Closed-Circuit RO Pilot Testing: Proving High Recovery Before You Build

At a glance. Closed-circuit RO (CCRO) runs in short semi-batch cycles. A Tech Inc. CCRO Pilot Test Skid measures the recovery, flux, scaling margin and cleaning interval your water allows.

How the cycle works

1. Feed enters the loop at the same rate as permeate leaves.

2. A circulation pump keeps crossflow through one to three short vessels.

3. Pressure rises as the loop concentrates.

4. At the set recovery, a flush valve pushes the brine out with fresh feed, and production carries on.

CCRO, batch RO and conventional RO

• Conventional RO: steady state, several stages, recovery usually limited to 75 to 85% on brackish water.

• CCRO: semi-batch, single stage, recovery often 90% or more on suitable feeds.

• Batch RO: concentrate held in a pressurised work exchanger so pressure follows osmotic pressure; aims at the lowest energy.

What a pilot should log

• Pressure, flow and conductivity through every cycle.

• Recovery at which scaling starts, with and without antiscalant.

• Normalised flux and pressure drop over weeks.

• Energy per cubic metre of permeate.

Frequently asked questions

How long should a trial run? At least four to eight weeks, longer for seasonal feeds.

Can results scale up? Yes; the skid uses standard 4- or 8-inch elements.

Send your water analysis to mail@techincresearch.com for a trial plan.