IMPACT OF FLUSHING AND FILTRATION SYSTEM ON PERFORMANCE OF MICRO IRRIGATION SYSTEMS - Management, Performance, and Applications of Micro Irrigation Systems - page 79

different for removal of CO 3 , Ca, and total solids from WW. The small fi ltration ef-
fi ciencies by fi lters were in agreement with other published works [2, 28]. Capra and
Scicolone [9] observed similar performance by disk and media fi lters. In sand fi lters,
the smaller effective size of sand particles has effect on the sand fi ltration effi ciency
[15]. The combined fi ltration system always gave better results than individual fi lters,
for example, F1 and F2.

6.3.2 EVALUATION OF EMITTER FLOW RATE
Emitter flow rate variations were evaluated with Analysis of Variance (ANOVA) by
maintaining no variation in pressure so that the flow rate variation will only be af-
fected by the clogging of emitters. ANOVA for variations in average flow rate under
different filtration systems for beginning, end of season and after flushing are pre-
sented in Table 2.

TABLE 2 Significance level ( P -value) of the statistical model and of each factor and interaction
for emitter flow rate.

Parameter Time

Beginning End of season After flushing

Model *** (R 2 =0.95) ***(R 2 =0.91) ** (R 2 =0.84)

Filter (F) n.s. *** **

Emitter placement (EP) n.s. * n.s.

F × EP n.s. *** **

n.s.: not significant, P> 0.05; *: P <0.05; **: P <0.01;
***: P <0.001.

Maximum reduction in fl ow rate (7%) was observed with fi lter F1 under subsur-
face drip (30 cm depth) while the minimum (4.8%) with combination fi lter. Reduc-
tion in fl ow rate with F2 was 5.34%, which is between the values of F1 and F3 as
mentioned above. Effect of fi ltration system as well as emitter placements are factors
responsible for emitter fl ow rate and subsequently emitter clogging. The results from
statistical analysis revealed that, after the end of crop season, there was signifi cant
effect of fi lter, emitter placement and their interaction. At the beginning of the experi-
ment there was no signifi cant effect of emitter placement and their interaction with fi l-
ter. It is obvious because emitters were new at the beginning and had negligible chance
of clogging. After continuous use of the system, clogging takes place and effect of dif-
ferent fi ltration systems starts affecting the fl ow rate. After fl ushing, fi ltration systems
were signifi cantly different but emitter placement was nonsignifi cant. But interaction
of fi ltration system with emitter placement was signifi cant ( P <0.01). Good fi ltration
system can control these anomalous results. This indicated clogging to be a dynamic
phenomenon and to change with time [26].