water sources classification. clogging factors inorganic suspended matter

Water Sources

Classification

Clogging FactorsInorganic Suspended Matter

Soil Classification by Particle Size

Biological Growth

• Phytoplankton (Algae and Bacteria)

Organic matter in WaterOrganic matter in Water

• Bacteria

• Algae

• Phytoplankton

• Zooplankton

Bacteria

• Aerobic + Anaerobic

• Sludge formation

Courtesy of Nu3

Algae

• There is a cyclic seasonal pattern in the development of algae. In winter, when there is little light and low temperatures, the growth of algae is minimal. In spring when temperatures rise and there is an increase in radiation as well as in the availability of nutrients, Blossoming occurs.

Algae that Cause Clogging of Filters

Algae

• Water source (River, lake)

• Water tanks (Settling pool, Reservoirs)

• On dripline surface.

Plankton Plankton

• Zooplankton• Phytoplankton

Zooplankton

• The size of zooplankton varies within the range of 0.2-30 mm.

Types of Minerals

• Carbonates

• Iron

• Fertilizers

• Silt

Bacterial slime can be classified into three groups

Chemical Sediments

Others

Immediate Indication

Carbonate Scaling

Water + Carbon dioxide + Calcium carbonate Water + Carbon dioxide + Calcium carbonate Calcium Hydrogen Calcium Hydrogen carbonatecarbonate

HH22O + COO + CO22 + CaCO + CaCO33 Ca(HCOCa(HCO33))2(aq)2(aq)

חימוםחימום

Temperature & ScalingLangelier Index vs Temperature

-1

-0.5

0

0.5

1

1.5

0 3 8 12 16 19 24 29 34 41

Temperature (C)

LI

Scale begin

Warming of Driplines

45 Cº

28 Cº

20 Cº

16 Cº

Water temperature: control

• White tubing

• Subsurface installation

• Shading

Fertilizers

• Wrong mixtures

• Phosphorous – Calcium

• Sulfate – Calcium

• Phosphorous – Iron

• High pH

• Dirt

0

200

400

600

800

1000

1200

1400

0 c 5 c 10 c 20 c 25 c 30 cTemp C

Urea

Ammonium Sulfate

Potassium Nitrate

Potassium Sulfate

PotassiumChlorideMAP

Dissolution ( gr/L ) of some fertilizersDissolution ( gr/L ) of some fertilizers

Insoluble Sediment

Interactions

Soluble Ion Soluble Ion

CaNo3 H3PO4

D.C.P

Wrong mixtures: Examples

• Calcium – Phosphorous

• Calcium – Sulfate

• Magnesium + “

• Wrong dilution of P acid in hard water.

FertilizersCa Nitrate + MAP

Iron Symptoms

Iron Sedimentation

• Accumulation on surface

Water Quality Testing

• It can generally be stated that clogging problems due to the occurrence of impurities in irrigation water become more acute if the water has a high content of:

• Suspended particles of organic or inorganic matter.

• Precipitate-forming elements.• Bacteria that secrete slime.

Hardness

Turbidity

• The turbidity of a water sample is a measure of the ability of its suspended and colloidal materials to diminish the penetration of light through the sample.

• Turbidity is measured by means of a turbidimeter

Water Analysis

• Particle-size Distribution - This test is performed by counting the particles and establishing their size distribution.

• Hydrogen Sulfide (H2S) - Water from deep wells may require H2S determination. Portable test-kits are available for rapid field testing.

Iron and Manganese

Microbial Population

Water Quality CriteriaA water classification system for indicating clogging

hazard in trickle systems (Bucks and Nakayama - 1980)

Classification of Drip Irrigation Water Quality

Natural Water Quality Classification

Evaluation of Carbonate Sedimentation

Chlorination

Chlorination is based on the injection of various chlorine compounds into

the irrigation water.

Chlorination - Functions• It creates an environment in which algae can no

longer develop.• It acts as an oxidizing agent, causing the

decomposition of organic matter.• It prevents the agglomeration and sedimentation of

organic suspended matter.• Its oxidizes substances such as iron and

manganese, producing insoluble compounds that can then be removed.

• Eliminating sulfur bacteria.

