ArticlePDF Available

Abstract and Figures

Experimental tests are carried out to evaluate the impact of treated wastewater (TWW) on the discharge of five different types of emitters which are commonly used. Two water qualities, fresh water (FW) and treated wastewater, and five types of emitters, GR, Nein (NE), Edin (ED), Corona (CO), and Rain Bird (RB) are tested. The values of chemical properties for FW show mostly low clogging potential on emitter performance. The clogging potential for TWW varied from low to medium. The exception was for pH where there was severe clogging potential for both water types. The performance of emitters was tested by measuring the emitter discharge and estimating the average emitter discharge (Qavg), coefficient of variation (CV), emission uniformity coefficient (EU), and Christiansen uniformity coefficient (CU). The average discharges for different types of emitters were analyzed and compared at P ≤ 0.05. The CO and RB emitter types did not show any signs of clogging whereas the GR, NE, and ED emitter types showed signs of clogging. The results of CV, EU, and CU values showed that the performances of emitter types GR, NE, ED were classified as low or moderate clogging potential. In contrast, the CO and RB emitters were classified as moderate or high clogging potential.
Content may be subject to copyright.
Field evaluation of the performance of different irrigation
emitter types using treated wastewater
Naji K. Al-Meeh, Ibrahim Bashabsheh, Samer Talozi and Taha A. Al-Issa
ABSTRACT
Experimental tests are carried out to evaluate the impact of treated wastewater (TWW) on the
discharge of ve different types of emitters which are commonly used. Two water qualities, fresh
water (FW) and treated wastewater, and ve types of emitters, GR, Nein (NE), Edin (ED), Corona (CO),
and Rain Bird (RB) are tested. The values of chemical properties for FW show mostly low clogging
potential on emitter performance. The clogging potential for TWW varied from low to medium. The
exception was for pH where there was severe clogging potential for both water types. The
performance of emitters was tested by measuring the emitter discharge and estimating the average
emitter discharge (Q
avg
), coefcient of variation (CV), emission uniformity coefcient (EU), and
Christiansen uniformity coefcient (CU). The average discharges for different types of emitters were
analyzed and compared at P0.05. The CO and RB emitter types did not show any signs of clogging
whereas the GR, NE, and ED emitter types showed signs of clogging. The results of CV, EU, and CU
values showed that the performances of emitter types GR, NE, ED were classied as low or moderate
clogging potential. In contrast, the CO and RB emitters were classied as moderate or high clogging
potential.
Naji K. Al-Meeh (corresponding author)
Department of Natural Resources, Faculty of
Agriculture,
University of Science and Technology,
P.O. Box 3030 Irbid,
Jordan
E-mail: nmeeh@just.edu.jo
Ibrahim Bashabsheh
National Center for Agricultural Research and
Extension (NCARE),
Jordan, Ministry of Agriculture,
Amman,
Jordan
Samer Talozi
Civil Engineering Department, Faculty of
Engineering,
Jordan University of Science and Technology,
P.O. Box 3030 Irbid,
Jordan
Taha A. Al-Issa
Department of Plant Production, Faculty of
Agriculture,
University of Science and Technology,
P.O. Box 3030 Irbid,
Jordan
Key words |drip irrigation, emitter clogging, emitter types, treated wastewater, water quality
ABBREVIATIONS
CO Corona emitter
CU Christiansen uniformity coefcient
CV coefcient of variation
ED Edin emitter
EU emission uniformity coefcient
FW fresh water
GR GR emitter
NE Nein emitter
Q
avg
average discharge
RB Rain Bird emitter
TWW treated wastewater
INTRODUCTION
In many parts of the world, agriculture is still considered
the main user of water and it is becoming more
challenging to meet the water demand in agriculture
especially with fresh water (FW). For reducing the
demand on FW in agriculture, treated wastewater
(TWW) is used as another source of irrigation. TWW is
suitable to be used in drip irrigation more than other
methods of irrigation because it minimizes the health
risks for farmers and product consumers (Capra & Scico-
lone ). Drip irrigation with TWW may offer an
efcient way to deal with water shortages for agricultural
crops (Capra & Scicolone ). It has the advantage of
high water content in the root zone but its performance
depends on water quality because it may cause emitter
clogging (Bouya et al. ). Emitter clogging is a serious
problem in drip irrigation where different types of
emitters are available in the market. The factory perform-
ance characteristics of these emitters are usually
evaluated using clean water. Clogging reduces emission
240 © IWA Publishing 2015 Water Quality Research Journal of Canada |50.3 |2015
doi: 10.2166/wqrjc.2015.043
uniformity (EU) which, in turn, affects drip irrigation ef-
ciency. The eld distribution uniformity depends on
manufacturing variation, pressure, temperature, clogging,
and material fatigue (Ozekici & Sneed ;Capra & Sci-
colone ,). Uniformity decreases as the length of
lateral increases (Mansour et al. ). It is necessary to
choose the emitters that show an acceptable performance,
particularly under reclaimed water (Ravina et al. ).
Emitter clogging decreases the water distribution
efciency, which leads to a reduction in water use ef-
ciency and crop production. Clogging of emitters is the
most difcult problem encountered in the operation of
drip irrigation systems. It is not easy to detect, clean, or
replace clogged emitters. Emitters can be clogged by par-
ticles in the water supply, precipitates, or bacterial slimes
resulting from dissolved calcium or other salts in the
water supply (Keller & Bliesner ). The availability of
biological clogging agents (algae and protozoa) in irriga-
tion water will increase the percentage of clogging
emitters, leading to the reduction of the average discharge
as well (Dehghanisanij et al. ). This reduction
depends on emitter characteristics and water operating
pressure. It has been indicated that antagonistic microor-
ganisims can be utilized for the treatment of clogging in
drip irrigation systems (Sahin et al. ). The ow rate
of CaCO
3
-clogged emitters increased in drip lines that
were treated with bacterial suspensions (Eroglu et al.
). Using the reclaimed wastewater treated by biologi-
cal aerated lter for drip irrigation system is more
suitable than wastewater treated with uidized-bed reac-
tor (Li et al. ).
