Molecular Oscillation Technology: New Phenomenon toReduce Emitter Clogging in Trickle IrrigationKhadijeh Barati1; Behrouz Mostafazadeh-Fard2; and Ali-Asghar Sheikhbahaei3

Abstract: The Merus ring which is made by Merus Company in Germany is a new device that can be installed on a feed pipeline to reduceemitter clogging in trickle irrigation. Merus technology works using specifically modulated molecular oscillations or lattice oscillations and isnot based on the use of fields created by electric coils or magnets. This study was performed in a field belonging to Isfahan University ofTechnology (Iran) to investigate the effects of the Merus ring on emitter clogging. Two main treatments of irrigation water, with and withoutthe Merus ring, and three subtreatments of irrigation water salinity were used. The results showed that the irrigation water treatment had asignificant effect on average emitter discharge at the 1% level. The average emitter discharge was higher for the treatment with the Merus ringcompared to the treatment without the Merus ring. For both irrigation water treatments, the average emitter discharge decreased during theexperiment, but the decrease was higher for the treatment without the Merus ring. Moreover, the irrigation water treatment had a significanteffect on the distribution uniformity of the emitters at the 5% level. The distribution uniformity was higher for the treatment with the Merusring compared to the treatment without the Merus ring. Therefore, application of the Merus ring is recommended to achieve lower emitterclogging, higher distribution uniformity, and better irrigation performance. DOI: 10.1061/(ASCE)IR.1943-4774.0000769. © 2014 Ameri-can Society of Civil Engineers.

Author keywords: Distribution uniformity; Emitter clogging; Merus ring; Trickle irrigation.

Introduction

Of the 8 million ha of irrigated land in Iran, 7.6 million ha (95%)are under surface irrigation and 0.4 million ha (5%) underpressurized irrigation. With limited renewable water resourcesand annual rainfall, particularly during the past two decades, dripirrigation systems have been introduced in agricultural regions ofIran to increase water use efficiency (Ahmad Aali et al. 2009).

Drip irrigation, also called trickle irrigation or microirrigation, isa localized irrigation method that slowly and frequently provideswater directly to the plant root zone (Evans 2000). Due to limitedwater resources and the environmental consequences of commonirrigation systems, drip irrigation technology is attracting more at-tention and playing an important role in agricultural production.Emitter clogging has often been recognized as a serious issueand one of the most important concerns in drip irrigation systems,resulting in lowered system performance and water stress to non-irrigated plants (Capra and Scicolone 1998; Povoa and Hills 1994).Partial and total clogging of emitters is closely related to the qualityof the irrigation water and occurs as a result of multiple factors,including physical, biological, and chemical agents (Coelho andResende 2001; Gilbert et al. 1981; Pitts et al. 1990). Filtration,chemical treatment of water, and flushing of laterals are means gen-erally applied to control emitter clogging (Nakayama andBucks 1991).

Liu and Huang (2009) conducted a laboratory experiment tostudy emitter performance with the application of freshwater andtreated sewage effluent (TSE). They revealed that the values ofreduction in emitter discharge for TSE treatments were greater thanthose for freshwater treatments.

One of the major causes of emitter clogging is calciumprecipitation. This problem correlates to a high pH of applied water,a high concentration of CaCO3 in water, and excessive variations inenvironmental temperature (Nakayama and Bucks 1991).

Chemical clogging, through salt precipitation, is very difficult tocontrol. The general recommendation for preventing chemical clog-ging is to decrease the pH of the water by acid injection to a valuewhere salt precipitation does not occur (Ahmad Aali et al. 2009).

De Melo et al. (2008) studied the effects of calcium andmagnesium carbonates on emitter clogging and distributionuniformity of water in trickle irrigation. They found that emitterclogging caused a reduction in water distribution uniformity andan increase in the emitter variation coefficient.

Magnetic water is obtained by passing water through permanentmagnets or through electromagnets installed in or on a feed pipeline(Higashitani et al. 1993). Water passing through a magnetic fieldmight acquire new properties. Magnetic treatment of hard water iscurrently used to prevent scale formation on hot surfaces, particu-larly in hot exchangers, as well as in domestic equipment. Thistreatment process has been developed to replace chemical watertreatment methods employing chemical products that might beharmful to the environment and human health. Comprehensive ex-perimental studies were carried out on the modification of theCaCO3 precipitation process by magnetic treatment.

Kobe et al. (2001) studied different forms of CaCO3 crystals. Thecrystals were grown from tap water and model water, both with andwithout a magnetic field. Separate aragonite crystals were formed inthe treated water and clusters of calcite in the untreated water. Theresearchers observed that under the influence of a magnetic fieldgreater than 500 mT, the nucleation and subsequent growth ofaragonite could be used as a way to prevent scale. According to

1Ph.D. Student, Water Engineering Dept., Isfahan Univ. of Technology,Isfahan 84156-83111, Iran (corresponding author). E-mail: Kh_barati@yahoo.com

2Professor, Water Engineering Dept., Isfahan Univ. of Technology,Isfahan 84156-83111, Iran.

