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\begin_body

\begin_layout Title
Flocculator and Sedimentation Tank Optimization
\end_layout

\begin_layout Author
Marion Alberty, Ju Khuan Pan, Kester Wilkening
\end_layout

\begin_layout Date
May 11th, 2012
\end_layout

\begin_layout Section
Introduction
\end_layout

\begin_layout Standard
Currently AguaClara plants do a satisfactory job of delivering clean water
 to communities, and there has been a lot of research into how to optimize
 each individual process within AguaClara plants.
 However, there is a need to optimize the plants as a whole in order to
 reduce construction and operating costs.
 This has become especially important since the addition of the stacked
 rapid sand filter.
 With the filter, the target turbidity from the sedimentation tank effluent
 can be increased, i.e.
 the water can be incrementally dirtier coming out of the sedimentation
 tank.
 This could mean two of the largest processes within AguaClara plants, flocculat
ion and sedimentation, may be over-designed.
 If the size of either of these two systems can be reduced, AguaClara plants
 could become even more affordable.
 This will increase the availability of AguaClara plants to communities
 in need of effective water treatment technologies.
 
\end_layout

\begin_layout Standard
The goal of our research is to optimize the overall effectiveness of AguaClara
 plants by focusing on flocculation and sedimentation.
 This will be done by observing the effects of varying the different parameters
 that control the design of each process.
 In the Spring 2012 semester, an optimal sedimentation tank upflow velocity,
 
\begin_inset Formula $V_{SedUp}$
\end_inset

 , was determined to be 2mm/s.
 Some important insights about implementing floc recycle were also obtained.
 The next parameters to be studied are detailed in the Future Work section
 of this paper.
\end_layout

\begin_layout Section
Literature Review
\end_layout

\begin_layout Subsection
Coagulant
\end_layout

\begin_layout Standard
In the masters’ thesis presented by Matt Hurst 
\begin_inset CommandInset citation
LatexCommand cite
key "key-3"

\end_inset

, optimal alum dosages were studied for 10, 100, 200 and 500 NTU raw water.
 For raw water with a turbidity of 100 NTU, the variability of turbidity
 in the tube settlers significantly decreased as alum dosages were increased
 from 25 mg/L to 45 mg/L.
 Optimal dosages of alum for 100 and 200 NTU raw water were noted to be
 45 mg/L and 65 mg/L, respectively.
 It was also noted that performance did not deteriorate at higher dosages
 of alum in either case.
 Testing for optimal alum dosages was also done for raw water of 10 and
 500 NTU.
 Using the four data points acquired, the following empirical relationship
 for optimal alum dosages was attained:
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
Alum_{Dosage}(mg/L)=7.8(Turbidity)^{0.4}\label{eq:DesiredAlumDose}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
This could be a conservative estimate, in particular for 500 NTU water,
 nevertheless it will be used as the initial coagulant dose in the system.
 As with other portions of the water clarification process, the coagulant
 dosage in the system will be examined and possibly changed.
 
\end_layout

\begin_layout Subsection
Rapid Mix and Flocculation
\end_layout

\begin_layout Standard
The velocity gradient (
\begin_inset Formula $G$
\end_inset

) in the rapid mix system is a key parameter to determine how well the influent
 water and coagulant (alum) are mixed.
 The velocity gradient is a measure of how the layers of fluid move at different
 speeds across the cross section of the rapid mix tubing.
 These differential speeds cause shear forces that mix the raw water and
 alum, such that the suspended solids in the water are coated with alum.
 These 
\begin_inset Quotes eld
\end_inset

sticky
\begin_inset Quotes erd
\end_inset

 particles can then collide to form bigger flocs in the flocculator.
 The calculation of 
\begin_inset Formula $G$
\end_inset

 is defined under the “Methods” section of this paper, and the desired value
 of 
\begin_inset Formula $G$
\end_inset

 will determine the dimensions of the rapid mix.
 The desired value for 
\begin_inset Formula $G$
\end_inset

 in rapid mix is 500 
\begin_inset Formula $s^{-1}$
\end_inset

, as determined by the jar test performed by Dan Smith 
\begin_inset CommandInset citation
LatexCommand cite
key "key-5"

\end_inset

.
\end_layout

\begin_layout Standard
Ian Tse, et.
 al (2011)
\begin_inset CommandInset citation
LatexCommand cite
key "key-6"

\end_inset

, discusses the relationship between 
\begin_inset Formula $G$
\end_inset

 inside a laminar flow flocculator and collision potential.
 The value of 
\begin_inset Formula $G$
\end_inset

 determines the dimensions of the flocculator similar to the process for
 designing the rapid mix unit.
 However, the optimal 
\begin_inset Formula $G$
\end_inset

 for flocculation is much smaller, ranging from 30 to 100 
\begin_inset Formula $s^{-1}$
\end_inset

.
 Below 30 
\begin_inset Formula $s^{-1}$
\end_inset

, there is insufficient mixing to provide collisions .
 Above 100 
\begin_inset Formula $s^{-1}$
\end_inset

, the velocity gradient is so large that it starts to break up larger flocs.
 The goal of flocculation is to have flocs that are large enough so that
 they are able to settle out before leaving the sedimentation tank.
 
\end_layout

\begin_layout Standard
Residence time, 
\begin_inset Formula $\theta$
\end_inset

, is the amount of time in seconds the particles are in the flocculator.
 Collision potential is a measure of the ability of the laminar flow reactor
 to produce collisions, and it is described by:
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
CollisionPotential(unitless)=G(\theta)\label{eq:CollisionPotential}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
Residence time is largely dependent on the length of the flocculator.
 One of the goals of this research is to reduce the residence time of the
 flocculator, which will reduce the size of the actual flocculators in AguaClara
 plants.
 Since the apparatus in this experiment will be optimizing the residence
 time, it is important that the velocity gradient be within the desired
 range.
 In actual AguaClara plants the flocculators are turbulent, so in that case
 energy dissipation is used to determine the overall flocculation potential.
 However, for lab purposes, laminar flow allows the use of 
\begin_inset Formula $G$
\end_inset

 to determine flocculator dimensions.
\end_layout

\begin_layout Subsection
Sedimentation Tank
\end_layout

\begin_layout Standard
The final report of the AguaClara Sedimentation Tank Hydraulics Team
\begin_inset CommandInset citation
LatexCommand cite
key "key-2"

\end_inset

 reported that a mixture of raw water and clay with a turbidity of 100 NTU
 and a coagulant dosage of 
\begin_inset Formula $45mg/L\, Alum$
\end_inset

 can form a floc blanket.
 However, according to Matt Hurst
\begin_inset CommandInset citation
LatexCommand cite
key "key-3"