For the same kind of emitters, when the total sus-
pended solids and organic matter content increases, the
percentage of totally clogged emitters is expected to
increase; however, the mean emitted discharge, the EU
coefcient, and the operating time of the lters between
cleaning operations are expected to decrease (Capra &
Scicolone ,). The emitter performance character-
istics are affected by water quality, emitter type, and time
of operation (Lui & Huang ). However, it was found
that the coefcient of variation (CV) and percentage of
clogging for the TWW were greater than those values for
fresh water. Also, the values of EU and coefcient uniform-
ity (CU) for TWW treatments were lower than those for the
fresh water. The authors also indicated that chemical pre-
cipitation was the main reason for emitter clogging due
to high pH and ion concentration in TWW. Furthermore,
they indicated that the online emitters showed better
anti-clogging than the inline emitters for irrigation with
TWW.
The causes of clogging vary from one location to
another (Nakayama & Bucks ). Therefore, the perform-
ance of emitters needs to be evaluated under eld conditions
where wastewater is used.
Many studies (Capra & Scicolone ;Bouya et al.
;Lui & Huang ) have examined the impact of
TWW on the performance of emitters under TWW. How-
ever, no research has been conducted on the impact of
TWW on the performance of the emitters currently used
by farmers. The irrigation water around the study area
comes from Al-Ramtha water treatment plant (Jordan),
and was not mixed with any other water resources. The
main objective of this study is to evaluate the impact of
TWW on the discharge of different types of emitters.
MATERIALS AND METHODS
Experimental site
Field experiments were conducted near a water treatment
plant located 7 km north of Ramtha (32 W350north latitude
and 35 W590east longitude) and an elevation of 490 m above
sea level. The experiments were conducted during the
summer and spring seasons of 2008 and 2009. The inlet of
Ramtha wastewater treatment plant was 100% domestic
wastewater and it was a secondary mechanical treatment
process that employed the activated sludge-extended aera-
tion method of treatment.
Water resources and qualities
FW and TWW were used to test the performance character-
istics of different emitters. FW came from local municipal
tube wells, usually used for drinking purposes. The main
parameters of water qualities tested were the pH, SAR,
EC, TSS, Ca, Mg, TDS, Na, K, Fe, Cl, Mn, CO
3
,HCO
3
,
241 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
SO
4
,NO
3
, B, P, biochemical oxygen demand (BOD
5
),
chemical oxygen demand (COD), and FC (Escherichia
coli). The chemical and biological parameters for FW and
TTW are presented in Table 1.
The FW was passed through the screen lter then the
disk lter. The TWW was passed through the sand lter
followed by screen and disk lters. The sand lter con-
sisted of a layer of gravel with a diameter of 8 to 16 mm
and another layer with a diameter of 1 to 8 mm. The
screen lter consisted of a diameter of 1.6 mm and the
disk lter had 250 mesh/in
2
. The cleaning was based on
the losses of pressure between the inlet and outlet for
each lter.
Emitters
Five types of emitters were tested using FW and TWW.
These types were the GR, Nein (NE), Edin (ED), Corona
(CO), and Rain Bird (RB). These emitters were commonly
used by farmers in Jordan, and were manufactured by differ-
ent factories. The specications of these emitters are
summarized in Table 2.
Experimental layout
The experiment layout consisted of three replicates
(blocks). In each block, the ve different emitters and
Table 1 |Chemical and biological analysis of FW and the TWW
Fresh water Treated wastewater
Parameter Units # of readings Mean
a,b
# of readings Mean
a,b
pH 7 8.19 (0.38) (severe) 5 8.02 (0.28) (severe)
EC
c
dS/m 7 1.20 (0.17) 5 2.72 (0.34)
SAR
d
6 2.68 (0.38) 5 10.78 (3.56)
TSS
e
ppm 5 6.4 (9.2) (low) 5 51.8 (15.0) (low)
TDS
f
ppm 7 933.85 (91.00) (medium) 6 1554 (181) (medium)
Fe ppm 3 0.11 (0.01) (medium) 3 0.2 (0.08) (severe)
Mn ppm 3 0.01 (0.006) (low) 3 0.04 (0.01) (low)
Ca ppm 7 70.17 (9.09) 5 68.32 (8.04)
Mg ppm 7 44.09 (9.90) 5 39.91 (3.59)
Na ppm 7 133.76 (50.27) 5 455.77 (152.08)
K ppm 7 14.04 (9.48) 5 48.28 (7.12)
Cl ppm 6 211.44 (34.89) 5 652.75 (182.66)
CO
3
ppm 4 5.63 (2.25) 4 4.88 (3.09)
HCO
3
ppm 4 76.25 (13.87) 4 117.43 (13.29)
SO
4
ppm 4 212.04 (127.40) 4 326.64 (238.12)
NO
3
ppm 7 21.57 (16.25) 5 13.60 (8.07)
B ppm 5 0.05 (0.05) 4 0.125 (0.08)
P ppm 7 0 (0.00) 5 0.11 (0.17)
BOD
5
ppm 4 12.0 (13.11) 4 41.05 (25.93)
COD ppm 4 28.25 (27.73) 4 62.75 (64.59)
FC (E. coli) MPN/100 ml 2 2 (0.00) 2 20.00 (0.00)
a
Standard deviation.
b
Clogging potential (Bucks et al. 1979;Nakayama & Bucks 1991).
c
Electrical conductivity.
d
Sodium adsorption ratios.
e
Total suspended solids.
f
Total dissolved solids.
242 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
the two water types were tested. Emitters were installed
50 cm apart on a 10-m long lateral (a total of 20 emitters
for each lateral and 60 emitters of each emitter type were
divided into three blocks). Thus, each block contained 10
laterals. Consequently, each lateral tested one type of
emitter with one type of water. The lateral lines were
raised using rigid iron rods at a height of 20 cm above
soil surface. Under each emitter, water pots with a
capacity of 2 l were located to collect the discharge of
emitters.
The irrigation system consisted of two tanks (each with a
capacity of 2 m
3
), a pump, valves, lters, pressure gauges, a
ow meter, lateral pipes (20 mm diameter) as shown in the
schematic diagram of the experiment in Figure 1.
Estimating initial emitters characteristics
Using FW only, emitter discharge values were measured in
the eld at two operating pressures (100 and 200 kPa) for
new emitters as a rst trial under eld conditions. Measure-
ments were used to estimate the initial values (
i
)of
coefcient of variation (CV
i
), the discharge exponent (X
i
),
and the discharge coefcient (Kd
i
). An operating pressure
of 138 kPa was used for conducting the rest of the exper-
iments, which included the two water types and ve
emitter types.
