Showing posts with label Water. Show all posts
Showing posts with label Water. Show all posts

Sea Water Through Sea Water Reverse Osmosis Engineering Essay

This paper evaluates the use of energy recovery devices in sea water reverse osmosis. A Pressure exchanger is theoretically compared to other energy recovery configurations resulting in an energy recovery of around 60%. A test rig was implemented by first creating a CAD model of a pressure exchanger on solid edge, manufacturing it and implementing it in a small scale reverse osmosis system. Future work includes fixing minor defects with the test rig in order to carry out experimentation.

Key Words: Reverse Osmosis, Energy Recovery, Pressure Exchanger

Fresh water is defined as containing less than 1000 mg/L of salts or total dissolved solids (TDS). Above 1000 mg/L, properties such as taste, color, corrosion propensity, and odor can be adversely affected. [1]

With reference to fig. 1, The U.S. Geological Survey found that 97% of Earth’s water is located in the ocean, the remaining 3% makes up for the fresh water composition. Out of this 3%, around 2% of it is located in the ice caps and glaciers; the remaining 1%t includes surface water which comprises of swamps, lake and rakes. The remaining percentage is made up of brackish water, slightly salty water found as surface water in estuaries and as groundwater in salty aquifers. [1]

Today, the production of potable water has become a global challenge. With reference to fig. 2 projected population growth and demand exceed conventional available water resources. At present, around 1 billion people are without access to clean drinking water and approximately 40% of the world population lives in water shortage regions. [2]

Increasing demand & decreasing supply of water has led to ideas such as water conservation and water transfer or dam construction being implemented although they are still not sufficient to cope up with the population growth. Misuse or overuse of traditional fresh water resources such as lakes, rivers, and groundwater result in them either diminishing or becoming saline. At present due to global development, the introduction of few new water resources are available to support daily clean drinking water needs. The facts indicated above clearly show us that salt water desalination has emerged as the prime candidate to provide fresh drinking water to sustain future generations across the globe. According to a recent graph by ERI Inc., by 2016 capital expenditures for desalination will exceed 16 billion$ out of which more than 13$ is expected to be targeted for SWRO. This massive injection of finances will successfully incorporate additional clean drinking water production for all sorts of communities using conventional water treatment and fresh water resources. [3], [4], [5], [6], [7], [8]

A solvent moves from an area of low solute concentration, through a membrane, to an area of high solute concentration through osmosis. The movement of a pure solvent to equalize solute concentrations on each side of a membrane generates a pressure and this is the "osmotic pressure." With reference to fig 3. applying an external pressure to reverse the natural flow of pure solvent, thus, is reverse osmosis. [10]

Fig. 4 represents a typical reverse osmosis system which comprises of a high pressure pump and a membrane. The High pressure pump pressurizes sea water through a reverse osmosis membrane at pressure of approximately 60 bar as this is what’s needed in order to overcome the osmotic pressure. 40% of the flow from the membrane results as fresh water output while the remaining 60% is concentrated brine that is rejected with a great pressure loss. This pressure loss is fed back to the system using energy recovery devices which are detailed in 1.4.

The energy consumption still remains the major operational cost component due to the high pressure pumps required to feed water to the RO process. These pumps are responsible for more than 40% of the total energy costs [2]. Reducing energy consumption is, therefore, critical for lowering the cost of desalination and addressing environmental concerns. [9]

Before the concentrate stream is sent for disposal, pressure from the stream is recovered by passing it through an ERD. When an ERD is used, a fraction of the feed must bypass the primary high-pressure pump and a booster pump is used to account for pressure losses in the RO membrane modules, piping, and ERD. The fraction of power recovered depends on the type and efficiency of the equipment used. [11]

Greenlee et al. (2009) & Wang et al. (2004) discussed the two broad classes of ERDs. Class I devices use the hydraulic energy of the RO concentrate by first converting the energy to centrifugal mechanical energy and then back to hydraulic energy. This is a two-step process. Class II devices use hydraulic power to cause a positive displacement within the energy recovery device and this transfers the hydraulic energy directly in a one step process. [12]

Stover (2007) provided a detailed description of Class I Centrifugal ERDs (such as the pelton wheel, reverse running turbine pump and turbo charger). They are limited in capacity and are usually optimized for narrow flow and pressure operating conditions. Initially, Francis turbines were applied, but they were replaced by pelton turbines that operated at higher efficiency in high-head applications and provided a maximum possible efficiency of 90% [13] Oklejas (2005) mentioned the turbo charger consists of an impeller and turbine on the same shaft, this is typically used in smaller capacity RO installations as its efficiency ranges from 55% to 60%. [14].

Mirza (2008) discussed mechanically coupled reverse running turbine pump that have efficiencies in the range of 75% to 85%. For the submersible generator type, the overall efficiency is in the 62% to 75% range. Therefore, this type of ERD is not suitable for a low flow range. [16]

At present, most of the desalination plants use a Class II type of ERD namely a pressure or work exchanger that can achieve efficiencies greater than 95% (Greenlee et al. 2009). The PWE transfers the hydraulic energy of the pressurized RO concentrate stream to the RO feed water stream. [13],[15] PWE systems can be categorized as two types: those that provide a physical barrier (piston) between the RO concentrate stream and feed side of the system, such as a Dual Work Exchanger Energy Recovery (DWEER), and those without a physical barrier such as a Pressure Exchanger (Cameron and Clemente 2008; Mirza 2008). In the case of a DWEER, the system is based on moving pistons in cylinders which is well suited for a wide range of water viscosities and densities, but results in a large foot print (Mirza 2008). A Pressure exchanger device has higher efficiency since no transformational losses occur in the device, higher capacity is achieved by arranging several devices in series. Disadvantages include limited flow rates, high noise levels requiring a sound abatement enclosure (Mirza, 2008) and the degree of mixing that occurs between the feed water and concentrate stream. A feed salinity increase of 1.5%e3.0% caused by such mixing will increase the required feed pressure for the RO system (Wang et al. 2005). [16],[17]

