Perseverance is a virtue of the one that wishes to prevail'

1

• Perseverance is a virtue of the one that wishes
  to prevail.
• o
• Persevere and trust God and you will reach your
  intention.
• --- Jaime Pérez

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Chapter XI

• Chloration

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Chapter XI Chloration

• INTRODUCTION
• Drip irrigation is a technique extensively used
  in arid and semi-arid regions of the world.
• The system consists of applying water slowly and
  frequently into the soil with emitters or
  drippers distributed throughout the laterals
  (drip lines).
• The principal problems are
• The obstruction of the laterals (drip lines).
• The obstruction of the filters .

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Chapter XI Chloration

• INTRODUCCION
• These obstructions are caused by
• Physical solid particles in suspension.
• Chemical precipitation of insoluble compounds.
• Biological macro organisms y micro organisms.
• The preventive maintenance is the best solution
  to reduce or to eliminate the obstructions in the
  emitters or components of the system .

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Chapter XI Chloration

• WHAT IS CHLORATION?
• The chlorination is simply the addition of
  chlorine to water. The chlorine, when it
  dissolves, acts as an oxidation agent and attacks
  the microorganisms, such as the algae, fungi and
  bacteria.
• This procedure has been used for many decades to
  purify the drinking water.

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Chapter XI Chloration WHAT IS CHLORATION?

• The chloration solves effectively and
  economically the problem of obstruction of the
  emitters or drippers due to biological agents.

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Chapter XI Chloration

• WATER QUALITYWater Source
• It is necessary to conduct the physical and
  chemical analysis of the water before designing a
  drip irrigation system and choosing an
  appropriate filtration system .
• For this analysis, it is important to take a
  representative sample of the water . If the water
  source is subsurface (e.g. deep well), the sample
  must be taken an hour and a half after the pump
  begins to work .
• When the water source is superficial (lake
  rivers, pools or open channels), the samples must
  be taken at the surface, the center and at the
  bottom of a water source .

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Chapter XI Chloration

• WATER QUALITY
• It is important to analyze the sample for
  suspended solids, dissolved solids and the
  acidity (pH), macroorganisms and microorganisms.
• The acidity of the water must be known, since it
  is a factor that affects the "chemigation
  directly" and therefore the chloration. For
  example, the chloration for the control of
  bacteria is ineffective for a pH gt 7.5.
  Therefore, it is necessary to add acid to lower
  the pH of irrigation water and to optimize the
  biocide action of the chlorine compound.

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WATER QUALITY

• If a chemical analysis of the water is known, we
  can predict the obstruction problems and take
  suitable measures. In addition, a program of
  adequate service and maintenance can be developed.

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Chapter XI Chloration
Table 1a. Criteria that indicates risk of
obstruction of the emitters.
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Chapter XI Chloration
Table 1b. Criteria that indicates risk of
obstruction of the emitters.
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Chapter XI Chloration
Table 1c. Criteria that indicates risk of
obstruction of the emitters.
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Chapter XI Chloration

• WATER QUALITY
• The factors are classified in order of the risk
  of obstruction From low to severe.
• When the water contains amount of solids, salts,
  and bacteria within the acceptable limits, then
  the risk of clogging is reduced.

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Chapter XI Chloration

• WATER QUALITY
• Also the particles of organic matter can combine
  with bacteria and produce a type of obstruction
  that cannot be controlled with filtration system.
• The fine particles of organic matter are
  deposited within the emitters and are cemented
  with bacterias such as Pseudomonas and
  Enterobacter. This combined mass causes clogging
  of the emitters. This problem can be controlled
  with super chloration at the rate of 1000 ppm
  (mg/L).

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Chapter XI Chloration

• WATER QUALITY
• The obstruction caused by the biological agents
  constitutes a serious problem in the drip
  irrigation system that contains organic sediments
  with iron or hydrogen sulfide.
• Generally, the obstruction is not a serious
  problem if the water does not have organic
  carbon, which is a power source for the bacteria
  Promotes the bacterial growth. There are
  several organisms that increase the probability
  of the obstructions when there are ions of iron
  (Fe) or hydrogen sulfide (H2S).
• Algae in surface water can add carbon to the
  system. The slime can grow on the inner surface
  of the pipes.