For the new emitters, the discharge exponent (X
i
)was
estimated using Equation (1), and the discharge coefcient
(Kd
i
) was estimated using Equation (2)
Xi¼
log Qavg1
Qavg2

log Havg1
Havg2
 (1)
where Q
avg1
is the average discharge at operating pressure
(H
avg1
) of 200kPa, Q
avg2
is the average discharge at operat-
ing pressure (H
avg2
) of 100 kPa
Kdi¼Qavg
H0:5
avg
! (2)
The main parameters used to evaluate an emitters
performance are the mean discharge of the emitters
(Q
avg
) in each lateral, the CV, the EU coefcient, and
Christiansen uniformity coefcient (CU). Average
Table 2 |Specications of manufacturing emitters
Emitter type Specications
GR emitters In-line emitters, pressure compensated
4 L/h, 150 kPa, self-ushing, area
cross-section
Nein emitters (NE) On-line emitter, pressure compensated
4 L/h, 150 kPa, un-self-ushing, area
cross-section
Eden emitters (ED) On-line emitter, pressure compensated
3.8 L/h, 150400 kPa bar, self-ushing,
area cross-section
Corona emitters (CO) On-line emitter, pressure compensated
4.0 L/h, 150 kPa bar, self-ushing, area
cross-section
Rain Bird emitters (RB) On-line emitter, pressure compensated
3.8 L/h, 150 kPa bar, self-ushing, area
cross-section
Figure 1 |Schematic diagram of the irrigation system for testing different emitters (GR, NE, ED, CO, and RB).
243 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
Table 3 |Initial testing characteristics of emitters with fresh water during the rst trial
Emitter
types
Coefcient of variation
(CV
i
%)
Discharge exponent
(X
i
)
Discharge coefcient
(Kd
i
)
Manufacturer discharge
(L/h)
Initial mean discharge
(L/h)
GR 0.21 0.14 2.85 4.0 4.4
NE 0.23 0.47 0.81 4.0 3.5
ED 0.09 0.03 3.32 3.8 3.6
CO 0.05 0.16 2.06 4.0 3.8
RB 0.19 0.02 4.02 3.8 4.3
Figure 2 |The average discharge (L/h) for ve emitter types under FW and TWW.
244 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
discharge was estimated by dividing the summation of
individual discharge in each lateral line on the number
of emitters. The CV was calculated by dividing the
standard deviation for the emitters in each lateral line
on the average discharge of emitters. The EU was esti-
mated by dividing the mean discharge of the lower
quarter in each lateral line on the average discharge as
well.
Figure 3 |The coefcient of variation (CV%) for ve emitter types under FW and TWW.
245 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
The CU was calculated using Equation (3)
CU ¼1P
n
i¼1
qiQavg
nQavg
0
B
B
@1
C
C
A
×100 (3)
where q
i
is the individual emitter discharge in liters (l), Q
avg
is the average discharge of observations, nis number of
observations.
Field measurements
From each lateral, 10 out of 20 emitters were tested. Every
other emitter on the lateral was selected. Emitter discharge of
10 minutes was collected using a graduated cylinder and con-
verted to liters per hour. Every week, the system was run for
2 hours every other day with 1 day off per week. After 16
hours of operation time, a set of emitter discharge readings
was measured. In total, nine sets of readings were recorded.
The head loss along the lateral was maintained within 10% of
the inlet head pressure. Laterals were ushed every 2 weeks
for 5 minutes each time; after conducting the testing, the col-
lected data were subjected to analysis of variance (ANOVA)
using SAS software (SAS ). Means were separated using
Fishers least signicant difference at 0.05 probability level.
RESULTS AND DISCUSSION
Water quality
The chemical and biological water quality parameters for
fresh (FW) and TWW are presented in Table 1. According
to their classication, the present study found that pH
value for FW (8.19) was higher than that for TWW (8.02),
while both of them had severe potential on the emitter clog-
ging. The values of TDS for FW and TWW have medium
clogging potential on emitter performance and the values
of Fe in FW have low clogging potential compared with Fe
values in TWW. Based on these values, the clogging poten-
tials of the emitters were varied between low and moderate.
The values of Mn in FW and TWW have a little clogging
potential on emitter performance.
The impact of pH on clogging potential was classied as
<7.0 (slight), 78 (medium), and >8.0 (severe) (Nakayama &
Bucks ). The potential of biological oxygen demands
(BOD
5
) on emitter clogging were classied as <15 ppm
(low), 1540 ppm (medium), and >40 ppm (severe) (Capra
&Scicolone). In this study, the potential value of the
concentration of BOD
5
for FW on emitter clogging is
12.0 ppm (low) and for TWW is 41.1 ppm (severe). Increasing
the suspended solids and organic matter (which are related to
BOD
5
) would lead to an increase in the percentage of clogged
emitters and a decrease in the emitter discharge and EU
(Capra & Scicolone ). Also, the salt concentration in
the water did not cause emitter clogging because the EC
values of the FW (1.2 dS/m) and TWW (2.27 dS/m) are low.
Initial characteristics of new emitters
The characteristics of variation coefcient (CV
i
), discharge
exponent (X
i
), and discharge coefcient (Kd
i
) for new
emitters were estimated and are presented in Table 3.
Table 4 |Classication of test results for the different emitter types under FW and TWW
according to the CV classication (Bralts 1986)
Well:
CV ¼010%
Moderate:
CV ¼1129% Poor: CV >30%
Emitter type FW TWW FW TWW FW TWW
GR 11 75 13
NE 20 57 22
ED 12 65 22
CO 45 53 01
RB 22 77 01
Table 5 |Classication of test results for the different emitter types under FW and TWW
according to the CV classication (ASAE EP405.1. 2003)
Well: CV <10%
Moderate:
CV ¼1020% Poor: CV >20%
Emitter type FW TWW FW TWW FW TWW
GR 11 43 45
NE 20 14 65
ED 12 23 64
CO 44 33 22
RB 22 56 21
246 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
The CV values were classied as <5% (excellent) 57%
(average) 711% (marginal), 1115% (poor), and >15%
(unacceptable) (Ozekici & Sneed ). The study found
that the CV
i
values for GR, NE, and RB were 21, 23, and
19%, respectively. The CV
i
values for ED and CO were 9
and 5%, respectively. According to another study (Bralts
), the GR, NE, and RB emitters were classied as
having a good performance, while the ED and CO have a
moderate performance. The X
i
value characterized the
ow regime and operating pressure and this varies from 0
to 1. When X
i
is less than 0.5 for tested emitters, less dis-
charge will be affected by pressure variation and the
emitters are characterized as compensated emitters. When
X
i
is greater than 0.5, the discharge is affected by pressure
Figure 4 |The emission uniformity (EU) for ve emitter types under FW and TWW.
