Industrial RO Plant Manufacturer in Gurgaon: How Do You Compare Two Quotes When One Has a Lower Recovery Rate?
Two quotes for the same industrial RO plant can look almost identical on the first page. Both promise the same permeate output, both list similar pumps and membranes, and the prices are within a few per cent of each other. The difference hides in one figure that many buyers never examine: the recovery rate. A plant that recovers 60% of its feed water and a plant that recovers 75% can both produce the same amount of permeate, but they draw very different volumes of water from the source, discharge very different volumes of reject, and cost very different amounts to run. This article works through the comparison with numbers, so the choice rests on the arithmetic rather than the headline price.
The figures below are a worked example. Your own quotes will have their own assumptions, and the method is what matters.
What Recovery Rate Actually Controls
The Definition
Recovery is the share of feed water that becomes permeate:
Recovery (%) = permeate flow ÷ feed flow × 100
The remaining feed leaves as reject, also called concentrate. Recovery is a design choice, and it is limited by the scaling tendency of the feed water and the membrane's ability to operate with a more concentrated reject stream.
Why Recovery Affects Almost Everything Else
A change in recovery changes the feed volume the plant draws, the reject volume it discharges, the pressure it needs, the chemical dose it requires, and the frequency of membrane cleaning. Two plants with the same permeate output and different recovery rates are therefore not comparable on price alone. They are different machines doing different amounts of work on the same source.
The Worked Comparison
The Two Proposals
Consider two quotes for a plant producing 10 m³/hr of permeate, on a feed water with TDS of 700 mg/L and hardness that requires antiscalant dosing.
Proposal A: recovery 75%, quoted price ₹18 lakh
Proposal B: recovery 60%, quoted price ₹16 lakh
Proposal B looks ₹2 lakh cheaper, which is the figure most buyers focus on. The rest of the comparison shows what the cheaper quote is actually buying.
Feed Volume
For Proposal A, feed flow = 10 ÷ 0.75 = 13.3 m³/hr.
For Proposal B, feed flow = 10 ÷ 0.60 = 16.7 m³/hr.
Proposal B draws 3.4 m³/hr more water from the source, which is 25% more than Proposal A. Over 20 operating hours a day for 300 days, that is 3.4 × 20 × 300 = 20,400 m³ of extra source water a year.
Reject Volume
For Proposal A, reject flow = 13.3 − 10 = 3.3 m³/hr.
For Proposal B, reject flow = 16.7 − 10 = 6.7 m³/hr.
Proposal B produces twice as much reject as Proposal A. That reject carries the dissolved solids the membrane removed, and where it must be treated or disposed of, the cost sits with the owner, not the manufacturer. Over a year, the extra reject for Proposal B is 3.4 × 20 × 300 = 20,400 m³ of concentrate that has to go somewhere.
Concentrate Concentration
The reject from Proposal B is more concentrated, because the same dissolved solids are carried in a smaller share of the feed. Using a simple mass balance, the reject TDS is roughly the feed TDS multiplied by the feed-to-reject ratio, adjusted for rejection. At 60% recovery, the reject is concentrated about 1.6 times above feed; at 75% recovery, about 2.0 times above feed, once the membrane's rejection is accounted for in a simplified way. The higher-recovery plant produces a more concentrated reject, which is harder to handle and has greater scaling risk. The point to take from this is that recovery is a trade between water saved and the concentration of the waste, not a free gain.
Running Cost Comparison
Energy
Higher recovery usually means a higher operating pressure at the membrane, because the osmotic pressure of the more concentrated feed is greater. Assume the high-pressure pump runs at about 11 bar for Proposal B and about 13 bar for Proposal A, reflecting the higher concentration in the later stages of the array.