\end_inset

, when influent turbidity is reduced (<5 NTU) the floc blanket is eventually
 washed out.
 For the experiments presented in the thesis, raw water turbidity ranged
 from 10 to 500 NTU.
 Improved performance was found to correlate with the height of the floc
 blanket.
 However, tube settlers were necessary to achieve an effluent turbidity
 of less than 1 NTU.
 The optimum floc blanket height can be interpreted as being 45 cm, as floc
 blanket performance did not appear to improve beyond that height in cases
 where tube flocculation was present.
 Previous AguaClara research has shown that at the inflow of the sedimentation
 tank, a conical geometry is best to re-suspend settling flocs that are
 drawn down and can be propelled upwards by the inflow jet
\begin_inset CommandInset citation
LatexCommand cite
key "key-1"

\end_inset

.
\end_layout

\begin_layout Subsection
Tube Settlers
\end_layout

\begin_layout Standard
Angled tube settlers are a compact way to remove low NTU water from the
 top of the sedimentation tank.
 It has been shown in current AguaClara plants that an angle of 
\begin_inset Formula $60^{o}$
\end_inset

 is an optimal design for angled tube settlers.
 The angled tubing decreases the distance flocs have to fall to hit the
 side of the tubing.
 Since the velocity at the wall of the tube settler is very low, the flocs
 can then roll down the side of the tube settlers and back into the sedimentatio
n tank.
 
\end_layout

\begin_layout Standard
The Final Report from the AguaClara Floc Roll-up Tube Settlers Team
\begin_inset CommandInset citation
LatexCommand cite
key "key-4"

\end_inset

 analyzes the phenomena of floc roll-up.
 They found that this failure is caused by high velocity gradients in the
 tube settlers, which arise from either too small of a tube diameter or
 too high of an upflow velocity causing floc particles to travel up the
 tube settlers.
 These failure points have been taken into consideration and are detailed
 under the Methods section.
\end_layout

\begin_layout Subsection
Floc Recycle
\end_layout

\begin_layout Standard
In 
\begin_inset CommandInset citation
LatexCommand cite
key "key-8"

\end_inset

, McLane, John C.
 details the success of a floc recycle system in treating raw water with
 a wide ranging turbidity (4 to 3000 NTU) at a water treatment plant in
 Fort Madison.
 A submersible sump pump was installed at the bottom of the settling tank,
 to extract settled sludge and reintroduce it back into the plant just before
 rapid mix.
 Over a period of 7 years, the recycle system proved to be extremely successful
 at improving the water quality of the finished water.
 Regardless of the incoming turbidity, turbidity of the effluent from the
 sedimentation basin has stabilized at about 3.0 NTU, a 90% reduction from
 the values of 30 to 50 NTU achieved previously.
 Heterotrophic plate counts, a test for bacteria, were also reduced from
 >100,000/mL to < 10/mL in the sedimentation basin effluent.
 The success of floc recycle in this water treatment plant is the inspiration
 behind the incorporation of floc recycle into the team's research this
 semester.
\end_layout

\begin_layout Section
Methods
\end_layout

\begin_layout Subsection
Plant Schematic
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Graphics
	filename Lab System Diagram (Simple).png
	width 13cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Plant-Schematic"

\end_inset

Plant Schematic
\end_layout

\end_inset


\end_layout

\end_inset

 
\end_layout

\begin_layout Standard
The team created a detailed plant schematic to aid in the design calculations
 for our experiments.
 The design was based on the previous setup that was present in the laboratory
 and the suggestions given in the team’s challenge document.
 This enabled the group to easily organize the results from calculations
 of tube size, sedimentation tank diameter, flocculator coil diameter and
 tube settler outflow locations on the schematic in a manner that was easily
 understandable and user friendly.
 The simplified version presented above only depicts the planned experimental
 setup without dimensions and design decisions.
 
\end_layout

\begin_layout Standard
The physical experimental setup is presented in the following figures.
 
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset space \hspace{}
\length 1cm
\end_inset


\begin_inset Graphics
	filename Expt Set Up Final.PNG
	width 11cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Experimental-Setup-(Front"

\end_inset

Experimental Setup (Front view)
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset space \hspace{}
\length 2.5cm
\end_inset


\begin_inset Graphics
	filename Expt Setup Side View.png
	width 7cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Experimental-Setup-(Side"

\end_inset

Experimental Setup (Side view)
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsubsection
Floc Hopper Design
\end_layout

\begin_layout Standard
The floc hopper controls the height of the floc blanket in the sedimentation
 tank, and also allows time for the floc blanket overflow to consolidate
 and dewater.
 For experimental purposes, a floc hopper was created by placing a wye connectio
n above the desired height of the floc blanket (See Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Floc-Hopper"

\end_inset

).
 A compression fitting is used to connect the pipe to tubing, and the outflow
 from the wye is controlled by a manual valve.
 The floc blanket flows over the wye and flocs settle down to the manual
 valve.
 During 3 NTU operation, the manual valve is closed, causing the flocs to
 consolidate within the miniature floc hopper.
 The outlet valve is opened periodically in order to waste the dewatered
 flocs.
 This process mimics the actual cleaning process that would occur for a
 full scale floc hopper in an AguaClara plant.
 
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset space \hspace{}
\length 3cm
\end_inset


\begin_inset Graphics
	filename Floc Hopper.png
	width 7cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Floc-Hopper"

\end_inset

Floc Hopper
\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Subsubsection
Floc Recycle Design
\end_layout

\begin_layout Standard
The floc recycle line allows a limited amount of flocs from the floc blanket
 to be pumped back into the beginning of the flocculator.
 The floc recycle line draws flocs from just below the top of the floc blanket.
 It was determined that the density of the flocs within the floc blanket
 is uniform enough that flocs can be pulled out at any height within the
 floc blanket, and this should not decrease the effectiveness of the floc
 recycle.
 
\end_layout

\begin_layout Standard
Once the floc-water mixture is in the floc recycle line, it was observed
 that flocs may begin to settle out onto the walls of the line.
 To prevent this settling from occurring, the velocity in the tubing must
 be high enough to overcome the settling velocity of the flocs.
 The velocity in the tubing is affected by the tube diameter of the floc
 recycle line, plant flow rate, and floc recycle ratio.
 
\end_layout

\begin_layout Standard
The floc recycle system then reintroduces the turbid water back into the
 main system just after the rapid mix and before the flocculator.
 It is thought that inserting recycled flocs at this point will provide
 the newly mixed, 
\begin_inset Quotes eld
\end_inset

sticky
\begin_inset Quotes erd
\end_inset

 particles with more suspended solids to 
\begin_inset Quotes eld
\end_inset

stick
\begin_inset Quotes erd
\end_inset

 onto and form flocs.
 Floc recycling is expected to increase the floc solids concentration in
 the flocculator and thus, increase collision potential within the flocculator.
 As a result, it is likely that the length of the flocculator or coagulant
 dose could be decreased when floc recycle is implemented.
 
\end_layout

\begin_layout Subsubsection
Elevated Waste Line
\end_layout

\begin_layout Standard
The waste line was elevated above the source of the raw water in order to
 increase the total head of the water moving through the experimental set
 up.
 The additional elevation head translates to an increase of pressure in
 the flocculator.
 This increase of pressure prevents dissolved gases from escaping out of
 solution and creating bubbles within the set-up.
 At the highest point of the waste line, an aeration tube was also added
 to allow any air trapped within the line to escape to the atmosphere (See
 Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Elevated-Waste-Line"

\end_inset

).
 
