33 cm of freeboard. In the future, more baffles could be installed near the front of the tank, and the extra freeboard will ensure that the tank does not overflow due to the increase in headloss.

The first baffle was placed a distance of 35.5 cm from the start of the first channel. Additionally, the last baffle in the first channel and the first baffle in the second channel are 35 cm from the tank wall to allow space for the uturn hole. The hole has an area of 0.3m^2 which is a sufficient size to guarantee that it will not break up the flocs. The hole is at the bottom of the tank, however, due to it's size it shouldn't matter rather the last baffle is an up or down one. The gtheta value for the entire tank is 5287. This value is acceptable.

Attached is the MathCAD file used to design the tank.

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Flocculation

...

to

...

Sedimentation Channel

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 Channel

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The

...

design

...

of

...

the

...

channel

...

connecting

...

the

...

flocculation

...

tank

...

to

...

the

...

sedimentation

...

tank,

...

while

...

a

...

seemingly

...

simple

...

connection,

...

has

...

many

...

constraints.

...

  • The

...

  • most

...

  • important

...

  • constraint:

...

  • the

...

  • channel

...

  • cross-sectional

...

  • area

...

  • must

...

  • be

...

  • large

...

  • enough

...

  • that

...

  • it

...

  • will

...

  • not

...

  • break

...

  • up

...

  • flocs

...

  • at

...

  • max

...

  • flow.

...

  • The

...

  • channel

...

  • must

...

  • be

...

  • shallow

...

  • enough

...

  • that

...

  • the

...

  • operator

...

  • can

...

  • reach

...

  • the

...

  • caps

...

  • to

...

  • the

...

  • sedimentation

...

  • inlet

...

  • pipes.

...

  • Ideally

...

  • the

...

  • channel

...

  • would

...

  • fit

...

  • in

...

  • the

...

  • otherwise

...

  • unoccupied

...

  • triangular

...

  • space

...

  • above

...

  • the

...

  • first

...

  • plate

...

  • settlers.

...

  • The

...

  • bottom

...

  • of

...

  • the

...

  • channel

...

  • will

...

  • be

...

  • the

...

  • level

...

  • of

...

  • the

...

  • platform.

...

  •   The

...

  • height

...

  • of

...

  • the

...

  • platform

...

  • will

...

  • dictate

...

  • whether

...

  • a

...

  • bucket

...

  • may

...

  • be

...

  • filled

...

  • from

...

  • the

...

  • plant

...

  • leveling

...

  • tank

...

  • in

...

  • order

...

  • to

...

  • mix

...

  • chemicals.

...

  •  

More information on the bucket problem is included in the "Plant Leveling Tank" portion of this report.   However, easy solutions to constraints #2 and #3 were found.  In order to provide easier access to the sedimentation inlet pipe caps in the bottom of the channel, a new design for the caps will be used.  A conceptual drawing of the caps is shown in Figure 8 below. The top of the sedimentation inlet pipes (shown as the tall pipes in the figure) will be flush with the bottom of the channel so there will be a smaller entrance loss.   The caps will use slip fittings rather than threaded fittings.  The threaded fitting at Ojojona are beginning to break, so slip fittings will provide a more sustainable design.  Thin handles, made of smaller PVC pipe, will be attached to the tops of the caps so that the operator can easily pull and push the caps off and on.  This will eliminate the need for the operator to reach his hands into the water, and this will eliminate the depth constraint.

Image Added
Figure 8. Drawing of Caps for Pipes leaving the Channel

The lamella constraint was solved by simply lengthening the sedimentation tank to allow for replacement of lamella that the channel would interfere with. However, it was desired to keep the tank as short as possible, so an attempt was made to interfere with as few lamella as possible.

A range of channel dimensions that would not break up flocs was determined using the "Channel_Dimensions" program created for the Marcala plant design. This program looked at the shear caused by water making the 90 degree turn into the channel. First the velocity required to achieve the given value of G, 15/sec, was determined.

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velocity required to achieve given G
velocity required to achieve given G

Where is simply the entrance loss coefficient of 0.5. The length of dissipation, L, was set to 2 times the width of the channel. This estimated value was used because the actual dissipation length was unknown. The determined velocity was used to find a depth for the input channel width given the continuity equation below.

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Flocculation to Sedimentation Channel Depth
Flocculation to Sedimentation Channel Depth

A range of channel dimensions that would not disturb the lamella was determined based on the geometry of the tank. The geometry of the sedimentation tank may be seen in Figure 9 and Figure 10.

An equation was developed to describe the total width of the channel that would not hit the lamella given a height of the channel. The total channel height included 20 cm of freeboard plus 12 cm for the thickness of the platform beneath the channel. The total channel width included 15 cm for the width of the brick wall.

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Flocculation to Sedimentation Channel Width
Flocculation to Sedimentation Channel Width

Depthlamella is the distance from the top of the tank walls to the lamella, 120 cm. ¿ is the angle of the lamella, 60 degrees.

