Water Treatment & Disinfection
Intake, process and effluent treatment: UV, ozone, denitrification, degassers.
Overview
Water treatment covers everything between raw source water and the fish, plus polishing before discharge — UV, ozone, CO₂ stripping, denitrification, pH control and effluent solids removal.
Where it is used
- RAS grow-out
- Hatcheries
- Marine indoor farms
- Sites with strict discharge rules
Typical applications
- Pathogen control on intake
- CO₂ stripping in closed loops
- Nitrate control for zero-discharge
- Effluent polishing
Benefits
- Biosecurity
- Regulatory compliance
- Consistent water chemistry
Limitations
- Ozone requires trained handling
- UV needs regular lamp replacement
- Denitrification adds complexity and cost
Typical project sizes: Applies to every RAS and most modern hatcheries.
UV vs Ozone vs Chlorination
| Parameter | UV | Ozone | Chlorination |
|---|---|---|---|
| Pathogen kill | Excellent | Excellent + organics oxidation | Good |
| Residual | None | Must be destroyed before tanks | Must be dechlorinated |
| CAPEX | Low–Medium | High | Low |
| OPEX | Lamp replacement | Power + O₂ | Chemicals |
| Best for | RAS, hatcheries | Marine RAS, ballast, effluent | Intake pretreatment |
Buying guide
How to evaluate suppliers
- UV dose validated to third-party standard
- Ozone destruct systems required
- Effluent design must meet local permit
Common purchasing mistakes
- Undersizing UV for peak flow
- Ignoring ozone destruction
- Treating effluent as an afterthought
Technical questions to ask
- What UV dose is guaranteed at end-of-lamp life?
- What ORP setpoint controls the ozone loop?
- What is the effluent guarantee?
Warranty considerations
- 12 months mechanical
- Lamp warranty separate
Maintenance
- Annual lamp replacement
- Quarterly quartz sleeve cleaning
- Monthly probe calibration
Expansion capability
- Reserve manifold capacity
- Modular UV reactors
Energy efficiency
- UV: 1–3 W per m³/h treated
- Ozone: 5–15 kWh per kg O₃
Lifecycle
- 10–15 years reactors, 1 year lamps, 5–7 years probes
Technical specification checklist
Line-by-line items you should include in a vendor-neutral technical specification. Download as CSV to hand to your engineer or drop straight into the RFQ Builder.
Budget guide
| Project size | Indicative CAPEX | Indicative OPEX |
|---|---|---|
| Hatchery water skid | USD 30–100k | USD 0.05–0.15/kg |
| Mid-size RAS | USD 200–800k | USD 0.15–0.30/kg |
| Large RAS + effluent | USD 1–5M | USD 0.20–0.50/kg |
Indicative ranges only. Real budgets depend on site, regulations, redundancy and scope. Use for internal planning — always validate with an engineering study.
Major cost drivers
- Design flow
- Discharge regulations
- Species sensitivity
Optional equipment
- Denitrification reactor
- Effluent solids belt press
- Automatic pH control
Installation notes
- Requires ventilation and safety systems for ozone
Operating cost notes
- UV lamps and probes dominate
Maintenance reserve
- Budget 4–6% CAPEX/year
Procurement checklist
- 1Water analysis of source and target
- 2Discharge permit review
- 3UV/ozone dose specification
- 4Safety plan for ozone
- 5Third-party commissioning test
Supplier evaluation matrix
Score each supplier from 0 to 10 on each factor. Weights are pre-set with defensible defaults — override if your context differs.
| Factor | Weight | |||
|---|---|---|---|---|
Third-party validated dose | 25 | |||
Effluent guarantee | 20 | |||
Safety systems | 15 | |||
Parts availability | 15 | |||
Lifecycle cost | 15 | |||
Lead time | 10 | |||
| Weighted total | 100 | 0.0 | 0.0 | 0.0 |
Decision wizard
Frequently asked questions
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