Field evaluation of the performance of different irrigation emitter types using treated wastewater

Abstract

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.

Full text

Field evaluation of the performance of different irrigation
emitter types using treated wastewater
Naji K. Al-Mefleh, 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 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 (Q
avg
), 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.
Naji K. Al-Mefleh (corresponding author)
Department of Natural Resources, Faculty of
Agriculture,
University of Science and Technology,
P.O. Box 3030 Irbid,
Jordan
E-mail: nmefleh@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 coefficient
CV coefficient of variation
ED Edin emitter
EU emission uniformity coefficient
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
efficient 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 effi-
ciency. The field 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
efficiency, which leads to a reduction in water use effi-
ciency and crop production. Clogging of emitters is the
most difficult 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 flow 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 filter for drip irrigation system is more
suitable than wastewater treated with fluidized-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
coefficient, and the operating time of the filters 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 coefficient of variation (CV) and percentage of
clogging for the TWW were greater than those values for
fresh water. Also, the values of EU and coefficient 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 field 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-Mefleh 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 filter then the
disk filter. The TWW was passed through the sand filter
followed by screen and disk filters. The sand filter 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 filter consisted of a diameter of 1.6 mm and the
disk filter had 250 mesh/in
2
. The cleaning was based on
the losses of pressure between the inlet and outlet for
each filter.
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 specifications of these emitters are
summarized in Table 2.
Experimental layout
The experiment layout consisted of three replicates
(blocks). In each block, the five 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-Mefleh 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, filters, pressure gauges, a
flow meter, lateral pipes (20 mm diameter) as shown in the
schematic diagram of the experiment in Figure 1.
Estimating initial emitter’s characteristics
Using FW only, emitter discharge values were measured in
the field at two operating pressures (100 and 200 kPa) for
new emitters as a first trial under field conditions. Measure-
ments were used to estimate the initial values (
i
)of
coefficient of variation (CV
i
), the discharge exponent (X
i
),
and the discharge coefficient (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 five
emitter types.
For the new emitters, the discharge exponent (X
i
)was
estimated using Equation (1), and the discharge coefficient
(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 emitter’s
performance are the mean discharge of the emitters
(Q
avg
) in each lateral, the CV, the EU coefficient, and
Christiansen uniformity coefficient (CU). Average
Table 2 |Specifications of manufacturing emitters
Emitter type Specifications
GR emitters In-line emitters, pressure compensated
4 L/h, 150 kPa, self-flushing, area
cross-section
Nein emitters (NE) On-line emitter, pressure compensated
4 L/h, 150 kPa, un-self-flushing, area
cross-section
Eden emitters (ED) On-line emitter, pressure compensated
3.8 L/h, 150–400 kPa bar, self-flushing,
area cross-section
Corona emitters (CO) On-line emitter, pressure compensated
4.0 L/h, 150 kPa bar, self-flushing, area
cross-section
Rain Bird emitters (RB) On-line emitter, pressure compensated
3.8 L/h, 150 kPa bar, self-flushing, 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-Mefleh 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 first trial
Emitter
types
Coefficient of variation
(CV
i
%)
Discharge exponent
(X
i
)
Discharge coefficient
(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 five emitter types under FW and TWW.
244 N. K. Al-Mefleh 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 coefficient of variation (CV%) for five emitter types under FW and TWW.
245 N. K. Al-Mefleh 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 ¼1P
n
i¼1
qiQavg

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 flushed 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
Fisher’s least significant 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 classification, 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 classified as
<7.0 (slight), 7–8 (medium), and >8.0 (severe) (Nakayama &
Bucks ). The potential of biological oxygen demands
(BOD
5
) on emitter clogging were classified as <15 ppm
(low), 15–40 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 coefficient (CV
i
), discharge
exponent (X
i
), and discharge coefficient (Kd
i
) for new
emitters were estimated and are presented in Table 3.
Table 4 |Classification of test results for the different emitter types under FW and TWW
according to the CV classification (Bralts 1986)
Well:
CV ¼0–10%
Moderate:
CV ¼11–29% 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 |Classification of test results for the different emitter types under FW and TWW
according to the CV classification (ASAE EP405.1. 2003)
Well: CV <10%
Moderate:
CV ¼10–20% 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-Mefleh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015