3Technical manager, Merus Iran Company, Isfahan 816361-4463, Iran.Note. This manuscript was submitted on August 6, 2013; approved on

April 21, 2014; published online on June 2, 2014. Discussion period openuntil November 2, 2014; separate discussions must be submitted for indi-vidual papers. This paper is part of the Journal of Irrigation and DrainageEngineering, © ASCE, ISSN 0733-9437/04014034(8)/$25.00.

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the literature, the efficiency of magnetic treatment depends on nu-merous parameters. For example, Chibowski et al. (2003) and Barrettand Parsons (1998) found that magnetic treatment applied on hardwater decreased the quantity of scale formation on the wall. Alimiet al. (2009) found that magnetic treatment affected calcium carbon-ate crystallization by increasing the total precipitate quantity and byfavoring its formation in bulk solution instead of its incrustation onpipe walls. Ahmad Aali et al. (2009) found that an acid injectiontreatment provided better performance compared to a magnetic field.

The Merus ring which is made by Merus Company in Germanyis a new device that can be installed on a feed pipeline to reduce saltprecipitation and to remove sediment from the pipes. A Merus ringis made of two halves that can easily be installed on the outside of apipe. The installation of a Merus ring on pipe is shown in Fig. 1.

Merus technology works using specifically modulated molecularoscillations or lattice oscillations and is not based on using fieldscreated by electric coils or magnets. The unique Merus technologydiffers effectively from the standard methods of water treatment.While for the most part conventional methods only treat symptoms,Merus technology has been used to solve the basic technical prob-lems caused by water for more than 10 years. This has been achievedby using water itself effectively against technical problems caused bywater, such as rust or lime scale. All conventional technologies onthe market, whether chemical or physical, work only at the point ofinstallation. Once the water passes through this point, such conven-tional methods of treatment can no longer control the water. Chemi-cal matter is added or magnetic fields produced in order to controlsalt precipitation, corrosion, and microbes in water. In some caseswhere physical devices are used, the changes undergone by limescale are not stable, and after a while conditions are converted tothe previous state. In the best conditions, physical methods have onlyan indirect effect on corrosion or microbes. Technically, it is not fea-sible for the necessary concentration of the substrate to spread uni-formly throughout an entire system. The factors and circumstancesdescribed previously, together with the water remaining in part of thesystem for a long period of time, frequently lead to suboptimalresults or even to the failure or malfunctioning of conventionalmethods (Dworshak 2013).

The principles behind the functioning of Merus rings are newand hard to understand; scientists still debate them. Therefore, the

theoretical background of this method relies on empirical research,assumptions, and logical conclusions (Dworshak 2013).

Each element and each molecule has its own typical naturalmolecular oscillation. This natural oscillation is unique andcompares well with the human fingerprint. Merus is able to isolate,record, and store these oscillations of, for instance, rust. Based onthese original oscillations, Merus develops new active oscillations.The aim is to influence the original oscillation of the element inquestion through new active oscillations in such a way thatultimately the physical properties of the element or of the moleculeare modified in the water. In principle, there is a fundamentaloscillation for every substance contained in fluids. The Merus ringaffects these oscillations. Fig. 2 shows the effect of a Merus ring ona substance’s fundamental oscillation (Dworshak 2013).

According to Fig. 2, starting from fundamental oscillations, aMerus ring emits new active oscillations. This occurs without anyexternal energy input; only energy supplied by environmentalwarmth is used. The water absorbs these active oscillationsand spreads them in the direction of its flow faster than the actualflow velocity of the water. The mathematical result of fundamen-tal oscillation and active oscillation interference will be zero ifthese two kinds of oscillation are 180° phase-delayed and bothhave the same amplitude [Fig. 2(a)]. If fundamental oscillationand active oscillation are in-phase, then resonance will occur[Fig. 2(b)]. In water, active oscillations interfere with fundamen-tal oscillations and alter the characteristics of substances. Theactive oscillations of a Merus ring are subject to certain interfer-ences caused by environmental influences, such as electromag-netic pollution. Depending on their intensity, these influencesare capable of reducing or even erasing the effect of Merus ringson water. Hence, Merus rings must be installed with a clearanceof at least 50 cm from any electric conductor. Merus technologycan be used in all piping materials, even in mixed-metal systems.Furthermore, the devices should be installed in such a way thatthey are protected from splash water so as to avoid surface cor-rosion (Dworshak 2013).