M. Barreto et. al. (2010) worked on a RO kinetic energy recovery system which is in the form of a closed loop. feed water accumulated in one of the pressure exchangers is pressurized with a high pressure pump (HPP) by making a closed circuit between the membrane output and the reverse osmosis module input, where a water tank (pressure exchanger) and a booster pump are fitted into the line. It also consists of inertia valves, expansion bladder. The water entering or leaving them, which must be pressurized or depressurized, is always in continual motion to avoid unnecessary consumption of kinetic energy that arise from stops in the operation . Certain advantages include: Reduced specific energy consumption & total cost, 97% energy efficiency, reduced capacity of the HPP, Decrease in the amount of antiscalant needed and low mixing percentage between seawater and brine in the isobaric chamber. [5]

Xiaopeng Wang et. Al. (2010) worked on a positive displacement (PD) ERD known as the FS-ERD that was mainly composed of three portions, a rotary fluid switcher, two pressure cylinders and a check valve nest. The rotary fluid switcher was the core component that consisted of four joint ports and two working phases similar to a two position four-way valve. When the FS-ERD accomplishes its pressurizing stroke (and also the depressurizing stroke), the switcher would rotate to working phase II at a low speed of 7.5 rpm driven by motor, which denotes that the stroke modes in cylinders are alternated to each other. The switcher accomplishes its phase change by rotating its multi-channel rotor around the switcher's shell. Single alone and parallel operation (Flow rate and pressure fluctuations) tests showed that the parallel operation of two sets of ERDs can not only extend the capacity of the system but also remarkably improve the stability and continuity of the working streams to and from the ERDs. The maximum recovery efficiency achieved is 95%. The long contact time (20 to 60 seconds) between the brine and seawater in the isobaric chambers results in some intermixing, resulting and an increase in the membrane feed salinity of up to 1.5%. [18]

From the literature review it is clear that isobaric ERDs deliver higher efficiency than centrifugal devices, but centrifugal devices are generally better characterized and are easier to maintain and operate. Rotary isobaric devices provide a unique combination of isobaric and centrifugal features with high energy transfer efficiency, no maintenance, and easy operation

The pressure exchanger comprises of a Rotor (the only moving device) that rotates about a longitudinal axis and has a plurality of continuous rotor channels having openings on each rotor end face arranged around the longitudinal axis of the rotor with the rotor channels communicating with the connection openings of the housing via flow openings formed in the housing such that during the rotation of the rotor the rotor channels alternately carry high pressure liquid and low pressure liquid from the respective first and second liquid systems. This is enclosed in housing along with hydrodynamic bearings. On either side of the rotor, end covers are fixed with inlet and outlet connection openings for each liquid. The end covers and rotor are enclosed in a sleeve. [13]

With reference to Figure 3, Low pressure sea water enters the pressure exchanger and fills rotor, this sea water is then exposed to high pressure concentrate from the membrane. Pressure transfers directly from the concentrate to the sea water inside the rotor ducts. Spent concentrate leaves the rotor ducts as it gets pushed out by low pressure sea water. The ducts of the rotor functions like a carousel charging and discharging. Water around the narrow gap in the rotor serves as a lubricant. [13]

In the design stage for inlets into the rotor channels, the flow ratios are based on velocity triangle diagrams in which the circumferential component c u generates a driving torque for the rotor as a momentum force. This circumferential component is designed to be larger than the circumferential velocity U of the rotor. The rotor inlet edges formed between the openings of the rotor channels with the wall surfaces which follow in the direction of flow are constructed so that the resulting relative flow of the rotor is received without impact by the rotor channels and is deflected in the direction of the rotor channel length.

Such a design of the inlet of the rotor channels also includes the advantage that when there is a change in volume flow, the triangle diagram of the velocity at the inlet of the rotor channels undergoes an affine change, i.e., the circumferential component c u changes to the same extent as the oncoming flow velocity c of the liquid. Thus the driving torque acting on the rotor also increases, leading to an increase in the rotor rpm. With an increase in rotor rpm, the frictional moment acting on the rotor and having a retarding effect also increases. Due to the linear relationship between the driving torque M I which increases with an increase in the circumferential component c u and the frictional moment M R which increases in proportion to the rotational speed, the circumferential velocity of the rotor is always established so that the triangle diagrams of the velocity conditions which prevail at the rotor inlet are similar for all volume flows. There is thus a self-regulating effect which guarantees the condition of impact-free oncoming flow for each volume flow established. The rotational speed of the rotor is thus corrected based on the congruent velocity triangle diagrams and an impact-free oncoming flow of the rotor channels for volume flows of the main flows that are altered due to system conditions.

A rotor is constructed in multiple parts, whereby a rotor part having straight rotor channels on its end faces is provided with one or two incoming flow plates, and inlet openings and/or downstream channel beginnings which make the channel flows uniform are arranged in the incoming flow plates.

Rotor channels having a trapezoidal cross section are arranged so they are axially parallel to and concentric with the axis of rotation of the rotor , with wall surfaces designed as webs running radially between the rotor channels extending between the rotor channels. The openings in the rotor channels arranged on the end face of the rotor have additional rounded surfaces on their radially outer corners in the manner of inclined surfaces that widen diagonally outward, so that each opening is slightly enlarged.

Opposite the openings of the rotor with its axially parallel rotor channels, The velocity triangle diagram for a liquid flowing into the rotor, comprising velocity vectors U, w and c, where the arrows indicate the directions and the magnitudes of the various velocities, where:

U=circumferential velocity of the rotor

w=relative flow in the opening upstream from the rotor channel

c=absolute flow of the liquid flowing out of the housing and to the rotor, where:

c u =circumferential component of the absolute flow and

c x =axial component of the absolute flow,

?c u =driving velocity for the rotor=c u -U

a=angle of flow of the absolute flow c

ß=angle of flow of the relative flow

The flow to the rotor 1 is passed through a housing part opposite the rotor (not shown) which is opposite the rotor so that the flow in the stationary reference system strikes the rotor 1 as an absolute flow c at the angle a. The rotor 1 rotates with the circumferential velocity U and accordingly the relative flow w strikes it at the angle ß. The circumferential component c u of the absolute flow c is greater by ?c u than the circumferential velocity U of the rotor, thus ensuring the required driving torque of the rotor.