247 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
variation and the emitters are characterized as uncompen-
sated emitters. Where X
i
¼0 is for fully compensated
emitters. The X
i
values for ED and RB emitters are less sen-
sitive to pressure variation since their X
i
values are closer to
zero while the sensitivity to pressure variation for GR, CO,
and NE emitters increased from zero, respectively.
Average discharge
The average discharge over time for the ve emitters types
with both the FW and TWW are presented in Figure 2.
The main effect of water quality on the emitter discharge
was not signicant (P¼0.05). The main effect of interaction
for the water quality, time of operation, and emitter type on
average discharge was signicant at the level of 0.05 prob-
abilities. Generally, the average discharge varies with
emitter discharge, water quality, and operational times
(Lui and Huang ).
For FW and TWW, the trend line between the average
discharge and times of operation (hours) for GR emitters
decreases with an operational time of 144 hours. For the
FW and TWW, the average discharge of GR emitters
varied from 4.06 to 2.97 L/h and from 4.80 to 2.90 L/h,
respectively. The average discharge of GR emitters at FW
and TWW water type was higher than the manufacturing
discharge (4 L/h) from the beginning of operational time
until 64 to 80 hours. Then, it started to drop down below
4 L/h until it reached around 2.90 L/h at the end of the
operational time of 144 hours.
For the NE and ED emitter types, the average discharge
was below the manufacturing discharge (4 L/h). The aver-
age discharge of NE emitters varied from 3.73 to 2.66 L/h
and 3.67 to 2.81 L/h for FW and TWW, respectively. The
average discharge of ED emitters varied from 3.80 to
2.88 L/h and from 3.85 to 2.79 L/h for FW and TWW,
respectively. The maximum average discharge of CO emit-
ters was 4.31 L/h and the minimum was 3.31 L/h for the
FW. For the TWW, the maximum average discharge of CO
emitters was 4.25 L/h and the minimum was 2.94 L/h. The
values of average discharge for the CO emitter type were
below the manufacturing discharge (4 L/h) up to 96 hours
of operational times, then increased to reach about 4.25 L/h
at the end of the operation time for both the FW and
TWW. For CO emitters, the average discharge for four out
of nine times tests (with operational time of 16 hours) for
FW was higher than the corresponding time tests for TWW.
The average discharge of RB emitters varied from 4.55
to 3.47 L/h and from 4.41 to 3.59 L/h for FW and TWW,
respectively. The overall mean discharge of the RB emitters
was around 4 L/h. It was found that average discharge at RB
was closer to the manufacturing discharge, followed by the
CO under both FW and TWW. The general trend line of
emitter discharge for both water qualities (FW and TWW)
decreased with increasing the operational time. For NE
emitters for TWW, the trend line shows an increase as the
operational time increased, but for FW, the trend line
decreases as the operational time increases. For ED, CO,
and RB emitters under both water qualities, the trend line
increased slightly as the operational time increased. The
CO and RB emitter types did not show any sign of clogging
while the GR, NE, and ED emitter types showed signs of
clogging. It was noticed that the NE and ED emitter types
needed continuous cleaning for both FW and TWW
during operation. It was evident with increasing operational
time that the average emitter discharge decreases and the
number of clogged emitters increases.
Coefcient of variation
Figure 3 shows the CV of the emitter discharges for the differ-
ent emitter types. The CV values of emitters under FW varied
from 9 to 37% (GR), 6 to 40% (NE), 8 to 31% (ED), 5 to 26%
(CO), and 10 to 24% (RB). The CV values for the GR, NE, and
ED were high and for the CO and RB were low. For the TWW,
the CVs varied from 10 to 37% (GR), 17 to 43% (NE), 9 to
38% (ED), 3 to 35% (CO), and 5 to 24% (RB).
Table 6 |Classication of test results for the different emitter types under FW and TWW
according to the EU classication (Keller & Bliesner 1990)
Low: EU <60%
Moderate:
EU ¼6075% High: EU >75%
Emitter type FW TWW FW TWW FW TWW
GR 12 43 44
NE 00 56 33
ED 21 40 38
CO 00 21 77
RB 00 11 88
248 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
In general, the CV values for each emitter of CO and RB for
FW treatments were close to those values for TWW during an
interval of 16 hour tests. The numbers of the time tests for CV
values for TWW were lower than those for FW with an excep-
tional situation for the ED emitter. The CV values were
classied as 010%, 1129%, and greater than 30% to have
good, moderate, and poor performance of emitters, respectively
(Bralts ). According to this classication of CVs, the values
of CVs for the emitter types GR, NE, and ED were classied as
having a poor performance while the values of CVs for CO and
Figure 5 |The coefcient uniformity (CU) for ve emitter types under FW and TWW.
249 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
RB emitters fall in the category of well or moderate class.
Another classication (ASAE EP..) for CV values for
a line source considered that <10% is good, 1020% is moder-
ate, and >20% is poor. Most of the tests for the CV values for
GR, NE, and ED fall in the category of moderate or poor
class. While CO and RB emitters were classied as good or
moderate performance. Results of CV values for this study
were compared to other classications (Bralts ;ASAE
EP..)(Tables 4 and 5). By comparing the CV values
for each type of emitter, the number of tests for FW and
TWW are closer to each other. The majority of the tests fall
into the medium classication.
EU coefcient
The estimated EUs for the ve emitter types under FW and
TWW are shown in Figure 4. EU of emitters for FW varied
from 90 to 55%, 9258%, 9058%, 9573%, and 8865%
for GR, NE, ED, CO, and RB, respectively. For, TWW,
EU values varied from 88 to 62%, 8062%, 9562%, 97
70%, 9668%, for GR, NE, ED, CO, and RB, respectively.
EU less than 60% is considered relatively low and a value
that exceeds 75% value is recommended (Keller & Blies-
ner ). Another study (ASAE EP..)indicated
that EU between 80 and 90% for a line source is
recommended.
It was found that the EU for the GR, NE, and ED varied
from low to moderate while the EU values for CO and RB
varied from moderate to high. These results indicate that
the last two emitter types are more recommended for use
with TWW. Most of the tests for the EU values for GR,
NE, and ED fall in the category of moderate and high
(Table 6), whereas most of the tests for CO and RB fall in
the category of high performance. This study found that
the EU performances for CO and RB emitters were high,
and are recommended more than GR, NE, and ED emitters.
