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November 19, 2019
13:11
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SulfiLogger_Manual_EN_203.pdf
BEST PRACTICES
W
ASTEWATER INSTALLATIONS
When installing the SulfiLogger™ sensor in sewer networks, the following may serve as guidelines:
• Hydrogen Sulfide (H
2
S) is developed under oxygen free conditions in sewers which typically occurs in
force mains (pumped sewer lines). The concentration of dissolved H
2
S increases when the residence
time and/or temperature of the wastewater increase. H
2
S is released at the end of the pipe, where
the wastewater is again in contact with air (head space). This can be a simple overflow to gravitational
sewer lines, a pump sump for a subsequent force mains pump line, a buffer tank or similar.
• The easiest and recommended way of deploying the SulfiLogger™ sensor for H
2
S monitoring in sewer
networks is to install the sensor to a connecting extension pipe. The pipe must be secured to either
the sewer wall or suspended using a steel wire attached at the inlet screen. Make sure the selected
installation method protects the sensor, as a free hanging installation in turbulent water may cause
the sensor to hit well walls or other objects.
• The dissolved H
2
S is released to gas phase during the first stretch of an aerated sewer. The exact dis-
tance of release depends on many different parameters such as turbulence and ventilation conditions,
but in general it is advisable to measure as close to the end-of-pipe of the force main as possible to get
a realistic measure of the initial H
2
S concentration.
• The SulfiLogger™ S1/X1-1120-5mgL sensor can be mounted at access points directly on the force
main. This can either be done by attaching the sensors threaded fitting to the pressure pipe or through
a dedicated load-lock system at the chosen position on the pipe. Note however, that liquid velocities
are often high in pressurized pipes, and hence there is an increased risk of sensor damage associated
with this type of measurements.
• In general it is recommended that the SulfiLogger™ sensor is mounted in a way where it is either
always submerged or always out of the water (in the head space). Interpretation of data can be difficult
if the SulfiLogger™ sensor is intermittently submerged. Furthermore, a mounting at a position where
the SulfiLogger™ sensor gets in and out of the water often leads to an increased risk of biofouling and
scaling, which significantly limits the time with reliable data in a field deployment.
• To minimize the need for regular sensor cleaning, it is advisable to select a measurement location with
adequate flow and turbulence around the sensor. It is advisable to avoid stagnant water conditions
whenever possible, as stagnant water gives ideal conditions for biofouling. For new installations in
wastewater environments it is recommended to inspect and clean the sensor once per week initially
to ensure stable operations and then adjust the maintenance routine based on the inspected fouling
conditions.
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