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Chapter XI Chloration

• WATER QUALITY
• The combination of fertilizer and the heating of
  the polyethylene pipes (black) due to sunlight
  can promote the formation and development of
  these microorganisms.
• Many of the water sources contain carbonates and
  bicarbonates that serve like an inorganic power
  source to promote slime growth also autotrophic
  bacteria (that synthesize their own food) are
  developed.

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Chapter XI Chloration

• WATER QUALITY
• The algae and the fungi are developed in the
  surface waters.
• The filamentous algae form a gelatinous substance
  in the pipes and emitters, which serve as a base
  for the development of slime.
• Another type of obstruction can also happen when
  the filamentous bacteria precipitate the iron
  into the insoluble iron compounds (Fe).
  

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Chapter XI Chloration

• Slime growth
• The bacteria can grow within the system in
  absence of light and produce a mass of the slime
  or cause the precipitation of the iron or sulfur
  dissolved in water.
• The slime can act like an adhesive substance that
  agglutinates fine clay particles sufficiently
  large enough to cause clogging.

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Chapter XI Chloration

• Growth of Algae in the Water Source.
• One of the most frequent problems is the growth
  of algae and other aquatic plants in the surface
  water that can be used for drip irrigation.
• The algae grow well in the surface water. The
  problem becomes serious if the water source
  contains nitrogen, phosphorus or both.
• The algae can cause obstructions in the
  filtration system. When the screen filters are
  used, the algae can be entangled in the sieves
  (screen) of the filter. In high concentration,
  these aquatic microorganisms can create problems
  in the sand filters. This requires a frequent
  flushing and cleaning of the filters.

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Chapter XI Chloration

• Types of Algae
• The main groups of organisms in surface water are
  classified like protists, plants and animals. The
  protists include bacteria, fungi, protozoa and
  algae are and most important organisms for drip
  irrigation, specially the bacteria and the algae.
  
• Algae are unicellular organisms or multicellular
  autotrophic and photosynthetic and requires
  organic compounds to reproduce. The major
  nutriments are carbon dioxide, nitrogen and
  phosphorus. The minor elements like iron, copper
  and manganese also are important for the
  development of these organisms.

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Chapter XI Chloration

• FOUR CLASSES OF ALGAE
• Green
• These are fresh water species that contain
  chlorophyll and other pigments used in the
  photosynthesis process.
• Mótile
• These form colonies when mature It has flashy
  green color and it is unicellular and
  flagellated. The flagella are those that make
  motile in the water.

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Chapter XI Chloration

• FOUR CLASSES OF ALGAE
• Green-yellows
• These are found in fresh water and salt water.
  The majority is unicellular the diatom are most
  important in this group.
• Green-blue
• These are unicellular organisms with flagella.
  These can form big masses in the surface water.
  In addition, these can use nitrogen from the
  atmosphere.

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Chapter XI Chloration PRINCIPLE OF CHLORATION

• The principle of chloration for treating the
  water by drip irrigation is similar to those that
  are used to purify the water for drinking
  purpose.
• When the chlorine in gaseous state (Cl2)
  dissolves in water, the chlorine molecule is
  combined with water in a reaction called
  hydrolysis. The hydrolysis produces hypochloric
  acid (HOCL Reaction /1/). Following this
  reaction, the hypochloric acid enters an
  ionization reaction as shown in reaction /2/.

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Chapter XI Chloration Table 2. Basic forms
and reactions of chlorine.
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Chapter XI Chloration Table 2. Basic forms and
reactions of chlorine..
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Chapter XI Chloration PRINCIPLE OF CHLORATION

• The hypochloric acid (HOCL) and the hypochlorite
  (OCL) are known as free available compounds and
  are responsible for controlling the
  microorganisms in the water. The equilibrium of
  these depends on the temperature and pH of the
  irrigation water.
• When the water is acid (low pH) the equilibrium
  moves to the left, resulting in an increase of
  HOCl. When the water is alkaline (high pH), the
  chlorine increases in the form of OCl-.

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Chapter XI Chloration PRINCIPLE OF CHLORATION

• The efficiency of HOCl is 40 to 80 times greater
  than OCl-. Therefore, the efficiency of the
  chloration depends greatly on the acidity (pH) of
  the water source.
• Reaction /1/ produces hydrogen ions (H) that can
  increase the acidity. The basicity depends on the
  amount of added chlorine and the buffer capacity
  of the water.

