IMPACT OF FLUSHING AND FILTRATION SYSTEM ON PERFORMANCE OF MICRO IRRIGATION SYSTEMS - Management, Performance, and Applications of Micro Irrigation Systems - page 81

TABLE 3 (Continued)

Filter Depth of

placement of
lateral

UC (%)

Beginning End of

season

After flushing

Disk (F2) Surface 98.89 96.12 96.64

15 cm 98.91 95.00 96.27

Combination of F1
and F2

Surface 99.01 96.60 97.49

15 cm 99.05 95.20 96.34

At the end of season, surface and subsurface drip with combination fi lters shows
highest UC 96.67% and 95.70%, respectively. It indicates that WW with combination
fi lters can give better fi ltration in comparison with single fi lters. Signifi cant improve-
ment in UC was observed after fl ushing of the system. Higher improvement in UC
was observed in subsurface drip in comparison to surface drip after fl ushing (Table
3). Higher improvements in the SDI emitters may be explained by exit of ingested
external soil particles, which may stuck in the biofi lm at the emitter outlet leading to
increased clogging. Installation of air/vacuum relief valves at the high elevation points
can help prevent soil ingestion in SDI [17]. Effl uent chlorination has been found to be
effective in reducing clogging caused by biofi lm growth [27, 29]. Chemical treatments
such as acidifi cation can be also used for increasing chlorination effectiveness [22].

6.4 CONCLUSIONS
Drip emitters experienced continuous use of wastewater from different filtration sys-
tem and revealed that filtration with a combination of gravel and disk filter was most
appropriate strategy against emitter clogging. It resulted in a better emission unifor-
mity and reasonable lower reduction in discharge. Filters can be used for significant
removal of for turbidity, total solids, carbonate and bicarbonate available in wastewa-
ter. Filter, emitter placement and their interaction have significant effect on emitter
clogging. Flushing is helpful in partial removal of emitter clogging. It gives significant
improvement in discharge and uniformity coefficient. This revealed that the flushing
at 2 kg.cm -2 pressure is adequate when it was performed at the end of the irrigation
season. Pressure compensating emitters may be good choice over the nonpressure one
when applying wastewater. It is also recommend that an air/vacuum relief valve may
be used for subsurface drip irrigation to avoid ingestion of soil particles due to forma-
tion of soil solution.

6.5 SUMMARY
Filtration plays a vital role to improve the efficacy and reduce the maintenance of
micro irrigation systems. The experiment was conducted to evaluate the convention-
al micro irrigation filters (gravel media filter, disk filter and their combination) for
wastewater filtration. Physical, chemical and biological parameters of wastewater re-
sponsible for emitter plugging, such as total solids, turbidity, Ca, Mg, CO 3 and HCO 3