The number of time tests for EU values under TWW was
higher than those under FW for GR, ED, CO, and RB emit-
ters with an exceptional case for the NE.
Coefcient uniformity
The estimated CU values for the ve emitter types for FW
and TWW are shown in Figure 5. For FW, CU values of
emitters varied from 94 to 68%, 9667%, 9577%,
9685%, and 9381% for GR, NE, ED, CO, and RB, respect-
ively. They varied under TWW from 92 to 73%, 8763%, 95
72%, 9570%, and 9580% for GR, NE, ED, COR, and RB,
respectively. If the CU is less than 75%, the CU is considered
relatively low while a value greater than 84% is rec-
ommended (Keller & Bliesner ). This study found that
the CU values for the GR, NE, and ED varied from a mod-
erate-to-high performance uniformity (Table 7). These CU
values for emitters (GR, NE, and ED) are acceptable since
the numbers of time tests out of nine time tests were greater
than 75%. The CU values for CO varied from moderate to
high and the CU values for RB mostly fall in the category
of a high uniformity of performance. These results indicated
that the CO and RB emitter types are more recommended
than other emitters. The numbers of time tests for CU
values for TWW were higher than those at FW for ED and
RB emitters with the exception of the GR NE, and CO
emitters.
CONCLUSIONS
The results showed that the effect of water type on the
emitter discharge of each emitter type was not signicant.
The operational time and emitter type have a signicant
effect on the emitter discharge. The values of pH for
FW and TWW were greater than 8; they have severed
clogging potential on emitter discharge. The values of
TSS, Fe, and Mn for FW have a little clogging potential.
The values of TSS, TDS, and Fe for TWW have a
medium clogging potential on emitter performance.
Table 7 |Classication of test results for the different emitter types under FW and TWW
according to the EU classication (Keller & Bliesner 1990)
Low: CU <75%
Moderate:
CU ¼7584% High: CU >84%
Emitter type FW TWW FW TWW FW TWW
GR 11 23 65
NE 22 45 32
ED 02 52 35
CO 01 52 35
RB 00 22 77
250 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
Average discharge for each emitter type has not always
declined from the beginning to the end of the operational
time. The NE and ED emitters registered an average dis-
charge below the manufacturing discharge while the
average discharges of CO and RB emitters were closer
to the manufacturing discharge. Most of the CV values
for the average discharge of emitters for GR, NE, and
ED emitters were higher than the values for CO and
RB emitters; whereas most of the values of EU and CU
for GR, NE, and ED emitters were lower than those for
CO and RB emitters. Flushing the drip irrigation system
is recommended during operational time to reduce the
clogging of emitters. Overall, the classication of the
GR, NE, and ED emitters can be described as having a
moderate-to-low performance, respectively, and for the
CO and RB emitters as having a moderate-to-high
performance.
ACKNOWLEDGEMENTS
Special thanks to Jordan University of Science and
Technology and the National Center for Agricultural
Research and Extension for their support for this research.
The authors have declared no conict of interest.
REFERENCES
ASAE EP405.1.  Design and Installation of Microirrigation
Systems: Standards. Society for Engineering in Agricultural,
Food, and Biological Systems, St Joseph, MI, USA.
Bouya, A. O., Yamamoto, T., Fujiyama, H. & Miyamoto, K. 
Assessment of emitter discharge in microirrigation system as
affected by polluted water.Irrig. Drain. Syst. 21,97107.
Bralts, F. V.  Field performance and evaluation. In: Trickle
Irrigation for Crop Production: Design, Operation and
Management (F. S. Nakayama & D. A. Bucks, eds). Elsevier,
Amsterdam, The Netherlands, pp. 216240.
Buck, D. A., Nakayama, F. S. & Gilbert, R. G.  Trickle
irrigation water quality and preventative maintenance.Agri.
Water Manage. 2, 149162.
Capra, A. & Scicolone, B.  Emitter and lter tests for
wastewater reuse by drip irrigation.Agri. Water Manage. 68,
135149.
Capra, A. & Scicolone, B.  Recycling of poor quality urban
wastewater by drip irrigation systems.J. Clean. Product. 15
(16), 15291534.
Dehghanisanij, H., Yamamoto, T., Rasiah, V., Utsunomiya, J. &
Inoue, M.  Impact of biological clogging agents on lter
and emitter discharge characteristics of microirrigation
system.Irrig. Drain. 53, 363373.
Eroglu, S., Sahin, U., Tunc, T. & Sahin, F.  Bacterial application
increased the ow rate of CaCO
3
-clogged emitters of drip
irrigation system.J. Environ. Manage. 98,3742.
Keller, J. & Bliesner, R. D.  Sprinkle and Trickle Irrigation.
John Wiley and Sons, Inc., New York, USA.
Li,Y.K.,Lui,Y.Z.,Li,G.B.,Xu,T.W.,Lui,H.S.,Ren,S.M.,Yan,
D. Z. & Yang, P. L.  Surface topographic characteristics
of suspended particulates in reclaimed wastewater and effects on
logging in labyrinth drip irrigation emitters.Irrig. Sci. 30,4356.
Lui, H. J. & Huang, G. H.  Laboratory experiment on drip
emitter clogging with fresh water and treated sewage efuent.
Agri. Water Manage. 96, 745756.
Mansour, H. A. G., Tayel, M. Y., Abd El-Hady, M. A., Lightfoot, D.
A. & El-Gindy, A. M.  Modication of water application
uniformity among closed circuit trickle irrigation systems.
J. Earth Environ. Sci. 1(1), 19.
Nakayama, F. S. & Bucks, D. A.  Water quality in drip/trickle
irrigation: a review.Irrig. Sci. 12, 187192.
Ozekici, B. & Sneed, R. E.  Manufacturing variation various
trickle irrigation on line emitters.Appl. Eng. Agri. 11,235240.
Ravina, I., Pas, E., Sofer, Z., Marcu, A., Schischa, A., Sagi, G.,
Yechialy, Z. & Lev, Y.  Control of clogging in drip
irrigation with stored treated municipal sewage efuent.Agri.
Water Manage. 33, 127137.
Sahin, U., Anapali, O., Donmez, M. F. & Sahin, F.  Biological
treatment of clogged emitters in a drip irrigation system.J.
Environ. Manage. 76, 338341.
