Monitoring Operational Maintenance. To properly maintain the 3,000-GPH ROWPU, it is important for you to ensure that
personnel are performing media filter backwash, RO element cleaning, systems flush, detergent cleaning, and citric acid
cleaning as required. It is equally important to maintain a regular schedule of routine shutdown maintenance. By rotating the
sequence among all the ROWPUs assigned to a water-point for a 4-hour shutdown, you should have only one ROWPU shut
down at any one time. Even if you are required by conditions to conduct additional shutdown maintenance, you should still
only have one ROWPU shutdown at any one time.
Supervising Backwash Media Filter. During a typical filter run (time between backwashes), the turbidity will initially
decrease with time. After a time it will increase, this indicates a filter that is loaded with dirt and cannot efficiently remove
dirt thereby requiring backwashing. In monitoring this, you will need to record the media filter outlet turbidity at one-hour
intervals. Operators will note the time and polymer pump settings on DA Form 1713R (Figs. 16 and 1-7). This log contains
information basic to the best operation of the ROWPU. For instance, if the turbidity recorded is more than 0.5 NTU higher
than the lowest recorded turbidity, the filter is no longer efficiently removing dirt and needs backwashing. You need to
monitor that operators are backwashing the media filter at least once each day. They need to backwash every six hours if the
following conditions prevail:
On rivers and lakes with high organic content where turbidity is over 15 NTU and the temperature is over 70F.
Whenever media filter outlet turbidity increases by more than 0.5 NTU over the lowest reading since the last backwash.
Whenever the media filter plugged light and warning horn go on.
Whenever the pressure drop reading is over 20 PSID.
Monitoring RO Element Cleaning. You need to monitor the RO element cleaning when the elements become fouled. If the
polymer has been carefully optimized and scale inhibitor, such as sodium hex, has been used, this fouling will be slow in most
water sources. Rapid fouling, however, can occur in some water sources even when the polymer has been correctly
optimized. Maintaining routine detergent cleaning at 100-hour intervals, as indicated by the high-pressure pump hour meter,
helps reduce this fouling. Fouling may continue to build; it can be detected by changes in operating performance. You would
then need to direct the operators to perform an extended RO element cleaning.
In performing troubleshooting, it is important for you to ensure that it is done in
accomplished in accordance with TM 10-4610-232-12 and TM 5-6115-545-12.