Because of the relative oncoming flow angle ß, which is different from zero, the oncoming flow of the rotor channels in the relative system is not free of impact. Consequently, separations in the form of eddies are constantly developing in the openings in the rotor channels and as a result an irregular velocity profile is established within the flow in the remaining path of the rotor channels. These irregular velocity profiles lead to the mixing problems.

(Kochanowski, 2007)

Reverse osmosis systems consisting of a pressure exchanger, pelton turbine and no energy recovery device have been analyzed below. Block diagrams of each energy recovery device had been constructed to asses and analyze the forces acting on the fluid.

The fluid flow through the rotor channels is viscous.

Mixing occurs in the rotor channels

Eg. Efficiency =

Mixing =

A

B

C

D

E

F

G

H

m3/day

130

111

19

111

130

13

117

117

bar

2.5

2.5

62.0

59.8

62.0

0.0

60.4

2.0

ppm

35,000

35,000

35,000

35,436

35,616

200

39,551

39,137

Fresh Water Output

13 m3/day

Membrane recovery rate

10%

Membrane feed pressure

62.0 bar

Membrane differential pressure

1.6 bar

Pressure Exchanger Low Pressure discharge pressure

2.0 bar

Feedwater salinity

35,000 mg/l

Motor frequency

50Hz

Cost of power

0.10 $/Kwh

High pressure Pump efficiency

90%

High pressure Pump motor efficiency

87%

Booster pump efficiency

48%

Booster pump motor efficiency

88%

Booster pump VFD efficiency

97%

Pump efficiency

90%

Motor efficiency

87%

Power consumed

1.7 KW

Pump efficiency

48%

Motor efficiency

88%

VFD efficiency

97%

Power consumed

0.7KW

Unit flow

4.9 m3/hr

Lubrication per array

0.2 m3/hr

Lubrication flow

5%

Differential pressure High Pressure side

0.6 bar

Differential pressure Low Pressure side

0.5 bar

Efficiency

93.7%

Mixing at membrane feed

1.8%

Operating capacity

71.6%

Power Savings

9.0KW

Estimated CO2 Savings

47tons/year

Specific power consumption

kWh/m3

4.34

Power cost saved with the pressure exchanger

$/year

7,913

Recovery

10%

Membrane differential

bar

1.6

A

C

F

G

m3/day

130

130

13

117

bar

2.5

60.9

0.0

59.3

mg/l

35,000

35,000

200

39,551

Mechanical energy recovered

0.0 KW

HP pump shaft power

15.4 KW

Motor shaft power

15.4 KW

Motor electrical power

17.2 KW

HP Pump efficiency

57%

HP Pump motor efficiency

90%

Net transfer efficiency

57%

Total power consumption

17 KW

Specific power consumption

31.75 KWh/m3

A

E

F

G

H

m3/day

130

130

13

117

117

bar

2.5

60.9

0.0

59.3

0.0

mg/l

35,000

35,000

200

39,551

39,551

Turbine efficiency

56%

HP Pump efficiency

57%

HP Pump motor efficiency

90%

Net transfer efficiency

32%

Mechanical energy recovered

4.5KW

HP pump shaft power

15.4KW

Motor shaft power

10.9KW

Motor electrical power

12.2KW

Recovery

10%

Membrane differential

1.6 bar

Total power consumption

12 KW

Specific power consumption

22.47 KWh/m3

Power saved with Pressure Exchanger

18.13 KWh/m3

81%

Cost saved with Pressure Exchanger

8,604

Based on the tabulated values give above a certain set of trends and variations can be observed

Considering all the aspects taken into account for the direction of this project it seems the results obtained are viable.

With reference to fig 22. as the recovery rate increases the brine concentration, and the membrane flow is insufficient to remove the salts that deposit on the membrane surface. This in turn increases the pressure drop, thus increasing the HPP energy consumption by decreasing the efficiency of the pressure exchanger.

With reference to fig. 23, the pressure drops and viscous friction associated with the pressure exchanger can be explained

The pressure of the feed water flowing from the Pressure exchanger is slightly lower than the pressure of the brine fed to it.

Similarly, the pressure at the brine outlet of the Pressure exchanger is slightly lower than the pressure at the feed water inlet.

With reference to fig. 24, as the flow rate increases, the mixing that takes place between the high pressure sea water exit of the pressure exchanger and the sea water pressurized by the high pressure pump reduces.

Mixing is one of the biggest issues in a pressure exchanger design even though trapezoidal channels are employed.

With reference to fig. 25, the rotor sits on hydrodynamic bearings. Around the rotor a narrow gap filled with water serves as lubrication that helps it spin at a constant rate of approx... 1200 rpm. At a higher flow rate the amount of lubrication provided to the hydrodynamic bearings reduces and settles to around 3.5% at around 200 m3/day

With reference to fig. 26, fig. 27, fig. 28 and fig. 29 the amount of energy recovered by the pressure exchanger is almost 30% more than what a conventional pelton turbine can achieve followed by a saving of almost 60% in a system with no energy recovery device. The high pressure pump accounts for almost 70% of the energy in the reverse osmosis process, introducing a pressure exchanger reduces the energy consumption as compared to any other system. Lower flux rates and lower recovery rates generally result in lower system energy consumption. Fitting a pressure exchanger in plants without any energy recovery would result in massive savings/year. This would even encourage new businesses and would eventually lead to water abundance!

As the recovery ratio increases, the power cost saved decreases; an optimal system would function at 40% recovery.

With reference to fig. 30, The limit is 80%; past that a trend is observed where in the pressure exchanger efficiency is lesser than that of the pelton wheel for higher recovery ratios.

The two most important measures of energy recovery device performance are energy transfer efficiency and concentrate-feedwater mixing, both of these have been met at a very high scale using the pressure exchanger energy recovery device.

Compared to older energy recovery systems, RO systems consume 15 to 35% less power with pressure exchangers

Reduced High pressure pump consumption and system power consumption drop.