Today, Merus has a database containing a large number of activeoscillations, each with a specific task. These active oscillations arerecorded on an oscillation carrier, much like writing on a data car-rier (CD/DVD). The carrier of active oscillations, which is actuallythe hardware of the Merus ring, is made from a silica–aluminumalloy. This alloy can store an almost unlimited number of activeoscillations and emit them in water in a constant and stable form,largely independently of the ambient temperature. The activeoscillations are modulated according to the lattice oscillation ofaluminum. Due to the ambient heat, the aluminum lattice oscillatesand consequently the active oscillations are emitted by Merus ring.The oscillations are positioned in the lattice structure much like aparasite and are thus continually and simultaneously created. Theactive oscillations create a field within the ring that penetrates allthe piping material and thus passes into the water. Due to its bipolarproperties, water can absorb, store, and spread active oscillations

Fig. 1. Installation of Merus ring on pipe

Fig. 2. Effect of Merus ring on substance fundamental oscillation: a) 1800 phase-delayed; b) in-phase

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throughout the entire water leg that follows. In the water, the activeoscillations interfere with the natural oscillations of, for example,rust, lime scale, and iron. Due to these interactions, the behavior ofthe substances released into the water that come into contact with itis modified. The result is that the rust molecules disintegrate into anunstable form and are washed out. Iron no longer reacts with Fe2O3

but with Fe3O4 (magnetite), which is largely inert to further formsof corrosion. Lime remains dissolved in water longer and crystal-lizes out to a much lesser extent (Dworshak 2013).

Lime scale and other salts in dissolved form can be found inalmost all water. The lime scale contained in water remains assolution as long as there is sufficient CO2 in the water. If thetemperature of the water rises, then CO2 gases escape and lesslime scale stays soluble in the water. This sedimentation precip-itates and finally clogs the pipes, valves, or other components ofthe system. To avoid this problem, water is treated chemically,particularly in critical applications. This relatively costly(because of the chemicals and service) method is often notfinancially expedient in the case of applications that use largeamounts of water. Merus technology is a very competitivelypriced alternative. The oscillations emitted by Merus devices intowater modify the structure of lime scale in a lasting and effectiveway. This means that the lime scale can be bonded much better bywater and thus only precipitates at considerably higher temper-atures or much higher concentrations. If the flow in a pipelineor machine is strong enough, the lime scale that is depositeddespite the increased solubility is carried away by the water. Inno- or low-flow conditions, lime is deposited in a soft, slushyconsistency (lime sludge), which can be wiped or sprayed awayvery easily without chemicals (Dworshak 2013).

Electrical fields also have a severe impact on treated water. Ifthe piping runs through or along strong electrical fields, the oscil-lations in the water overlap. In this situation, regarding the systemdevelopment, a lot of Merus rings might be installed. However, be-cause installed devices recharge water continuously, installingmany of them is seldom necessary. Depending on pipe size anddischarged water, there are different types of Merus rings and theycan influence up to a certain volume of water. Finally, it is rarelynecessary to install devices in series (Dworshak 2013).

Merus rings are used in areas ranging from small dishwashers,machines, and tools to huge pipe bundle heat exchangers in thechemical industry and heavy industry to prevent or reducesedimentation in pipes. But to date no study has been conductedon the effect of Merus rings on emitter clogging of trickleirrigation. The objective of this study was to investigate the ef-fects of Merus rings and water salinity on trickle irrigation systemperformance.

Materials and Methods

This study was performed during the summer of 2010 in anexperimental field (32°32′N, 51°23′E), at an elevation of approxi-mately 1,630 m above sea level, located at Isfahan University ofTechnology in Iran. A trickle irrigation experiment was used tocollect data. The trickle irrigation system had two subunits, onefor irrigation water with a Merus ring and one for irrigation waterwithout a Merus ring. Each subunit had nine laterals, spaced0.5 m apart, with an external diameter of 16 mm and length of25 m, which received water from a submain pipe with an externaldiameter of 25 mm. Each lateral had 50 emitters, spaced 0.5 mapart. Control valves were installed at the beginning of eachsubunit, and the subunits were spaced 2 m apart.

Each subunit was divided into three sections for three irrigationwater salinity treatments, and each section had three laterals.During irrigation, one lateral of each section received the desiredirrigation water salinity treatment by closing the valves located atthe beginning of the other laterals. This means that three lateralsfrom each subunit were irrigated with the same irrigation watersalinity at the same time, and after that three more laterals wereirrigated with a different irrigation water salinity. This procedurecontinued until all irrigation water salinity treatments were applied.Each irrigation water salinity treatment was applied on one day.In total, 30 irrigations, at irrigation intervals of 3 days and3 h for each irrigation operation time, were applied. An electricpump supplied water to the laterals from the water source at adesired pressure of 80 kPa (0.8 atm). The in-line, long-path,non-pressure-compensating emitters that were used, which go bythe trade name Iran Drip, have a discharge of 4 L=h and operateat a pressure of 80 kPa. All pipes used in the system were poly-ethylene. Due to negligible head loss across the lateral, the lateralinlet pressure was nearly the same as the operating pressure of theemitter.The schematic drawing of the experimental system is shownin Fig. 3. Two main treatments of irrigation water with a Merus ring(RT) and without a Merus ring (T) and three subtreatments of irri-gation water salts, including S1, S2, and S3, were used. The chemi-cal characteristics of the irrigation water salinity treatments areshown in Table 1. The experiment was performed with three rep-lications, and the field had no crop cover. One Merus ring with adiameter of 1.9 cm was installed around the submain pipe beforethe entrance of water to the laterals (Fig. 3).