Image Added
Figure 9 . Side view of a Sedimentation Tank. The blue outline represents the water level at 2 m of depth and the green lines represent lamella. Dimensions are in meters

Image Added
Figure 10. Side view of one Lamella in the Sedimentation Tank. Lamella shown as green line.

A graph was made by combining the dimensions determined from each method.

Image Added
Figure 11. Graph comparing Channel Dimension Constraints from the floc break-up and lamella constraints (Constraints #1 and #3)

Preliminary design of the plant leveling tank suggested that bucket would be able to be filled if the channel water depth was approximately 50 cm; with a platform thickness of 12 cm and a freeboard of 20 cm, this would correspond to a channel height of 75 cm. Figure 11 shows that a height of 82 centimeters is right near the ideal range of the graph where the floc breakup line and lamella line are nearest to each other.

For the designed channel, the difference between the width of the channel that would fit in the triangle above the lamella (23.35 cm) and the actual outer width of the channel (45 cm) is 23.35 cm. This value must be added to the length of the sedimentation tank so that the same amount of lamella may be included.

Design parameters for the channel are below.

  • G value: 15 / sec
  • Dissipation Length: 2 x width
  • Channel Inner Dimensions: 30 cm wide x 50.5 cm deep (depth of water)
  • Channel Outer Dimensions: 45 cm wide x 82.5 cm deep (Depth from top of wall to bottom of platform)
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Sedimentation

...

Inlet Pipes

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 Pipes

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The

...

sedimentation

...

inlet

...

pipes

...

were

...

designed

...

using

...

the

...

method

...

described

...

in

...

the

...

"Pipe

...

Design"

...

portion

...

of

...

this

...

paper.

...

In

...

order

...

to

...

keep

...

the

...

pipes

...

to

...

a

...

manageable

...

size,

...

it

...

was

...

decided

...

that

...

long

...

radius

...

turns,

...

with

...

a

...

K-value

...

of

...

0.45,

...

must

...

be

...

used.

...

These

...

pipes

...

will

...

create

...

less

...

shear

...

during

...

turns

...

so

...

that

...

a

...

smaller

...

G

...

value

...

may

...

be

...

maintained.

...

Long

...

radius

...

pipes

...

are

...

available

...

in

...

Honduras.

...

The

...

constraint

...

for

...

these

...

inlet

...

pipes

...

was,

...

again,

...

to

...

not

...

break

...

up

...

flocs.

...

In

...

order

...

to

...

keep

...

flocs

...

intact,

...

the

...

G-value

...

had

...

to

...

be

...

below

...

15/sec

...

in

...

the

...

pipes.

...

A

...

dissipation

...

length

...

equal

...

to

...

the

...

diameter

...

was

...

used

...

in

...

calculations.

...

This

...

meant

...

that

...

the

...

limiting

...

portion

...

of

...

the

...

entrance

...

pipes

...

will

...

be

...

the

...

entrance

...

to

...

the

...

pipes

...

which

...

have

...

a

...

K-value

...

of

...

0.5.

...

The

...

equations

...

used

...

to

...

find

...

the

...

G

...

values

...

are

...

listed

...

below.

...

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Relationship between G and Head loss
Relationship between G and Head loss

Equation 24
Equation 25
Equation 26
Equation 27
Equation 28
Equation 29

The K value is 0.5 for the entrance and 0.45 for a pipe turn. Thus the 0.5 for the entrance is used in calculations because it will achieve the highest G value. The flow rate is equal to 1/12 the total plant flow rate.

However, this will result in a pipe diameter slightly over 6 inches (6.13in).

...

Using

...

the

...

dissipation

...

length

...

of

...

one

...

diameter,

...

a

...

6

...

inch

...

pipe

...

will

...

reach

...

a

...

G

...

value

...

of

...

16.2.

...

If

...

instead

...

the

...

dissipation

...

length

...

is

...

set

...

to

...

2

...

times

...

the

...

diameter,

...

then

...

the

...

pipe

...

size

...

will

...

be

...

6

...

inches

...

(5.55

...

in)

...

with

...

a

...

maximum

...

G

...

value

...

of

...

2.9.

...

The

...

pipe

...

sizes

...

found

...

in

...

Honduras

...

have

...

a

...

slightly

...

larger

...

inner

...

diameter

...

than

...

the

...

nominal

...

diameter

...

which

...

they

...

are

...

listed

...

under,

...

as

...

may

...

be

...

seen

...

in

...

Table

...

3

...

in

...

the

...

Appendix.

...

The

...

6

...

inch

...

drainage

...

pipe

...

will

...

be

...

used

...

because

...

there

...

are

...

long-radius

...

turns

...

available

...

for

...

it.

...

The

...

diameter

...

of

...

this

...

pipe

...

will

...

be

...

large

...

enough.

...

There

...

has

...

been

...

some

...

concern

...

that

...

the

...

inlet

...

pipes

...

will

...

be

...

difficult

...

to

...

anchor.