Using the hydraulic power relation, power = flow × pressure ÷ efficiency, and taking 75% pump efficiency:
Proposal A: 13.3 m³/hr × 13 bar ÷ 0.75 ≈ 13.3 × 1,300,000 ÷ (3,600 × 0.75) ≈ 6.4 kW
Note: the calculation here uses the high-pressure pump on the feed flow. The actual figures depend heavily on the membrane selection and the array design, so a manufacturer should state the pressure and flow for each quote.
Proposal B: 16.7 m³/hr × 11 bar ÷ 0.75 ≈ 16.7 × 1,100,000 ÷ (3,600 × 0.75) ≈ 6.8 kW
Proposal B has a larger feed pump and a slightly lower operating pressure, but it draws more water through the system, so the net energy per cubic metre of permeate is close, and in this simplified case Proposal B uses slightly more. The energy difference is less important than the water and reject difference, which is where most of the running cost hides.
Pumping of Source Water
If the source is a borewell, the extra water in Proposal B means more pumping at the borewell. Assume the borewell pump lifts water 40 metres at 75% efficiency. The extra 3.4 m³/hr over 6,000 operating hours a year is 20,400 m³. The energy needed to lift that water is:
Hardly significant on its own, but the cost of the water itself, if it is metered or purchased, can be considerable. Where the source is a municipal supply, the extra 20,400 m³ at the local tariff is the figure to use.
Chemicals
Antiscalant dose is set by the scaling tendency at the design recovery. A higher recovery concentrates scaling salts more, so the antiscalant requirement rises. Assume Proposal A needs 4 mg/L of antiscalant and Proposal B needs 3 mg/L, because B operates at lower concentration in the reject. Feed flow determines the chemical use:
Proposal A: 13.3 m³/hr × 4 g/m³ × 20 h × 300 days = 319 kg a year
Proposal B: 16.7 m³/hr × 3 g/m³ × 20 h × 300 days = 301 kg a year
Those two figures are close, which shows that the chemical comparison depends on the dose the manufacturer specifies and the way the scaling calculation was done. The question to ask is how each dose was derived, not simply which is lower.
Membranes
Membrane life depends on the flux, the feed quality, and the concentration of the reject. A plant running at high recovery may have a shorter membrane life if the scaling and fouling are not well controlled, while a plant at lower recovery may last longer but cost more in water and reject handling. The membrane cost per year is set by the replacement interval, so the quoted warranty and the expected life should be compared directly.
Putting the Numbers Together
The following simplified annual comparison uses the assumptions above, with reject disposal costed at an illustrative ₹20 per cubic metre and source water at ₹15 per cubic metre.
On these illustrative figures, Proposal B's ₹2,00,000 price advantage is overtaken by roughly ₹7,14,000 a year in extra water and reject handling. Even if the reject were free to discharge and the water were free to draw, the energy and chemical figures would not, on their own, reverse the comparison.
The exact figures will differ, and where the source water is cheap and the reject can be discharged without treatment, the gap may narrow. Where water is scarce or costly, or where the reject must be treated before disposal, the gap widens. Either way, the cheapest quote is not necessarily the lowest cost plant over its life.
What to Ask Each Manufacturer
What recovery rate is the quote based on, and is it guaranteed?
What feed flow and reject flow does each quote imply at the stated permeate output?
What operating pressure is assumed, and what pump efficiency?
What antiscalant dose is specified, and how was it derived from the water analysis?
What is the expected membrane life at this recovery, and does the warranty depend on it?
What reject stream volume and concentration must be handled on site?
A Practical Way to Compare
Put both quotes on the same sheet. Calculate the feed volume, reject volume, and annual source water use for each, using the same operating hours. Multiply the water and reject volumes by the local costs. Add the energy, chemical, and membrane costs, and compare the totals over five years, not one. The quote with the lower price can turn out to be the more expensive plant once the water and reject are priced in. Commercial RO Plant is the best industrial RO plant manufacturer in Gurgaon at best affordable price and quality.
If you have two quotes in front of you, Commercial RO Plant can run the same comparison on your own feed analysis, operating hours, and local water and disposal costs, and show where the lower-price quote ends up over five years.
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