Reverse Osmosis / Nanofiltration Systems

RO and NF remove soluble components of the wastewater that are not removed by the primary treatment. In most cases the purified water is reused.

Reverse Osmosis skid 

 

Our Approach

Dynatec uses reverse osmosis membranes to remove dissolved elements.  Typically, the wastewater has been treated with other processes such as ultrafiltration before it is introduced into the Nanofiltration or Reverse Osmosis membranes.

Reverse osmosis is capable of rejecting soluble constituents of aqueous streams such as bacteria, salts, sugars, proteins, a wide range of organics and color. The separation of ions with Nanofiltration (NF) and Reverse Osmosis (RO) is aided by charged particles. This means that dissolved ions that carry a charge, such as salts, are more likely to be rejected by the membrane than those that are not charged, such as organics. The larger the charge and the larger the particle, the more likely it will be rejected.

 

The Technology

Available in Various Molecular Weight Cut-Offs. Reverse Osmosis (RO) allows the separation of particles as small as ions from a solution. Reverse osmosis is used to purify water and remove salts and other impurities in order to improve the color, taste and properties of the fluid. It can be used to purify fluids such as ethanol, which will pass through the reverse osmosis membrane, while rejecting other ions and contaminants from passing. The most common use for reverse osmosis is in purifying water. It is used to produce water that meets the most demanding specifications.

Reverse osmosis (RO) uses a membrane that is semi-permeable, allowing the fluid that is being purified to pass through it, while rejecting the contaminants that remain. Most Nanofiltration (NF) and Reverse Osmosis (RO) systems are operated in crossflow to allow the membrane to continually clean itself. As some of the fluid passes through the membrane, the rest continues downstream, sweeping the rejected species away from the membranes. The processes of Nanofiltration (NF) and Reverse Osmosis (RO) require a driving force to push the fluid through the membrane, and the most common force is pressure from a pump. The higher the pressure, the larger the driving force. As the concentration of the fluid being rejected increases, the driving force required to continue concentrating the fluid increases.

Various grades of Nanofiltration (NF) and Reverse Osmosis (RO) membranes are available, from low rejection/low pressure membranes to "Sea-Water" membranes which operate at relatively high pressures but also have the highest rejections of salt (sodium chloride).

 

Wastewater Reverse Osmosis Systems

Dynatec specializes in reverse osmosis systems designed to treat wastewater. This differs significantly from other RO systems that are often designed to treat potable water only. The design features allow the system to be controlled to accomodate the variable characteristics and minimize reject volume and minimize fouling.

 

Internal Recycle

By employing an internal recycle we are able to maintain the minimum flow requirements for the membranes, and obtain high recovery percentages.  Recovery can be as much as 98% with the RO system, depending on wastewater characteristics.

 

Wastewater Elements

Dynatec uses membranes that are designed to treat wastewater with residual COD, which is the primary foulant in wastewater RO systems. These membranes resist fouling in wastewater applications where other membranes may fail.

 

Integrated CIP

The membrane skid has an integrated clean-in-place (CIP) system on the skid. This is especially important for wastewater reuse systems because the cleaning frequency of the skid is often higher than in other RO applications. With an integrated CIP system, cleaning is fast and easy, minimizing the operator’s time.

 

High Quality Controls & Instrumentation Package

Dynatec uses instrumentation with analog signals such as flow meters and pressure transmitters where others often use pressure gauges and manually read flow meters. This along with PLC operation improves system performance, and allows the system to be monitored remotely, again minimizing operator involvement in the system operation.

Information Sheets