...

The

...

anchoring

...

system

...

in

...

Figure

...

12

...

is

...

recommended.

...

Image Added
Figure 12. Anchor for Sedimentation Inlet Pipe. Picture drawn by John Erickson.

The design parameters for the inlet pipes are below:

  •   G value: 15 / sec
  •   Dissipation Length: Pipe Diameter or 2 x Pipe Diameter
  •   Number of Inlet Pipes per Sedimentation Tank: 4
  •   Diameter of Inlet Pipes: 6 in
  •   Horizontal Lengths: 0.95 m, 1.7 m, 2.45 m, and 3.2 m (see Figure 14)
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...

Sedimentation Tank

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 Tank

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The

...

original

...

design

...

of

...

the

...

sedimentation

...

tank

...

was

...

determined

...

using

...

the

...

"Main

...

Program"

...

developed

...

by

...

the

...

Design

...

Team

...

in

...

Spring

...

2007.

...

The

...

sedimentation

...

tank

...

was

...

set

...

to

...

a

...

water

...

depth

...

of

...

2

...

m,

...

the

...

same

...

depth

...

as

...

the

...

tank

...

in

...

Ojojona.

...

A

...

settling

...

velocity,

...

Vc,

...

of

...

10

...

m/day

...

was

...

used

...

as

...

this

...

seemed

...

to

...

work

...

in

...

Ojojona.

...

The

...

width

...

of

...

the

...

sedimentation

...

tank

...

was

...

set

...

to

...

42

...

inches,

...

the

...

width

...

of

...

available

...

lamella

...

material.

...

The

...

length

...

of

...

the

...

tank

...

was

...

determined

...

from

...

the

...

upwards

...

velocity

...

in

...

the

...

tank.

...


Equation

...

30

...


Where

...

Llamella

...

is

...

the

...

length

...

of

...

the

...

lamella,

...

blamella

...

is

...

the

...

space

...

between

...

the

...

lamella,

...

and

...

¿

...

is

...

the

...

angle

...

of

...

the

...

lamella.

...

This

...

Vup

...

value

...

was

...

used

...

with

...

the

...

flow

...

rate

...

to

...

determine

...

the

...

necessary

...

active

...

length

...

of

...

the

...

tank

...

using

...

the

...

continuity

...

equation.

...

However,

...

part

...

of

...

the

...

length

...

of

...

the

...

tank

...

is

...

not

...

used

...

because

...

the

...

space

...

after

...

the

...

bottom

...

of

...

the

...

last

...

lamella

...

cannot

...

be

...

used

...

by

...

water

...

moving

...

upward.

...

So

...

the

...

total

...

length

...

of

...

the

...

tank

...

was

...

calculated.

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Total Length of Sedimentation Tank
Total Length of Sedimentation Tank

The number of lamella was simply the number of lamella that would fit into the tank.
However, due to the space used by the channel and by the sedimentation tank exit pipes, the length of the sedimentation tank had to be increased as follows.

  • Initial Inside Dimensions: 4.2 m long, 42" wide
  • Add on 23.35 cm for channel
  • Add on 16 cm for 6" sedimentation exit pipe
  • Total Length: 4.6 m

Image Added
Figure 13. Sedimentation Tank length additions due to the channel and launder. Black lines represent lamella and dotted lines represent displaced lamella.

The wall height of the sedimentation tank was set to the wall height of the end of the flocculation tank.

The ends of the four inlet pipes in the sedimentation tank were spaced out evenly by determining the active length of the tank and dividing by the four pipes. Given the increase in tank length it is easiest to determine the active length as.

Include Page
Active Length of Sedimentation Tank
Active Length of Sedimentation Tank

The spacing between each pipe will be Lactive/4 and the spacing at the ends will be half this value.

Image Added
Figure 14. Side view of a Sedimentation Tank. The approximate location of entrance pipes can be seen.
Design parameters for the sedimentation tanks are below.

  • Depth: 2 m
  • Wall Height: 2.1 m
  • Vc: 10 m/day
  • ¿: 60 degrees
  • Llamella: 40 in , 91 cm
  • Width: 42 inches
  • Total Length: 4.6 m
  • Active Length: 3.745m
  • Lamella Spacing : 5 cm (measured as the normal distance between the lamella)
  • Lamella Horizontal spacing: ????
  • Number of Lamella: 64 per tank
  • Spacing between Inlet Pipes: 0.94 m
Wiki Markup
{cloak}

Wiki Markup
{toggle-cloak:id=Sedimentation Sludge Manifold}

...

Sedimentation

...

Sludge Manifold

Wiki Markup
 Manifold

{cloak:id=Sedimentation Sludge Manifold}

The

...

sedimentation

...

tank

...

in

...

Ojojona

...

has

...

had

...

problems

...

with

...

sludge

...

building

...

up

...

in

...

the

...

bottom

...

of

...

the

...

tank.