During each measurement, 25 emitters along each lateral wereselected for discharge measurement. The same emitters were usedfor discharge measurement during the irrigation season. Theemitters’ discharges were measured using the volumetric method.The discharges for emitters were determined by measuring thevolume of emitted water from each emitter for 3 min. After fielddata collections, the average discharge of emitters (qa), coefficientof variation of emitter discharge (CV), emission uniformity (Eu),absolute emission uniformity (Eua), Christiansen’s uniformity co-efficient (Uc), statistical uniformity of emitter discharge (Us), andvariations in emitter discharge (qvar) were determined using theequations given by Keller and Karmeli (1974).

The following notations were used to measure the systemperformance parameters (qa, CV, Eu, Eua, Uc, Us, qvar): t1, atthe beginning of the irrigation season for the first irrigation; t2,at the end of the first month of the irrigation season for the10th irrigation; t3, at the end of the second month of the irrigationseason for the 20th irrigation; and t4, at the end of the irrigationseason for the 30th irrigation.

To investigate the variations in the chemical characteristics ofwater discharged from the emitters, water samples were collectedat the middle and end of the experiment for emitters located at thebeginning and end of laterals. Then, the electrical conductivity, pH,cations such as calcium, magnesium, and sodium, and anions suchas bicarbonate and chloride were measured, and the Langeliersaturation index (LSI) was then determined.

The following notations were used to measure the chemicalcharacteristics of discharged water from emitters: tc1, initialchemical characteristics of irrigation water salinity treatments atthe beginning of the irrigation season for first irrigation (with anaverage temperature of 25°C); tc2, in the middle of the irrigationseason (with an average temperature of 27°C); tc3, at the end ofthe irrigation season (with an average temperature of 30°C); d1,for emitters located at the beginning of laterals; and d2, for emitterslocated at the end of laterals. Statistical analyses were carried outusing SAS software.

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Results and Discussion

As previously mentioned, the principles behind how Merus works,namely, to modify the physical properties of substances containedin water by means of specially developed oscillations, are new andhard to understand. Scientists still heatedly debate these principles.Therefore, the theoretical background of this method relies onempirical research, assumptions, and logical conclusions. Thissituation is similar to nineteenth-century experimental physics,when phenomena were discovered and then tested for reproducibil-ity, and finally a theory was developed on the matter.

In this part, at first, to avoid repetition, we provide a generalanalysis that can be used for all results of this research. A Merusdevice programs to carry active oscillations. These active oscilla-tions are steadily emitted into the water to be treated by means ofBrownian movement. Water is capable of storing these oscillationsand passing them on. In water, active oscillations encounter naturaloscillations of the substances in it, for example, calcium carbonate,and interfere with them. Thus, the entire oscillation pattern in wateris affected. In this way, various alterations are made. For instance,lime no longer solidifies as quickly and is flushed out continuouslywith the normal flow. In other words, the Merus ring reduces saltprecipitation in emitters, which causes a reduced level of clogging

in the emitters and, consequently, a greater uniformity of distribu-tion of water.

Note that for all statistical analyses presented in figures in thissection, values followed by at least one common character are notstatistically different at the 0.05 probability level. Each value in thecharts is an average of three replications.

System Performance Parameters

Average Discharge of Emitters

The analysis of variance presented in Table 2 shows that the effectsof irrigation water type (RTor T), irrigation water salinity, and sam-pling time on qa was significant at the 1% level. As shown in thistable, the interaction effects of some of the parameters on the aver-age discharge of emitters (qa) are significant. For example, the in-teraction effect of irrigation water type with sampling time on qa isshown in Fig. 4, which shows that as the time increases, qa de-creases, and the reduction in qa is lower for irrigation water witha Merus ring. These results indicate that as the time increases,precipitation forms in the emitters for both types of irrigation watertreatments. But the Merus ring reduces salt precipitation in emitters,

Fig. 3. Experimental system layout and elements

Table 1. Chemical Characteristics of Irrigation Water Salinity Treatments

TreatmentEC

(dS=m) pHNaþ

(meq=L)Ca2þ

(meq=L)Mg2þ

(meq=L)HCO−

3

(meq=L)Cl−

(meq=L)Sodium adsorption

ratio (SAR)

S1 0.47 7.80 0.96 3.4 1 3.8 1 0.64S2 1.7 7.62 8.45 6.4 4.4 6.8 7 3.64S3 2.9 7.51 16.81 8.8 5.6 9.6 12 6.26

Note: EC = electrical conductivity.

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and consequently the values of qa are higher for RT treatments. Liuand Huang (2009) studied the performance of three commonly usedemitter types. They found that a reduction in emitter discharge wasaffected by water quality and time of operation.

Results showed that the qa for irrigation water with a Merus ringis higher than without a Merus ring for all irrigation water salinitytreatments. This can be explained by the fact that the use of a Merusring that reduces precipitation causes lower emitter clogging.The highest qa is associated with an irrigation water salinity ofS1 and the lowest qa with an irrigation water salinity of S3. Thisresult indicates that the use of water with higher salinity in trickleirrigation systems has a greater potential to induce emitter clogging.