A restricted operating range and mixing of the two liquids found in the rotor channels during operation.

7 Conclusions

The global water crisis has reached such a stage where action is needed right now. This paper looks into recovering energy for a typical reverse osmosis in order to make it more affordable and efficient. From the results presented above it is quiet clear that the pressure exchanger fulfils what has been mentioned.

From the literature review, we gather key information about the different types of energy configurations used. It was necessary to understand how a reverse osmosis system works. Each part in detail. Assume certain parameters and calculate system outputs.

A block diagram of the reverse osmosis system with 3 different energy recovery configurations was drawn. Certain parameters regarding efficiency, feed pressure...etc were assumed. Next these inputs values were fed into the system, a set of equations were used in order to calculate flow, pressure...etc at each point and ultimately the system power consumption and performance. The analysis shows that the pressure exchanger recovery system recovers almost 95% of the energy wasted in the brine.

To further investigate this proposal, a CAD model of the pressure exchanger was built in CAD, drawings were obtained and it was manufactured using acrylic. A household reverse osmosis unit was purchased for testing. Obtaining experimental results from the test rig would be ideal to validate the theoretical results. A real life model would include losses as well which would provide useful insight.

A CAD model of the pressure exchanger was created in solid edge; drawings for each part were produced and handed over to the workshop where manufacturing took place using acrylic.

A rod was purchased to be inserted through the apparatus. On either end covers pipe fittings for the LP, HP Sides were connected.

Silicon Glue was used to place the parts in place.

The system would be tested out by measuring the flow, pressure and salinity at each point. This would be later validated by the theoretical results obtained.

A reverse osmosis system consisting of a pressure exchanger was modeled as shown in figure 5, 6 and 7.

Perform experimentation and obtain values for pressure, flow rate and salinity at each point.

Install fluid bearings (hydrodynamic) to the pressure exchanger model.

Replace the existing pipes and fittings with larger diameter counterparts.

First of all I would like to thank my supervisor Dr. Sarim for not only being a great supervisor but for being a great friend. Mr. Mohamed the lab technician also deserves a special note as it was with him that the test rig was able to be set up. Credit goes out to my colleagues for guiding me in case of any hurdle faced.



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Water Quality Dissolved Oxygen Biology Essay

Figure 4.1 show the temperature and DO concentration in EM treated water sample and control water sample. The reading has been taken once in 2 days by using YSI 52 CE DO meter (S.N 06L1446) for 26 days in a row in unit mg/L (ppm). The optimum range of DO concentrations for tilapia culture is between 5.00 ppm - 8.30 ppm. Lower than 5.00 ppm, the fish will distress and if the concentration of DO less than 2.00 ppm the potency of fish dies is high.


Figure 4.1: Concentration of DO in EM Tank and Control Tank


Base on figure 4.1, the concentration of DO starting from day 0 till day 26th not shown an obvious changed in both water samples. At day 0, the DO concentration for EM treated water sample is 5.06 ppm and at the end of the study which is at day 26th, the concentration of DO in EM treated water sample is 5.15 ppm. The highest concentration of DO in was appeared at day 24th which is 5.92 ppm. In contrast, the lowest concentration of DO in EM treated water sample is 4.79 ppm which at day 10th. For EM treated water, the DO concentration at day 8th (4.86 ppm) and at day 10th (4.79 ppm) were recorded below the optimum concentration.


Conversely, the highest concentration of DO in Control water sample is 5.83 ppm which at day 8th. On the contrary, the lowest concentration was recorded at day 20th which is 4.88 ppm. Furthermore, the DO concentration at day 4th (4.97 ppm) and day 20th (4.88 ppm) appeared at low then optimum concentration. Even though the concentrations of DO at both days are slightly low then optimum concentration, this was not affected the Tilapia culture.


Theoretically, the temperature of water sample will affect the concentration of DO. Oxygen becomes less soluble in water as the temperature increases (Geer and Kamila, 2005). Meaning that, warm water is less capable in dissolving the gases like oxygen while cold water has greater ability in holding oxygen. How ever, those days which the DO concentration were shown not in the optimum range, the temperature was lower (24°C) compared to others (Figure 4.1). However, this fact was assumed to show negative result due to the deepness of the probe when DO concentration reading. More deep of water from the surface, the temperature and DO are lower compare to the temperature and DO at the surface. Therefore, the more deep the probe of DO meter goes from the surface during reading, the lower the temperature and the DO concentration.


In conclusion, the concentrations of DO for both tanks are almost the same. No significantly changed in DO concentrations due to the aeration system that has been used to supply the oxygen. Therefore, the hypothesis can be made as the used of EM are not affecting the levels of DO in Tilapia culture. The level of DO is mainly control by aeration system. Even the surrounding temperature can affect the DO concentration, but it is not indicate an obvious change to the DO concentration.


Temperature also acts as an important parameter which needs to be checked in fish culture. The temperature of EM treated water samples were in range of 24-27°C and in control water samples were in the range of 24-26 °C. From figure 4.2, the data had shown there was no significant change through out the whole study. More over, the temperature of the water for both tanks was not away from the optimum range which is between 20 and 35 °C.


Figure 4.2: Temperature in EM Tank and Control Tank


For EM treated water sample, the lowest temperature recorded was 24°C, while the highest temperature was 27°C. In contrast, the lowest temperature for control water sample was same with EM treated water sample which is 24 °C but the highest temperature recorded in control water sample is 26 °C.


In general, the temperature for both tanks was control by the environment. Due to the location of the culture tanks which was under the roof, the heat from the sun are not directly affect the temperature. Moreover, in rainy day the temperature reading is not dropped significantly because the rain water does not drop into the culture tank and the volume of water in culture tanks remain the same.