...

For

...

the

...

Támara

...

water

...

treatment

...

plant,

...

a

...

new

...

sludge

...

drainage

...

system

...

will

...

be

...

put

...

in

...

place

...

to

...

allow

...

for

...

drainage

...

of

...

the

...

sludge

...

at

...

the

...

bottom

...

of

...

the

...

tank

...

without

...

draining

...

the

...

entire

...

tank.

...

The

...

drainage

...

system

...

will

...

consist

...

of

...

one

...

pipe

...

in

...

the

...

bottom

...

of

...

the

...

tank

...

with

...

orifices

...

for

...

the

...

sludge

...

and

...

water

...

to

...

enter.

...

This

...

pipe

...

will

...

be

...

in

...

a

...

channel

...

in

...

the

...

sedimentation

...

tank

...

floor

...

so

...

that

...

it

...

will

...

not

...

interfere

...

with

...

the

...

lamella

...

support

...

structure.

...

The

...

lamella

...

will

...

sit

...

on

...

a

...

table

...

resting

...

on

...

the

...

bottom

...

of

...

the

...

sedimentation

...

tank,

...

as

...

they

...

did

...

in

...

Ojojona.

...

It

...

is

...

desirable

...

to

...

limit

...

any

...

extra

...

pipes

...

on

...

the

...

floor

...

of

...

the

...

sedimentation

...

tank.

...

The

...

sludge

...

manifold

...

was

...

designed

...

using

...

the

...

"Manifolds"

...

program

...

developed

...

by

...

the

...

Fall

...

2007

...

CEE

...

454

...

class.

...

This

...

program

...

sets

...

the

...

spacing

...

between

...

orifices

...

in

...

the

...

manifold

...

at

...

ten

...

centimeters,

...

and

...

uses

...

the

...

length

...

of

...

the

...

tank

...

to

...

determine

...

the

...

number

...

of

...

orifices.

...

The

...

time

...

to

...

empty

...

the

...

tank

...

is

...

set

...

at

...

30

...

minutes,

...

and

...

the

...

initial

...

flow

...

rate

...

through

...

the

...

drain

...

is

...

found

...

as

...

twice

...

the

...

average

...

flow

...

rate

...

through

...

the

...

drain

...

(the

...

constant

...

rate

...

required

...

to

...

drain

...

the

...

tank

...

in

...

15

...

minutes).

...

The

...

diameter

...

of

...

the

...

sludge

...

manifold

...

is

...

found

...

by

...

an

...

iterative

...

process

...

using

...

the

...

following

...

equation.

...

Include Page
Manifold Diameter
Manifold Diameter

The headloss through the manifold, but not through the orifices is calculated as follows.

Include Page
head loss through the manifold
head loss through the manifold

HLpipe is the headloss through a normal pipe as shown in the Pipe Design section of this paper, and n is the number of orifices. Finally, the size of the orifices is found using the orifice equation. The allowable headloss in the orifice equation is the height of water in the sedimentation tank, minus the head loss in the manifold, and minus the velocity head at the end of the manifold.

Equation 35

The diameter for a sludge line, which would drain only the sludge from the tank, was found using the Pipe Design method. This sludge line would be attached to the sludge manifold right before the main drain valve so that it could be opened to let a smaller flow through. The maximum headloss for this pipe was set at 200 cm with two 90 degree turns. Both the sludge line and sludge manifold pipes will empty into the waste collection tank underneath the platform. The valve to open these pipes will be under the platform as well so that the operator may open and close them while looking at the water quality leaving the tank.

Design parameters for the sedimentation sludge manifold are as follows.

  •   Space between Orifices: 10 cm
  •   Time to Empty Tank: 30 min
  •   n - Number of Orifices: 45
  •   Qratio - Ratio of flow between first and last orifice: 0.95
  •   Dmanifold - Diameter of Pipe: 4 in
  •   Orifice Diameter: 0.9 cm
  •   Sludge Line/ Drain Line Diameter: 1.5 in
  •   Qdrain - Maximum drain flow rate: 652.93 L/min
  •   Head loss through the manifold: 2.43 cm
  •   The velocity head: 9.2 cm
  •   Head loss through the orifices: 1.88 m
Wiki Markup
{cloak}

Wiki Markup
{toggle-cloak:id=Sedimentation Tank Launder / Exit Pipes}

...

Sedimentation

...

Tank

...

Launder

...

/

...

Exit Pipes

Wiki Markup
 Pipes

{cloak:id=Sedimentation Tank Launder / Exit Pipes}

The

...

launders

...

leaving

...

the

...

sedimentation

...

tanks

...

were

...

designed

...

in

...

a

...

similar

...

manner

...

as

...

the

...

sedimentation

...

sludge

...

drain

...

manifold.

...

The

...

length

...

between

...

the

...

orifices

...

was

...

assigned

...

a

...

value

...

of

...

