Reverse Osmosis System Fault Diagnosis ①
RO system fault has mainly three types: dialysis water lower, salt- infiltration raising and pressure-drop increasing. Much appearance must be analyzed to find reason to resolute problem.
1, Lower water-output volume
Against to standardized low water-input volume, to find problem from next steps:
A, First stage has problem means depositing of particles
B, Last stage has problem means dirt.
C, All stages have problem means block.
Besides, salt –penetrate volume is common, too high or too lower. Different appearance means different fault.
1.1, Common salt-penetrate volume at lower water-out volume
Following reason cause salt-penetrate volume:
A, Microbiology and NOM.
Next data changing means membranes element is polluted by microbiology at front of system:
★ Water-out volume lower under same input water pressure and recycling
★ System recycling lower, if bio pollution breeding large sum of bio matter under same input water pressure
★ Under same recycling volume, for keeping same water-out volume, water-input pressure must be raised ,but if operating as the abovementioned method for long time, the water-input pressure may cause vicious circle, cleaning in future shall be difficult.
★If pollution is serious in wide zone or sludge blocking, system different pressure shall raise clearly, thus different pressure at both ends of pressure volume may be decided as reference data, so it is necessary to set a pressure verify meter.
★At first, salt-penetrate volume is nominal or lower, when large sum of pollution appear, salt-penetrate volume shall raise fast.
★ When input water, concentrated water or large sum of microbiology in water means bio pollution has generated.
★Surface of microbiology membranes is smooth and with bad taste.
★Burning on fire, the taste of microbiology membranes is same as hair. Bio pollution is caused by microbiology activity too strong water-input and unaffective method is carried. Its repairing method is as following:
◆Clean and sterilize whole system, including pre-treatment and membranes, attention : whole system must be cleaned and sterilized completely to avoid renew pollution
◆ To install or optimization treat system against to microbiology pollution in raw water.
◆Immersing and cleaning with LDR-812 Cleaner (Ph=11)
◆ Anti-pollution membranes element may be used.
B, Protection medicine expired
If protection medicine is used for a long time, too heat or oxide, membranes element protected in sodium bisulfite liquid may be meanwhile polluted, thus, them may be immersed and cleaned with LD-812 Cleaner to renew water-output volume of membranes element. If the membranes element shall be continued stored, the protection liquid must be replaced and stored in shady, dry and dark.
C, Wetting is not completed
After dry, the small holes to support net sulfone in membranes element has not be wetted, it shall cause water-input volume lower, then it shall be wetted.
1.2 Lower water-output volume high salt- penetrate volume
This situation is common fault, its reason may be :
A, colloid pollution
Following steps may be done:
★ To check SDI value record of raw water, SDI value is not recorded normally or pre-treatment with fault.
★ To analysis left matter on SDI test membranes.
★To analysis left matter on safe-filter pith.
★ To check and analysis left matter on No. one element of fist stage.
Repairing method is as following:
◆ To clean element accordance with polluted situation.
◆ To adjust, correct or amend pre-treatment.
B, Metal oxide pollution and plug
This appearance collects mainly at the first stage, to install flow meter at each stage of water-output to find fault. Common reason is as next items:
◆ Water-input including Fe or Al
◆ Water-input including H2S and air entering, it creates curing salt and may curing deposit if water-output contacting with air.
◆ Partial elements of tube, pressure volume and top of membranes may be polluted.
To finding reason accordance with next steps:
◆To analysis Fe or Al in raw water.