SAS Institute  The SAS System for Windows 8.2. SAS Institute,
Cary, NC, USA.
First received 23 October 2013; accepted in revised form 16 February 2015. Available online 7 April 2015
251 N. K. Al-Meeh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015
... The mean values for each chemical and biological water quality parameter for TWW are presented in Table 2. The clogging risk was evaluated according to the classification proposed by the water quality criteria for emitter clogging [12,20,21]. The water quality parameters of pH (8.2), TDS, Mn, and Fe were used as a guide to determine the potential of emitter clogging. ...
... The pH values show a severe potential to cause emitter clogging for any water type. This is consistent with the findings of Al-Mefleh et al., and Al-Mefleh and Al-Raja [21,22]. However, the hardness characteristic (Ca and Mg) is another factor that might cause the precipitation of carbonate, leading to an increase in the potential of emitter clogging. ...
... According to the classification proposed by the water quality criteria for emitter clogging [20], these values had a moderate potential for emitter clogging, as shown through the results of Capra and Scicolone, and Al-Mefleh and Al-Raja [12,23]. However, Al-Mefleh et al. indicated that the salt concentration in the TWW does not cause emitter clogging because the EC values of the TWW are low [21]. The mean values of Mn (0.50 mg/L), Ca (98.6 mg/L), and Fe (0.11 mg/L) have a low amount of emitter clogging potential. ...
Article
Full-text available
This study aims to investigate the influence of treated wastewater (TWW) on the hydraulic performance of drip irrigation emitters. A field experiment was conducted in order to test two types of online emitters, a low pressure (LP) and a standard pressure (SP), at different working pressures (0.25 bar, 0.50 bar, and 1.00 bar) using TWW. The emitters were initially evaluated in the laboratory and the field for the discharge exponent (X), discharge coefficient (Kd), average emitter discharge (Qavg), coefficient of variation (CV), distribution uniformity (DU), the mean discharge ratio (Dra), and the main degree of clogging (DC). The main effect of the emitters on the hydraulic parameters of irrigation performance was not significant, while the operational pressure and operational time of irrigation had a significant effect. For the LP emitter, the average emitter discharge was 7.6, 7.7, and 7.8 Lh−1 at 0.25, 0.50, and 1.00 bar, respectively. For the SP emitter, the average emitter discharge was 7.6, 7.8, and 7.8 Lh−1 at 0.25, 0.50, and 1.00 bar, respectively. The EU values for the LP and SP emitters varied from low to moderate at 0.25 bar, as the EU values at 0.50 and 1.00 bar were considered high for both emitter types.
... A range of water quality parameters can be analysed to determine the potential for emitter clogging. Some studies (Capra and Scicolone, 2004;Liu and Huang, 2009;Li et al., 2009;Al-Mefleh et al., 2015) have investigated the following water quality parameters: pH, total iron, hydrogen sulfide, suspended solids, dissolved solids, manganese, calcium, magnesium, and the number of bacteria. The potential for clogging varies depending on the emitter's dimension, the position of the lateral lines, and flow type, which can be either laminar or turbulent (de Kreij et al., 2003). ...
... It has also been reported that emitter performance depends on the emitter type, the duration of system operation, and the quality of water used for irrigation (Liu and Huang, 2009). A recent study found that while the water type (FW or TWW) had no significant effect on emitter discharge, operational time and emitter type had a significant effect on emitter discharge (Al-Mefleh et al., 2015). ...
... Nevertheless, in spite of such precautions, roots and clay particles can still clog drip emitters in systems that are buried below the soil surface (Wang et al., 2005). Some field studies (Ebrahimi et al., 2012;Al-Mefleh et al., 2015) have been conducted to determine the impact of water quality on SDI emitter performance. Others (Al-Mefleh and Abu-Zreig, 2013;Qiaosheng et al., 2007) have examined the wetting pattern produced by SD and SDI. ...
Article
Full-text available
A field experiment was conducted to study the effect of water quality types of fresh water (FW) and treated wastewater (TWW) and envelope materials of coarse sand (CS), fine sand (FS), and control (CO) on emitter performance, dry matter yield (DMY), and water use efficiency (WUE) under subsurface drip irrigation.The main interaction effect of water quality type and envelope material on coefficient of variation, Christiansen uniformity coefficient, and emission uniformity was not significant (P < 0.05), but they have a significant effect on the average emitter discharge (Qavg), DMY, and WUE. The means of Qavg for FW with CS, FS, and CO were 7.13, 6.94, 2.65 L/h, and for TWW, they were 6.78, 6.84, and 2.35 L/h, respectively. The DMY under FW with CS, FS, and CO was 3083.87, 1367.95, and 417.45 kg/ha, and under the TWW, it was 2409.5, 1347.4, and 417 kg/ha, respectively.
... These scenarios are: 1) substantially reduce water consumption without lowering crop production; 2) using the same water volume with a significantly increased production; or 3) simultaneously reduce water volume and increase production (Lamm and Camp, 2007;Thompson et al., 2009). Additionally, subsurface drip irrigation may generate greater physical and nutritional quality of the harvest products and several more advantages such as facilitating the cultural works of the crop and allow the use of treated or contaminated water with biological agents (Song et al., 2006;Al-Mefleh et al., 2015). ...
... This behavior was due to a problem of dripper clogging and not to a design or installation problem of the irrigation system. The dripper clogging was caused by the manufacturing characteristics of the emitters (Al-Mefleh et al., 2015) because this problem was not observed in the manufactured tape for surface irrigation that was subject to the same soil and handling conditions (Figure 3). In the two studied types of tape, a greater degree of plugging of the drippers was observed in the subsurface irrigation, a behavior inverse to that observed by Hills et al. (1989), becoming larger as the installation of the tapes deepened. ...
Article
Due to the high acquisition costs of drip tape for subsurface irrigation (SDI), in some places of Mexico drip tape made for surface irrigation (DI) is been used for subsurface irrigation, instead of SDI drip tape. However, effects in production, emitter discharge uniformity and its clogging vulnerability is unknown. The objective of this study was to compare the effect on tomato fruit yield and irrigation quality from SDI and DI drip tapes, both with same diameter and emitter flow, installed superficially and at the subsurface at different depths: 10, 15 and 25 cm. The experiment was realized in a greenhouse and the texture of the soil used for the planting was sandy loam, in plastic containers. In the eight installed drip treatments nutrient solution and irrigation conditions were the same. An ANOVA showed that the main effects of tape type and the installation depths on yield were not statistically significant (α=0.05). A higher yield was observed with DI drip tape and this increased as the depth of the tape increased, unlike the SDI drip tape that showed a contrary tendency. A higher emitters discharge uniformity and a lower clogging degree in the DI drip tape was obtained. Results suggest that, for at least a crop cycle, and under similar conditions to this experiment, it is possible to use DI tape, without affecting the crop production and with a lower acquisition cost.