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Chapter XI Chloration PRINCIPLE OF CHLORATION

• The sodium hypochlorite NaOCl and the calcium
  hypochlorite Ca (OCl)2 hydrolyze and produce
  OH- ions that tend to lower the acidity of the
  water (reactions /3/ and /4/).
• If the pH is extremely low, the gaseous chlorine
  (Cl2) predominates and can be dangerous.
  Therefore, it is recommended to store the sources
  hypochlorite compounds separate from solids.

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Chapter XI Chloration PRINCIPLE OF CHLORATION

• Also the available free chlorine reacts with
  oxidizing compounds (like iron, manganese and
  hydrogen sulfide) and produces insoluble
  compounds, which must be removed from the system
  to avoid clogging.
• The chlorine has two important chemical
  properties At a low concentration (1 to 5 mg/L),
  it acts as a bactericidal. At a high
  concentration (100 to 1000 mg/L), it acts as an
  oxidizing agent which can disintegrate particles
  of organic matter. It is necessary to watch,
  because the chlorine at these high levels can
  affect the growth of some plants.

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Chapter XI Chloration

• SOURCES OF COMMERCIAL CHLORINE
• Sodium Hypochlorite, NaOCl
• Sodium hypochlorite is liquid and is commonly
  used as whitener for clothes. It can be easily
  decomposed at high concentrations, in the
  presence of light and heat. It must be stored at
  room temperature in packages resistant to
  corrosion.
• This compound is easy to handle. The amounts can
  be measured precisely and causes less problems of
  obstruction.

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Chapter XI Chloration

• SOURCES OF COMMERCIAL CHLORINE
• Calcium Hypochlorite, Ca (OCl)2
• Calcium hypochlorite is available commercially as
  dust, granulated or in pellets. It is well
  soluble in water and is quite stable under
  appropriate storage conditions. It must be stored
  at room temperature in a dry place and in
  packages resistant to corrosion.
• When this compound is mixed in a concentrated
  solution, it forms a suspension that contains
  calcium oxalate, calcium carbonate and calcium
  hydroxide. These compounds can obstruct the drip
  irrigation system.

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Chapter XI Chloration

• SOURCES OF COMMERCIAL CHLORINE
• Gaseous chlorine, Cl2 gas
• It is available in liquid form at high pressure
  in cylinders from 45 kg to 1000 kg.
• Table 3 shows the equivalent amounts of chlorine
  for different commercial sources and the required
  amount to treat 1233 m3 (1 acre-foot) of water to
  obtain one ppm of chlorine.
• 3. The sodium hypochlorite is safer than
  gaseous chlorine and avoids calcium precipitates
  in the emitters, which can happen when using
  calcium hypochlorite.

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Chapter XI Chloration
Table 3a. Required amounts of chlorine.
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Chapter XI Chloration
Table 3b. Required amounts of chlorine.
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Chapter XI Chloration
Table 3c. Required amounts of chlorine
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Chapter XI Chloration
Table 3d. Required amounts of chlorine .
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Chapter XI Chloration

• Gaseous chlorine, Cl2 gas
• It is more economical to use than the gaseous
  chlorine in large systems. In small systems, it
  is appropriate to use sodium or calcium
  hypochlorite. The use of gaseous chlorine is
  preferred in situations where the addition of
  sodium and calcium can be detrimental to the
  crop.
• It is necessary to observe that gaseous chlorine
  is dangerous under certain conditions. Thus the
  instructions on the label must be followed.
• It is necessary to observe that gaseous chlorine
  is dangerous under certain conditions. Thus the
  instructions on the label must be followed.

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Chapter XI Chloration

• CHLORATION METHOD
• The chloration in a drip irrigation system can be
  continuous or in intervals, depending on the
  desired results. Application at intervals is
  appropriate, when the objective is to control the
  growth of microorganisms in lateral lines,
  emitters or in other parts of the system.
• The continuous treatment is used when we want to
  precipitate the iron dissolved in the water, to
  control algae in the system or where it is not
  reliable to use the treatment at intervals.