4

...

times

...

the

...

space

...

between

...

lamella,

...

and

...

the

...

launder

...

flow

...

rate

...

value

...

was

...

simply

...

the

...

plant

...

flow

...

rate

...

divided

...

by

...

three.

...

Because

...

there

...

was

...

concern

...

about

...

the

...

launder

...

pipes

...

obstructing

...

access

...

to

...

the

...

channel,

...

the

...

launders

...

will

...

turn

...

and

...

run

...

below

...

the

...

channel,

...

as

...

shown

...

in

...

Figure

...

14,

...

passing

...

through

...

the

...

sedimentation

...

tank

...

wall

...

below

...

the

...

platform.

...

After

...

exiting

...

the

...

sedimentation

...

tank,

...

the

...

pipes

...

will

...

travel

...

below

...

the

...

platform

...

and

...

up

...

into

...

the

...

plant

...

leveling

...

tank.

...

The

...

diameter

...

of

...

these

...

exit

...

pipes

...

between

...

the

...

launders

...

and

...

the

...

plant

...

leveling

...

tank

...

will

...

be

...

the

...

same

...

size

...

as

...

the

...

launders.

...

Design

...

parameters

...

for

...

the

...

sedimentation

...

tank

...

launders

...

are

...

as

...

follows.

...

  •   Head

...

  • loss

...

  • through

...

  • the

...

  • orifices:

...

  • 3.1cm

...

  •   Qratio:

...

  • 0.95

...

  •   Total

...

  • head

...

  • loss

...

  • between

...

  • the

...

  • sedimentation

...

  • tank

...

  • and

...

  • the

...

  • level

...

  • control

...

  • tank:

...

  • 5.4

...

  • cm

...

  •   Launder

...

  • Length:

...

  • 4.2

...

  • m

...

  •   Launder/

...

  • Exit

...

  • Pipe

...

  • Diameter:

...

  • 6

...

  • in

...

  •   Orifice

...

  • Spacing:

...

  • 20

...

  • cm

...

  • (on

...

  • each

...

  • size)

...

  •   Number

...

  • of

...

  • orifices:

...

  • 36

...

  • (18

...

  • on

...

  • each

...

  • side)

...

  •   Orifice

...

  • size:

...

  • 2.2

...

  • cm

...

  •   Exit

...

  • Pipe

...

  • Lengths:

...

  • Pipe

...

  • a

...

  • -

...

  • 3.6

...

  • m,

...

  • Pipe

...

  • b

...

  • -

...

  • 4.4

...

  • m,

...

  • Pipe

...

  • c

...

  • -

...

  • 6.0

...

  • m

...

  •   Number

...

  • of

...

  • Turns

...

  • in

...

  • Exit

...

  • Pipe:

...

  • Pipe

...

  • a

...

  • -

...

  • 5,

...

  • Pipes

...

  • b

...

  • &

...

  • c

...

  • -

...

  • 4

...

(Pipe

...

numbering

...

is

...

shown

...

in

...

Figure

...

4)

...

The

...

flow

...

distribution

...

between

...

the

...

three

...

tanks

...

was

...

compared

...

in

...

the

...

following

...

way:

...


First,

...

the

...

loss

...

coefficient

...

for

...

orifice

...

flow

...

was

...

determined

...

in

...

the

...

following

...

way:

...

K

...

=

...

1

...

*

...

dpipe4

...

_

...


Kor2

...

d

...

or4

...

nor2

...

Using

...

the

...

dimensions

...

of

...

the

...

launder,

...

this

...

becomes

...

K

...

=

...

1

...

*

...

(0.1524m)4

...

_

...

=

...

4.47.

...


(0.63)2

...

(0.022m)4

...

(36)2

...

The

...

other

...

minor

...

losses

...

are

...

90

...

degree

...

elbows

...

(Kelbow

...

=

...

0.9)

...

and

...

exit

...

losses

...

from

...

a

...

pipe

...

that

...

is

...

smooth

...

with

...

the

...

bottom

...

of

...

the

...

flow

...

control

...

tank

...

(Kexit

...

=

...

1).

...

Major

...

(frictional)

...

losses

...

are

...

insignificant

...

over

...

these

...

short

...

distances.

...

In

...

the

...

case

...

of

...

four

...

elbows,

...

the

...

sum

...

of

...

the

...

minor

...

losses

...

is

...

9.07,

...

and

...

the

...

case

...

of

...

five

...

elbows,

...

the

...

sum

...

of

...

the

...

minor

...

losses

...

is

...

9.97.

...

The

...

following

...

shows

...

the

...

relationship

...

between

...

loss

...

Ktotal

...

and

...

flow

...

(Q)

...

hL

...

=

...

k

...

V2

...

/2g

...

and

...

Q

...

¿

...

(hL

...

/Cp),

...

where

...

¿CP

...

=

...

f

...

Lmanifold/Dmanifold

...

+

...

¿K

...


So,

...

Q

...

¿

...

(

...

1/

...