... Clogged emitter replacement, cleaning, and detection are difficult tasks. According to Al-Mefleh et al. (2015), precipitates, particles in the water supply, or bacterial slime from dissolved calcium or other salts in the water supply can all clog emitters. The reasons behind clogging vary depending on the place (Nakayama and Bucks, 1991). ...
Article
Full-text available
Clogging is a serious problem in drip irrigation, especially when using saline groundwater; this may cause uneven water distribution. However, efficient and environmentally friendly methods are rarely available for mitigating clogging. In the present study, an innovative and environmentally friendly technology using ultrasonic waves within radio frequency without the use of chemicals to treat emitter clogging, is evaluated. The objectives of this study were to evaluate the chronological changes in the emitter flow rate and the effect of ultrasonic (US) water treatments on solving the problem of emitter clogging in the field. The performance of the drip irrigation system is tested by measuring emitter discharge and estimating the average emitter discharge (qav), the manufacturer coefficient of variation (CVm), the distribution uniformity of the lowest quarter (DUlq), the application efficiency (AE) and the Christiansen uniformity coefficient (CUC). The results showed that the qav for the emitters improved from 3.37 l/h before treatment to 4.1 l/h after 180 h of US irrigation water treatment. The DUlq and the AE of the drip irrigation system were respectively 76.7% and 69.1% before treatment, due to the presence of salts in the groundwater, which caused emitter clogging. After 180 hours of US water treatment, DUlq and AE improved to respectively 90.3% and 81.3%. This improvement led to saving about 15% of the daily irrigation water. This study showed that ultrasonic water treatment is highly effective as chemical-free treatment method with great potential for preventing emitters clogging in drip irrigation systems, and could be further promoted in drip irrigation with saline groundwater.
... The maximum values of flow rate are increments in the outlet flow of the drippers caused by variations in the manufacturing process or by the influence of water quality inside the pipes, as observed by Busato & Soares (2010), who reported increment of 1% in the flow rate of the dripper subjected to irrigation with lower-quality water, in 700 h of use. Naji et al. (2015) observed that the operational time and type of dripper have significant effect on the relative flow rate. The degree of clogging represents the variation in the flow rate of the emitters in relation to the proposed value, which in this case is the flow rate of the brand-new drippers. ...
Article
Full-text available
The use of alternative water sources for irrigation such as wastewaters, promotes innumerous benefits, but investigations must be conducted to minimize the negative effects of this technique. Clogging drippers are of the limitations. This study aimed to monitor the clogging of three models of labyrinth-type drippers subjected to irrigation with wastewater from treated domestic sewage, through statistical quality control using Shewhart charts. The drippers tested were as following: Dripper Streamline 16080 model (Netafim®); Taldrip model (Naadanjain®); and Dripper Tiran 16010 model (Netafim®). The system was installed with five lateral lines per model of dripper on a bench at the field in the Brazilian semi-arid region. The system was evaluated every 36 h of operation at eight collection points in each lateral line, totaling thirty-three evaluations at the end of the experiment, which corresponded to a total of 1188 h of operation. Dripper clogging was identified by the statistical control charts with 432, 540 and 360 h for the drippers Streamline 16080 model, Taldrip model and Tiran 16010 model, respectively, indicating the moment to apply a cleaning process. The monitoring through statistical quality control allowed simultaneously identifying the variability of the process and the reduction in flow rates, identifying the moment of clogging of the system and to carry out actions of unclog.
Article
Full-text available
Water application efficiency of microirrigation systems (MIS) may depend, at least partially, on algae and protozoa (biological clogging agents, BCAs) induced filter and emitter clogging. In this study we assessed the impact of BCA-induced changes on water discharge rate and distribution uniformity from (i) emitters with different water flow cross-section (CS) area, pressure compensation (PC) systems, and inbuilt filtration areas (FAs), and (ii) filters either made of urethane, sand, or disk in the Tohaku irrigation project in Japan. In a field experiment, four types of on-line emitters on each of four laterals and four types of in-line emitters on each of another four laterals were assessed for BCA-induced emitter discharge performance without using filters in the field irrigation line. The emitters' discharge rate increased with increasing CS, FA, and working pressure (WP) and decreased when the emitters were on-line in the laterals and with increasing BCA counts. Because BCAs are the only dynamic variable in the above relationship, we conclude that BCA-induced clogging is a major issue when filters were not installed in field irrigation lines. The filter performance assessment based on the number of backwashings required to restore the working pressure to the recommended level indicated that BCA filtering by the sand filter was highest, followed by disk and urethane, respectively.
Article
Full-text available
Drip irrigation is the most effective and reliable method for reclaimed wastewater irrigation. Emitter clogging is the major problem for extending the drip irrigation technology. The existence of suspended particulates in irrigation water is the main reason for the emitter clogging. However, the reclaimed wastewater quality is extremely complex, and there is a series of physical, chemical, and biological reactions between suspended particulates and other materials contained such as microorganisms, which make the characteristics of suspended particulates in reclaimed wastewater complicated. In this paper, two types of widely used wastewaters treated with fluidized-bed reactor (FBR) and biological aerated filter (BAF) processes respectively were selected. The scanning electron microscope (SEM) technology and fractal theory were used to quantitatively describe the characteristics of the surface topography of suspended particulates. The results showed that the suspended particulates in two reclaimed wastewater were flocculent and porous. The pore system mainly consisted of solid suspended particulates, and most areas between the particulates were filled with microbes and extracellular polymers (EPS). The complex structure of biofilms was formed. That the biofilms grew and detached in irrigation system and deposited continuously at the inlet and outlet of labyrinth path was the major reason for the emitter clogging. The surface topography of suspended particulates in both reclaimed wastewaters showed fractal and multifractal characteristics, and the fractal dimension could not characterize the local and microsingularity of particulates but multifractal dimension could. The uniformity of the distribution of sediment pores increased with the size. Comparatively, the uniformity of suspended particulates in reclaimed wastewater treated by FBR was lower. With operation of reclaimed wastewater irrigation system, the average discharge of emitters decreased continuously with obvious fluctuations. The clogging degree of emitters was low during the first 256h, and the clogging degree of the two types of reclaimed water was similar. But then, the degree of clogging increased greatly, and the FBR treatment on the emitters discharge were more obvious than BAF. It was closely related to the growth, detachments and sediment of biofilms in the irrigation system. Hence, using the reclaimed wastewater treated by BAF for drip irrigation is more suitable.