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\begin_inset space \hspace{}
\length 4cm
\end_inset


\begin_inset Graphics
	filename Elevated Waste Line.jpg
	height 8cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Elevated-Waste-Line"

\end_inset

Elevated Waste Line Schematic
\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Design Decisions
\end_layout

\begin_layout Standard
A MathCAD file was used to calculate the operating parameters and dimensions
 required for the experimental setup.
 
\end_layout

\begin_layout Standard
The team's objective is to test the range of parameters listed in Table
 
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:Range-of-parameters"

\end_inset

 while meeting the constraints established by the literature review.
 
\end_layout

\begin_layout Standard
\begin_inset Float table
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "tab:Range-of-parameters"

\end_inset

Range of parameters to test
\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Tabular
<lyxtabular version="3" rows="6" columns="4">
<features tabularvalignment="middle" tabularwidth="80text%">
<column alignment="center" valignment="top" width="20text%">
<column alignment="center" valignment="top" width="15text%">
<column alignment="center" valignment="top" width="25text%">
<column alignment="center" valignment="top" width="15text%">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Parameter
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Symbol
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Method
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Parameter Range
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Flocculator length
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $L_{Floc}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
5 solenoid valves to select the inlet location
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
1 m, 2 m, 5 m, 10 m, 20 m
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Sedimentation upflow velocity
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $V{}_{SedUp}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vary the flow rate through the entire plant with maximum collision potential
 and capture velocities 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $1\,\frac{mm}{s}$
\end_inset

, 
\begin_inset Formula $1.5\,\frac{mm}{s}$
\end_inset

, 
\begin_inset Formula $2\,\frac{mm}{s}$
\end_inset

, 
\begin_inset Formula $2.5\,\frac{mm}{s}$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Ratio of upflow to capture velocity
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\Pi_{Capture}=\frac{V_{Capture}}{V_{SedUp}}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
5 solenoid valves to select the outlet location from tube settler
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.05, 0.1, 0.15, 0.2, 0.25
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Recycle flow rate ratio
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\Pi_{Q_{Recycle}}=\frac{Q_{Recycle}}{Q_{Plant}}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
variable speed peristaltic pump on recycle line
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0, 0.02, 0.05, 0.1, 0.2
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Raw water turbidity
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
pinch valve based on measured turbidity
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $3\, NTU$
\end_inset

, 
\begin_inset Formula $500\, NTU$
\end_inset


\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsubsection
Sedimentation Tank
\end_layout

\begin_layout Standard
The lab-scale sedimentation tank is a vertical, clear pipe.
 Its inner diameter, 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none

\begin_inset Formula $D_{SedTank}$
\end_inset


\family default
\series default
\shape default
\size default
\emph default
\bar default
\strikeout default
\uuline default
\uwave default
\noun default
\color inherit
, and the upflow velocity, 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 determine the total plant flow rate, 
\begin_inset Formula $Q_{Plant}$
\end_inset

.
\end_layout

\begin_layout Standard
The inflow from the flocculator into the sedimentation tank has to be delivered
 by a pipe with a minimum diameter, 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none

\begin_inset Formula $D_{FlocToSedMin}$
\end_inset

,
\family default
\series default
\shape default
\size default
\emph default
\bar default
\strikeout default
\uuline default
\uwave default
\noun default
\color inherit
 calculated using Equation
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:D.IntoSed"

\end_inset

.
 
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
D_{FlocToSedMin}=\left(\frac{Q_{Plant}}{\varepsilon_{Max}^{\frac{1}{3}}}\frac{4\Pi_{Jet}}{\pi}\right)^{\frac{3}{7}}\label{eq:D.IntoSed}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
The value of 
\begin_inset Formula $\varepsilon_{Max}$
\end_inset

= 
\begin_inset Formula $10\;\frac{mW}{kg}$
\end_inset

 and
\begin_inset Formula $\Pi_{Jet}$
\end_inset

 = 0.4 used in AguaClara plants is also assumed here.
 The jet from the pipe will be discharged at the bottom of a cone to facilitate
 the formation of a floc blanket.
\end_layout

\begin_layout Standard
The tube settler is a clear PVC pipe connected to the top of the sedimentation
 tank at 60 degrees to the horizontal.
 It has the same inner diameter as the sedimentation tank, so 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none

\begin_inset Formula $D_{TubeSettler}$
\end_inset


\family default
\series default
\shape default
\size default
\emph default
\bar default
\strikeout default
\uuline default
\uwave default
\noun default
\color inherit
 = 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none

\begin_inset Formula $D_{SedTank}$
\end_inset


\family default
\series default
\shape default
\size default
\emph default
\bar default
\strikeout default
\uuline default
\uwave default
\noun default
\color inherit
.
 Instead of varying the absolute value of capture velocity, the 
\begin_inset Formula $\frac{V_{SedUp}}{V_{Capture}}$
\end_inset

 ratio will be changed.
 
\end_layout

\begin_layout Standard
In order to achieve the desired 
\begin_inset Formula $\frac{V_{SedUp}}{V_{Capture}}$
\end_inset

 ratio, the length of the tube settler is calculated according to Equation
 
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:L.TubeSettler"

\end_inset

.
 There will be multiple outflow locations along the tube settler, controlled
 by solenoid valves.
 
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
L_{TubeSettler}=\frac{D_{TubeSettler}\left(\frac{V_{TubeUp}}{V_{Capture}}-1\right)}{\cos\alpha_{TubeSettler}*\sin\alpha_{TubeSettler}}\label{eq:L.TubeSettler}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
where
\begin_inset Formula $\alpha_{TubeSettler}=\frac{\pi}{3}$
\end_inset

 is the angle of the tube settler to the horizontal and 
\begin_inset Formula $V_{TubeUp}$
\end_inset

 is the vertical velocity component in the tube settler.
 