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Chapter XI Chloration

• GENERAL RECOMMENDATIONS
• Inject chlorine before the filters. This
  controls the growth of algae or bacteria in the
  filters that otherwise would reduce the
  filtration efficiency. This also allows the
  filtration of any precipitate caused by the
  injection of chlorine.
• Calculate the amount of chlorine to inject. It is
  necessary to know the volume of water to be
  treated, the active ingredient of the chemical
  compound to be used and the desired concentration
  in the treated water.

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Chapter XI Chloration

• GENERAL RECOMMENDATIONS
• The chlorine should be injected when the system
  is in operation. .
• One should take samples from the water at the
  nearest drippers and most distant drippers to
  determine the chlorine level at these points.
  Allow sufficient time so that the lines are
  filled with the chlorine solution. .
• Adjust the injection ratio. Repeat steps 4 and 5
  until the desired concentration in the system is
  obtained

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Chapter XI Chloration

• Recommended chlorine concentrations
• Continuous treatment - In order to prevent the
  growth of algae or bacteria. Apply from 1 to 2
  mg/L continuously through the system..

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Chapter XI Chloration

• Recommended chlorine concentrations
• Treatment at intervals - In order to eliminate
  the algae or bacteria. Apply from 10 to 20 mg/L
  for 60 minutes. The frequency of the treatment
  depends on the concentration of these
  microorganisms in the water source.

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Chapter XI Chloration

• Concentraciones recomendadas de cloro
• Super chloration - In order to dissolve the
  organic matter and in many cases the calcium
  precipitated in the drippers. Inject chlorine at
  a concentration from 500 to 100 mg/L, depending
  on the case. After this, close the system and
  leave it for 24 hours, to clean all the secondary
  and lateral lines. It helps to clean the
  obstructions in the secondary and lateral lines.
  We have to be careful while applying these
  amounts, since these chlorine levels can be toxic
  to certain crops.

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Chapter XI Chloration
Table 4a. Typical dosages of chlorine
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Chapter XI Chloration
Table 4a. Typical dosages of chlorine
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Chapter XI Chloration

• Chlorine Requirements
• Chlorine requirements must be known before the
  chloration. The chlorine, gaseous (Cl2) or sodium
  hypochlorite, is a biocide that must be applied
  in the amounts and at recommended concentrations.
  
• The excess of chlorine in the irrigation water
  can cause damage to the young plants or young
  trees. On the other hand, the low levels do not
  solve the problems associated with the growth of
  microorganisms in the irrigation water.

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Chapter
XI Chloration

• Chlorine Requirements
• The chlorine is a very active and toxic agent at
  high concentrations, therefore it must be handled
  carefully. When it is injected in the irrigation
  lines, some chlorine reacts with inorganic
  compounds and organic substances of the water or
  it adheres to them.
• In most wells and water sources, from 65 to 81
  of the chlorine is lost by this type of reaction.
  
• The chlorine (like hypochlorous acid) that
  adheres to the organic matter or that reacts with
  other compounds does not destroy microorganisms.
  For this reason, it does not have value as a
  biocide agent.

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Chapter XI Chloration

• Chlorine Requirements
• The free chlorine (the excess of hypochlorous
  acid) is the agent that inhibits the growth of
  bacteria, algae and other microorganisms in the
  water. Therefore, it is indispensable to
  establish the chlorine requirements before the
  chloration. In this way, we can maintain the
  desired concentrations of available chlorine.
• In order to inhibit the growth of microorganisms,
  a minimum contact time of 30 minutes is required
  (45 minutes of injection). It also requires a
  minimum concentration of 0.5 to 1.0 mg/L of
  available chlorine measured at the end of the
  drip line and 62.0 to 3.0 mg/L of available
  chlorine at the injection point.

