Treatment Technology

Membrane filtration water treatment

Reverse osmosis and nano-filtration water purification and separation systems

The "Clear Concept" Separations Systems offer complete package Reverse Osmosis and Nano-Filtration Systems, skid mounted and ready for field installation. The systems incorporate all required components and are carefully tailored to each installation after considering source water quality goals and local operation conditions.

The system components include raw water pump, chemical injection, pre-filtration, pressure pump, pump control valves, by-pass and recirculation controls, flow meters and pressure instruments.

The membranes are spiral wound, composite polyamide, 4" or 8" (100 mm to 200 mm) diameter, by Hydranautics. The design is developed by using Hydranautics' exclusive membrane projection software which calculates data for membrane selection, system configuration and operation.

Ongoing research and development provides a multitude of membrane types and satisfies the demands for varied end-user applications. These include high or low rejection, low pressure, energy saving systems, and high or low recovery requirements.

Control systems are fully automatic and PLC based. Each system is programmed for the specific application and can incorporate SCADA communication. Water quality is monitored by on-line conductivity and pH meters. Alarms and automatic shutdown interlocks assure reliability and protection of the membranes.

The membrane filtration process


Raw water is fed to the system at 15-30 psi (103 - 207 kPa). The pH is first optimized by chemical addition and, if required, an anti-scalent is also injected. A 5-micron pre-filter removes suspended solids and provides chemical mixing.


A pump then increases water pressure to a pre-determined membrane feed value. A control valve regulates the feed pressure, sustains the pump suction pressure, and relieves abnormally high membrane feed pressures.


Membranes housed within an array of pressure vessels separate the feed into permeate (pure water) and concentrate (the rejected water containing an increased level of dissolved salts). Usually, each pressure vessel contains 2 to 8 membranes. Several stages of membrane vessels are often provided to maximize overall recovery. The concentrate from an upstream stage is fed to a downstream stage for retreatment. The number of vessels usually reduces with each stage as the feed flow also reduces.


The treated permeate is collected from each stage and metered. Usually it is discharged at low pressure with no backpressure on the membranes.


The concentrate stream is regulated with manual control valves and may be split between discharge to drain and re-circulate to downstream stages. Re-circulation is most common on high recovery systems. Both drain and re-circulation stream are metered.

Special features

Clear Concept's standard design incorporates several special features. These include automatic, timed membrane flush, membrane cleaning systems and panel mounted pressure, flow and water quality monitors. Variable speed pumps may be used on variable output systems. Full SCADA systems with remote monitoring and control also can be provided. Controls and meters are centrally located for easy inspection and optimization by plant operators.

Plant features

  • T2/pH
  • reads parts per million and pH units to quickly determine the TDS and pH of almost any solution
  • we recommend and supply a hand-held TDS/pH meter for easy reference on feed water quality, and on system sample ports
  • panel meters: direct reading, variable area flow meters are used for flows up to 200 gpm (7571/min).
  • systems are configured and built to comply with specific site conditions and water
  • systems include a wide selection of panel indicators and alarms
  • our water treatment experts offer you advice and "state-of-the-art" water treatment plants for all types of water applications:
    • DAF, dissolved air flotation plants
    • ST, tube settler clarification systems
    • DF, direct filtration plants with flocculation
  • Hydranautics offer a full range of membranes, including:
    • reverse osmosis
    • nano-filtration and ultra-filtration
    • high or low rejection
    • low energy
    • low fouling
    • high or low recove