Fluence has extensive experience in designing and manufacturing reverse osmosis (RO) systems, which are used in desalination and many other water purification processes. RO uses a cross-flow membrane separation process that can reject macromolecules and dissolved substances in a solvent, usually water. Substances retained in the separation discharge stream may be organic or inorganic, and generally have a size of a few angstroms. Separation depends on molecular weight, geometry, load, and other factors.
Some applications of RO include:
- Seawater desalination
- Rejection of boron >95%
- Elimination of bromides
- Recovery of RO concentrate with high TDS
- Reuse of effluent water
- CIP water recovery
There are several types of reverse osmosis membranes available on the market, including high-rejection, low-pressure, fouling-resistant, and heat-sanitizable. Choosing the right type and number of membranes for a project depends on both the quality of the water to be treated and the required quality of the finished product (permeate).
Due to variations in quality, it's generally necessary to condition feed water to maximize the life of the membranes, and to avoid clogging, encrustation, or degradation.
Fluence works closely with the manufacturer to ensure the most effective membrane is used in the best technical solution. Some of the competitive advantages of Fluence’s RO systems include:
- Skids built entirely in stainless steel
- Lowest concentrate rejection in the market
- Process reliability
- 24/7 after-sales service
- Low operating cost
- Longer life of filter elements
- Best-in-class pretreatment for high-SDI content
- Preventive maintenance that maintains and improves performance of membranes
At Fluence, our engineers have developed some of the most efficient and cost-effective reverse osmosis systems on the market. Here are a few of our innovations in reverse osmosis.
Membranes Sanitized With Hot Water
In response to requests from our food and beverage customers, Fluence has developed a reverse osmosis system specifically for food applications, where sanitization plays a critical role.
In addition to standard configuration (built-in CIP, permeate rinse, noninvasive accessories), we’ve significantly improved maintenance tasks with reverse osmosis membranes that can be sanitized with 85ºC water – without the addition of biocides. The sanitization cycle can be sustained for 60 to 90 minutes each without damaging the element.Reverse Osmosis Cases With Clamp Connections
As a response to market demand, we now offer the possibility of configuring high-pressure piping systems with clamp connections for both the concentrate and the permeate parts of the system.
This makes it easier to prevent contamination after cleaning cycles.Power Recovery
Fluence designs, manufactures, and maintains a large number of seawater desalination plants. In the constant pursuit of the best choices for our customers, our engineering department has developed a wide range of energy recovery solutions.
In a seawater desalination plant that uses reverse osmosis, energy consumption is the highest operating cost, making up about 40% of the total. Up to 65% of this is used by the high-pressure pumps. Much of this energy is stored as potential energy in the pressurized concentrate of the final stage of reverse osmosis.
Energy recovery units capture the energy from pressurized concentrate with solutions that include turbo chargers (centrifugal recuperators) and pressure exchangers (isobaric recuperators, or PX).
- In a turbo charger, the pressurized concentrate drives a turbine, which in turn drives a centrifugal pump that acts as a booster. Efficiency of these units varies with flow rate, reaching a maximum of 70%.
- PX transfers the high pressure of the brine to the low-pressure, pretreated inlet water. This has an efficiency rate of up to 98%. The discharge pump must pressurize a lower flow of water, equivalent to the product flow rate. This, combined with its high efficiency, makes PX the best solution for maximum energy savings.
The use of energy recovery units can reduce energy consumption by 30% for turbo chargers, and up to 45% for PX. These systems work with smaller high-pressure pumps, which means lower energy consumption in new plants and refurbished existing plants. A speed variator can be incorporated into the recovery system for even greater efficiency.