Coefficient of Variation of Emitter Discharge andVariations in Emitter Discharge

The analysis of variance presented in Table 2 shows that the effectof irrigation water type, irrigation water salinity, and sampling timeon CV was significant at 1% level. As shown in the table, theinteraction effects of some of the parameters on CVare significant.For example, the interaction effect of irrigation water type andsampling time on CV is shown in Fig. 5. This figure indicates thatas the time increases, the CV increases for both types of irrigationwater treatment and the increases in CV are lower for irrigationwater with a Merus ring. As the time increased, emitter cloggingoccurred for both types of irrigation water treatment that caused anincrease in CV during the experiment. But, because of the effect ofthe Merus ring on the reduction in emitter clogging, the amounts ofCV are lower for RT treatments. It should be noted that results

similar to those obtained for CV were obtained for emitter dis-charge variation (qvar).

The results of this study showed the amounts of CV for irriga-tion water with a Merus ring are lower than without a Merus ringfor all irrigation water salinity treatments. The CV has an inverserelation to the average emitter discharge. With regard to the fact thatthe Merus ring reduces emitter clogging, the amounts of CV for RTtreatment are lower than with T treatment. On the other hand, thisfigure also shows that the highest CV is associated with an irriga-tion water salinity of S3 and the lowest CV with an irrigation watersalinity of S1. The use of water with more salinity has a greaterpotential to induce emitter clogging and, consequently, an increasein the CV.

Emission Uniformity, Absolute Emission Uniformity,Christiansen’s Uniformity Coefficient, StatisticalUniformity of Emitter Discharge

The analysis of variance presented in Table 2 shows that the effectof type of irrigation water on Eu was significant at the 5%level. The effect of irrigation water salinity and time of samplingon Eu was significant at the 1% level. As shown in the table, theinteraction effect of irrigation water with time of sampling on Euwas significant at the 5% level. The result of this interaction effectis shown in Fig. 6. Similar results were obtained for Eua, Uc,and Us.

Fig. 6 presents the variations in Eu for both types of irrigationwater treatment during the experiment. This figure shows that astime goes on, Eu decreases for both types of irrigation watertreatment and the reduction in Eu is less for irrigation water with

Table 2. Analysis of Variance for System Performance Parameters

Source of variationDegrees

of freedom

Mean squares

qa CV EU EUa Uc Us qvar

I 1 0.168a 3.957a 10.253b 3.622a 3.298a 3.957a 5.01 × 10–4a

Error 2 1.08 × 10–4 0.018 0.219 0.08 0.023 0.018 1.39 × 10–6

S 2 0.867a 1.909a 16.306a 2.489a 1.096a 1.909a 3.6 × 10–4b

S × I 2 0.073a 0.243a 0.439 0.725b 0.104 0.243a 1.51 × 10–4

Error 8 0.001 0.013 0.42 0.12 0.06 0.013 6.39 × 10–5

t 3 2.228a 4.419a 6.899a 7.837a 2.947a 4.419a 0.004a

t × I 3 0.075a 0.168a 0.403a 0.215a 0.144a 0.168a 9.77 × 10–5b

t × S 6 0.22a 0.096a 0.137 0.066 0.079a 0.096a 1.02 × 10–4b

t × I × S 6 0.009a 0.008 0.03 0.042 0.01 0.008 3.1 × 10–5

Error 36 1.48 × 10–4 0.017 0.107 0.05 0.019 0.017 3.47 × 10–5

Note: I = irrigation water type (with or without Merus ring); S = irrigation water salinity; t = sampling time; CV coefficient of variation; Uc = uniformitycoefficient; Us = statistical uniformity of emitter discharge.aSignificance at 1% level.bSignificance at 5% level.

Fig. 4. Interaction effect of irrigation water type with sampling timeon qa

Fig. 5. Interaction effect of irrigation water type and sampling timeon CV

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a Merus ring. Emission uniformity is directly proportional to lowquarter emitter discharges and inversely proportional to the averageemitter discharge. Both of these parameters were higher for RTtreatments and decreased for both types of irrigation watertreatment during the experiment. According to the obtained results,low quarter emitter discharges were more affected by emitterclogging compared to the average emitter discharge. Thus, onthe whole, Eu decreased for both types of irrigation water treatmentduring the experiment (due to an increase in emitter clogging overtime and, consequently, a reduction in the low quarter emitterdischarges) and the reduction in Eu was less for irrigationwater with a Merus ring (due to the effect of the Merus ring onthe reduction in emitter clogging and, consequently, the increasein the low quarter emitter discharges). Research has shown thatpartial or complete clogging drastically reduces water applicationuniformity (Nakayama and Bucks 1981).

