Municipal and village RO plants
Cut reject volume from community RO plants.
- Village RO units
- Town water supply RO
- Rural drinking water schemes
RESEARCH PARTNERSHIP / 02
Developed withInstitute of Chemical Technology, MumbaiIndia's chemical technology institute since 1933
Pilot scaleDelivered by Rispri Labs
RO reject management.
Turn waste into resource.
Rispri Labs delivers forward osmosis systems, developed with ICT Mumbai, that recover clean water from RO reject at under 2 bar and return the concentrate as fertiliser solution or industrial brine. Less waste, more water, no high-pressure pumps.
RESEARCH TO REALITYRispri Labs × ICT Mumbai
ICT Mumbai
What it means for you
Turn RO reject into water and fertiliser.
86 of 100
litres of RO reject turned back into clean water in pilot runs.
Under 2 bar
about the pressure in a car tyre, instead of 55–80 bar for high-pressure RO.
Waste → fertiliser
With a potash draw, what's left goes to farms as nutrient solution.
Performance
More water from every litre of reject.
Every RO plant produces a salty reject stream that is expensive to dispose of and increasingly restricted. Forward osmosis pulls clean water out of it at very low pressure and turns what is left into something useful.
- 86%
- Of RO reject dewatered on a 13.6 m² pilot module
- 28.9L/m²·h
- Membrane flux with a salt draw solution
- 0.1–2bar
- Operating pressure, with no high-pressure pumps
- 70%
- Dewatered using a potash fertiliser draw
Figures are from the research team's pilot-scale trials. Performance on your stream is confirmed in our laboratory before design.
Challenge and response
The problems this solves.
- 01The challenge
RO reject disposal is costly and tightly regulated.
How we solve itRecover most of the water and cut the volume that needs disposal.
- 02The challenge
Second-stage RO on reject needs very high pressure and scales fast.
How we solve itForward osmosis runs at 0.1 to 2 bar, with no high-pressure pumps.
- 03The challenge
Conventional forward osmosis wastes energy regenerating its draw.
How we solve itThe diluted draw is resaturated and reused, or sold, so no thermal regeneration is needed.
- 04The challenge
Concentrate has no value and goes to evaporation ponds.
How we solve itIt becomes fertigation solution, industrial brine or syrup.
How it works
The process, step by step.
- 1
Draw
A saturated draw of salt, potash, urea or sugar creates a strong osmotic pull.
- 2
Transfer
Pure water crosses the membrane from the reject into the draw at 10 to 50 °C.
- 3
Resaturate
The diluted draw is topped up with fresh salt and sent back round.
- 4
Reuse
Surplus draw leaves as brine, fertigation solution or syrup for a buyer.
Use cases
Where rO reject treatment and recovery delivers.
Industrial RO and ZLD front end
Recover water and shrink the load on evaporators.
- Boiler feed RO
- ETP tertiary RO
- ZLD pre-concentration
Fertigation from reject
Use a potash or urea draw and send the diluted draw to farms.
- Potash and urea draws
- Drip irrigation
- Farmer producer organisations
Seawater pre-concentration
Draw fresh water from seawater with no high-pressure stage.
- Coastal industries
- Island and remote supply
- Salt works feed
Saleable brine
Sell concentrated salt draw as industrial brine.
- Chemical industry feed
- Regeneration brine for softeners
- Salt recovery
Hotels and campuses
Recover water from on-site RO and cut tanker supply.
- Hotels and resorts
- Universities
- Hospitals
Comparison
How it compares.
| Factor | Second-stage RO / evaporation | Rispri solution |
|---|---|---|
| Operating pressure | 55–80 bar for high-salinity RO | 0.1–2 bar |
| Energy | High-pressure pumps or steam | Low-pressure circulation |
| Draw recovery | Thermal regeneration in conventional FO | Resaturation or direct sale; no regeneration step |
| By-product | Waste brine for disposal | Fertigation solution, brine or syrup |
| Fouling | Foulants compacted at high pressure | Low pressure keeps fouling easier to reverse |
Standards and regulations
Designed around the rules that apply to you.
We design each system to meet your consent conditions and the regulations for your sector, and our laboratory reports against them.
- NGT directions on RO systemsRecovery and reject-water management requirements for RO installations.
- IS 10500:2012Drinking water quality for recovered product water.
- Environment (Protection) Rules, 1986Limits for any reject that is discharged.
- State consent conditionsPlant-specific limits on reject disposal and evaporation ponds.
Industries served
Built for the sectors that need it most.
- Municipal water supply
- Packaged drinking water
- Hotels and resorts
- Agriculture
- Seawater desalination
- Industrial utilities
Why Rispri
Institute science. Industrial delivery.
Institute-developed technology
Built on patented and peer-reviewed research from our partnership with ICT Mumbai.
Tested on your stream
Our accredited laboratory characterises your water or waste before design and verifies results after.
Engineering since 1999
The team that builds ETPs, STPs and ZLD plants across India takes each solution from pilot to full scale.
One accountable partner
Design, supply, installation, commissioning, operation and testing under one contract.
Questions
Frequently asked questions.
How is forward osmosis different from RO?
RO pushes water through a membrane with high pressure. Forward osmosis pulls it through using a concentrated draw solution, so it runs at under 2 bar and avoids the energy and scaling problems of high-pressure RO on salty reject.
What happens to the draw solution?
The diluted draw is resaturated with fresh salt and reused, or it leaves the plant as a product such as fertigation solution or brine. This avoids the energy-hungry regeneration step that conventional forward osmosis needs.
How much water can be recovered?
On a 13.6 m² pilot module, 76.9% of RO reject was dewatered with a salt draw in a single pass, and up to 86.5% in recirculation. Results for your reject are confirmed in our laboratory and on a pilot.
Can the recovered draw really go to farms?
Yes. With potash or urea as the draw, the diluted solution carries nutrients that suit drip fertigation. Potash draws dewatered about 70% of the reject in pilot runs.
Is it ready for my plant?
The process has run at pilot scale on real RO reject and seawater. We begin with a pilot module on your site to size the full system.
Research partnerships
More solutions from our partnerships.
THE NEXT STEP
Prove it on
your own stream.
Send us a sample or tell us about your site. We will test it, recommend a configuration and set up a pilot.
Request a pilot