Reactions of Chlorine with Water

• Hydrolysis: H20+CL2 = HOCL + H++ CL-

• Ionization: HOCL = H++ OCL-

• Effective chlorination is influenced by the following factors:

• Available chlorine (concentration and type).

• pH

• Contact time

• Temperature

Distribution of HOCL and OCL- in Water at indicated pH levels

Chlorination Materials

Comparison Between Different Forms of Chlorine

Safety PrecautionsSafety Precautions

Active chlorine preparations are strong oxidation agents and as Active chlorine preparations are strong oxidation agents and as such such are toxic to human beings and livestockare toxic to human beings and livestock. Read the . Read the manufacturer safety instructions on the label of the package before manufacturer safety instructions on the label of the package before applying the treatment and act accordingly.applying the treatment and act accordingly.

Direct contact with chlorine may cause burns, blindness and may Direct contact with chlorine may cause burns, blindness and may even be fatal. Therefore, protective glasses, gloves, shoes and even be fatal. Therefore, protective glasses, gloves, shoes and suitable clothing must be used when handling chlorine to prevent suitable clothing must be used when handling chlorine to prevent contact with exposed parts of the body.contact with exposed parts of the body.

Solid chlorine tablets are dangerous when they comes in Solid chlorine tablets are dangerous when they comes in contact with fertilizer concentrates contact with fertilizer concentrates and may cause an explosion.and may cause an explosion.

Keep hypochlorite in an opaque container, sealed against light and Keep hypochlorite in an opaque container, sealed against light and air, since they cause decomposition of the material and reduce its air, since they cause decomposition of the material and reduce its concentration.concentration.

Do not mix chlorine and fertilizer concentrates, Inject these Do not mix chlorine and fertilizer concentrates, Inject these materials by separate injector pumps or inject them one after materials by separate injector pumps or inject them one after the other.the other.

Chlorine is not effective for prevention of scale formation Chlorine is not effective for prevention of scale formation or its decomposition.or its decomposition.

Application

• Continuous injection of chlorine at low, uniform concentration (normally 1-10 ppm), throughout the entire irrigation cycle.

• Intermittent injection at higher concentration (normally over 10 ppm) once or several times during the irrigation cycle (for a duration of up to approximately 20 minutes per day).

• Super chlorination at a concentration of 50 ppm, for a duration of 5 minutes during the irrigation cycle

Recommended method: Application of the chlorine by injection Recommended method: Application of the chlorine by injection for one hour during each irrigation cycle, together with injection for one hour during each irrigation cycle, together with injection of acid for pH reduction.of acid for pH reduction.

Methods of Chlorination

When calculating the desired chlorine concentration, the following factors should be considered

• The availability of chlorine depends on its form:

• Chlorine gas: 100% availability.

• Calcium hypochlorite: 65 - 70% availability

• Sodium hypochlorite: 5 - 15% availability

Chlorine concentrationChlorine concentration

Application of high doses of chlorine may cause a much too Application of high doses of chlorine may cause a much too rapid decomposition of the organic sediments and result in rapid decomposition of the organic sediments and result in the clogging of the drippers.the clogging of the drippers.

It should be borne in mind that the chlorine concentration in It should be borne in mind that the chlorine concentration in the system weakens in time, depending on the distance from the system weakens in time, depending on the distance from the point of injection. the point of injection.

Chlorine concentration at the end of the system is, therefore, Chlorine concentration at the end of the system is, therefore, generally lower. This should be taken into account when generally lower. This should be taken into account when calculating the required chlorine dose, so as to ensure the calculating the required chlorine dose, so as to ensure the required residual level at the distal points of the system.required residual level at the distal points of the system.

Recommended Concentration of Free Chlorine in Water (ppm) for various purposes

Chlorination Control

The chlorination processThe chlorination process

• It is recommended applying chlorination treatment as near It is recommended applying chlorination treatment as near as possible to the drip lines to ensure that the sediments do as possible to the drip lines to ensure that the sediments do not migrate from the main pipe system, or sub-mains, to the not migrate from the main pipe system, or sub-mains, to the drip lines.drip lines.

• Check the sensitivity of the crop to chlorine.Check the sensitivity of the crop to chlorine.