Chemical Characteristics of Emitted Water

Electrical Conductivity

The analysis of variance presented in Table 3 shows that the effectof type of irrigation water, irrigation water salinity, and time of

sampling on EC was significant at the 1% level. As shown inthe table, the interaction effects of some of the parameters onEC are significant. For example, the interaction effect of irrigationwater type and sampling time on EC is shown in Fig. 7. This figureindicates that as the time increases, EC decreases for both types ofirrigation water treatment. The reduction in EC was lower for irri-gation water with a Merus ring. This can be explained by the factthat as the time increases, precipitation occurs in emitters for bothtypes of irrigation water treatment. But the Merus ring reduces saltprecipitation in emitters, and consequently the reduction in EC islower for irrigation water with a Merus ring. In other words, forirrigation water with a Merus ring, smaller amounts of salt are de-posited in the emitters and more salts are continuously flushed outwith the normal flow. Liu and Huang (2009) found that chemicalprecipitation was the main cause of emitter clogging due to a highpH and ion concentration. According to the results of this study, theEC of irrigation water with a Merus ring is higher than that withouta Merus ring for all irrigation water salinity treatments. The Merusring reduces salt precipitation in emitters and consequently causes ahigher salt solution in water and a higher EC of water. On the otherhand, smaller amounts of salt are deposited in emitters and moresalts are continuously flushed out with the normal flow.

Acidity

The analysis of variance presented in Table 3 shows that theeffect of irrigation water salinity and time of sampling on pHwas significant at the 1% level. The results showed that pHvariations were not constant process during the experiment.

Calcium, Magnesium, Sodium, and BicarbonateContent

The analysis of variance presented in Table 3 shows that theeffect of type of irrigation water, irrigation water salinity, samplinglocation, and sampling time on Ca2þ content was significant at the1% level. As shown in the table, the interaction effects of some ofthe parameters on Ca2þ are significant. For example, the interaction

Fig. 6. Interaction effect of irrigation water type and sampling timeon Eu

Table 3. Analysis of Variance for Chemical Characteristic Measurements of Emitted Water

Source of variationDegrees

of freedom

Mean squares

LSIEC pH Ca2þ Mg2þ Naþ HCO–3 Cl–

I 1 0.108a 9.3 × 10–7 4.24a 0.926 3.8b 1.713 0 0.033a

Error 2 7.1 × 10–4 6.2 × 10–5 0.024 0.063 0.102 0.203 0 3.18 × 10–4

S 2 47.723a 0.763a 208.738a 176.93a 2033.34a 256.69a 1,092a 0.325a

S × I 2 0.035a 2.3 × 10–5 0.658a 0.144a 1.559a 0.343 0 0.001Error 8 8.66 × 10–4 3.7 × 10–5 0.037 0.004 0.036 0.142 0 0.001D 1 3.7 × 10–6 8.3 × 10–6 0.03b 0.013 0.017 0.001 0 9.3 × 10–5a

d × I 1 3.7 × 10–6 9.3 × 10–7 0.003 0.006 0.017 0.001 0 3.3 × 10–5a

d × S 2 9.3 × 10–7 2.78 × 10–6 0.01a 0.004 0.011 3.7 × 10–4 0 2.6 × 10–5b

d × I × S 2 9.3 × 10–7 9.3 × 10–7 0.001 0.001 0.011 3.7 × 10–4 0 1.11 × 10–5a

Error 12 1.85 × 10–6 8.3 × 10–6 0.001 0.004 0.004 7.4 × 10–4 0 2.78 × 10–6

tc 2 0.215a 1.79 × 10–4b 8.95a 2.064a 6.237a 4.006a 0 0.003a

tc × I 2 0.051a 9.3 × 10–7 1.263a 0.286a 1.347a 0.646a 0 0.011a

tc × S 4 0.062a 7.87 × 10–6 1.116a 0.363a 2.34a 0.679a 0 0.002a

tc × I × S 4 0.017a 1.07 × 10–5 0.205a 0.05a 0.529a 0.133a 0 0.001b

tc × d 2 3.7 × 10–6 2.78 × 10–6 0.008 0.004 0.006 0.001 0 4.82 × 10–5

tc × I × d 2 3.7 × 10–6 6.48 × 10–6 0.001 0.001 0.006 0.001 0 1.11 × 10–5

tc × S × d 4 9.3 × 10–7 1.39 × 10–6 0.003 0.002 0.003 3.7 × 10–4 0 1.48 × 10–5

tc × S × d × I 4 9.3 × 10–7 2.3 × 10–6 0.001 3.7 × 10–4 0.003 3.7 × 10–4 0 5.56 × 10–6

Error 48 4.4 × 10–4 2.5 × 10–5 0.009 0.008 0.023 0.037 0 1.72 × 10–4

Note: I = type of irrigation water (with or without Merus ring); S = irrigation water salinity; tc = sampling time; CV = electrical conductivity.aSignificance at 1% level.bSignificance at 5% level.

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effect of irrigation water type and sampling time on Ca2þ is shownin Fig. 8. The reasons given for the effect on EC apply to Ca2þ aswell. It should be noted that similar results were obtained for Mg2þ,Naþ, and HCO−

3 ions.The results showed no significant difference in Ca2þ content

between the beginning and the end of the laterals for irrigationwater salinity treatments, but the amount of Ca2þ was higher forthe location of d1 at the S2 and S3 irrigation water salinities. Thismeans that some Ca2þ precipitated along the pipe and then caused alower level of irrigation water Ca2þ at the end of the laterals at thed2 location.

