AQUAPHOR APRO 1000 LPH, Manual

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10.5 MEMBRANE FUNCTIONING TIPS
10.5.1 LOW FLOW
If the system suffers from loss of normalized permeate flow performance and the problem can be localized, the gen-
eral rule is:
▪
First stage problem: deposition of particulate matter; initial biofouling
▪
Last stage problem: scaling
▪
Problem in all stages: advanced fouling
The reasons of the low flow:
1. Biofouling and Natural Organic Matter (NOM):
Causes for biofouling are mostly the combination of a biologically
active feedwater and improper pretreatment.
The corrective measures are:
▪
Clean and sanitize the entire system, including the pretreat-
ment section and the elements
▪
An incomplete cleaning and disinfection will result in rapid
re-contamination.
▪
High pH soak and rinse
▪
Installation of Fouling-Resistant (FR) elements
2. Aged Preservation Solution
Elements or RO systems preserved in a bisulfite solution can also become biologically fouled, if the preserva-
tion solution is too old, too warm, or oxidized by oxygen. An alkaline cleaning usually helps to restore the per-
meate flow. Renew preservative solution if storing elements. Store in cool, dry, dark environment.
10.5.2 LOW FLOW AND HIGH SOLUTE PASSAGE
a. Colloidal Fouling
To identify colloidal fouling:
▪
Review recorded feedwater SDIs. The problem is sometimes due to infrequent excursions or pretreat-
ment upsets.
▪
Analyze residue from SDI filter pads.
▪
Analyze accumulations on pre-filter cartridges.
▪
Inspect and analyze deposits on feed scroll end of 1 st stage lead elements.
b. Metal Oxide Fouling
Metal oxide fouling occurs predominantly in the first stage.
The problem can more easily be localized when permeate
flow meters have been installed in each array separately.
Common sources are:
▪
Iron or aluminium in feedwater
▪
Hydrogen sulfide with air in feedwater results in metal
sulfides and/or elemental sulfur
▪
Corrosion of piping, vessels or components upstream
of membrane elements.
The corrective measures are:
▪
Clean the membrane elements as appropriate.
▪
Adjust, correct and/or modify the pretreatment
▪
Retrofit piping or system components with appropriate materials