Article
Full-text available
Drip irrigation, combined with wastewater reuse, may offer the most effective and efficient way to cope with water shortage for crops and protect the environment receiving wastewater. Emitter and filter clogging are the main problems in the operation of drip systems in developing countries and small communities where treated wastewater is of poor quality. The main results of experimental trials on the behaviour of several kinds of filter and drip emitters using poor quality municipal wastewater are: the performance of the emitters and filters depends on the quality of the wastewater; Total Suspended Solids (TSS) influence the percentage of totally clogged emitters, the mean discharge emitted, the emission uniformity, and the operating time of the filter between cleaning operations; vortex emitters were more sensitive to clogging than labyrinth emitters; no significant difference was observed between the same kind of emitter placed on soil or sub-soil; gravel media and disk filters assured better performance than screen filters. The use of wastewater with a TSS greater than 50 mg l−1, did not permit optimal emission uniformity to be achieved.
Article
The efficiency of trickle irrigation systems depends directly on the uniformity with which water is discharged from the emission devices throughout the system. Ideally, all emitters in the system should discharge equal amounts of water. One major cause of flow rate difference between two identical emitters from the same manufacturer is the manufacturing variation. This study compared manufacturers' rated discharges and coefficient of manufacturing variation values with tested values for various on-line emitters. Discharge rates from different types of trickle irrigation emitters were collected at five different pressure levels. Pressure compensating emitters were tested at 100, 150, 200, 250, and 300 kPa (15, 21.8, 29.0, 36.3, and 43.5 psi). Nonpressure compensating emitters were tested at 75, 100, 125, 150, and 175 kPa (10.9, 15, 18.1, 21.8, and 25.4 psi). Emitter discharge rates and coefficient of manufacturing variation were compared with manufacturers' specifications. At the suggested operating pressure of 100 kPa (15 psi) only 11 of the 17 emitters had flow rates within 10% to those claimed by the manufacturers. This was particularly true for the noncompensating emitters. Measured values of coefficient of manufacturing variation were higher than those specified by the manufacturers. High coefficients of manufacturing variation could result in low emission uniformities. Designs based on supplied data may deliver too little water to some plants and too much water to others. Designs should be based on reliable test data, not on manufacturer's supplied data.
Article
ximum application uniformity of closed circuit trickle irrigation systems designs. Laboratory tests carried out for Two types of closed circuits: a) One manifold for lateral lines or Closed cir-cuits with One Manifold of Trikle Irrigation Sys-tem (COMTIS); b) Closed circuits with Two Manifolds of Trikle Irrigation System (CTMTIS), and c) Traditional Trikle Irrigation System (TTIS) as a control. Three lengths of lateral lines were used, 40, 60, and 80 meters. PE tubes lateral lines: 16 mm diameter; 30 cm emitters distance, and GR built-in emitters 4 lph when operating pressure 1 bar. Experiments were conducted at the Agric. Eng. Res. Inst., ARC, MALR, Egypt. With COMTIS the emitter flow rate was 4.07, 3.51, and 3.59 lph compared to 4.18, 3.72, and 3.71 lph with CTMTIS and 3.21, 2.6, and 2.16 lph with TTIS (lateral lengths 40, 60, and 80 meters respec-tively). Uniformity varied widely within individual lateral lengths and between circuit types. Under CTMTIS uniformity values were 97.74, 95.14, and 92.03 %; with COMTIS they were 95.73, 89.45, and 83.25 %; and with TTIS they were 88.27, 84.73, and 80.53 % (for lateral lengths 40, 60, 80 meters respectively). The greatest uniformity was observed under CTMTIS and COMTIS when using the shortest lateral length 40 meters, then lateral length 60 meters, while the lowest value was observed when using lateral length 80 me-ters this result depends on the physical and hy-draulic characteristics of the emitter and lateral line. CTMTIS was more uniform than either COMTIS or TTIS. Friction losses were decreased with CTMTIS in the emitter laterals at lengths 40 meters compared to TTIS and COMTIS. There-fore, differences may be related to increased friction losses when using TDIS and COMDIS.
Article
The intensive treatment of irrigation water required for the proper operation of drip irrigation systems is presently an accepted practice. To control emitter clogging, we need to know the basic causes of clogging. The major clogging factors have been identified and control measures developed to prevent emitter malfunction. All emitter clogging problems, however, have not been solved primarily because of cost. The main approach to control clogging is proper water treatment. The type of treatment is based on the quality of the irrigation water, which can be classified in terms of its physical, chemical and biological composition. The causes of emitter clogging and possible water treatment and preventive measures to maintain reliable operation are reviewed.
Article
A drip irrigation system has the advantage of maintaining high water content near the plant root. However, its performance depends on water quality as it may induce the emitter clogging. In the Tohaku National Irrigation Project, in western Japan, mist spray emitters are widely used for irrigation in the field and greenhouses for vegetable and orchard crops. Seven emitters of different types were evaluated for the variation in their discharge rate without filter. The statistical analysis of mean discharge ratio and the coefficient of variation of the performance of emitters along a lateral line in the field indicated that the mist spray emitters had the best performance for irrigation in Tohaku area, particularly the new emitters or 1-year old emitters. The results suggest that after using the emitter line for two irrigation seasons it should either be replaced in the third season or washed carefully if further used.
Article
Emitter clogging is a major problem incurred in the operation of drip irrigation systems, especially when these systems utilize treated wastewater effluent stored in surface reservoirs. In an attempt to seek solutions to the problems arising from the presence of suspended particles, algae, zooplankton and other organisms in the reservoirs, as well as to prevent clogging in the supply lines and in downstream sections of the drip laterals, a series of filter and drip emitter clogging trials was set up. The trials were conducted with two water supplies. The first (1987–1990) was water from the Kfar Barukh reservoir, which stores storm run-off, treated sewage effluent and National Carrier water. The second (1991–1992) was water from the Burgata reservoir, which stores only secondary effluents. This paper reports on the performance of manual and automatic screens, discs and media filters and of different types of emitters, as well as on the effect of chemical treatments designed to control clogging.