The CV values were classified as <5% (excellent) 5–7%
(average) 7–11% (marginal), 11–15% (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 classified as
having a good performance, while the ED and CO have a
moderate performance. The X
i
value characterized the
flow 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 five emitter types under FW and TWW.
247 N. K. Al-Mefleh 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 five 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 significant (P¼0.05). The main effect of interaction
for the water quality, time of operation, and emitter type on
average discharge was significant 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.
Coefficient 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 |Classification of test results for the different emitter types under FW and TWW
according to the EU classification (Keller & Bliesner 1990)
Low: EU <60%
Moderate:
EU ¼60–75% 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-Mefleh 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
classified as 0–10%, 11–29%, and greater than 30% to have
good, moderate, and poor performance of emitters, respectively
(Bralts ). According to this classification of CVs, the values
of CVs for the emitter types GR, NE, and ED were classified as
having a poor performance while the values of CVs for CO and
Figure 5 |The coefficient uniformity (CU) for five emitter types under FW and TWW.
249 N. K. Al-Mefleh 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 classification (ASAE EP..) for CV values for
a line source considered that <10% is good, 10–20% 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 classified as good or
moderate performance. Results of CV values for this study
were compared to other classifications (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 classification.
EU coefficient
The estimated EUs for the five emitter types under FW and
TWW are shown in Figure 4. EU of emitters for FW varied
from 90 to 55%, 92–58%, 90–58%, 95–73%, and 88–65%
for GR, NE, ED, CO, and RB, respectively. For, TWW,
EU values varied from 88 to 62%, 80–62%, 95–62%, 97–
70%, 96–68%, 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.
Coefficient uniformity
The estimated CU values for the five emitter types for FW
and TWW are shown in Figure 5. For FW, CU values of
emitters varied from 94 to 68%, 96–67%, 95–77%,
96–85%, and 93–81% for GR, NE, ED, CO, and RB, respect-
ively. They varied under TWW from 92 to 73%, 87–63%, 95–
72%, 95–70%, and 95–80% 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 significant.
The operational time and emitter type have a significant
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 |Classification of test results for the different emitter types under FW and TWW
according to the EU classification (Keller & Bliesner 1990)
Low: CU <75%
Moderate:
CU ¼75–84% 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-Mefleh 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 classification 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 conflict 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. 21,97–107.
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. 216–240.
Buck, D. A., Nakayama, F. S. & Gilbert, R. G.  Trickle
irrigation water quality and preventative maintenance.Agri.
Water Manage. 2, 149–162.
Capra, A. & Scicolone, B.  Emitter and filter tests for
wastewater reuse by drip irrigation.Agri. Water Manage. 68,
135–149.
Capra, A. & Scicolone, B.  Recycling of poor quality urban
wastewater by drip irrigation systems.J. Clean. Product. 15
(16), 1529–1534.
Dehghanisanij, H., Yamamoto, T., Rasiah, V., Utsunomiya, J. &
Inoue, M.  Impact of biological clogging agents on filter
and emitter discharge characteristics of microirrigation
system.Irrig. Drain. 53, 363–373.
Eroglu, S., Sahin, U., Tunc, T. & Sahin, F.  Bacterial application
increased the flow rate of CaCO
3
-clogged emitters of drip
irrigation system.J. Environ. Manage. 98,37–42.
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. 30,43–56.
Lui, H. J. & Huang, G. H.  Laboratory experiment on drip
emitter clogging with fresh water and treated sewage effluent.
Agri. Water Manage. 96, 745–756.
Mansour, H. A. G., Tayel, M. Y., Abd El-Hady, M. A., Lightfoot, D.
A. & El-Gindy, A. M.  Modification of water application
uniformity among closed circuit trickle irrigation systems.
J. Earth Environ. Sci. 1(1), 1–9.
Nakayama, F. S. & Bucks, D. A.  Water quality in drip/trickle
irrigation: a review.Irrig. Sci. 12, 187–192.
Ozekici, B. & Sneed, R. E.  Manufacturing variation various
trickle irrigation on line emitters.Appl. Eng. Agri. 11,235–240.
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 effluent.Agri.
Water Manage. 33, 127–137.
Sahin, U., Anapali, O., Donmez, M. F. & Sahin, F.  Biological
treatment of clogged emitters in a drip irrigation system.J.
Environ. Manage. 76, 338–341.
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-Mefleh et al. |Performance of emitter using treated wastewater Water Quality Research Journal of Canada |50.3 |2015