Figure 4.3 show the concentration of Total Ammonia Nitrogen (TAN) in EM treated water sample and control water sample. Starting from day 0 to day 10th, the TAN concentration in both water samples increased quite in the same way. At day 0, the TAN concentration in EM treated water sample is 1.64 ppm and rose to 4.85 ppm at day 10th. On the other hand, the TAN concentration in control water sample rose from 1.65 ppm at day 0 to 4.90 ppm at day 10th. However, the concentrations of TAN in both water samples show major differences starting from day 12th to day 26th. The TAN concentration in control water sample started to acumulate at higher rate compared to EM treated water sample from 4.92 ppm at day 12th to 5.25 ppm at day 26th. On the contrary, TAN concentration in EM treated water sample show in decreased (33.70%) from 4.57 ppm at day 12th to 3.03 ppm in day 26th.


Figure 4.3: Concentrations of Total Ammonia NH3-N


The waste from fish pallet was proven to be the main contributor to the TAN concentration in water. For that reason, the concentration of TAN in control water sample was significantly increased by time. The ammonia cycle in control tank was not effective enough to reduce the concentration of TAN. This fact is mainly due to the lack of bacteria that utilized ammonia. In contrast, the decreased concentration of TAN starting from day 12th to day 26th in EM treated water sample was mainly due to the used of EM treatment. The microorganisms in EM were proven to be effective in reducing the TAN concentration. Moreover, the microorganisms such as Nitrosomonas and Nitrobacter that can make use of ammonia as energy source may be include in the consortium of microorganisms in EM.


Besides, the concentration of TAN will affect the pH of the water (refer chapter 4.1.4) and the concentration of Un-ionized ammonia (refer chapter 4.1.5). Since ammonia is alkaline, it will indicate higher pH value when its concentration increases. Moreover, the greater the concentration of TAN, the higher concentration of Un-ionized ammonia will produce in the water system (Ruth and Craig, 2005)


The value of the pH has an effect toward the toxicity of ammonia and increasing in pH will increase the toxicity of ammonia. The recommended value for Tilapia culturing is between 6 - 8 ppm (Tilapia culturing technique, Lembaga Kemajuan Pertanian MADA). If pH readings are beyond this range, fish growth is reduced and at values below 4 or above 10, mortalities will occur.


Figure 4.4: The pH Values in EM Tank and Control Tank


Figure 4.4 shows the pH value for EM treated water sample and control water sample. The pH values for both tanks were increased for the first 10 days. At day 10th where the EM solution was introduced to the EM tank, the pH values for EM treated water samples were started to decrease. On the contrary, the pH values for control water sample still show an increase.


For the first 10 days, the pH value for EM treated water sample increase from 7.13 ppm to 7.46 ppm. While, pH value in control water sample had been increase from 6.98 ppm to 7.81 ppm. After 2.5 L cultured of EM was added to the EM tank at day 10th, the pH value in EM treated water sample has slightly decreased from 7.46 ppm to 7.27 ppm. While, the pH values in control water sample still increased until 8.31 ppm toward the end of the study (day 26th). For EM treated water sample, the value of pH remain in the recommended pH value and still suitable for the culture of Tilapia. Whereas, the pH values in control tank at day 14th, 16th, 18th, 22nd, 24th and 26th (figure 4.4) has go beyond the recommended range of pH value for Tilapia culture (6-8 ppm).


These results proved that the use of EM in aquaculture will reduce the pH level to suitable pH range for the Tilapia culture. Since the pH value is related with concentration of total ammonia in water, the used of EM will solve both problems. Hence the production cost will decrease and the productivity of Tilapia will increase by using EM.


Figure 4.5 shows the concentration of un-ionized ammonia (UIA) in both EM treated water sample and control water sample. UIA is a toxic form and the toxicity begins as low as 0.05 ppm. If the UIA is higher than 0.05 ppm, the fish gill is being damaged. As the concentration rises above 0.05 ppm it causes more and more damage and at 2.0 ppm fish will die. The UIA can be calculated from the concentration of TAN multiply by the Fraction Factor (Appendix 7). Prior to the calculation of the UIA, the pH and temperature of the water sample need to be determined.


Figure 4.5: Concentrations of Un-ionized Ammonia (UIA)


It was shown that the concentration of UIA in EM treated water sample shown an increase from day 0, 0.0098 ppm to 0.0686 ppm at day 12th. The concentration of UIA is related to the concentration of TAN. Since there was an increasing in TAN concentration in EM treated water sample for the first 10 days (Figure 4.3), therefore, the UIA in EM treated water sample was increased from day 0 to day 12th. However, after EM has been introduced, the concentration of UIA was slightly decreased (57.58%) from 0.0686 ppm at day 12th to 0.0291 ppm at day 26th. This happened because the decreasing of TAN (33.70%) in EM treated water sample from day 12th to day 26th (Figure 4.3).


On the other hand, the concentration of UIA in control water sample was increased with time. The concentration of UIA at day 0 is 0.0099 ppm and rose significantly to 0.4620 ppm at day 26th. This observable fact was due to the increasing of TAN in control water sample. In general, the higher the concentration of TAN, the grater the concentration of UIA in water sample.


Figure 4.6 show the concentration of nitrite in EM treated water sample and control water sample. Started from day 0 to day 10th, the nitrite concentration in both water samples increased in the similar manner. At day 0, the nitrite concentration in EM treated water sample is 0.036 ppm and rose to 0.427 ppm at day 10th. On the other hand, the nitrite concentration in control water sample rose from 0.042 ppm at day 0 to 0.453 ppm at day 10th. But after addition of EM into EM treated tank, the concentration of nitrite in both water sample show noticeably differences starting from day 12th to day 26th. The nitrite concentration in control water sample started to increase at higher rate compared to EM treated water sample from 4.92 ppm at day 12th to 5.25 ppm at day 26th. In contrast, nitrite concentration in EM treated water sample show in decreased from 0.299 ppm at day 12th to 0.193 ppm in day 26th (35.45%).


Figure 4.6: Concentration of Nitrite NO2-N in EM Treated Water Sample and Control Water Sample


Since nitrite is the product of the ammonia metabolisms in nitrogen cycle, the concentration of TAN will affect the concentration of nitrite. In conclusion, EM was proven in reducing the concentration of nitrite due to the reducing of TAN concentration.


