Water treatment and liquid filtration
Water as feedstock and water as effluent: treating it to the process requirement and returning the clean water to production. The scheme starts with a raw water analysis: pre-treatment, membrane stage, polishing, disinfection and what happens to the concentrate — all in one calculation.
Wherever water quality defines the process
- Power: boiler and district heating make-up
- Pharmaceuticals and beverage production
- Electronics and electroplating
- Chemicals and refining
- Food production
- Settlements and sites without a centralised supply
The stages a scheme is built from
- Pre-treatment: media, carbon, softening
- Membrane stage: UF, reverse osmosis
- Polishing: EDI, ion exchange
- Disinfection: UV, ozone, dosing
- Tanks, pumps, piping and instrumentation
- PLC automation with a water quality log
Desalination, clarification and closing the loop
Under pressure the membrane passes water and retains dissolved salts — the main stage wherever water of stable composition is required.
- Salt rejection ≥ 97–99% on new membranes
- Feed salinity up to 10,000 mg/l without special measures
- Permeate recovery 10–65% — depends on composition and scheme
A hollow-fibre membrane retains suspended solids, colloids, bacteria and viruses while passing dissolved salts — a clarification stage, not desalination.
- Dead-end or cross-flow mode with backwash
- Typical position — pre-treatment ahead of RO
- Water high in iron needs prior oxidation
Continuous desalination in an electric field without chemical regeneration — the stage after reverse osmosis where high-purity water is required.
- Continuous regeneration, no acid or caustic
- Only after RO permeate of the specified quality
- Resistivity monitoring and PLC control
The same membrane technology, but different pressure, different piping materials and different energy demand. For sites without a freshwater source, coastal plants and highly mineralised wells.
- Brackish water 1,000–10,000 mg/l, sea water up to 38,000 mg/l
- Rejection ≥ 98%, recovery on sea water 10–40%
- Energy recovery unit and permeate remineralisation to drinking standards
A membrane bioreactor combines biological treatment with membrane separation: a membrane replaces the secondary clarifier, and the outlet water is fit for reuse.
- Smaller footprint than the classic scheme at the same load
- Industrial effluent with organic load and closed water loops
- High-fat effluent needs pre-treatment
The answer to «where does the concentrate go»: under vacuum the water evaporates at low temperature, the condensate returns to production and the contaminants stay in a small residue.
- About +37 °C at a vacuum of ≈ −95 kPa, with a heat pump
- The residue holds salts, heavy metals, oils and additives
- For large volumes of dilute water — membranes first, evaporation after
Equipment that protects the membranes and ties the scheme together
A housing with a filter bag: a simple coarse liquid filtration stage that is cheap to service — for protecting membranes and pumps.
- Housing in AISI 304 / 316L, typically up to 0.7 MPa
- Single-bag and multi-bag designs, quick-opening lid
- Not suitable as the only stage ahead of RO
The fine stage ahead of the membranes: cartridges of a defined rating in a stainless steel housing — where a repeatable filtration rating is required.
- Cartridge length 20" / 30" / 40", count selected by flow
- Seals matched to the medium and temperature, air vent
- Block quickly on heavily contaminated water — bag stage first
Media filters and softeners: the first line of defence for the whole scheme — solids, iron, chlorine and hardness are removed here.
- Media: sand, gravel, activated carbon, ion exchange resin
- Automatic backwash by time or volume, regeneration with brine
- They do not reduce salinity — no substitute for desalination
The final microbiological barrier and precise chemical dosing across the whole scheme: UV, ozone, antiscalant, coagulant and pH correction.
- UV — no chemicals and no effect on taste
- Ozone — a strong oxidant that acts on both colour and odour
- UV does not get through turbid water; ozone needs an off-gas destruction unit
A stainless mesh basket instead of a disposable bag: the element is washed and put back — where the contamination is coarse and predictable.
- Scale, sand, chips, fibre: protecting pumps and heat exchangers
- In-line or Y-type design, AISI 304 / 316L
- Not for fine filtration — the mesh cannot deliver it
The balance of plant: storage and chemical make-up tanks, vessels for membrane elements, feed and recirculation pump sets.
- Tanks: AISI 304 / 316L or FRP, insulated where needed
- Membrane vessels — steel or FRP by pressure and medium
- Volume is sized by hourly flow and reserve time, not «just in case»
Where selection starts
We do not select equipment without a water analysis: the scheme is built from five answers.
| Question | What is needed |
|---|---|
| Water analysis | salinity, hardness, iron, turbidity |
| Permeate requirement | a standard or the production regulation |
| Flow rate | m³/h and the daily consumption profile |
| Temperature | the winter minimum — it sets the membrane area |
| Where the concentrate goes | discharge, evaporation or return |
Typical parameters
| Parameter | Value |
|---|---|
| RO: salt rejection | ≥ 97–99% on new membranes |
| RO: feed salinity | up to 10,000 mg/l without special measures |
| RO: permeate recovery | 10–65% — depends on composition and scheme |
| Desalination: inlet salinity | brackish water 1,000–10,000 mg/l, sea water up to 38,000 mg/l |
| Desalination: recovery | 10–40% on sea water, rejection ≥ 98% |
| Water temperature | +2 … +40 °C |
| Bag and cartridge housings | AISI 304 / 316L, typically up to 0.7 MPa; cartridges 20" / 30" / 40" |
| Evaporation | about +37 °C at a vacuum of ≈ −95 kPa; wetted materials AISI 304 / 316 |
| Power supply | 380 V / 50 Hz |
We do not promise membrane life without pre-treatment data.
What we provide
- Raw water analysis and scheme calculation
- Membrane selection by actual composition, not «by flow rate»
- Installation, commissioning and staff training
- Service: membrane cleaning, cartridge replacement, chemicals
What we do not do
- We do not select equipment without a water analysis
- We do not install RO where softening is enough
- We do not promise membrane life without pre-treatment data
- If there is nowhere to send the concentrate, RO does not fit
Water treatment questions
Do I need reverse osmosis, or is softening enough?
RO when the salinity is beyond what ion exchange can handle, or when water of the same composition is needed year-round. Where softening is enough, RO costs more to run, so we do not install it. The water analysis gives the answer.
Does ultrafiltration reduce salinity?
No. UF retains suspended solids, colloids, bacteria and viruses but passes dissolved salts — salinity is unchanged. It is a clarification and pre-treatment stage ahead of RO; bringing salts down is RO’s job.
What has to come before EDI?
Reverse osmosis: EDI only works on RO permeate of the specified quality. With unstable feed water quality, or without an RO stage ahead of it, EDI does not fit. Its advantage is continuous regeneration without acid or caustic.
Where does the concentrate go?
Three options: discharge, evaporation or return. Where discharge is banned or expensive, vacuum evaporation is used: the water evaporates at about +37 °C at ≈ −95 kPa and the condensate returns to production. For large volumes of dilute water — membranes first, evaporation after; volatile organics need a separate stage.
Do you guarantee membrane life?
Not without pre-treatment data. Without pre-treatment the membranes foul within weeks; life depends on the water analysis, the media and carbon stages, antiscalant dosing and the cleaning schedule.
Bag or cartridge filter?
Bag — the coarse stage: the operator changes the consumable quickly, it copes with variable contamination, but it cannot be the only stage ahead of RO. Cartridge — the fine stage with a repeatable rating that protects the expensive membrane stage; it blocks quickly on heavily contaminated water.
Read on
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