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\author 809928942 "Heidi Rausch" 
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\begin_layout Title
Low Flow Stacked Rapid Sand Filtration - Progress Report
\end_layout

\begin_layout Author
Mihir Gupta, Kris LaPan, Rachel Proske
\end_layout

\begin_layout Date
September 21, 2012
\end_layout

\begin_layout Section*
Introduction
\end_layout

\begin_layout Standard
The goal of this research project is to modify the current design of the
 Low Flow Stacked Rapid Sand Filter (LFSRSF) so that it may be implemented
 by Agua Para el Pueblo and used in any subsequent water treatment facilities.
 Previously, a stack
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ed
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 rapid sand filtration system was designed to remove the 
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remaining
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 particles
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 remaining after sedimentation
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 in an efficient manner prior to chlorination and distribution.
 However, this method is 
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inappropriate
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insufficient
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 for flows less than 6 liters per second.
 Smaller communities, who have water treatment plants with less flow, are
 unable to use this system.
 Thus, a design and prototype low flow filter was created within the last
 year.
 However, the design is not fully complete, and testing and modification
 of the system is necessary before 
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it can be
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being
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 implemented in a plant.
 Also, an accurate mathematical model 
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of the design 
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will be created to assist in s
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caling
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izing
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 the filter for multiple flows.
 The first LFSRSF is projected to be installed by January 2013.
\end_layout

\begin_layout Section
Literature Review
\end_layout

\begin_layout Subsection

\series bold
Monroe's Filtration Theory notes from 2011
\end_layout

\begin_layout Standard
The material provided by Professor Weber-Shirk illustrates current practices
 and to-date comprehension of sand filtration systems.
 These techniques include the slow sand, rough gravel, dynamic gravel, rapid,
 and stacked rapid filtration.
 These filtration methods have the
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ir
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re
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 relative range of applicability, which is primarily based on the constraints
 of the water treatment facility.
 From the previously listed techniques for sand filtration systems, a subset
 of systems based on sand depth can be observed; including slow, rapid and
 stacked rapid.
 Slow sand filtration is a method which utilizes low flow rates to remove
 particulates and colliods from the raw water.
 However drawbacks of this system include high head losses and periodic
 cleaning of the sand.
 Rapid sand filtration is another filtration method which permits approach
 velocities of 0.7-2.8 mm/s.
 The filtration process uses layered media including anthracite, sand, and
 gravel progressing from top to bottom, respectively.
 A difference between the rapid and slow sand filtration systems is that
 rapid sand filtration utilizes a back wash process which fluidizes the
 sand layer effectively cleaning it.
 An additional depth based filtration system called stacked rapid sand filtratio
n (SRSF) is a technique which uses a similar approach to treat raw water
 as the rapid sand filter.
 This modification includes stacking multiple sand layers as opposed to
 having several rapid sand filtration units in parallel.
 The greatest benefit from this geometric alteration is the reduction in
 water required for the backwashing process.
\end_layout

\begin_layout Subsection
Fundamentals of Fluid Mechanics 3rd Edition by Munson, Young, and Okiish
\end_layout

\begin_layout Standard
Fundamentals of Fluid Mechanics provides background theory and knowledge
 on water flow through pipes, including head loss equations and minor loss
 coefficients.
 For example, when calculating minor head loss of an expansion or contraction,
 the velocity in the equation is the velocity through the smaller diameter
 pipe (or the larger given velocity).
 Knowledge from this book will be referenced when determining head losses
 through the manifolds and orifices.
\end_layout

\begin_layout Section
Methods
\end_layout

\begin_layout Subsection
MathCAD Model
\end_layout

\begin_layout Standard
The modeling between the inlet tank and to the first split in the pipes
 has been completed.
 This includes finding major and minor head losses in each pipe by measuring
 the diameters of each tube and determing the minor headloss coefficients
 for the four 90 degree bends, the contractor, and the freefall location
 where water spills out of a 1 inch pipe into a 2.5 inch pipe.
 According to Fundamentals of Fluid Mechanics the velocities used to calculate
 the minor losses would be the velocities through the smaller diameter pipe
 in the case of a contraction or expansion.
 Overall, we determined the head loss through the first set of pipes to
 be 0.4 meters.
\end_layout