\end_layout

\begin_layout Standard
To check that 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none

\begin_inset Formula $D_{TubeSettler}$
\end_inset


\family default
\series default
\shape default
\size default
\emph default
\bar default
\strikeout default
\uuline default
\uwave default
\noun default
\color inherit
 and 
\begin_inset Formula $Q_{Plant}$
\end_inset

 will not cause floc roll-up, Equation
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:S.Min"

\end_inset

 was used, which is derived in
\begin_inset CommandInset citation
LatexCommand cite
key "key-7"

\end_inset

.
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
D_{TubeSettler}\geq\frac{3V_{TubeUp}d_{Floc}}{V_{Capture}\sin^{2}\alpha_{TubeSettler}}\label{eq:S.Min}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
d_{Floc}=d_{0}*\left(\frac{18V_{Capture}\Phi\nu_{H2O}}{gd_{0}^{2}}\frac{\rho_{H2O}}{\rho_{Floc,0}-\rho_{H2O}}\right)^{\frac{1}{D_{Fractal}-1}}\label{eq:d.Floc}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
where 
\begin_inset Formula $d_{Floc}$
\end_inset

 is the diameter of a floc with a sedimentation velocity equal to the capture
 velocity, 
\begin_inset Formula $d_{0}=1\,\mu m$
\end_inset

 is the primary particle diameter (clay and coagulant), 
\begin_inset Formula $\Phi=\frac{45}{24}$
\end_inset

 is a shape factor for drag on flocs, 
\begin_inset Formula $\rho_{Floc,0}$
\end_inset

 is the density of primary floc particles, 
\begin_inset Formula $D_{Fractal}$
\end_inset

 is 2.3.
\end_layout

\begin_layout Subsubsection
Flocculator 
\end_layout

\begin_layout Standard
The flocculator must have a velocity gradient between 30 to 100/s.
 The average 
\begin_inset Formula $G$
\end_inset

 in laminar tube flow is defined by Equation 
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:Gs"

\end_inset

for a straight tube, where 
\begin_inset Formula $Q$
\end_inset

 is the volumetric flow rate and 
\begin_inset Formula $r$
\end_inset

 is the inner radius of the tube.
 
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
G_{Straight}=\frac{8Q}{3\pi r^{3}}\label{eq:Gs}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
For a coiled flocculator, the method outlined by Tse et.
 al.
\begin_inset CommandInset citation
LatexCommand cite
key "key-6"

\end_inset

 is used to calculate 
\begin_inset Formula $G$
\end_inset

:
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
G_{Coiled}=G_{Straight}(1+0.033(\log(De))^{4})^{\frac{1}{2}}\label{eq:Gc}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
Where 
\begin_inset Formula $De=\frac{VD}{\nu}\left(\frac{D}{2D_{Coil}}\right)^{\frac{1}{2}}$
\end_inset

is the Dean number, 
\begin_inset Formula $D$
\end_inset

 is the inner diameter of the tube, 
\begin_inset Formula $D_{Coil}$
\end_inset

 is the diameter of curvature, and 
\begin_inset Formula $\upsilon$
\end_inset

 is the kinematic viscosity of the fluid.
 
\end_layout

\begin_layout Standard
The inner diameter of the tube flocculator, 
\begin_inset Formula $D_{Floc}$
\end_inset

, and the diameter of the coil, 
\begin_inset Formula $D_{FlocCoil}$
\end_inset

, was varied in order to achieve 
\begin_inset Formula $G_{Coiled}$
\end_inset

 of within 
\begin_inset Formula $30s^{-1}$
\end_inset

 to 
\begin_inset Formula $100s^{-1}$
\end_inset

.
 
\end_layout

\begin_layout Subsubsection
Rapid Mix
\end_layout

\begin_layout Standard
There will be a pump to deliver coagulant from the coagulant stock tank.
 This flow rate, 
\begin_inset Formula $Q_{CoagStock}$
\end_inset

, will determine the dosage.
 Hence, the appropriate flow rate of the pump will depend on the turbidity
 of the raw water and the total plant flow (See Equation 
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:Q.CoagStock"

\end_inset

).
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
Q_{CoagStock}=\frac{Q_{Plant}C_{CoagDose}}{C_{CoagStock}}\label{eq:Q.CoagStock}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
Where 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none

\begin_inset Formula $C_{CoagDose}$
\end_inset

 is the desired coagulant dose, and 
\begin_inset Formula $C_{CoagStock}$
\end_inset

 is the concentration of coagulant in the coagulant stock tank.
 
\end_layout

\begin_layout Standard

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
Using the empirical formula (See Equation 
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:DesiredAlumDose"

\end_inset

) developed by Hurst (2009)
\begin_inset CommandInset citation
LatexCommand cite
key "key-3"

\end_inset

, 
\begin_inset Formula $C_{CoagDose}$
\end_inset

 is approximately 
\begin_inset Formula $15mg/L$
\end_inset

 for 3 NTU water and 
\begin_inset Formula $95mg/L$
\end_inset

 for 500 NTU water.
 
\end_layout

\begin_layout Standard
The rapid mix system is a coiled tube.
 To achieve good mixing, the desired 
\begin_inset Formula $G$
\end_inset

 in the rapid mix coil is 
\begin_inset Formula $500s^{-1}$
\end_inset

.
 Equations 
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:Gs"

\end_inset

 and 
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:Gc"

\end_inset

 apply here as well.
 The inner diameter of the rapid mix tubing, 
\begin_inset Formula $D_{RapMix}$
\end_inset

 and the diameter of the coil, 
\begin_inset Formula $D_{RapMixCoil}$
\end_inset

, were varied in order to achieve the desired range of 
\begin_inset Formula $G$
\end_inset

.
 However, the team decided to relax the constraints on 
\begin_inset Formula $G$
\end_inset

 and use a tubing size that was more readily available instead.
 
\end_layout

\begin_layout Standard
Another constraint for the rapid mix system is that the point of mixing
 between the raw water and coagulant should occur at most 
\begin_inset Formula $1\, second$
\end_inset

 away from the rapid mix coil, in order to reduce the opportunity for the
 coagulant to precipitate on itself.
 This can easily be ensured by minimizing the length of tubing between the
 point of mixing and the coil.
\end_layout

\begin_layout Subsubsection
Summary of Design Decisions
\end_layout

\begin_layout Standard
Tables 
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:Summary-of-Dimensions"

\end_inset

 and 
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:Summary-of-Operating"

\end_inset

 summarize the design decisions we have made for the first iteration of
 our experiments.
 
\end_layout

\begin_layout Standard
\begin_inset Float table
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "tab:Summary-of-Dimensions"

\end_inset

Summary of Dimensions
\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Tabular
<lyxtabular version="3" rows="15" columns="3">
<features tabularvalignment="middle" tabularwidth="100text%">
<column alignment="center" valignment="top" width="20text%">
<column alignment="center" valignment="top" width="0">
<column alignment="center" valignment="top" width="0pt">
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Parameter
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Symbol
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Values
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Inner Diameter of Pipe into Sedimentation Tank
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
\begin_inset Formula $D_{FlocToSedMin}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\frac{3}{16}in$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Inner Diameter of Sedimentation Tank
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
\begin_inset Formula $D_{SedTank}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $1.033in$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Inner Diameter of Tube Settler
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
\begin_inset Formula $D_{TubeSettler}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $1.033in$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Location of Tube Settler Outlet
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
\begin_inset Formula $L_{TubeSettler}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $0.989m,0.464m,0.289m,0.202m,0.149m$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Inner Diameter of Flocculator
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $D_{Floc}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\frac{3}{16}in$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Diameter of Flocculator Coil
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $D_{FlocCoil}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $12cm$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Inner Diameter of Rapid Mix
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $D_{RapMix}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\frac{1}{8}in$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Diameter of Rapid Mix Coil
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $D_{RapMixCoil}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $9cm$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Concentration in Coagulant Stock Tank
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
\begin_inset Formula $C_{CoagStock}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $2g/L$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Coagulant Dose for 3 NTU water
\end_layout

