Sodium Metabisulphite (SMBS)
Sodium metabisulphite (SMBS) is a reducing agent used to remove free chlorine from water before it reaches RO membranes, to dechlorinate treated effluent before discharge, and to make preservation solution for stored membranes.
- Supplied by Zyax Chem, Mumbai
- Send your water or process details for a recommendation
- Bulk packs, delivered across India
- What it does
- Neutralises free chlorine and other oxidisers
- Used in
- RO pre-treatment, effluent and STP outlets, membrane storage
- Forms
- White powder in bags
- How it is applied
- Dissolved in water and dosed with a dosing pump
What is Sodium Metabisulphite (SMBS)?
Chlorine is added to raw water to control bacteria, but polyamide RO membranes are damaged by even small amounts of free chlorine. SMBS reacts with chlorine and converts it to harmless chloride, protecting the membranes downstream.
SMBS is also used to remove excess chlorine from treated sewage or effluent before discharge or reuse, and as the main ingredient of preservation solution for membranes taken out of service.
Where SMBS is used
- Dechlorination of RO feed after chlorination and carbon filters
- Dechlorination of STP and ETP outlet water
- Preservation solution for stored or idle RO membranes
- Removing residual oxidisers in process water
How to use SMBS
- Prepare a solution of SMBS in clean water in the dosing tank; make fresh solution regularly, as it loses strength when exposed to air.
- Dose continuously with a dosing pump after the chlorination point and before the cartridge filter.
- Monitor chlorine after the dosing point (ORP or a chlorine test) to confirm it is zero.
- Avoid big overdoses, which waste chemical and can encourage bacterial growth.
Choosing the right grade
To recommend a product and starting dose, send us:
- Free chlorine level in the feed
- Flow rate of the water to be dechlorinated
- Whether it is for RO feed, effluent outlet or membrane storage
Handling and safety
Keep dry and sealed. Avoid breathing dust, and do not mix with acids, which releases sulphur dioxide gas. Wear gloves and eye protection.
Safety data sheet and technical data sheet available on request.
Grades and specifications
Typical values for each grade we supply. Technical data sheet and safety data sheet available on request.
Sodium metabisulphite (SMBS) powder
For dechlorinating RO feed water and for membrane storage solutions.
| Form | White powder |
|---|---|
| HS code | 28321090 |
Dechlorination powder for RO
Synthetic blend prepared as a solution on site. Reacts quickly with free chlorine to protect polyamide membranes.
| pH | 2.0 to 3.0 |
|---|---|
| Appearance | White powder |
| Solubility in water | Completely soluble |
| Specific gravity (solution) | 1.05 to 1.10 |
| HS code | 38249022 |
Ready-to-use dechlorination and storage liquid
Liquid for dechlorinating RO feed and for preserving membranes during shutdowns.
| pH (as such) | 2.5 to 3.5 |
|---|---|
| Appearance | Liquid |
| Solubility in water | Completely soluble |
| Specific gravity | 1.05 to 1.10 |
| HS code | 38249022 |
Related products
- RO membrane cleaners
- RO biocide
- pH booster
- Remineralisation minerals
- Antiscalant balls
- RO antiscalant
- All RO Antiscalants & Membrane Cleaners
Frequently asked questions
Why is SMBS dosed before an RO plant?
To remove free chlorine, which damages polyamide RO membranes. SMBS converts chlorine to chloride before the water reaches the membranes.
How long does SMBS solution last?
SMBS solution slowly loses strength once mixed, especially when exposed to air, so make up fresh solution regularly in a covered tank.
Do you publish prices for Sodium Metabisulphite (SMBS)?
Prices depend on the grade, pack size and quantity, so we quote on request. Send your requirement on WhatsApp at +91 98333 22685 or through the form on this page.
Get a quote for Sodium Metabisulphite (SMBS)
Tell us the application, quantity and your water or process details. We do not publish prices; our team replies with a recommendation and quote.
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