Nanofiltration (NF)
The middle ground — hardness and colour out, energy cost down.
The technology explained.
Nanofiltration uses spiral-wound membranes with a molecular-weight cut-off of approximately 200–400 Da. NF rejects divalent ions (Ca²⁺, Mg²⁺, SO₄²⁻) at 85–99%, passes a portion of monovalent ions, and removes natural organic matter and tannins — at operating pressures and energy costs well below full RO.
- Removes hardness (Ca²⁺, Mg²⁺) at 85–99% rejection.
- Removes natural colour, tannins and dissolved organic carbon.
- Reduces sulphate, fluoride and other divalent species.
- Lower energy consumption than RO (typically 0.3–0.8 kWh/m³).
- Selectively passes some monovalent ions, retaining beneficial mineralisation.
- Tea-coloured river and dam feeds where colour and organics dominate.
- Hardness reduction without full demineralisation.
- Sulphate removal on agricultural or municipal feeds.
- Sites where RO's energy cost cannot be justified by the dissolved load.
- ×Not effective on high-TDS or seawater feeds — full RO is required.
- ×Sodium and chloride pass through largely unrejected.
- ×Membrane fouling profile demands proper pre-treatment, just like RO.
- ×Application requires careful design — wrong membrane choice undersizes or overspends.
Where Nanofiltration is used.
- Hardness and colour removal
- Tannin and DOC reduction
- Sulphate removal
- Selective ion removal between UF and RO
How HidroVerse deploys Nanofiltration.
We deploy NF where the brief is hardness, colour or organics — not full demineralisation. Membrane selection, recovery and array configuration are designed against the feed and the target water quality.
A typical Nanofiltration treatment chain.
Nanofiltration is one stage in a multi-barrier train — pre-treatment and post-treatment are non-optional.
Pre-treatment
Cartridge or media filtration to bring SDI₁₅ below 5; antiscalant dosing matched to the feed-water saturation indices; chlorine removal where required.
Core stage
Spiral-wound NF membranes at 5–10 bar feed pressure with engineered recovery and concentrate management.
Post-treatment
Re-mineralisation only where the brief demands it; disinfection (UV or chlorine) downstream of the membrane.
Waste handling
Concentrate disposed under consented discharge; spent membranes returned to manufacturer recycler.
Buyer's guide.
The questions every commercial buyer should put on the table before signing for a water system. Can't see yours? Send us a brief — a HidroVerse specialist replies within one business day.
Yes — we keep a current reference list organised by application and scale. After a short qualifying call we release names, contacts and (with the host's permission) site-visit options. The conversation between two operations managers is the most honest reference we can offer; we do not gate-keep it.
We start with a SANAS-accredited feed-water panel, profile your demand against verified occupancy or production data (not brochure numbers), and specify against the worst-credible feed and peak demand — with disclosed margins. If a simpler technology will hit the brief, we'll specify the simpler technology and tell you why. We do not earn more by over-spending you; we earn more by you renewing service contracts year after year.
PFD, P&IDs, sizing calculations against verified influent data, equipment schedules with serial numbers, control philosophy, pre-treatment justification, waste-handling and regulatory compliance trail. Audit-ready by an external ECSA-registered engineer is the standard we design to — not a brochure pack with marketing fluff.
Pre-treatment is technology-specific (sediment, hardness, chlorine, biological load) and non-optional. Skipping it is the single largest cause of premature failure on every membrane, media bed and disinfection stage. Watch for suppliers quoting only the core stage — they are selling you a 12-month problem.
Every consumable and major component has a quantified replacement trigger (differential pressure, flow drop, UV intensity drop, salt-passage drift). Replacement schedules and trigger limits are written into the HidroVerse Care contract — visible, auditable and triggered on monitoring data, not guesswork.
Critical components are specified with duty/standby and automatic fail-over so a single failure does not stop supply. Our SLA on critical lines is 4 hours on site; the median lived response over the last 14 months is 2 hours 40 minutes. Telemetry triggers tickets before the operator notices — most failures are flagged, not phoned in.
Continuous telemetry on flow, pressure, conductivity, turbidity and on-skid water quality. Monthly SANAS-accredited compliance sampling is included on HidroVerse Care — not invoiced piecemeal. The audit pack builds itself monthly so when DWS or your insurer arrives, the file is ready in 30 minutes.
Potable applications: SANS 241:2015 (mandatory under the Water Services Act 108 of 1997), the National Water Act 36 of 1998 for abstraction and discharge, NSF/ANSI component certification, WHO Guidelines for design margin. Wastewater: the relevant DWS discharge authorisation under General Authorisation 665 or a site-specific Water Use Licence. We sign off against the legal floor and design to a margin above it.
Survey 1–2 weeks, design 2–4 weeks, install 4–10 weeks, commissioning and proof of compliance 1–2 weeks — typically 8–14 weeks for a lodge or estate, longer for mining and municipal. Delays come from civil works, third-party council approvals and architectural changes; the engineered scope rarely slips.
Survey, lab analysis, design pack, equipment, install, commissioning, operator training, the first year of monthly compliance sampling and the agreed scope of HidroVerse Care. Civils, electrical reticulation, third-party council fees and any architectural integration work are quoted separately and scheduled into the contract. If your quote has 'allowances' and 'provisional sums' across the page, you are buying a future invoice.