\end_inset
</cell>
<cell multirow="3" alignment="center" valignment="middle" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
\begin_inset Formula $C_{CoagDose}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
\begin_inset Formula $15mg/L$
\end_inset

 
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Coagulant Dose for 200 NTU water
\end_layout

\end_inset
</cell>
<cell multirow="4" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
\begin_inset Formula $65mg/L$
\end_inset

 
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Coagulant Dose for 500 NTU water
\end_layout

\end_inset
</cell>
<cell multirow="4" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout

\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
\begin_inset Formula $95mg/L$
\end_inset

 
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Tubing from Coagulant Stock Tank to Rapid Mix Coil
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $L_{Stock2RapMix}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $0.17in$
\end_inset


\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Inner Diameter of Floc Recycle Line
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $D_{FlocRecycleLine}$
\end_inset


\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
\begin_inset Formula $\frac{1}{8}in$
\end_inset


\end_layout

\end_inset
</cell>
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\end_inset


\end_layout

\end_inset


\end_layout

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\begin_inset Caption

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LatexCommand label
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Summary of Operating Conditions
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\end_inset


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\length 2.5cm
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Turbidity (NTU)
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500
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1.352
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\end_inset


\end_layout

\begin_layout Subsubsection
Converting Desired Flow Rates to Pump Speeds
\end_layout

\begin_layout Standard
Table 
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:Pump-Speeds-corresponding"

\end_inset

shows the flow rates that can be achieved by a peristaltic pump for different
 tubing sizes.
 It can be used to calculate the equivalent pump speeds (rpm) for desired
 flow rates.
 
\end_layout

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wide false
sideways false
status open

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\begin_inset Caption

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Pump Speeds corresponding to different tube sizes and flow rates (Peristaltic
 Pumps)
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LatexCommand label
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\end_inset


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Tubing Number
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13
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14
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18
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Max Pump Speed (rpm)
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100
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100
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100
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100
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Max Flow Rate (mL/min)
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6.0
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21.0
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80.0
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280
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380
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\end_layout

\end_inset


\end_layout

\begin_layout Standard
Given a tubing number, this relationship can be used to find the corresponding
 pump speed:
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
RPM_{Tubing}=\frac{Q_{Desired}}{Q_{Tubing,Max}}*RPM_{Tubing,Max}\label{eq:RPMofPeristalticPump}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
Where the subscript 
\begin_inset Quotes eld
\end_inset

Tubing
\begin_inset Quotes erd
\end_inset

 indicates that the values of the parameters correspond to the selected
 tubing size.
 Table 
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:Peristaltic-Pump-Tubing"

\end_inset

 shows the sizes of the peristaltic pump tubing used for the three pumps
 in the experimental set up.
\end_layout

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wide false
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status open

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\begin_inset Caption

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LatexCommand label
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Peristaltic Pump Tubing Sizes in the Experimental Set Up
\end_layout

\end_inset


\end_layout

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Pump Number
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Purpose of Pump
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Peristaltic Pump Tubing Size
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1
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</cell>
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To deliver raw water into the plant
\end_layout

\end_inset
</cell>
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16
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1
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To deliver water into the influent turbidimeter
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17
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2
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To deliver coagulant into the rapid mix system
\end_layout

\end_inset
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13
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3
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</cell>
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\begin_inset Text

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To recycle flocs
\end_layout

\end_inset
</cell>
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\begin_inset Text

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14
\end_layout

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</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Order of Experiments 
\end_layout

\begin_layout Standard
Table 
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:Proposed-Order-of"

\end_inset

details the proposed order in which the team planned to vary each parameter
 for this semester.
 Each test should be done at both 500 and 3 NTU in order to test the upper
 and lower limits of expected influent turbidities in an AguaClara plant.
 The tests will be paired with another of the same turbidity so that there
 is less transition time between tests.
 During the 3 NTU tests, a floc blanket will first be built at 200 NTU.
 The system will then transition into a 3 NTU state before continuing with
 the rest of the experiment.
\end_layout

\begin_layout Standard
The first column in the table below describes the proceeding order of experiment
s.
 Once an optimal variable is found, that variable will be used throughout
 the rest of the experiments.
\end_layout

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wide false
sideways false
status collapsed

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\begin_inset Caption

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\begin_inset CommandInset label
LatexCommand label
name "tab:Proposed-Order-of"

\end_inset

Proposed Order of Experiments
\end_layout

\end_inset


\end_layout

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Goals
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\begin_inset Formula $L_{Floc}$
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\begin_inset Text

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\begin_inset Formula $\Pi_{Capture}$
\end_inset


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\begin_inset Text

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\begin_inset Formula $\Pi_{Q_{Recycle}}$
\end_inset


\end_layout

\end_inset
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\begin_inset Text

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Turbidity
\end_layout

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Test System, Build Floc Blanket
\end_layout

\end_inset
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20 m
\end_layout

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1 mm/s
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0.1
\end_layout

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0
\end_layout

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\begin_inset Text

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200 NTU
\end_layout

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<row>
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Maintain Floc Blanket
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20 m
\end_layout

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1 mm/s
\end_layout

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0.1
\end_layout

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0
\end_layout

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<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

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3 NTU
\end_layout

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<row>
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Maintain Floc Blanket
\end_layout

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20 m
\end_layout

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2 mm/s
\end_layout

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0.1
\end_layout

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0
\end_layout

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\begin_inset Text

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3 NTU
\end_layout

\end_inset
</cell>
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<row>
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\begin_inset Text

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Optimal Floc Recycle Ratio
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
20 m
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2 mm/s
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vary
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Optimal Floc Recycle Ratio
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
20 m
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2 mm/s
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vary
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
500 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Min Flocculator Length, maintain floc blanket
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vary
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2 mm/s
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
500 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Min Flocculator Length, maintain floc blanket
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vary
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
2 mm/s
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Max/Optimal 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
Upflow Velocity
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
minimum
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vary
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Max/Optimal 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none
Upflow Velocity
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
minimum
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vary
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0.1
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
500 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Max/Optimal Capture Velocity Ratio
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
minimum
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
500 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Max/Optimal Capture Velocity Ratio
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
minimum
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
vary
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Optimal Coagulant dose
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
minimum
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Optimal Coagulant dose
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
minimum
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
3 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Optimal Coagulant dose
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
minimum
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
0
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
500 NTU
\end_layout

\end_inset
</cell>
</row>
<row>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
Optimal Coagulant dose
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
minimum
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
optimal
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Plain Layout
500 NTU
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Process Controller
\end_layout

\begin_layout Standard
Process Controller software was used to automate the experimentation process.
 Process Controller controls the pumps and solenoid valves, and collects
 data from the turbidimeters at 5-second intervals.
 
\end_layout

\begin_layout Standard
Each experiment was coded as a process controller method file, broken down
 into separate, independent 
\begin_inset Quotes eld
\end_inset

states
\begin_inset Quotes erd
\end_inset

.
 Each state keeps the system running under a different set of conditions.
 Boolean expressions in the form of 
\begin_inset Quotes eld
\end_inset

rules
\begin_inset Quotes erd
\end_inset

 are then used to switch between the states.
 
