The client challenge
ROCS, an NGE subsidiary specialising in maritime and port works, was in charge of a port quay renovation project in Mayotte. To concrete the structures, the company needed large quantities of water — but in an island territory like Mayotte, the drinking water network is fragile and under heavy pressure.
The challenge was twofold:
- Not impacting Mayotte's water network, already in deficit, by drawing large quantities of water for industrial use
- Producing water compliant with NF EN 1008 standard for concrete mixing water, which imposes strict requirements on physicochemical quality (pH, chlorides, sulphates, suspended solids, etc.)
The only resource available in abundance without impacting the local network was seawater. ROCS therefore needed a compact, transportable unit capable of desalinating seawater to produce NF EN 1008-compliant mixing water, in full autonomy on the construction site.
Nomado was commissioned to design, build and commission this bespoke unit.
The Nomado solution
Nomado designed and deployed a compact reverse osmosis desalination unit, fully integrated in a 20-foot DRY container, complemented by a 50 m³ flexible bladder tank. The complete system was designed to be transported and operated in an island environment, without any support infrastructure.
Our approach combined compactness, NF EN 1008 normative compliance and full operational autonomy on an isolated maritime construction site.
Reverse osmosis desalination process
The unit produces 500 l/h of NF EN 1008-compliant mixing water from seawater, through the following treatment chain:
Multi-stage pre-treatment
- Disc filtration: removal of coarse particles and floating debris from raw seawater
- Sand filter: downstream protection by removal of fine suspended solids and residual turbidity
- Microfiltration: final barrier before the reverse osmosis membranes, removing colloids and micro-organisms that could foul the membranes
Desalination by reverse osmosis
- Reverse osmosis membranes under 55 bar pressure: removal of dissolved salts, chlorides, sulphates and other ions incompatible with NF EN 1008-compliant concrete production
Post-treatment and pH correction
- Final pH correction: adjustment of the physicochemical characteristics of produced water to guarantee full compliance with NF EN 1008 standard
Format and logistics
- 1 × 20' DRY container: integrating the full treatment chain, transportable by sea to Mayotte
- 1 × 50 m³ flexible bladder tank: buffer storage of produced water to supply the construction site continuously, independently of the unit's production schedule
Results achieved
- 500 l/h of mixing water compliant with NF EN 1008 produced in full autonomy from seawater
- Zero impact on Mayotte's water network: the ROCS port construction site drew no water from the already-deficit local infrastructure
- Compact containerised unit, transported and commissioned in an island environment without support infrastructure
- Controlled investment, scalable system and regulatory treatment solution