\begin_layout Standard
Throughout these calculations, the flow is the rate through the plant.
 However, once the pipe splits into two or more pipes in parallel, the summation
 of the flows through the pipes are equal to the total flow through the
 plant.
 Also, since the pipes are in parallel, the head losses must be equal through
 each parallel system, which means the flow through each varies.
 There are 6 possible paths the fluid can take.
 The next stage in modelling will be to set-up an iterative program that
 will determine the flow through each path with the following constrains:
 head loss in each of the paths are equal and the sum of the flow rates
 through the system equal the total flow through the plant.
\end_layout

\begin_layout Subsection
AutoCAD 3D Drawing
\end_layout

\begin_layout Standard
A visual illustration of the current low flow rapid sand filter is currently
 being created in autocad 2013.
 In order for the drawing to be correct, it was necessary create a hand
 drawn sketch of the existing LFSRSF and acquire all pipe lengths and diameters,
 as well as height at various locations.
 The hand sketch with appropriate dimensions is currently being utilized
 as a template for creating an existing AutoCAD drawing of the filtration
 unit.
\end_layout

\begin_layout Section
Analysis
\end_layout

\begin_layout Standard
The head loss calculated through the first set of pipes was 0.4 meters.
 This may be significant since these head losses are from only a third of
 the pipes in the system and the head losses through the sand is expected
 to be high.
 The head losses along the 1 inch pipes and the expansion make up 66% of
 the head loss through the first set of pipes.
 A possible method to reduce the head loss is to increase the diameters
 of the 1 inch pipe, which will lessen the frictional head losses as well
 as decrease the minor loss coefficient in the expansion.
 If the 1 inch diameter pipes are enlarged to 2.5 inches in diameter, the
 total head loss through the first set of pipes 
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will be
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is
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 0.3 meters.
 This is something to be considered if the sum of the head losses throughout
 the filtration system is too high.
\end_layout

\begin_layout Section
Future Work
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\begin_inset Note Note
status open

\begin_layout Plain Layout

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I think that the conclusions section should come before future work
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\end_layout

\end_inset


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\end_layout

\begin_layout Subsection
MathCAD Model
\end_layout

\begin_layout Standard
The MathCAD model is only a 3rd of the way complete.
 The next step is to set-up the iterative program and finish calculating
 the head losses through the rest of the system.
 This will set the basis for which flow path receives what percent of the
 total flow through the plant.
 Also, a smaller program will be written specifically for the head losses
 and flow rate during backwash.
 All of this data will be compared to experimental flow data to ensure that
 the model is correct.
 Depending on the results of the model, the filtration system may need to
 be modified to decrease head loss.
 This can be done by increasing pipe diameters, exchanging valves types,
 etc.
 All of this information should be known by next week.
\end_layout

\begin_layout Subsection
Experimental Flows
\end_layout

\begin_layout Standard
Within the next week, the process controller will be set-up using a stamp
 control box, turbidimeters, pumps, and a computer.
 Once everything is set up, the flows will be calculated and compared to
 the mathematical model.
 Necessary changes in pipe size and/or valve type will be conducted, and
 the flows will be tested again.
 If everything is operating properly, sand will be added to the filter.
 Then, the flows through the system will be collected again.
\end_layout

\begin_layout Subsection
AutoCAD 3D Drawing
\end_layout

\begin_layout Standard
The completed AutoCAD drawing will consist of the full scale system with
 the same layout and orientation as the actual.
 Upon completion of the existing system drawing, it will be possible to
 update the file to illustrate any pipe or layout modifications deemed necessary
 based on head loss calculations.
\end_layout

\begin_layout Section
Conclusion
\end_layout

\begin_layout Standard
The first two weeks of working on the project consisted of understanding
 how the filtration system operates and what needs to be done.
 Steps towards accomplishing these goals (creating a mathematical model
 and drawing a 3D model of the system) have begun.
 Within the coming weeks, the mathematical model and 3D drawing will be
 completed and the process controller will be set-up to calculate and compare
 flow rates throughout the system.
 Depending on the amount of head loss through the system, pipe diameter
 sizes may be enlarged before adding sand to the filtration system.
 The ultimate goal of having an operating design to be sent to Honduras
 by January is still feasible.
 Methods of simpler construction will also be considered within the coming
 months.
\end_layout

\end_body
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