\end_layout

\begin_layout Standard
To illustrate, three states will be required in order to run the system
 at both 200 and 3 NTU: one to run it at 200 NTU, one for the transition
 between the two turbidities, and one to run it at 3 NTU.
 A rule for maximum elapsed time would control the duration of the first
 and last states, while a rule for the value of the influent turbidity would
 govern the duration of the transition state.
\end_layout

\begin_layout Subsection
Data Processing
\end_layout

\begin_layout Standard
MathCAD is used to process the experimental data that is collected by Process
 Controller.
 Functions are used to extract the run time, influent and effluent turbidity
 data from the Process Controller data log.
 The extracted data is then smoothed by taking the average of every 10 data
 points.
 
\end_layout

\begin_layout Standard
There are two ways to visualize the results of each experiment: the user
 can specify one particular state to analyze, or choose to analyze all states
 within an experiment.
 The resulting array of smoothed values will be plotted over the duration
 of each state if the user desires to view only the data from one selected
 state.
 For the user who prefers to see data from the entire experiment, a single
 averaged turbidity value will be calculated for each state and plotted
 against the state number.
 The user will be able to specify the particular time interval within each
 state for which to average the turbidity values.
 The team has decided to average the turbidity values that occurred 0.5 to
 2 hours after the beginning of each state.
 Since all states run for at least 2 hours, the system should probably have
 settled into a steady state during that interval.
 Both methods of data analysis will be presented in the team's results and
 discussion.
 
\end_layout

\begin_layout Standard
MathCAD is also used to compute performance statistics such as the 
\begin_inset Formula $pC*$
\end_inset

 during a particular state.
 
\begin_inset Formula $pC*$
\end_inset

 is a measure of turbidity removal efficiency that is independent of influent
 turbidity, and is calculated using the following equation:
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
pC*=-\log\left(\frac{EffluentTurbidity}{InfluentTurbidity}\right)\label{eq:pC*}
\end{equation}

\end_inset


\end_layout

\begin_layout Section
Results and Discussion
\end_layout

\begin_layout Subsection
Building and Maintaining a Floc Blanket
\end_layout

\begin_layout Standard
Several experiments were performed to test the system's ability to build
 and maintain a floc blanket at various values for 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

.
 Good performance (<3 NTU effluent turbidity) was observed throughout the
 the experiment where 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 was 2 mm/s (See Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Effluent-Turbidity-Overview"

\end_inset

).
 In the first state where the floc blanket was built with an influent turbidity
 of 200 NTU, effluent turbidity underwent minor fluctuations in the first
 hour before the floc blanket had begun to build up (See Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Effluent-Turbidity-st1"

\end_inset

).
 At approximately 2.5 hours into this state, effluent turbidity approached
 a steady-state value below 1 NTU.
 This time scale seemed to correspond with the floc blanket reaching the
 floc hopper.
 In the third state, the floc blanket was maintained at an influent turbidity
 of 3 NTU.
 A trend of increasing effluent turbidity is apparent over the duration
 of approximately 4 hours, but effluent turbidity was consistently below
 1 NTU (See Figures 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Effluent-Turbidity-st3"

\end_inset

).
 pC* also remained quite steady for the duration of the third state at about
 0.6 (See Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:pC*-in-st3"

\end_inset

).
 An image of the top of the floc blanket at the end of the experiment is
 shown in Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:FlocBlanketMeta14St3"

\end_inset

.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Graphics
	filename Meta14 Effluent Overview.png
	width 12cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Effluent-Turbidity-Overview"

\end_inset

State-Averaged Effluent Turbidity when 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 is 2 mm/s.
 The red dotted line indicates the 3 NTU threshold.
 
\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Graphics
	filename Meta14 E St1.png
	width 12cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Effluent-Turbidity-st1"

\end_inset

Effluent Turbidity in 500 NTU Building State (State 1)
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Graphics
	filename Meta14 IE St3.png
	width 12cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Influent-&-Effluent-st3"

\end_inset

Influent & Effluent Turbidity in 3 NTU Maintenance State (State 3)
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Graphics
	filename Meta14 E St3.png
	width 12cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Effluent-Turbidity-st3"

\end_inset

Effluent Turbidity in 3 NTU Maintenance State (State 3)
\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Graphics
	filename Meta14 pC St3.png
	width 12cm

\end_inset


\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:pC*-in-st3"

\end_inset

pC* in 3 NTU Maintenance State (State 3)
\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset space \hspace{}
\length 3cm
\end_inset


\begin_inset Graphics
	filename Meta14 St3 Top of Floc Blanket.png
	height 8cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:FlocBlanketMeta14St3"

\end_inset

Top of Floc Blanket at the end of 3 NTU Maintenance State (State 3)
\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Standard
The same experiment was repeated with 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 incremented to 2.25 mm/s.
 A floc blanket was built and maintained, but effluent turbidity could not
 be maintained below 3 NTU throughout the experiment (See Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Meta15 Effluent-Turbidity-Overview"

\end_inset

).
 This indicated that a 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 of 2.25 mm/s was too high, and that optimizations of other parameters should
 probably proceed with a 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 of 2 mm/s or a value between 2 to 2.25 mm/s.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Graphics
	filename Meta15 Effluent Overview.png
	width 12cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Meta15 Effluent-Turbidity-Overview"

\end_inset

State-Averaged Effluent Turbidity when 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 is 2.25 mm/s.
 The red dotted line indicates the 3 NTU threshold.
 
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Experimental Observations
\end_layout

\begin_layout Subsubsection
Flocculator Length Observations
\end_layout

\begin_layout Standard
It has been noticed that in experimental states where the influent turbidity
 was approximately 200 NTU or of comparable magnitude, that the flocs in
 the flocculator do not seem to increase in size after traveling half the
 length of the flocculator.
 From these observations, it appears that experiments of altering flocculator
 length could be very fruitful.
 However, similar observations have not been made for the flocs in the flocculat
or during states where influent turbidity was approximately 3 NTU or of
 comparable magnitude.
 At these states it is difficult to visually detect flocs in the flocculator,
 nonetheless track their size over the length of the flocculator.
\end_layout

\begin_layout Subsubsection
Floc Recycle Observations
\end_layout

\begin_layout Standard
An experiment was preformed where a 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none

\begin_inset Formula $\Pi_{Q_{Recycle}}$
\end_inset


\family default
\series default
\shape default
\size default
\emph default
\bar default
\strikeout default
\uuline default
\uwave default
\noun default
\color inherit
 of 0.1 was tested after maintaining a floc blanket at a 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 of 2 mm/s and influent turbidity of 3 NTU for 4 hours.
 Approximately 5 minutes prior to the beginning of floc recycle, the top
 of the floc blanket was quite sparse (See Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:The-Top-before"