• Do not use nitrogen fertilizers containing ammonium when Do not use nitrogen fertilizers containing ammonium when injecting chlorine. It causes the formation of compounds injecting chlorine. It causes the formation of compounds which dissolve with difficulty.which dissolve with difficulty.

•Chlorine should not be injected into the system when the Chlorine should not be injected into the system when the dissolved iron concentration in the water exceeds 0.4 ppm.dissolved iron concentration in the water exceeds 0.4 ppm.

The injection processThe injection process

aa. Select the required chlorine concentration according to the table. Select the required chlorine concentration according to the table

bb. Calculate the required flow rate of the chlorine into the system. Calculate the required flow rate of the chlorine into the system

cc. Select a suitable injector pump or mix the chlorine and water . Select a suitable injector pump or mix the chlorine and water to obtain a volume suitable for the injector pump.to obtain a volume suitable for the injector pump.

dd. Flush the system thoroughly, including the main pipe line, the . Flush the system thoroughly, including the main pipe line, the sub-mains and the drip lines.sub-mains and the drip lines.

ee. Inject the chlorine into the system.. Inject the chlorine into the system.

ff. Check the residual chlorine concentration at the terminal . Check the residual chlorine concentration at the terminal point of the system.point of the system.

gg. Verify that the quantity of chlorine meets the requirements. If it . Verify that the quantity of chlorine meets the requirements. If it is insufficient, add more chlorine.is insufficient, add more chlorine.

hh. Continue injecting the chlorine for the required period . Continue injecting the chlorine for the required period according to the application type (continuous or intermittent).according to the application type (continuous or intermittent).

ii. Thoroughly flush the pipe system and the drip lines at the . Thoroughly flush the pipe system and the drip lines at the end of the treatment.end of the treatment.

jj. It may be necessary to repeat the chlorine application more . It may be necessary to repeat the chlorine application more then once.then once.

Special Problems of Chlorination

• Loss of chlorine in storage tank


• Decrease in free residual chlorine concentration in the system


• Reaction of chlorine with water containing fertilizers


• Use of injection pumps

Other Chemicals to be Used in Reservoirs and Lakes

Copper Sulfate Treatment

• Copper sulfate can be used effectively to control algae in reservoirs

Treatment with Diesel Oil

Diesel oil floats on the water surface, Following treatment with diesel oil, concentration of suspended matter

decreases.

Dissolution of Sediments

Treatment with Acid

Treatment with acid is based on the injection of one of the variety of types of acid into the

irrigation water

Functions

• Prevents precipitation of dissolved solids.

• Dissolves existing precipitates.

• Improves efficiency of chlorination when applied in conjunction with chlorine.

Prevention

Types of acids used for injection into drip systemsTypes of acids used for injection into drip systems

The three acids most commonly used for injection into drip The three acids most commonly used for injection into drip irrigation systems are as follows:irrigation systems are as follows:

Hydrochloric acid (HCl) – a highly corrosive material, but Hydrochloric acid (HCl) – a highly corrosive material, but widely used in Israel owing to its low cost.widely used in Israel owing to its low cost.

Phosphoric acid (HPhosphoric acid (H33POPO44): This material, apart from its intended ): This material, apart from its intended

cleaning effect, acts as a source of phosphorous nutrient.cleaning effect, acts as a source of phosphorous nutrient.

Sulfuric acid (HSulfuric acid (H22SO4): This acid attacks most metals and is SO4): This acid attacks most metals and is

extremely hazardous for human beingsextremely hazardous for human beings..

Safety precautionsSafety precautions

Acids are toxic to human beings and animals. Read the safety Acids are toxic to human beings and animals. Read the safety instructions given by the manufacturer on the label of the instructions given by the manufacturer on the label of the package before applying the treatment and act accordingly.package before applying the treatment and act accordingly.

When dissolving the acid in water, When dissolving the acid in water, add the acid to the wateradd the acid to the water prepared previously in a suitable vessel. prepared previously in a suitable vessel. Do not add water to Do not add water to acidacid. Adding water to the acid is liable to generate considerable . Adding water to the acid is liable to generate considerable heat.heat.

Take measures to prevent the irrigation water treated with the Take measures to prevent the irrigation water treated with the acid from penetrating a water supply system upstream of the acid from penetrating a water supply system upstream of the point of injectionpoint of injection..