Gas Chromatography Mass Selective (GC-MS) detector should be used in this analysis. Due to some technical problem that cannot be accounted, alternatively, Gas Chromatography with Flame Ionized Detector (GC-FID) has been used. However, the chromatograph did not show the peak of interest but show a lot of unknown peaks.


This problem was believed due to the GC type that has been used. The GC-MS is more sensitive in detection because it detection is based on the mass of the compounds. In contrast, GC-FID detection is based on ionization. More over, GC-FID that being used is equipped with ultra-5 column which is semi-polar instead of ultra-1 column which is non-polar that needs to be used. Since GEO and MIB is semi volatile polar compound, the used of ultra-5 as a column is not good for separation of these compounds. Further more, the method used is well-matched with GC-MS but the same method has been used when running GC FID.


Conversely, sample preparation also one of the factor that contributed to this problem. Methanol has been used as a solvent in dilution of the standard samples which are GEO and MIB. Even though the solvent has been filtered with 0.45 µm and 0.2 µm filter membrane, but there were still impurities or contaminant occurs in the standard samples. This impurities and contaminant has shown in the chromatograph as unknown peak (Appendix 14-16). How ever, after methanol (solvent) or blank has been injected in GC, all the unknown peaks have been identified from the solvent itself (Appendix 16).


Therefore, as an alternative, the sensory evaluation method has been used to investigate the effect of EM in elimination of off-flavor in Red Tilapia.


Figure 4.7 and figure 4.8 show the graph of Average Score of Sensory Evaluation for EM treated fish sample and control fish sample. The four attributes that has been judged for 5 evaluation session were texture of the fish fillet, earthy taste of the fish, moisture and acceptability. The major attribute focused in this study was earthy taste in fish.


The evaluation session was carried out once in 3 days. It was started with first session that was held on day 13th followed by second session on day 17th, third session on day 21st, fourth session on day 25th, and last session on day 29th. At each session, six fish samples have been introduced to the panelist consisted of EM treated fish samples and control fish samples.


Figure 4.7: Average Score of Sensory Evaluation in EM Treated Fish Sample


Figure 4.8: Average Score of Sensory Evaluation in Control Fish Sample


The first attribute that has been study is texture of fish sample. The score vary from 1 for hard to 5, soft. Based on figure 4.9, the average score for EM treated fish sample and control fish sample not show significant differences. For the 1st session till the 3rd session, the average score given by the panelist for EM treated fish sample and control fish sample are almost the same. It was found that the 4th session of evaluation, the average score for EM treated fish sample is 4.2 while for Control fish sample, the average score is 3.5. On the other hand, at 5th session, the average score for EM treated fish sample is 4.1 compared to control sample which is 3.6.


Figure 4.9: Average Score in texture for EM treated fish sample and control fish sample According to Evaluation Session


In general, the fish samples that had treated with EM have higher quality of texture compare to control sample (Zulkafli A. R. Pemahaman asas-asas mutuair: panduan mudah untuk penternak. Unpublished note, Pusat Penyelidikan Perikanan Airtawar). Further study need to carry out to confirm this fact because the effect of EM on fish texture is time consuming process and need longer study period to see the result. From the Analysis of Variances (ANOVA), the data was significantly differ with p < 0.005 (Appendix 16).


Figure 4.10 show the distribution of earthy taste in EM treated fish sample and Control fish samples. The score vary from 1 (very dislike), 2 (dislike), 3 (neither dislike nor like), 4 (like) and 5 (very like). From the figure 4.12, the earthy tastes in EM treated fish sample show drastically increase in quality. In 1st session, the average score is 2.7 which mean the panelist not sure whether they like or dislike. But at the end of the study, at 5th session almost the entire panelist agreed that the earthy taste in EM treated fish sample has decreased and give an average score 4.5 (almost very like).


Figure 4.10: Average Score in Earthy Taste for EM treated Fish Sample and Control fish Sample According to Evaluation Session


On the other hand, the control fish samples did not show in drastic improvement on earthy taste. The average score are varying from 2.1 (dislike) for 1st session to 2.8 (neither dislike nor like) at the last session. The panelist agreed that the earthy taste is still in the fish sample after 5 session of evaluation.


As a hypothesis, the used of EM will reduce the earthy taste in the fish tissues. The earthy taste had change from dislike to almost like very much after treatment of EM to the fish sample. Based on this study, 16 to 20 days after treatment with EM was enough to reduce the earthy taste in fish sample. From the Analysis of Variances (ANOVA), the data was significantly differ with p < 0.005 (Appendix 17).


Figure 4.11 show the average score for moisture in EM treated fish samples and control fish samples. The scores vary from 1 (dry) to 5 (wet). For the 1st session, the average score for EM treated fish sample is 3.6 while for control fish sample, the average score is 3.3. Moreover, the average score for control fish samples at 2nd and 3rd session are similar which is 3.2. Towards the end of the evaluation session, the average score for EM treated fish sample is 4.1 compared to control fish sample 3.9.


Figure 4.11: Average Score in Moisture for EM treated Fish Sample and Control fish Sample According to Evaluation Session


In conclusion, the effects of using EM toward the moisture content in fish sample are not clearly defined in this study. Since there is no significant different in moisture content between EM treated fish sample and control fish sample, the hypothesis can be made as EM was not affect the moisture contain in fish tissue. May be other factors such as the genetic of the fish, aging or the way of sample preparation will affect the moisture contain in fish. Therefore, further study must be carry on by using different methods to determine the moisture content in fish. From the Analysis of Variances (ANOVA), the data was significantly differ with p < 0.005 (Appendix 18).


Figure 4.12 show the average score for acceptability in EM treated fish sample and control fish sample. For this attribute, the score vary from 1 (worse), 2 (bad), 3 (fair), 4 (good) and 5 (best). These attributes were judged to know the level of satisfactoriness toward the fish samples. In other word, this attribute was indicated that either the fish sample is satisfied to eat or not.