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Chapter XI Chloration

• Chlorine Requirements
• The following equations are used to calculate the
  gallons per hour (gph) of NaOCl (sodium
  hypochlorite) that must be injected to obtain the
  desired concentration of chlorine per minute
  (gpm)
• Formula for gpm of 10 NaOCl
• 0.0006 x (gpm desirable chlorine) x (discharge
  of the pump, gpm)
• Formula for gph of 5.25 NaOCl
• 0.000114 x (ppm desirable chlorine) x (discharge
  of the pump, gpm)

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Chapter XI Chloration

• Chlorine Requirements
• Formula for pounds by hectare of Cl2 (gas)
• 0.000998 x (ppm desirable chlorine) x
  (Discharge of the pump, gpm
• Gallons of liquid chlorine per hour
• (0.06 x ppm of desirable chlorine x discharge of
  the pump in gpm) / (porcentage of chlorine in the
  material)
• Dry chlorine in pounds per hour
• (0.05 x ppm x gpm) / (porcentage of chlorine in
  the material)

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Chapter XI Chloration

• Chlorine Requirements
• Dry chlorine in pounds per 1000 gallons of water
• (0.83 x ppm) / (porcentage og chlorine in the
  material)
• For chlorine gas take percentage of chlorine
  100 and calculate as dry chlorine

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Chapter XI Chloration

• D.P.D. Test Method
• It is essential to measure the chlorine when
  using liquid chlorine as bactericidal and
  algaecide in irrigation systems of low volume.
• Most of the methods of measuring chlorine that
  are used in the swimming pools are not adequate
  for irrigation systems. This is because many of
  these equipment measure only total chlorine, but
  not the residual free chlorine. An equipment
  "D.P.D." of good quality can measure total
  chlorine and the free available chlorine.

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Chapter XI Chloration

• D.P.D. Test Method
• The test equipment D.P.D. is very simple. The
  directions and procedures come with the
  equipment. The equipment is used to measure each
  type of chlorine. When applying these compounds,
  the water becomes pink in the presence of the
  chlorine.
• The more intense is the color, higher is the
  chlorine concentration. In order to know the
  chlorine concentration, the color of the water is
  compared with that of a calibrated chromatic
  chart.

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Chapter XI Chloration

• D.P.D. Test Method
• This method is beneficial and of great help when
  adequately injecting the amount of chlorine in
  the drip lines (chloration). Equipment D.P.D. is
  paid by itself with the chlorine that is being
  saved. It indicates the chlorine concentrations
  required for killing bacteria.
• One must remember that the free chlorine is the
  one that determines the biocide action. If there
  is not sufficient free chlorine available, the
  bacteria continue growing even though chlorine
  has been injected into the system. In other
  words, if the amount of total chlorine is not
  sufficient to maintain chlorine free in solution,
  the treatment gets is of no value.

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Chapter XI Chloration

• D.P.D. Test Method
• The test equipment D.P.D. can be purchased from
  the sellers of irrigation equipments or from
  chemical agents who are specialized in water
  treatment.

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Chapter XI Chloration

• EXAMPLES FOR CALCULATING THE AMOUNT OF CHLORINE
• A farmer wishes to use a cloth whitener (NaOCl -
  5 active chlorine or available) to reach a
  concentration of 1 ppm of chlorine at the
  injection point. The flow rate for the system is
  100 gpm. In what ratio the chlorine must be
  injected?

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Chapter XI Chloration

• IR Q x C x M /S
• Where IR Rate of chlorine injection
  (gallons/hour).
• Q Flow rate of the system (gallons/minute).
  
• C Desired Concentration of chlorine (ppm).
• S Percent of active ingredient ().
• M 0.006 for the liquid material (NaCOCl),
  or
• 0.05 for the solid material Ca (OCl)2
• IR (100 x 1 x 0.006) /5 0.21 gph

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Chapter XI Chloration

• EXAMPLES FOR CALCULATING
• THE AMOUNT OF CHLORINE
• A farmer wants to inject gaseous chlorine (Cl2)
  through the drip irrigation system at a
  concentration of 10 ppm. What will be the rate of
  injection of the gas? The flow rate of the system
  is 1500 gpm.

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Chapter XI Chloration

• IR Q x C x 0.012
• Where IR Rate of injection of chlorine
  (pound/day)
• Q Flow Rate of the system (gallons/minute)
• C Desired chlorine concentration (ppm)
• IR 1500 x 10 x 0.012 180 pounds per day

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Chapter XI Chloration

• Summary
• We conclude that this work will benefit persons
  who are interested in this process.
• Drip irrigation is effective and economical
  irrigation method.
• The drip irrigation method is effective for
  Puerto Rico.