This acid should not be injected into water containing dissolved This acid should not be injected into water containing dissolved iron. The treatment should be applied so as to reduce the pH iron. The treatment should be applied so as to reduce the pH level of the water to less than 6.5, in order to prevent formation level of the water to less than 6.5, in order to prevent formation of phosphate sediments.of phosphate sediments.

The acid does not react in a dangerous or toxic manner with The acid does not react in a dangerous or toxic manner with other salts or chemicals found in the irrigation water.other salts or chemicals found in the irrigation water.

Treatment Doses and FrequenciesTreatment Doses and Frequencies

In general, the more frequent the acid treatments, the lesser the In general, the more frequent the acid treatments, the lesser the risk of dripper clogging. The frequency of treatment should be risk of dripper clogging. The frequency of treatment should be adjusted according to the treatment purpose.adjusted according to the treatment purpose.

The treatment purposes are as follows:The treatment purposes are as follows:

aa. . Prevention of sedimentation – preventative treatment: Prevention of sedimentation – preventative treatment: continuous injection of acid at a low dosage prevents the continuous injection of acid at a low dosage prevents the settlement of carbonates. The acids should be injected to the settlement of carbonates. The acids should be injected to the system continuously at a concentration which will reduce the system continuously at a concentration which will reduce the pH of the water to 6-6.5.pH of the water to 6-6.5.

b. Dissolution of sediments – Aggressive treatment.

This treatment is applied when clogged drippers are located and/or when there is accumulation of salts on the walls of the drip line.

In addition, acids should be applied once or twice during the In addition, acids should be applied once or twice during the season according to the appearance of the accumulated season according to the appearance of the accumulated sediments. At times additional treatments may be needed.sediments. At times additional treatments may be needed.

Apart from the treatments during the season, it is Apart from the treatments during the season, it is recommended injecting acid into the system at the end of recommended injecting acid into the system at the end of each irrigation season.each irrigation season.

A pH level of 2 should be reached in the water.A pH level of 2 should be reached in the water.

c. Improving the effectiveness of chlorination.

Application methodApplication method

Make sure that the acid does not come into contact with those Make sure that the acid does not come into contact with those components of the irrigation system which are sensitive to acids.components of the irrigation system which are sensitive to acids.

Special points to be notedSpecial points to be noted

One treatment may not give optimum results. In which case the One treatment may not give optimum results. In which case the treatment should be repeated.treatment should be repeated.

The acid should be injected to the system by means of a fertilizer The acid should be injected to the system by means of a fertilizer injection pump. All parts of the pump must first be checked to injection pump. All parts of the pump must first be checked to ensure that they are resistant to acids.ensure that they are resistant to acids.

The acid should be applied at the nearest point to the drip lines so The acid should be applied at the nearest point to the drip lines so as not to dissolve sediments in the main pipe system since these as not to dissolve sediments in the main pipe system since these sediments might them migrate to the drippers.sediments might them migrate to the drippers.

Acid applications for dissolving sediments should be injected for Acid applications for dissolving sediments should be injected for 10 to 12 minutes.10 to 12 minutes.

Instructions for application of acidsInstructions for application of acids

Simple calibration enables verification of the quantity of acid Simple calibration enables verification of the quantity of acid required for the specified treatment.required for the specified treatment.

aa. Prepare a vessel with 1 liter of irrigation water.. Prepare a vessel with 1 liter of irrigation water.

bb. Fill a medical syringe with the acid.. Fill a medical syringe with the acid.

cc. Gradually drip the acid into the water while stirring. . Gradually drip the acid into the water while stirring. For each drop of water, add 1 cc of acid.For each drop of water, add 1 cc of acid.

dd. . Measure the pH level of the water until reaching the required Measure the pH level of the water until reaching the required level with pH meter or with litmus paper.level with pH meter or with litmus paper.

e. e. The quantity of dissolved acid in cc per liter of water = the The quantity of dissolved acid in cc per liter of water = the quantity of acid in liters required per cubic meter of irrigation quantity of acid in liters required per cubic meter of irrigation water.water.