Figure 4.12: Average Score in Acceptability and Earthy Taste for EM treated Fish Sample and Control fish Sample According to Evaluation Session


Figure 4.12, shown that the average score for EM treated fish sample always higher compared to control fish sample. In 1st session, average score for EM treated fish sample was 3.2 whereas control fish sample was 2.3. Towards the last session of the evaluation session, the average score for EM treated fish sample also higher than control fish sample. Overall, the average score for EM treated fish sample has change from Fair (3.2) to Good (4.3) toward the end. On the other hand, for control fish sample not show drastically change. For the 1st session the average score was bad (2.3) and at the lass session of evaluation the score is still at the same score (2.7) but a bit higher toward Fair score.


Moreover, figure 4.12 shows the relationship involving acceptability and earthy taste. The change in average score for acceptability for both sample were affected by the earthy taste in the fish sample. The less of earthy taste in the both fish samples or in other word the higher the average score in earthy taste indicate higher average score in acceptability.


Therefore, the earthy taste was the main problem contributed to the rejection of Tilapia in the local and global market. Even though there are other attribute that has been judged in this study, but the main attribute contributed to the negative response of tilapia was earthy taste. The used of EM has changed the panelist tolerability toward fish sample from fair to good (figure 4.12). From the Analysis of Variances (ANOVA), the data was significantly differ with p < 0.005 (Appendix 19).


Table 4.1 shows the comparison of the average CFU between the EM treated water sample and the control water sample. From the spread plate results, control soil sample recorded an average 6.0 x 107 CFU/mL at day 14th, 1.6 x 108 CFU/mL at day 19th, and 1.2 x 108 CFU/mL at day 24th. In general, the average microorganism colonies for EM treated water sample are 2.7 x 108 CFU/mL at day 14th, 5.7 x 108 CFU/mL at day 19th, and 6.5 x 108 CFU/mL at day 24th. Furthermore, by combining all these results, the average microorganism colonies for control water sample is 1.13 x 108 CFU/mL while the average microorganism colonies for EM treated water sample is 4.97 x 108 CFU/mL which is 4.398 times (339.82%) higher. In simple word, the application of EM has vitally increased the number of beneficial microorganisms in the water.


Table 4.1: Comparison of CFU


2.7 x 108


6.0 x 107


5.7 x 108


1.6 x 108


6.5 x 108


1.2 x 108


4.97 x 108


1.13 x 108



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The Effects Of Dehydration And Rapidly Consuming Water Biology Essay

Biology » The Effects Of Dehydration And Rapidly Consuming Water Biology Essay

Blood pressure measures the pressure applied against the inner walls of arteries, it differs throughout the body and is controlled by the contraction of the heart and can vary from person to person based upon their age, weight, and overall health. The two types of pressure are referred to as systolic pressure, when the ventricles contract and push blood through the body, and diastolic pressure, the ventricle fills with blood again. High blood pressure, when blood exerts a high amount of pressure because there is difficulty moving throughout the body, has proven to be an adverse health condition involving heart disease and stroke (www.freedrinkingwater.com 2009). Dehydration demonstrates a relationship with higher blood pressure and is referred to as ‘essential hypertension’ (Insel et al. 2010). There is a steady rise in blood pressure that indicates a shortening supply of water and the blood vessels react accordingly. Lumen or the tiny holes in the blood vessels are able to adapt, open and close, in response to the amount of blood. Studies have shown that only 8% of the insufficient water intake affects the volume of blood directly compared to the 66% imposed on the volume water in certain cells (Batmanghelidj 2003). However, the circulatory system shrinks by closing the lumen throughout the blood vessels. First, in the peripheral capillaries and eventually the larger vessels constrict in order to try and maintain full blood vessels. This gives a rise to tension or pressure throughout the blood vessels and a higher blood pressure overall (Batmanghelidj 2003).

There are other studies that show the importance of water balance and the key role of the antidiuretic hormone (ADH) (Purves et al. 2006). Water is such an essential part of the human body that there are specialized cells in the brain that detect the elevated sodium levels within the body and signal the pituitary gland to release ADH to indicate to the kidney that it should conserve water (Insel et al. 2010). This conserves blood volume and maintains blood pressure. When there are low levels of ADH not as much water is absorbed and dilute urine is produced. Water retention and intake dilutes the blood and expands blood volume. (Purves et al. 2006)

My experiment is to test the rapid consumption of water and the effects on blood pressure. My hypothesis is that the consumption of water will cause my blood pressure to drop because it will add to the fluidity of my blood and make is easier to pass through the arteries and the heart rate will drop because of the less pressure. The null hypothesis would be that the consumption of water would take no effect on blood pressure or cause a rise in blood pressure and heart rate. As the previous background information has shown, hydration can play a major role in high blood pressure and therefore adverse health.

The first instrument to note would be the sphygmomanometer, a device used to measure blood pressure. Before we drank the water we had to place the sphygmomanometer on correctly and take our basal blood pressure. We had all been in a resting position for around 2 hours, this qualified as enough time to take our initial basal blood pressures. To obtain accurate results the sphygmomanometer must be placed correctly over the brachial artery and pumped to around 150 mm Hg. The average of class was obtained by adding up all the systolic pressures and dividing by 26, the number of students conducting the test and the same was performed for the diastolic pressures. The first average basal blood pressure for the class was 104/70, the second 110/71 and the third was 107/70. The sphygmomanometer also displays the heart rate of the person using it. The class’s average basal heart rates were 77, 79 and 78 (beats per minute). Once the initial readings were complete the water was prepared to be consumed. The temperature of the water varied because there were students that had water bottles sitting out a room temperature for at least 2 hours while others had to fill them from the water fountain, which is chilled. Usually using a nalgene, 24 fl. oz of water were prepared to be consumed.

It can be assumed that most people in the classroom were slightly, if not significantly dehydrated because we had not drunk any water for at least 2 hours. The sphygmomanometer was prepared as before on the first partner, the water was rapidly consumed and the blood pressure and pulse was taken immediately after they were finished drinking. There was a 3 minute break between the next blood pressure reading so the other partner has the sphygmomanometer placed on their brachial artery and consumes the same amount of water and has their blood pressure and pulse was taken. The sphygmomanometer was traded between the two partners every three minutes to record the different blood pressures and pulse for the next 12 minutes. The average blood pressures for the corresponding 3 minute intervals were 120/79, 114/68, 111/71, 117/77, and 114/72. The average heart rates were 71, 70, 69, 71, and 71 likewise.

