Description
Sodium Metabisulfite (SMBS) Powder – 25 kg Bag | UV Water Systems Oman
Free chlorine is the most common cause of irreversible polyamide RO membrane damage in Oman. PAEW’s municipal supply is disinfected with chlorine, which is essential for safe tap water but immediately destructive to thin-film composite (TFC) membranes used in all modern RO systems. Even chlorine levels as low as 0.1 mg/L cause oxidative degradation of the polyamide barrier layer over time, permanently increasing salt passage and destroying rejection performance. Sodium Metabisulfite (SMBS) Powder, supplied by UV Water Systems in Muscat, is the standard chemical for neutralising free chlorine before it contacts the RO membranes. SMBS reacts instantaneously with chlorine at stoichiometric doses, converting it to harmless chloride ions.
How SMBS Dechlorination Works
When dissolved in water, SMBS releases sulphur dioxide (SO₂), which reacts with free chlorine (HOCl/OCl⁻) in a rapid, near-instantaneous reaction: Na₂S₂O₅ + Cl₂ + H₂O → 2NaHSO₄ + 2HCl. The reaction consumes chlorine completely at a dose ratio of approximately 1.47 mg SMBS per 1 mg Cl₂. In practice, a slight overdose of 3–5 mg/L is used to ensure full dechlorination. SMBS is typically injected as a 1–5% solution via a chemical dosing pump on the feed water line, upstream of the cartridge filter and RO unit. UV Water Systems configures SMBS dosing systems with ORP monitoring to verify continuous dechlorination.
Key Features and Benefits
- Immediate chlorine neutralisation: SMBS reacts with free chlorine within milliseconds of contact — no residence time required, making it suitable for inline injection even at high feed water flow rates.
- Protects membrane investment: A 25 kg bag of SMBS costs a fraction of one RO membrane element — proper dechlorination is the lowest-cost insurance for your membrane system.
- Easy to handle and dissolve: White powder dissolves readily in water at ambient temperature. Day tank preparation requires mixing one measured dose per batch.
- Doubles as storage biocide: At higher concentrations (500–1000 mg/L), SMBS solution is used to preserve RO membranes during shutdown periods, preventing biofilm growth.
- Widely available and cost-effective: UV Water Systems maintains SMBS stock in Muscat for immediate supply. Available in 25 kg bags for both small and large system requirements.
Technical Specifications
- Pack size: 25 kg bag
- Purity: Technical grade, ≥96.5% Na₂S₂O₅
- Dosage: 1.47 mg per mg Cl₂ (practical: 3–5 mg/L)
- Form: White crystalline powder
- Shelf life: 12 months in sealed bag, dry storage
- Quality: ISO 9001:2015 certified supply chain
Applications Across Oman
SMBS is used in every RO system fed from Oman’s chlorinated municipal network. UV Water Systems installs SMBS dosing systems on residential, commercial, and industrial RO units across Muscat — from home drinking water systems to hospital-grade RO plants. We also supply SMBS for membrane preservation on systems taken offline for maintenance or seasonal shutdown.
Frequently Asked Questions
Can I use activated carbon instead of SMBS for dechlorination? Yes — granular activated carbon (GAC) filtration is an alternative to chemical dechlorination, but GAC beds need periodic replacement or regeneration. SMBS dosing is preferred for large systems where continuous chemical injection is more economical than frequent media changes.
How do I monitor SMBS dosing effectiveness? Install an ORP (oxidation-reduction potential) sensor on the feed line after the SMBS injection point. A reading below +200 mV confirms complete dechlorination. UV Water Systems includes ORP monitoring in commercial and industrial RO skid builds.
UV Water Systems is an ISO 9001:2015 certified water treatment company based in Muscat, Sultanate of Oman, with 14+ years of experience. We supply, install, and service water treatment solutions for residential, commercial, and industrial clients across Oman. Call +968 9763 7786 or visit www.uvwater.biz.
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