(¿K)^(1/2))

...

Given

...

this,

...

the

...

difference

...

between

...

the

...

flow

...

between

...

the

...

paths

...

with

...

four

...

elbows

...

and

...

the

...

paths

...

with

...

5

...

elbows

...

is

...

4.8%.

...

This

...

is

...

an

...

acceptable

...

difference,

...

but

...

it

...

can

...

be

...

improved

...

by

...

putting

...

the

...

same

...

number

...

of

...

elbows

...

(5)

...

for

...

all

...

of

...

the

...

pipes,

...

even

...

if

...

it

...

is

...

not

...

necessary

...

spatially.

...

It

...

is

...

worth

...

one

...

extra

...

elbow

...

to

...

make

...

sure

...

that

...

the

...

flow

...

is

...

equal

...

between

...

the

...

three

...

sedimentation

...

tanks.

Wiki Markup

{cloak}

h2. 

Wiki Markup
{toggle-cloak:id=Plant Leveling Tank}

...

Plant

...

Leveling Tank

Wiki Markup
 Tank

{cloak:id=Plant Leveling Tank}

A

...

newly

...

designed

...

plant

...

leveling

...

tank

...

will

...

be

...

used

...

to

...

control

...

the

...

water

...

levels

...

in

...

the

...

Támara

...

plant.

...

After

...

dissatisfaction

...

with

...

the

...

Ojojona

...

pipe

...

elbow

...

system

...

was

...

expressed,

...

this

...

new

...

design

...

for

...

a

...

small

...

tank

...

with

...

a

...

weir

...

exit

...

was

...

developed.

...

Water

...

from

...

the

...

three

...

sedimentation

...

exit

...

pipes

...

will

...

enter

...

through

...

the

...

bottom

...

of

...

the

...

tank.

...

These

...

pipes

...

will

...

be

...

flush

...

with

...

the

...

bottom

...

of

...

the

...

tank

...

so

...

that

...

they

...

may

...

be

...

capped

...

with

...

a

...

slip

...

fitting

...

similar

...

to

...

the

...

sedimentation

...

inlet

...

pipes

...

to

...

make

...

it

...

possible

...

to

...

isolate

...

a

...

sedimentation

...

tank

...

for

...

draining

...

and

...

cleaning.

...

Water

...

will

...

collect

...

in

...

the

...

tank

...

and

...

leave

...

through

...

a

...

pipe

...

sticking

...

up

...

through

...

the

...

base

...

of

...

the

...

tank.

...

The

...

rim

...

of

...

this

...

pipe

...

will

...

function

...

as

...

a

...

weir

...

to

...

control

...

the

...

level

...

of

...

the

...

water.

...

If

...

the

...

flow

...

rate

...

of

...

the

...

plant

...

is

...

changed,

...

or

...

if

...

a

...

change

...

in

...

the

...

plant

...

water

...

level

...

is

...

desired,

...

the

...

height

...

and

...

shape

...

of

...

this

...

weir

...

may

...

be

...

changed

...

to

...

adjust

...

the

...

water

...

level

...

of

...

the

...

plant.

...

The

...

weir

...

pipe

...

will

...

go

...

down

...

through

...

the

...

platform

...

and

...

lead

...

to

...

the

...

distribution

...

tank.
Image Added Image Added
Figure 15.Left:

...

Launder

...

Pipe

...

exiting

...

a

...

Sedimentation

...

Tank.

...

Right:

...

Depiction

...

of

...

the

...

Támara

...

Plant

...

Leveling

...

Tank.

...

The

...

pipe

...

leading

...

to

...

the

...

distribution

...

tank

...

will

...

also

...

have

...

a

...

branch

...

opened

...

by

...

a

...

valve

...

that

...

would

...

allow

...

the

...

operator

...

to

...

direct

...

the

...

outgoing

...

water

...

to

...

the

...

waste

...

collection

...

tank

...

under

...

the

...

platform

...

instead

...

of

...

the

...

distribution

...

tank.

...

The

...

pipe

...

to

...

the

...

distribution

...

tank

...

must

...

slope

...

slightly

...

upward

...

to

...

ensure

...

that

...

no

...

water

...

will

...

flow

...

to

...

the

...

distribution

...

tank

...

when

...

the

...

valve

...

is

...

opened.

Image Added

The weir pipe will also be used for chlorine addition. Chlorine will be dripped directly into the center of this pipe to mix with the water leaving the plant.

All pipe sizing was done using the pipe design program. To determine the water height above the weir, the weir equation for a sharp-crested weir was used. PVC is closer to a sharp-crested weir than a broad-crested weir.

Equation 36

Where V1 represents the upstream velocity, which is very small. This means that the equation may be reduced.

Equation 37

Setting the length factor b to the circumference ¿D and solving for the water height above the weir, H, the final equation is arrived at.

Equation 38

The weir height was chosen to keep the 2m level of the sedimentation tank and to ensure that a bucket could be filled from the tank.