\end_inset

).
 However about 23 minutes later, after the start of floc recycle, the top
 of the floc blanket had become quite dense again (See Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:The-Top-After"

\end_inset

).
 A possible reason for this observation is that floc recycle could have
 resulted in more flocs forming in the flocculator and entering the sedimentatio
n tank to build a denser floc blanket.
 It is important to note that while 
\begin_inset Formula $Q_{Plant}$
\end_inset

 was maintained at 1.081 mL/s for the entirety of the experiment, during
 states where floc recycle was implemented, the velocity in the part of
 the sedimentation tank within the floc recycle loop increased to 2.2 mm/s,
 or the product of 
\family roman
\series medium
\shape up
\size normal
\emph off
\bar no
\strikeout off
\uuline off
\uwave off
\noun off
\color none

\begin_inset Formula $1+\Pi_{Q_{Recycle}}$
\end_inset


\family default
\series default
\shape default
\size default
\emph default
\bar default
\strikeout default
\uuline default
\uwave default
\noun default
\color inherit
 and 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

.
 This is because floc recycle increases the flow rate and thus the velocity
 of the water within the loop where floc-water mixture is circulated.
 This increase in 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 did not appear to negatively effect the floc blanket or effluent turbidity
 at this 
\begin_inset Formula $Q_{Plant}$
\end_inset

, but should be considered when designing further experiments.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset space \hspace{}
\length 3cm
\end_inset


\begin_inset Graphics
	filename Top of Sed Tank Prior to Floc Recycle.png

\end_inset


\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:The-Top-before"

\end_inset

The Top of the Floc Blanket 5 min.
 Prior to the Beginning of Floc Recycle
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset space \hspace{}
\length 3cm
\end_inset


\begin_inset Graphics
	filename Top of Sed Tank After Floc Recycle.png

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:The-Top-After"

\end_inset

The Top of the Floc Blanket 18 min.
 After the Beginning of Floc Recycle
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Decreasing Coagulant Dosage with Floc Recycle
\end_layout

\begin_layout Standard
The addition of floc recycle has the potential to streamline two aspects
 of AguaClara plant design: flocculator length and coagulant dose.
 Since coagulant makes up a significant percentage of the AguaClara plant
 operating costs, the team chose to explore this parameter before ending
 the semester.
 The design of this experiment was primarily driven by the following question:
 can coagulant dose be reduced when floc recycle is implemented, while still
 achieving < 3 NTU effluent? The team decided to proceed with a floc recycle
 ratio of 0.1, as this ratio did not seem to hinder floc blanket maintenance
 at a 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 of 2 mm/s.
 However, since floc recycle has the greatest impact when more flocs are
 recycled and the floc blanket is denser at a lower 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 , the team ran this experiment at 1.5 mm/s instead of 2 mm/s.
 As suggested by our instructor, Dr.
 Weber-Shirk, an estimate of the target coagulant dose was calculated by
 assuming linearity between the optimal dose at 200 and 3 NTU influent turbidity
 using Equation 
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:Proposed New Coag Dose at 3 NTU with floc recycle"

\end_inset

.
 However, the equation was altered to reflect the limitations of the physical
 set-up, while still minimizing coagulant dose at the 3 NTU state (Equation
 
\begin_inset CommandInset ref
LatexCommand ref
reference "eq:Actual New Coag Dose at 3 NTU"

\end_inset

).
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
C_{CoagDose,3NTU}=\frac{3}{200}*C_{CoagDose,200NTU}\label{eq:Proposed New Coag Dose at 3 NTU with floc recycle}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
C_{CoagDose,3NTU}=\frac{7}{130}*C_{CoagDose,200NTU}\label{eq:Actual New Coag Dose at 3 NTU}
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
Effluent turbidity data obtained from this experiment proved unreliable
 due to system errors.
 However, qualitative observations obtained from this experiment provided
 some insights.
 For example, lowering the coagulant dose at 3 NTU might cause the floc
 blanket to thin out.
 Pictures of the top of the floc blanket at 3 NTU and varying coagulant
 dosages are presented in Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:CoagDose"

\end_inset

.
\end_layout

\begin_layout Standard
In addition, it was observed that flocculator performance improved when
 floc recycle was implemented with a thick floc blanket.
 At a coagulant dose of 15 mg/L, a sample of flocculated water obtained
 from the system had a measured turbidity of 105 NTU.
 Given that the raw water turbidity was 3 NTU, this showed that floc recycle
 from a thick blanket was indeed increasing the suspended solids concentration
 within the flocculator.
 Visual observations of the flocculator corroborated this finding.
 Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Visible-flocs-forming"

\end_inset

 shows visible flocs within the flocculator when floc recycle was implemented
 at 3 NTU with a coagulant dose of 15 mg/L.
 Previously, flocs were not visible in the flocculator at 3 NTU.
 However, as the coagulant dose decreased, the floc blanket thinned, and
 the effect of floc recycle on increasing the flocculator turbidity seemed
 to decrease as well, as can be seen in Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Turbidity-of-Flocculated"

\end_inset

.
 However, the team definitely recommends repeating this experiment to confirm
 the validity of the aforementioned observations.
 
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset Graphics
	filename Floc Blanket with Varying Coagulant Dose.png
	height 2in

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:CoagDose"

\end_inset

Floc Blanket maintained with 3 NTU influent and varying coagulant dosages
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset space \hspace{}
\length 3cm
\end_inset


\begin_inset Graphics
	filename Flocculator with FRR 0.1.jpg
	width 7cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Visible-flocs-forming"

\end_inset

Visible flocs forming in the flocculator in the 3 NTU state with floc recycle
 ratio of 0.1
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\begin_inset space \hspace{}
\length 1cm
\end_inset


\begin_inset Graphics
	filename FlocWaterNTU vs CoagDose.png
	scale 75

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Turbidity-of-Flocculated"

\end_inset

Turbidity of Flocculated Water (NTU) against Coagulant Dose (mg/L) for 3
 NTU raw water
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Section
Conclusions
\end_layout

\begin_layout Standard
The team has spent the most of this semester preparing a solid foundation
 for future optimization research.
 Multiple experimental failures have spurred the team to make continuous
 improvements to the system design, and the result is a neat, relatively
 robust experimental system that should provide the next team with a good
 starting point for future optimization experiments.
 The most conclusive result obtained during the semester is that the system
 has the ability to consistently produce < 1 NTU water at a 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 of 2 mm/s and a 
\begin_inset Formula $\text{Π}{}_{Capture}$
\end_inset

 of 0.1.
 This performance is maintained even when the incoming raw water is as low
 as 3 NTU, as can be seen from Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Effluent-Turbidity-st3"

\end_inset

.
\end_layout

\begin_layout Standard
Although the team has not managed to optimize other parameters as planned,
 the potential to increase 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 from the current value of 1 mm/s to 2mm/s represents exciting possibilities
 for AguaClara, due to three main reasons.
 Firstly, this means that an AguaClara plant can produce water on the order
 of 0.1 NTU with the addition of a stacked rapid sand filter (assuming the
 SRSF has a 
\begin_inset Formula $pC*$
\end_inset

 of 1).
 Secondly, this means that the plant flow rate in existing AguaClara plants
 can be doubled, and the plan view area of sedimentation tanks in future
 AguaClara plant designs can be halved.
 Last but not least, this result also means that good performance can be
 maintained even at a 
\begin_inset Formula $V{}_{Capture}$
\end_inset

 of 0.2 mm/s, as compared to the current design 
\begin_inset Formula $V{}_{Capture}$
\end_inset

 of 0.1 mm/s.
 This suggests that the important parameter to design for is not the absolute
 value of the capture velocity, but rather the ratio of capture velocity
 to upflow velocity.
 Finally, it is important to emphasize that the achievement of < 1 NTU effluent
 turbidity in the system was contingent on the maintenance of a floc blanket
 within the sedimentation tank.
 