Chloride

The analysis of variance presented in Table 3 shows that the effectof irrigation water salinity on Cl− was significant at the 1% level.The results indicated that because sediment with a chloride base didnot form in the emitters, the amount of this ion was not reduced inthe discharge water from the emitters.

Langelier Saturation Index

The analysis of variance presented in Table 3 shows that the effectof type of irrigation water, irrigation water salinity, location of sam-pling, and time of sampling on the Langelier saturation index (LSI)was significant at the 1% level. As shown in the table, the inter-action effects of some of the parameters on LSI are significant.For example, the interaction effect of irrigation water type and sam-pling time on LSI is shown in Fig. 9. According to this figure, as thetime increases, LSI increases for RT treatments and decreases for Ttreatments. Generally, important factors affecting LSI are total dis-solved solids, concentration of calcium and bicarbonate, pH, andirrigation water temperature. As each of these factors increases,

LSI increases. In T treatments, the effect of salt reduction in waterdischarged from emitters (affected by precipitation in emitters) inthe reduction of LSI was greater than the effect of temperature onLSI. Thus, LSI decreased in this treatment. In RT treatments, theeffect of a temperature increase on LSI was greater than the effectof salt reduction in water discharged from emitters (affected by pre-cipitation in emitters) on LSI. Thus, LSI increased in this treatment.These results were obtained for water discharged from emitters, notfor irrigation water.

The results showed no significant difference between the begin-ning and the end of the laterals with respect to LSI for any of theirrigation water treatments. Table 3 also shows that the levels of theLSI are greater for RT treatment at both sampling locations. Theseresults illustrate that there is more salt in water discharged fromemitters in RT treatments, but, because of the effect of the Merusring on the reduction of salt precipitation, less salt precipitates inthe emitters and higher levels of salt in irrigation water salts resultin a higher LSI. According to the results of this study, there is nosignificant difference between the beginning and end of the lateralswith respect to LSI in irrigation water salinity treatments. Fig. 9also shows that the LSI is lower at location of d2 for irrigation watersalinity of S3. Some salts precipitated in the pipes, and lower levelsof irrigation water salt resulted in a lower LSI at the ends ofthe pipes.

Economic Comparison of Merus Ring with AcidInjection

In this study, acid injection was not used, and so an exact compari-son between the Merus ring and acid injection cannot be made. Butthe following approximate comparison was made.

A method that can be used to determine the quantity of acidneeded to adjust the pH of irrigation water to a level necessaryto prevent carbonate precipitation is acid titration (Nakayamaand Bucks 1986). Sulfuric acid and hydrochloric acid are com-monly used. Since precipitation occurs more readily in water witha high pH (above 7.0), precipitation of these compounds can beprevented by continuous injection (whenever the system is operat-ing) of a small amount of acid to maintain the water pH just below7.0 (Granberry et al. 2012). Waters vary in their response to acidbecause of their buffering capacity, but for most waters examinedwith an initial pH reading of 8, the pH decreased approximately byone unit with 0.5 meq=L acid. In general, a 1 meq=L acid additionwould lead to a final pH of between 6 and 6.5. The use of excessiveacid is uneconomical and may cause other problems, such as thecorrosion of metallic fittings (Nakayama and Bucks 1986). In ad-dition, chemical water treatment methods sometimes use chemicalproducts that might be harmful to the environment and human

Fig. 7. Interaction effect of irrigation water type and sampling timeon EC

Fig. 8. Interaction effect of irrigation water type and sampling timeon Ca2þ

Fig. 9. Interaction effect of irrigation water type and sampling timeon LSI

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health (Ahmad Aali et al. 2009). In this study, one Merus ring1.9 cm (0.75 in.) was used. This ring is able to support a flow rateof 4 m3=h, and its current price is US$330. The ring was chargedfor 1 year at the start of the experiment and then must be rechargedagain. For a comparison between the Merus ring and acid injection,let us suppose that 4,000 L of water passes through the pipe. Forcontinuous injection, with an irrigation interval of 1 day, one mustirrigate 365 times per year. As mentioned previously, 1 meq=L acidaddition would lead to a final pH of between 6 and 6.5. Thus, for4,000 L irrigation water, 4,000 meq acid is necessary (which isequal to 196.16 g sulfuric acid and 145.84 g hydrochloric acid).Considering a density of 1.84 g=cm3 for sulfuric acid and1.189 g=cm3 for hydrochloric acid, the equivalent volume of sul-furic acid is 106.61 × 10−3 L and the equivalent volume of hydro-chloric acid is 122.68 × 10−3 L. Sulfuric acid and hydrochloricacid (produced by Merck Company, Germany) cost approximatelyUS$17/L and US$15/L, respectively. Thus, for an irrigation time of1 h, the price of sulfuric acid injection is US$662 dollars(106.61 × 10−3 L × 17 × 365 ¼ US$662), and the price of hydro-chloric acid injection is US$672. Thus, the use of a Merus ring (atUS$330) is an economical approach to water treatment comparedto acid injection. In addition, the use of a Merus ring is very simple,and its application is not very complicated. It should be noted thatacid injection may cause corrosion of metallic equipment, whereasone of the uses of a Merus ring is to remove corrosion in a pipelinesystem.