Once water goes over the weir, it must freefall before flowing to the distribution tank. This is an important consideration in designing the piping to the distribution tank. A free fall distance of 15 cm is recommended. This design constraint must be considered when calculating the head loss in the pipe between the weir and the distribution tank.

The flow rate out of a tap on the plant leveling tank was determined to ensure that a 5 gallon bucket could be filled from the tank. This is an important consideration because the plant operator will need to fill buckets with clean water to mix the alum and chlorine solutions. The height of a five gallon bucket was measured to be 35.6 cm tall. The water height in the plant leveling tank is 47.7 cm (see Table xx) The water height above this bucket would be at least 8.7 cm. If a two inch pipe with one gate valve and one ninety degree turn is installed at the level of the bucket, the flow rate through the pipe, as determined by the pipe design program, will be 70 L/min. A five gallon bucket will fill in less than one minute. This calculation ignores the possibly loss of height in the tank due to the water removed. However, this change should be very small.

Image Added
Figure 17. Picture of a bucket being filled from the Plant Leveling Tank. Drawing not to scale.

The constraint on the size of the plant leveling tank is simply that it must be large enough to hold all of the pipes while leaving room for the pipes to be capped. The current design would accommodate the four 6" pipes (xx cm OD) lined up next to each with yy cm between the pipes . This will leave sufficient space in the tank. The wall height of the tank was set to the wall height of the channel.

The design parameters of the plant leveling tank will be as follows.

  •   Tank Size (Inside Dimensions): 1m x 0.70 m x 70.5 cm (tall)
  •   Weir Height from top of platform: 42.8 cm
  •   Height of Water Above Weir: 4.9 cm
  •   Exit Pipe Diameter: 6 inches
Wiki Markup
{cloak}

Wiki Markup
{toggle-cloak:id=Water Levels}
Water Levels

Wiki Markup
 Water Levels

{cloak:id=Water Levels}

The

...

water

...

level

...

throughout

...

the

...

plant

...

is

...

an

...

extremely

...

important

...

consideration

...

to

...

ensure

...

that

...

the

...

plant

...

will

...

function

...

correctly.

...

A

...

"Támara

...

Water

...

Levels"

...

program

...

was

...

created

...

to

...

determine

...

the

...

water

...

elevation

...

throughout

...

the

...

plant.

...

The

...

program

...

defines

...

the

...

elevation

...

reference

...

point,

...

Z=0m,

...

as

...

the

...

top

...

of

...

the

...

weir

...

because

...

the

...

weir

...

controls

...

the

...

level

...

of

...

the

...

plant.

...

Thus

...

it

...

is

...

simple

...

to

...

determine

...

the

...

affect

...

of

...

weir

...

height

...

adjustment

...

on

...

the

...

rest

...

of

...

the

...

plant

...

levels.

...

From

...

the

...

height

...

of

...

the

...

weir,

...

the

...

water

...

elevation

...

of

...

the

...

plant

...

leveling

...

tank

...

and

...

the

...

elevation

...

of

...

the

...

platform

...

are

...

determined.

...

Using

...

the

...

headloss

...

through

...

each

...

portion

...

of

...

the

...

plant

...

and

...

the

...

heights

...

of

...

each

...

tank

...

relative

...

to

...

the

...

platform,

...

the

...

water

...

elevations

...

and

...

depths

...

throughout

...

the

...

plant

...

can

...

be

...

calculated

...

as

...

a

...

function

...

of

...

plant

...

flow

...

rate.

...

All

...

headloss

...

values

...

are

...

calculated

...

within

...

the

...

program

...

using

...

methods

...

presented

...

throughout

...

the

...

paper.

...

However,

...

the

...

headloss

...

through

...

the

...

flocculation

...

tank

...

is

...

set

...

at

...

20

...

cm.

...

The

...

true

...

headloss

...

in

...

the

...

flocculation

...

tank

...

is

...

not

...

yet

...

known

...

because

...

the

...

baffle

...

design

...

has

...

not

...

been

...

created.

...

The

...

value

...

of

...

20

...

cm

...

was

...

chosen

...

because

...

it

...

will

...

leave

...

enough

...

headloss

...

to

...

achieve

...

good

...

flocculation.

...

Headloss

...

is

...

negligible

...

through

...

the

...

sedimentation

...

tank

...

and

...

channel.

...

Headloss

...

through

...

the

...

launders

...

is

...

taken

...

as

...

an

...

average

...

between

...

all

...

three

...

launders

...

because

...

each

...

exit

...

pipe

...

portion

...

has

...

a

...

different

...

headloss

...

due

...

to

...

the

...

different

...

lengths.

...

However,

...

headloss

...

from

...

the

...

the

...

orifices

...

into

...

the

...

launder

...

and

...

the

...

headloss

...

through

...

the

...

turns

...

to

...

the

...

plant

...

leveling

...

tank

...

are

...

much

...

more

...

significant

...

than

...

major

...

losses

...

in

...

this

...

case.