\end_layout

\begin_layout Standard
Another significant result from this semester’s experiments is that recycling
 flocs at a floc recycle ratio of 0.1 from the top of the floc blanket did
 not seem to interfere with floc blanket maintenance.
 Indeed, floc recycle seemed to improve flocculator performance by increasing
 the solids concentration within the flocculator when the plant influent
 was 3 NTU.
 Meanwhile, decreasing coagulant dosages seemed to reduce the benefit of
 floc recycle, by thinning out the floc blanket.
 If these observations persist even after repeated experiments, the team
 recommends prioritizing the maintenance of the floc blanket.
 Floc recycle can still be implemented to reduce the flocculator length,
 which will also result in significant cost savings.
 
\end_layout

\begin_layout Section
Future Work
\end_layout

\begin_layout Standard
Once data is obtained about the optimization of the coagulant dose, the
 floc recycle ratio can be optimized.
 Previously it was observed that at a floc recycle ratio of 0.05, flocs began
 to settle out in the floc recycle line.
 This can be prevented by using a smaller inner diameter floc recycle line,
 which will increase velocity through the line for the same flow rate.
 Optimal floc recycle ratio may depend on 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 due to the effect of upflow velocity on the floc blanket density, and it
 would be valuable to know the relationship between the two.
 
\end_layout

\begin_layout Standard
The location of the floc recycle influent line could be optimized.
 Currently the line pulls flocs out of the top of the sedimentation tank,
 and this increases the 
\begin_inset Formula $V{}_{SedUp}$
\end_inset

 in the part of the sedimentation tank that is below the floc recycle influent
 line.
 This could be detrimental to the formation and maintenance of a floc blanket,
 but if floc recycle ratio is decreased, then this effect also decreases.
 It would be interesting to vary the location of the floc recycle influent
 line and observe the impact on plant performance.
\end_layout

\begin_layout Standard
Other future work includes optimizing the flocculator length and the capture
 velocity ratio, as per the Spring 2012 Challenges
\begin_inset CommandInset citation
LatexCommand cite
key "key-1"

\end_inset

.
 Since the system has multiple degrees of freedom, it is not possible to
 have every parameter exactly optimal.
 In order to make decisions about which parts of the plant to optimize,
 the team recommends prioritizing parameters based on cost.
 It will be helpful to develop some preliminary cost criteria that illustrates
 which parts of the plant are the most expensive based on both construction
 and maintenance costs.
 With these costs as a guideline, the next team can then identify the processes
 that will have the most significant impact if they are reduced.
 Once this is developed, decisions can be made as this project goes forward
 about which parameters to keep constant at optimal values.
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
key "key-1"

\end_inset

AguaClara/Flocculator and Sedimentation Optimization.
 Rep.
 Cornell University, 11 Jan.
 2012.
 Web.
 23 Feb.
 2012.
 <https://confluence.cornell.edu/download/attachments/165972596/FSO.pdf?version=2&m
odificationDate=1326310611000>.
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
key "key-2"

\end_inset

Freeman, Jill, Wang Mahina, Khan Saied, and Hurst Matthew.
 AguaClara - Sedimentation Tank Hydraulics.
 Rep.
 Cornell University, 15 Dec.
 2011.
 Web.
 23 Feb.
 2012.
 <https://confluence.cornell.edu/download/attachments/117756976/Final+Report+Fa+20
11.pdf?version=1&modificationDate=1323982680000>.
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
key "key-3"

\end_inset

Hurst, Matthew W.
 "Evaluations of Parameters Affecting Steady-State Floc Blanket Performance."
 Thesis.
 Cornell University, 2009.
 AguaClara-Floc Blanket MS Thesis.
 Cornell University.
 Web.
 21 Feb.
 2012.
 <https://confluence.cornell.edu/display/AGUACLARA/Floc+Blanket+MS+Thesis>.
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
key "key-4"

\end_inset

Hurst, Matt, Monroe Weber-Shirk, Tanya Cabrito, Cosme Somogyi, Michael Adelman,
 Zachary Romero, Richard Pampuro, Rachel Phillipson, Sarah Long, Colette
 Kopon, Ying Zhang, Ashleigh Sujin Choi, Adela Kuzmiakova, Jae Lim, Alexander
 Duncan, Christine Catudal, Elizabeth Tutunjian, Ling Cheung, Kelly Kress,
 Tiara Marshall, and Leonard W.
 Lion.
 AguaClara/The Effect of Floc Roll-up on Clay-Aluminum Hydroxide Flocs.
 Rep.
 Cornell University, 2011.
 Web.
 23 Feb.
 2012.
 <https://confluence.cornell.edu/download/attachments/147947701/PSS+Final+Report.pd
f?version=1&modificationDate=1305585181000>.
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
key "key-8"

\end_inset

McLane, John C.
 
\begin_inset Quotes eld
\end_inset

Water Quality Improves by Recycling Settled Sludge.
\begin_inset Quotes erd
\end_inset

 OPF, Vol.
 30 Iss.
 1, January 2004, Page Range 15-18
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
key "key-5"

\end_inset

Smith, Daniel.
 "Informe De Pruebas PAC En Plantas AguaClara." Message to Karen Swetland.
 25 Jan.
 2011.
 E-mail.
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
key "key-6"

\end_inset

Tse, Ian C., Karen Swetland, Monroe L.
 Weber-Shirk, and Leonard W.
 Lion.
 "Fluid Shear Influences on the Performance of Hydraulic Flocculation Systems."
 Water Research 45.17 (2011): 5412-418.
 Science Direct.
 Elsevier, 23 Aug.
 2011.
 Web.
 23 Feb.
 2012.
 <http://www.sciencedirect.com/science/article/pii/S0043135411004544>.
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
key "key-7"

\end_inset

Weber-Shirk, Monroe L., and Leonard W.
 Lion.
 "Flocculation Model and Collision Potential for Reactors with Flows Characteriz
ed by High Peclet Numbers." Water Research 44.18 (2010): 5180-187.
 Science Direct.
 Web.
 23 Feb.
 2012.
 <http://www.sciencedirect.com/science/article/pii/S0043135410004136>.
\end_layout

\end_body
\end_document
