IMPACT OF FLUSHING AND FILTRATION SYSTEM ON PERFORMANCE OF MICRO IRRIGATION SYSTEMS - Management, Performance, and Applications of Micro Irrigation Systems - page 75

of media and disk fi lter in combination may be the good strategy to improve fi ltration
effi ciency was not studied for wastewater.
Subsurface drip irrigation (SDI) systems diminish human exposure to effl uents
and vandalism, but have a higher initial investment cost, and need careful and con-
sistent operation, maintenance and management. It must have good and consistent
fi ltration, water treatment, fl ushing and maintenance plans to ensure long economic
life [17]. Filtration systems do not normally remove clay and silt particles, algae and
bacteria because they are too small for typical economical fi ltration. These particles
may travel through the fi lters as individual particles, but then fl occulate or become at-
tached to organic residues and eventually become large enough to clog emitters [22].
To minimize the buildup of sediment and organic residues, regular fl ushing of
micro irrigation systems is recommended. The system should be designed such that
the mainline, laterals and valves are sized to permit a suffi cient fl ushing velocity (0.3
m sec -1 ) recommended by ASABE [5]. Flushing valves should be installed at the end
of mains, submains, and fl ush-lines (if present). The fl ush-lines provisions should be
made for fl ushing individual laterals that connect the downstream ends of the laterals.
A regular maintenance program of inspection and fl ushing will help signifi cantly in
preventing emitter clogging. Therefore, drip-line fl ushing is periodically needed to
remove these particles and organisms that are accumulated within the laterals [26].
The irrigation system should be designed so that it can be fl ushed properly. To be ef-
fective, fl ushing must be done at frequent intervals at appropriate velocity to dislodge
and transport the accumulated sediments [22].
Several researchers have different opinion about fl ushing frequencies: daily [27],
twice per week [29] and once per week [14, 29] with a secondary clarifi ed effl uent,
every two weeks with stored effl uents [27] and with a secondary effl uent [13] or fort-
nightly and monthly with stored groundwater [14]. However, in many areas, only one
fl ushing is carried out at the beginning and/or at the ending of irrigation season.
In India, untreated or partially treated municipal wastewater is frequently used
by the farmers for growing vegetables. There is need to develop the methodology for
using wastewater through drip irrigation system in combination with fi ltration and
fl ushing. Investigation is needed to conduct fi eld trials on drip irrigation system by
placing emitter laterals on surface and subsurface conditions under different fi ltration
and fl ushing strategies. This chapter discusses the effects of fi ltration and fl ushing on
clogging of surface and sub surface placed emitters in micro irrigation system using
municipal wastewater.
6.2 MATERIALS AND METHODS
6.2.1 WATER RESOURCES
Wastewater (WW) samples were collected across the drain passing through Indian Ag-
ricultural Research Institute (IARI), Pusa - New Delhi - India at 15 cm depth below
the water level surface. The preservation and transportation was performed according
to the standard methods [4]. Collected wastewater samples were analyzed for pH,
electrical conductivity (EC), total solids (dissolved and undissolved), turbidity, cal-
cium, magnesium, carbonate, and bicarbonate, according to the standard methods [4].