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Pre-Start-Up Check and Commissioning Audit

After having loaded the elements into the pressure vessels and before starting up the membrane unit, make sure that the whole pretreatment section is working in accordance with the specifications. If the pretreatment involved changing of the chemical characteristics of the raw water, then a full analysis of the water entering the membrane unit must be made. Furthermore, absence of chlorine, turbidity and SDI must be determined.

The raw water intake must be stable with respect to:

  • Flow
  • SDI
  • Turbidity
  • Temperature
  • pH
  • Conductivity
  • Bacteria (standard plate count)

The following checks of the pretreatment system and the membrane unit are recommended for the initial start-up (results to be included in the start-up report):

Pre-Start-Up Checklist

Corrosion resistant materials of construction are used for all equipment from the supply source to the membrane including piping, vessels, instruments and wetted parts of pumps
All piping and equipment is compatible with designed pressure
All piping and equipment is compatible with designed pH range (cleaning)
All piping and equipment is protected against galvanic corrosion
Media filters are backwashed and rinsed
New/clean cartridge filter is installed directly upstream of the high pressure pump
Feed line, including RO feed manifold, is purged and flushed, before pressure vessels are connected
Chemical addition points are properly located
Check/anti-siphon valves are properly installed in chemical addition lines
Provisions exist for proper mixing of chemicals in the feed stream
Dosage chemical tanks are filled with the right chemicals
Provisions exist for preventing the RO system from operating when the dosage pumps are shut down
Provisions exist for preventing the dosage pumps from operating when the RO system is shut down
If chlorine is used, provisions exist to ensure complete chlorine removal prior to the membranes
Planned instrumentation allows proper operation and monitoring of the pretreatment and RO system
Planned instrumentation is installed and operative
Instrument calibration is verified
Pressure relief protection is installed and correctly set
Provisions exist for preventing the permeate pressure from exceeding the feed/concentrate pressure more than 5 psi (0.3 bar) at any time
Interlocks, time delay relays and alarms are properly set
Provisions exist for sampling permeate from individual modules
Provisions exist for sampling raw water, feed, permeate and concentrate streams from each stage and the total plant permeate stream
Pressure vessels are properly piped both for operation and cleaning mode
Pressure vessels are secured to the rack or frame per manufacturer’s instructions
Precautions as given in Loading of Pressure Vessels (Section 4.1 & 4.2), are taken
Membranes are protected from temperature extremes (freezing, direct sunlight, heater exhaust, etc.)
Pumps are ready for operation: aligned, lubricated, proper rotation
Fittings are tight
Cleaning system is installed and operative
Permeate line is open
Permeate flow is directed to drain (In double-pass systems, provisions exist to flush first pass without permeate going through the second pass)
Reject flow control valve is in open position
Feed flow valve is throttled and/or pump bypass valve is partly open to limit feed flow to less than 50% of operating feed flow

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