...

A

...

minimum

...

free

...

fall

...

height

...

of

...

10

...

cm

...

was

...

set

...

between

...

the

...

grit

...

chamber

...

orifice

...

level

...

and

...

the

...

water

...

surface

...

in

...

the

...

rapid

...

mix

...

.

...

The

...

program

...

will

...

calculate

...

the

...

water

...

level

...

for

...

any

...

given

...

flow

...

rate

...

and

...

up

...

to

...

three

...

sedimentation

...

tanks.

...

The

...

number

...

of

...

sedimentation

...

tanks

...

and

...

the

...

flow

...

rate

...

have

...

been

...

varied

...

to

...

ensure

...

that

...

the

...

plant

...

will

...

still

...

run

...

properly.

...

The

...

program

...

outputs

...

a

...

graph

...

showing

...

the

...

different

...

water

...

heights

...

through

...

the

...

plant.

...

Image Added
Figure 18.Graphical output of Támara Water Levels program.

Water levels and depths for the proposed plant design are in Table 1. These levels are shown in Figure 19.

TABLE 1

Image Added
Figure 19. Drawing of Vertical Distances including Water Heights

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Wiki Markup
{toggle-cloak:id=Conclusions}
Conclusions

Wiki Markup
 Conclusions

{cloak:id=Conclusions}

A

...

basic

...

design

...

of

...

the

...

Támara

...

water

...

treatment

...

plant

...

has

...

been

...

completed.

...

However,

...

not

...

all

...

details

...

could

...

possibly

...

be

...

included

...

in

...

this

...

report.

...

A

...

3-D

...

drawing

...

will

...

be

...

created,

...

which

...

will

...

show

...

how

...

all

...

the

...

pipes

...

will

...

fit

...

in

...

and

...

where

...

they

...

will

...

lead.

...

Furthermore,

...

some

...

design

...

considerations

...

are

...

left

...

until

...

next

...

semester.

...

The

...

first

...

is

...

the

...

baffle

...

spacing,

...

as

...

detailed

...

earlier.

...

The

...

second

...

is

...

the

...

level

...

and

...

detail

...

of

...

the

...

alum

...

feeder

...

and

...

chlorine

...

feeder.

...

The

...

alum

...

feeder

...

and

...

chlorine

...

feeder

...

will

...

both

...

be

...

located

...

on

...

tables

...

in

...

the

...

plant.

...

The

...

plant

...

operator

...

in

...

Ojojona

...

has

...

expressed

...

the

...

desire

...

for

...

the

...

feeder

...

and

...

chemical

...

barrels

...

to

...

be

...

propped

...

up

...

above

...

the

...

tables

...

so

...

that

...

the

...

operator

...

may

...

easily

...

stand

...

on

...

the

...

tables.

...

This

...

table

...

height

...

has

...

been

...

specified

...

by

...

the

...

APP

...

engineer,

...

though

...

the

...

AguaClara

...

team

...

has

...

been

...

unable

...

to

...

find

...

its

...

exact

...

value.

...

The

...

chemical

...

feed

...

process

...

is

...

being

...

worked

...

on

...

by

...

an

...

AguaClara

...

team

...

this

...

semester.

...

Since

...

the

...

design

...

may

...

be

...

improved

...

and

...

it

...

is

...

not

...

a

...

permanent

...

poured

...

in

...

concrete

...

design,

...

this

...

will

...

be

...

left

...

for

...

a

...

later

...

date.

...

The

...

piping

...

from

...

the

...

plant

...

leveling

...

tank

...

to

...

the

...

distribution

...

tank

...

must

...

be

...

designed

...

as

...

well.

...

When

...

the

...

final

...

pipe

...

design

...

is

...

put

...

together

...

it

...

should

...

be

...

noted

...

that

...

freefall

...

from

...

the

...

weir

...

is

...

necessary.

...

If

...

possible,

...

up

...

to

...

2

...

m

...

of

...

freefall

...

should

...

be

...

designed

...

for

...

to

...

include

...

the

...

possibility

...

of

...

adding

...

in

...

a

...

rapid

...

sand

...

filter

...

in

...

the

...

future.

...

Throughout

...

the

...

report,

...

a

...

few

...

design

...

considerations

...

have

...

not

...

fit

...

in

...

any

...

detailed

...

sections,

...

so

...

they

...

are

...

included

...

here

...

to

...

ensure

...

they

...

are

...

not

...

forgotten.

...

  •  Tank Wall Thickness:

...

  • 1

...

  • brick

...

  • =

...

  • 15 cm
  •  Waste Collection Tank Size = Size of Plant Leveling Tank, 1m x 1m x 70.5 cm
  •  Platform thickness = 12 cm
Wiki Markup
 cm
¿ Waste Collection Tank Size = Size of Plant Leveling Tank, 1m x 1m x 70.5 cm
¿ Platform thickness = 12 cm
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