The independent variable was the amount of water consumed while the dependent variable was the blood pressure and pulse because it was what we were testing for. The constants for this experiment were time, the environment we were all in and the fact that water was consumed. This experiment was also paired because the same group of people that performed the basal readings conducted the rest of the experiment as well. There were 13 groups of two throughout the class and the same experiment was replicated in each pair.

Figure 1:

60 bpm

75 bpm

54 bpm

54 bpm

76 bpm

58 bpm

Table 1

Figure 2:

Range of Diastolic Data:

Range of Systolic Data:

Table 2 Table 3

Table 4

This experiment tested the results of rapidly drinking water when dehydrated on heart rate and blood pressure of subject. The results for the average heart rate seem to demonstrate that the pulse does not change very much with the consumption of water. As for the systolic and diastolic pressures, there are some changes after the water is consumed. There appears to be a spike in the systolic pressure around the 0 minute mark and then it decreases to about average again. The diastolic pressure is much more similar to the heart rate because it is relatively consistent to the average, no drastic changes. The t-test is much more than .05 and shows that the chance these results were random is very high. The ranges of each data set display the differences between each array of data.

My hypothesis states: that the consumption of water will cause the blood pressure and heart rate to drop. My prediction is that the water will add to the fluidity of my blood and make it easier to travel through the arteries and relieve pressure. My results did not support my hypothesis because there was an initial rise in systolic pressure after the water was consumed. The pressure never dropped significantly below the basal readings and therefore my hypothesis was not supported and the null hypothesis tested correctly. If you look at the t-test table (table 4) the p-values were very high, much higher than .05, and this shows that the results had a very high chance of being random. My new hypothesis would be the consumption of water will cause my blood pressure to rise. The reasoning behind this thought is that the water adds to the mass of blood flowing throughout the body and therefore, creates more pressure on the walls of the arteries and yields a higher pressure than before. Once the water is evened out throughout the body the pressure decreases to around the basal readings.

One of the most obvious errors about this lab was the gathering of information from the class. Time is always a constraint on lab work and we ran out of time before we could gather all our information together right after the experiment. Instead, our TA had to collect all the data and put it on a spread sheet. I believe there may have been some communication issues because there are parts of the data that are considered instrumental error and there are no numbers for calculations. The other error that I noticed was the temperature of the water because we didn’t actually see if everybody’s water was the same temperature or not. On that note, the amount of water also varied at times because not everybody was able to measure out 24 fl. Oz with a nalgene and had to estimate.

Looking at previously published work there is evidence that dehydration and hypotension (low-blood pressure) seem to go hand in hand (Weed 1999). Therefore, when hydrated the blood pressure will rise. This is the exact opposite of what I stated in my hypothesis because I thought that addition of water would lower the blood pressure. Heart rate is also low during dehydration but is more variable if it will change during re-hydration or not (Montain and Coyle 1992). Once again, this is the exact opposite of what I predicted in my hypothesis. It appears that most previously printed work does not support my hypothesis.

As I mentioned earlier the largest weaknesses I noticed in this experiment were time, communication between TA and student, volume and temperature of water. I would suggest that more time is set aside for the collection and processing of data stage in the experiment so that the entire class is able to get the full amount of information there instead of having the TA email everybody for their results and then making a spreadsheet. The experiment can also be better prepared with pre-measured cups of water with thermometers so the temperature and volume can be more consistent.

My conclusion to this experiment is that dehydration does have an effect on blood pressure, it causes it to rise. The water adds to the pressure against the walls of the arteries. There appears to be no direct effect on the actual heart rate after the water is consumed.

Batmanghelidj, F. 2003. Water: For Health, for Healing, for Life You're Not Sick, You're Thirsty!

New York: Warner Books. p 93-100.

"Health information- water alleviate symptoms High blood pressure /Cholesterol." Drinking Water Filters- Reverse Osmosis Water Purifiers & Water Softeners. Web. 01 Feb. 2010. .

Insel et al. 2010. Discovering Nutrition. London: Jones and Bartlett International. p. 400-403

Purves et al. 2003. Life The Science of Biology. 7th Edition. New York: Sinauer Associates and W. H. Freeman. p. 216-221



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6.04 Water Essay

WATER 101
5 Facts about how it's used in your body!
Water is used in body as a transport medium for different molecules,cells and other materials.
Water is a universal solvent which is used in body to dissolve many compounds such as sodium chloride and other salts.
Water in the body is also used as a metabolite and is used in many reactions. Also the reactivity of many compounds increases when they are dissolved in water.
Spermatozoa can only move by ther flagella in water.
Water is also used as a coolant in body and helps to regulate the body temprature in extremely hot conditions.

2 MYTHS ABOUT WATER
Myth No. 1: Drink Eight Glasses Each Day
Scientists say there's no clear health benefit to chugging or even sipping water all day.
Myth No. 2: Drinking Lots of Water Helps Clear Out Toxins
The kidneys filter toxins from our bloodstreams. Then the toxins clear through the urine.   So no drinking lots of water actually hinders the kidneys ability to filter toxins.

5 TRIVIA FACTS ABOUT WATER!
68.7% of the fresh water on Earth is trapped in glaciers.
1.7% of the world’s water is frozen and therefore unusable.
A ten meter rise in sea levels due to melting glaciers would flood 25% of the population of the United States.
If all of the water vapor in the Earth’s atmosphere fell at once, distributed evenly, it would only cover the earth with about an inch of water.
Approximately 400 billion gallons of water are used in the United States per day.

WAYS TO DEAL WITH DEHYDRATION!
Do not drink coffee, tea, soda, or any drink that contains high level of caffeine, sugar or alcohol, which can cause further dehydration.
To counter dehydration, you need to restore the proper balance of water in your body. Plain cool water (bottled) is the best way to replace lost body fluid, unsweetened fruit juice diluted with water or seltzer.



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