f. f. Prepare the items required for the treatment: the injector pump, Prepare the items required for the treatment: the injector pump, a vessel resistant to the acid, and the acid.a vessel resistant to the acid, and the acid.

g. g. Prepare the acid solution to be injected.Prepare the acid solution to be injected.

h. h. Open the water and flush the components of the system well, Open the water and flush the components of the system well, including the main pipe, the sub-mains, the flush-out lines and the including the main pipe, the sub-mains, the flush-out lines and the drip lines.drip lines.

i. i. Inject the acid solution into the system.Inject the acid solution into the system.

j. j. Check that the acid has reached the end of the most distant Check that the acid has reached the end of the most distant drip lines. The acid can be identified by sampling the pH of the drip lines. The acid can be identified by sampling the pH of the water.water.

k. k. Add water to the vessel and thoroughly flush the injection Add water to the vessel and thoroughly flush the injection pump from the acid residues.pump from the acid residues.

l. l. Continue to irrigate after completing the injection for an Continue to irrigate after completing the injection for an additional 30 minutes or so.additional 30 minutes or so.

m. m. Flush the irrigation system once again with clean water free Flush the irrigation system once again with clean water free of dissolved sediments.of dissolved sediments.

Dissolving

Improving efficiency of chlorination

Treatment with Sedimentation Retarders

Sedimentation retarders are chemicals of high molecular weight. They are soluble in water and contain various functional groups that retard the crystallization and sedimentation

of carbonates and sulfates.

A wide range of sedimentation retarders is available, such as:

• Calgon (polymetaposphate).

• Polyacrilates.

• Phosphonates.

• E.D.T.A based materials.

Treatment by means of Fish

Coagulation

• The most prevalent coagulant used is alum (aluminum sulfate), which appears in either dry or liquid form.

• Alum is fed at doses up to 200 mg/l with 10-40 mg/l doses being common.

Coagulation

• The primary purpose for adding coagulants to water is to destabilize colloidal dispersions of small discrete particles, which would not be removed by sedimentation and filtration. The coagulant assists in forming a floc, which can sink in a tank or filter and then be removed.

Solution of Special ProblemsOccurrence of Iron

Prevention

Oxidation

Oxidation treatments can be carried out by means of various procedures, such as

chlorination, aeration, potassium permanganate, etc.

Chlorination

Can be used to control iron deposition if the pH is below 6.5 and the iron concentration

is less than 3.5 ppm, If the pH is above 6.5 , the iron concentration must be below 1.5

ppm.

Aeration

Aeration causes the oxygen and water to react with the iron, as follows:

2Fe(HCO3)2 + 0.5O2 + 2H2O= 2Fe(OH)3+4CO2

Occurrence of Iron Prevention

• Sedimentation (settling) and filtration.

• Reclamation.

Occurrence of Manganese

Occurrence of Sulfur

Criteria for Selecting Chemical Treatment

• When the biological load is high - chlorine should be applied to prevent algae development and to decompose organic matter.

• When suspended matter is high and biological mass is present - chlorine should be applied to prevent agglomeration.


• When residual iron, sulfur or manganese (above 0.5 ppm) is present - chlorine should be applied to oxidize these compounds and settle them in the filtration system.

• When the water source is a reservoir - water should be treated by means of copper sulfate, diesel oil or fish.


• When dissolved solids and pH are high - acid treatment is beneficial.

• When chemical and biological factors are high - both acid treatment and bacteria control be considered.

Pumping depth

• If water is pumped directly from the bottom of the reservoir, then sand, silt and clay will be dragged into the irrigation system.

• If water is pumped from the surface of the reservoir,Then the contents of the upper water layer (branches, leaves, algae) will also be dragged into the irrigation system.

• The optimum pumping depth should be between 1.2-1.9 meters below water surface

Miscellaneous

• The pumping system (inlet pipe) should be protected against the infiltration of large bodies into the irrigation system.

• Before locating the pumping station, the main wind direction should be considered, in order to prevent floating material from drifting toward the pumping inlet.

Miscellaneous

• In reservoirs in which there is automatic primary filtration, backflushing water should be kept away from the pumping inlet.

• In reservoirs in which fish are grown, the pumping station should not be located near the feeding points.

water sources classification. clogging factors inorganic suspended matter

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