1

1
builds up and increases the throughput of the filtration

Filtration unit Report process. The speed of the suspension to pass through
the press depends on the viscosity of the liquid, the
J. Camilo Franco T. Chem. Eng. Dpt, Universidad de resistance and the thickness of the cake and the
La Sabana pressure drop across each stage of the press. The
displacement pump generates that the plate and frame
filter is fed with a suspension at a uniform speed. As
I. ABSTRACT more solids accumulate in the frame of each stage, the
filtration becomes slower. When sufficient cake
Press filters are a simple and reliable method to thickness has been removed from the frames, the
achieve an adequate separation obtaining a compact filtration is stopped, the press is removed and the cake
cake and a particle-free filtrate, such as cassava starch is removed from the frames. The strength of the cake
with an average size of 13.45 um. The objective of the increases over time as the cake builds up in the frame.
report is to evaluate the behavior of a cassava starch This resistance to the filtrate flow is proportional to the
solution based on the parameters of the Ergun volume of filtrate that has passed through the cake
equation, Darcy's equation and in turn to determine the (Lamanilao, 2014).
efficiency of the process. To carry out the practice 500 Measurement of the filtration behaviour and the cake's
g were dissolved in 10 L of water and mixed in a tank building characteristics of a mix fluid is fundamental to
that connects to the filter press. We obtained each of the fluid control and treatment. The characteristics of
the parameters established by the Ergun and Darcy the filtrate, such as oil, water, or emulsion content are
equations as well as an efficiency of 208.6% with a also important, these characteristics are affected by
pressure drop that decreases over time. The results different factors, as like the types and quantities of
obtained are not coherent with each other because a solids in the fluid, and their physical and chemical
decrease in pressure drop is obtained with a very small interactions. Temperature and pressure affect all these
permeability value, possibly due to the lack of characteristics. For this, tests are often run at both low
homogeneity in the mixture and the concentration of pressure and temperature, and elevated pressure and
cassava starch in the solution. temperature; different equipment and techniques are
Index Terms—Pressure, flow, pump, filtration, particle
required, the filtration measurements include the
diameter, humidity percentage. filtrate volume and filter cake thickness (Fann
instrument company, 2014).
The Carman-Kozeny equation is a relationship
II. INTRODUCTION implemented in fluid dynamics to calculate the
The diffusion of particles into a liquid where they are pressure drop of a fluid flowing through a packed bed
separated from a fluid is implemented in a variety of of solids. The equation is valid only for laminar flow
industrial treatments (wastewater treatment). One of (McCabe, Smith, & Harriot, 2005). The equation was
the most basic and implemented procedures in the derived by Kozeny and Carman from a starting point
industry along the history is the filtration. Filtration of:
can be performed on a wide variety of vacuum 1. A flow of modeling fluid in a bed packaged as a
equipment to rotary drums, the most common system laminar fluid flow in a collection of bending tubes that
to carry out this process is a filter press (BUDAPEST cross the packed bed.
UNIVERSITY OF TECHNOLOGY AND 2. The law describing the flow of laminar fluid in
ECONOMICS, 2010). straight tubes of circular section.
The filter press operates under pressure using the
filtering process of the cake. This means the transfer of
III. MATERIALS AND METHODS
a suspension through the press, which is equipped with
filter walls. The walls collect the particles in the Materials:
suspension and allow the passage to the solvent. As ● Water.
more suspension moves through the system, more cake ● Mixing tank.
● Cassava starch.
1 ● Filter press.
● Pump.
 2

● Tubing.
H (m) 0,013
● Moisture Analyser.
● Balance. u (Pa*s) 1,00x10-3
● Spoon.
● Plastic pail. U(m/s) 0,0068
● Data table.
*x (m) 13,45x10-6
Preparation of slurry: Feed solution
In order to prepare 10L of solution with 500g of p (kg/m3) 1000
cassava starch, the moisture content of a previous
slurry was measured in order to recycle used material. e 1,49
Recollection of Data *Average diameter value of the cassava starch particle consulted
The group divided between different tasks to pursue a in the literature (Hernandez et al, 2008)(Medina et al, 2008)
satisfactory run of the equipment. One member was in
charge of plug into power for the pump, another was in In the same way it was possible to calculate the
charge of having in steady state of the pump, another permeability value taking into account the Darcy
was seeking watching over the feed tank level (this was equation (2). Table 2 shows the values of each
very important, if the tank level was empty and the parameter as well as the permeability
pump continued to operate, air may enter in the pump
and provoke cavitation breaking the pump). The rest of
the team had to collect the data of filtrate rate, filling a
10L container with filtrate and taking the time of that (2)
filling. This filling rate was registered eight times. Table 2: Parameters to establish the permeability
Weighting the cake of solids according to the Darcy equation.
After the run was completed (just before the tank was
Parameter Value
empty), the operation was stopped, and the filters were
taken out of the filtration equipment. Then, the filtered Q(m3/s) 0,0068
cake was cleaned from the filters as much as it could
be using a spatula and putting the cake in a tared K(m2) 3,73x10-13
recipient. The solids were weighed, and the moisture
was measured. Later, with a sample of the moisture, it A(m2) 0,0134
was measured the humidity percentage of the moisture,
this is necessary in order to obtain the amount of water DP(Pa) 234422
in the total mass that was retain in the filtration unit.
u (Pa*s) 1x10-3

IV. RESULTS L(m) 0,013

In order to calculate the porosity of the medium (e) the The Darcy equation is used in systems with laminar
parameters of the Ergun equation (1) were established flow, for this reason it was necessary to verify that the
as shown in Table1. number of Reynolds (Re) was less than 2 with a
constant pressure drop. Equation (3) corresponds to the
formula to determine the number of reynolds.
(1)

