Watts R4X40-3 - Manual (Page 12)

G. TROUBLESHOOTING
RO MEMBRANE TROUBLE SHOOTING GUIDE
SYMPTOMS
Salt Passage Permeate Flow Pressure Drop Location Possible Causes Verification Corrective Action
Normal to
increased Decreased Normal to
increased
Predominantly
first stage Metal oxide Analysis of metal
ions in cleaning
solution. Improved pretreatment
to remove metals.
Cleaning with acid
cleaners.
Normal to
increased Decreased Normal to
increased
Predominantly
first stage Colloidal fouling SDI measurement
of feed/ X-ray
diffraction
analysis of
cleaning sol.
residue. Optimize pretreatment
system for colloid
removal. Clean with
high pH, anionic
detergent formulation.
Increased
Decreased Increased Predominantly
last stage
Scaling
(CaSO
4
, CaSO
3
,
BaSO
4
, SiO
2
)
Analysis of metal
ions in cleaning
sol. Check LSI of
reject. Calculate
maximum
solubility for
CaSO
4
, BaSO
4
,
SiO
2
in reject
analysis.
Increase acid addition
and scale inhibitor for
CaSO
3
and CaSO
4
.
Reduce recovery.
Clean with an acid
formulation for
CaCO
3
, CaSO
4
and
BaSO
4
.
Normal to
moderate
increase Decreased Normal to
moderate
increase
Can occur in
any stage Biological fouling
Bacteria count in
permeate and
reject. Slime in
pipes and vessels. Shock dosage of
sodium bisulfite.
Continuous feed of
low conc. bisulfite at
reduced pH. Peracetic
acid sterilization.
Clean with alkaline
anionic surfactant.
Chlorine dosage up-
stream with
dechlorination.
Replace cartridge
filters.
Decreased or
moderately
increased Decreased Normal All stages Organic fouling Destructive
testing, e.g. IR
reflection
analysis. Optimization of
pretreatment system
(e.g. coagulation
process.)
Resin/activated carbon
treatment. Clean with
high pH detergent.
Increased Increased Decreased Most severe in
the first stage Chlorine oxidant
attack Chlorine analysis
of feed.
Destructive
element test. Check chlorine feed
equipment and
dechlorination
equipment.
Increased Increased Decreased Most severe in
the first stage Abrasion of
membrane by
crystalline material Microscopic
solids analysis of
feed. Destructive
element test. Improved
pretreatment. Check
all filters for media
leakage.
Increased Normal to
increased
Decreased At random O-ring leaks, End
or side seal glue
leaks. Probe test.
Vacuum test.
Colloidal
material passage. Replace O-rings.
Repair or replace
elements.
Increased Normal to low Decreased All stages Conversion too
high. Check flows and
pressures against
design guidelines Reduce conversion
rate. Calibrate sensors.
Increase analysis and
data collection.