Conclusion

Results of the study presented here showed that a Merus ringreduces precipitation of Ca2þ, Mg2þ, Naþ, and HCO–

3 ions inemitters. In other words, Merus ring reduces salt precipitation inemitters and leads to reduced emitter clogging and, consequently,higher uniformity of water distribution. The results of systemperformance parameter measurements showed that irrigation waterwith a Merus ring has a significant effect on the average dischargeof emitters and trickle irrigation uniformity parameters. The useof a Merus ring in trickle irrigation is recommended to achievelower emitter clogging, higher distribution uniformity, and betterirrigation performance, especially in arid regions with higher irri-gation water salinity. The use of a Merus ring is simple, and it is aneconomical approach to water treatment compared to acid injection.

Acknowledgments

This research was funded by Isfahan University of Technology andMerus Iran Company. This assistance is gratefully acknowledged.

References

Ahmad Aali, Kh., Liaghat, A., and Dehghanisanij, H. (2009). “The effect ofacidification and magnetic field on emitter clogging under saline waterapplication.” J. Agric. Sci., 1(1), 132–141.

Alimi, F., Tlili, M. M., Ben Amor, M., Maurin, G., and Gabrielli, C. (2009).“Effect of magnetic water treatment on calcium carbonate precipitation:Influence of the pipe material.” Chem. Eng. Process. Process Intensif.,48(8), 1327–1332.

Barrett, R. A., and Parsons, S. A. (1998). “The influence of magneticfields on calcium carbonate precipitation.” Water Res., 32(3),609–612.

Capra, A., and Scicolone, B. (1998). “Water quality and distributionuniformity in drip/trickle irrigation systems.” J. Agric. Eng. Res.,70(4), 355–365.

Chibowski, E., Hotysz, L., and Szczes, A. (2003).“Adhesion of in situprecipitated calcium carbonate in the presence and absence of magneticfield in quiescent conditions on different solid surfaces.” Water Res.,37(19), 4685–4692.

Coelho, R. D., and Resende, R. S. (2001). “Biological clogging of netafim’sdrippers and recovering process through chlorination impact treatment.”American Society of Agricultural Engineers (ASAE), Sacramento, CA.

De Melo, R. F., Coelho, R. D., and Teixeira, M. B. (2008). “Clogging ofcommercial drippers by calcium and magnesium precipitates using fourlangelier saturation indexes.” Irriga, 13(4), 525–539.

Dworshak, R. (2013). “Merus, green and sustainable water treatment since1996.” ⟨http://www.merusonline.com⟩.

Evans, R. G. (2000). Microirrigation, Washington State Univ., IrrigatedAgriculture Research and Extension Center, 24106 North Bunn RoadProsser, Washington, DC.

Gilbert, R. G., Nakayama, F. S., Bucks, D. A., French, O. F., and Adamson,K. C. (1981). “Trickle irrigation: Emitter clogging and other flow prob-lems.” Agric. Water Manage., 3(3), 159–178.

Higashitani, K., Kage, A., Katamura, S., Imai, K., and Hatade, S. (1993).“Effects of magnetic field on the formation of CaCO3 particles.” J. Col-loid Interface Sci., 156(1), 90–95.

Keller, J., and Karmeli, D. (1974). “Trickle irrigation design parameters.”Trans. ASAE, 17(4), 678–684.

Kobe, S., Dražic, G., McGuiness, P. J., and Stražišar, J. (2001). “Theinfluence of the magnetic field on the crystallization form of calciumcarbonate and the testing of a magnetic water-treatment device.”J. Magn. Magn. Mater., 236(1–2), 71–76.

Liu, H., and Huang, G. (2009). “Laboratory experiment on drip emitterclogging with fresh water and treated sewage effluent.” Agric. WaterManage., 96(5), 745–756.

Granberry, D. M., Harrison, K. A., and Kelley, W. T. (2012). Dripchemigation: Injecting fertilizer, acid and chlorine, Univ. of Georgia,Cooperative Extension, Athens, GA, 1130.

Nakayama, F. S., and Bucks, D. A. (1981). “Emitter clogging effects ontrickle irrigation uniformity.” Trans. ASAE, 24(1), 77–80.

Nakayama, F. S., and Bucks, D. A. (1986). Trickle irrigation for cropproduction: Design, operation and management (developments inagricultural engineering), Vol. 9, Elsevier Science.

Nakayama, F. S., and Bucks, D. A. (1991). “Water quality in drip/trickleirrigation: A review.” Irrig. Sci., 12(4), 187–192.

Pitts, D. J., Haman, D. Z., and Smajstrla, A. G. (1990). Causes andprevention of emitter plugging in microirrigation systems, Instituteof Food and Agricultural Sciences (IFAS), Univ. of Florida, Gainesville,FL.

Povoa, A. F., and Hills, D. J. (1994). “Sensitivity of microirrigation systempressure to emitter plugging and lateral line perforations.” Trans. Am.Soc. Agric. Eng., 37(3), 793–799.

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