Table 1: Parameters to establish the voidage

according to the equation of Ergun (3)
Parameter Value
The value of the number of reynolds is 9,15 x10-2
DP (psi) 34 which indicates that the system is of laminar regime
and the equation of Darcy can be used for this case.
 3

The application of the Carman-Kozeny equation

The efficiency of the filtrate was determined by means requires precise measurements of the parameters of the
of the amount of cassava starch used with respect to porosity level of cassava starch; as the surface area of
the amount recovered. After performing the respective the cake and tortuosity, values that were not obtained
filtration, the material was recovered by removing each at the time of data collection. This value of porosity,
filter with the wet cassava starch. The initial sample obtained experimentally, is close to 97%, so it can be
was 500 g of cassava starch, and the one recovered considered wrong because of its high percentage, since
after filtration was 1070 g, including moisture. From this would mean that almost all the content of the
the recovered sample, 0.459 g was taken and it was sample is liquid, which is false. that a large amount of
determined that the percentage of dry mass the recovered material was a cake that had a necessary
corresponded to 97.48%, therefore the amount of dry strength to be rigid and have a defined shape.
mass recovered was 1043.036 g of starch. Therefore, For this filtration system, the concentration presents a
the filtration efficiency is 208.6%. direct proportionality with respect to the weight and
volume of each of the cakes with the recovered
V. ANALYSIS material. Also, the concentration of material obtained
As it can be evidenced in the previous data, there are in each filter was decreasing as the plates went
inconsistencies in them, such as a k out of the ideal through, so that the largest amount and weight in the
range, or a considerably high efficiency even though a first dish was obtained, as well as its volume.
large part of the mass could be recovered in the
filters.The permeability value (k) obtained for the When determining the efficiency of the filtering, it can
filtration of the cassava starch solution is very low and be shown that there is a great discrepancy in obtaining
is not consistent with what is observed in graph 1, in the data, since when reviewing the material recovery,
which it is evident that there is a decrease in pressure double the amount of material that had been entered
drop, since the smaller the value of the permeability into the system, however, this could be due to the
the amount of space between the starch particles amount of accumulated water that could have the
decreases, ie the pressure drop should increase. starch, therefore the percentage of dry mass was
determined, but according to the FAO the percentage
of dry mass that can exist in the cassava starch is
between 80 and 90%. But when performing the
humidity tests, the percentage of dry mass exceeds that
established by the study carried out for the analysis of
cassava starch. (Aristizabal, 2007)

VI. CONCLUSIONS
Juan Camilo Franco:
● The concentration has a direct impact on the
time required to filter a specific volume, this is
because a higher concentration can be
interpreted as a greater accumulation of solids
Graph 1: Pressure drop over the time in the frame of each stage (plate + filter), and
thus the resistance to Filtrate flows and
This behavior is explained due to the wrong way of filtration slows down.
taking and storing data at the time the filtering unit was ● By increasing the concentration, the efficiency
turned off. Another important reason that explains the of the system can be reduced due to the
unusual behavior on the obtained data is that at the saturation of the equipment, obtaining a
moment of turning off the system and separating each smaller quantity of recovered solid and a fluid
one of its plates, some of the cakes with wet cassava with a greater number of particles, which is
starch were stuck with others due to a bad position of desired to avoid, so that each system has its
the filters that were between the plates, causing a great limit of saturation with Regarding the
loss of initial material that was expected to be obtained concentration.
at the outlet of the filtering equipment.
 4

ed.), pp. 163–165. New York, United States:

Juliana Marcela Vasquez: McGraw Hill.
● The calculated value of voidage exceeds the Medina J, Salas J (2008) Morphological
allowed values for this parameter (0-1) Characterization of Native Starch Granule:
possibly due to the decrease in pressure drop Appearance, Shape, Size and its Distribution.
since based on the Ergun equation, the change Revista de Ingeniería. 27; 56-62
in pressure is inversely proportional to the Aristizábal, J., Sánchez, T., & Lorío, D. M. (2007).
voidage of the medium. Guía técnica para producción y análisis de
● The pressure drop over time decreases, which almidón de yuca. Roma: Organización de las
infers that there is a loss in cake compaction, Naciones Unidas para la Agricultura y la
however with the values obtained for voidage Alimentación.
and permeability it is evident that the cake
formed in the filters is highly compacted,
therefore it is established that there were errors
in the measurements.

Laura Paola Sarmiento

● One of the important factors before carrying
out any analysis is the verification and
calibration of each of the instruments. The
error regarding the amount of starch that
entered and that came out in the filtrate is due
to an instrumental error.
● It was evidenced that there was no pressure
drop since the output pressure of the system
never varied, it remained nil. This problem
arose because the water flow pump contained
no flow and it could not perform the output
reading. It can be said that the filtration was at
constant pressure.

VII. REFERENCES
BUDAPEST UNIVERSITY OF TECHNOLOGY
AND ECONOMICS. (2010). Filtration with frame
press filter. Budapest, Hungary: BUDAPEST
UNIVERSITY OF TECHNOLOGY AND
ECONOMICS.
Fann instrument company. (2014). High-Pressure,
High-Temperature Filter Press Instruction manual.
Houston, Texas, United States: Fann instrument
company.
Hernández M, Torruco J, Guerrero L, Betancour D
(2008) Caracterización fisicoquímica de almidones
de tubérculos cultivados en Yucatán, México.
Food science and technology. 28; 718-726
Lamanilao, J. (2014). Plate & frame filter press. Cebu,
Philipines: CEBU INSTITUTE OF
TECHNOLOGY UNIVERSITY .
McCabe, W. L., Smith, J. C., & Harriot, P. (2005).
Unit Operations of Chemical Engineering (seventh