Water treatment by membrane filtration

Water treatment with membrane filtration

Membrane filtration is often used as a post-treatment technique for effluent, usually in water recuperation or reuse. However, this technique is often used to treat specific wastewater and process waters, such as oil emulsions. 

Most filtration techniques can only filter undissolved particles from water. Microfiltration and ultrafiltration can only remove suspended particles from the pretreated wastewater. Consequently, dissolved salts, dyes, metal ions (which influence the conductivity of the water) and sugars remain in the wastewater. As a result, this water cannot be reused in the production process. Only reverse osmosis (RO) allows salts, metal ions, etc. to be removed.

Reverse osmosis allows for the highest degree of purification, physically, chemically, organically and bacteriologically. In waste water treatment, reverse osmosis technology is used for the production of ultra-pure water for industrial process water, nitrate removal, desalination of brackish and seawater, … .

Advantages  

  • Reliability of the materials
  • Fewer chemicals required
  • Relatively easy follow-up, once the installation is up and running
  • Efficient use of energy
  • No phase transition or change of aggregate state required

Disadvantages

  • Cost price of the membranes
  • Residual concentrated retentate must be collected or further treated

Application areas of membrane technology

  • Oil/water separation, treatment of lypophilic substances
  • Recycling of car wash water
  • Treatment of slurry
  • Treatment of wastewater from the cosmetics, food and beverage industry
  • Filtration of suspended matter from waste water
  • Removal of biomass
  • Separation of coolants
  • Separation of inks for flexo printing techniques
  • Reuse of process water
  • Rainwater recovery
  • Reuse of various effluents
  • Fluid degassing

Water treatment for the reuse of process and waste water

Reuse of wastewater and water recycling

Wastewater reuse - RO (reverse osmosis)

Water is becoming more and more expensive. Companies are paying more and more for the discharge of waste water. The need for maximum reuse of these wastewaters is increasing, especially for companies where water plays a major role in the production process (slaughterhouses, laundries, cosmetics production, food and beverage industry, textiles, etc.).

The use of an RO installation allows a substantial part of the wastewater to be reused in the production process. Your company can make considerable savings on water and discharge costs. Consequently, the investment can be recovered relatively quickly. Moreover, the operating costs are often significantly lower than the purchase price of tap water. Depending on the specific requirements of the customer, it is, for example, only one third of the purchase price of city water.

For each specific project, the feasibility is checked beforehand by means of efficiency and dimensioning tests on site. If necessary, a test installation is used. The final system is fully customised for the client. This is always in function of the type of wastewater, the intended quality for reuse and the economic aspects. 

The RO unit is mounted on a skid and forms a compact unit, easy to integrate in your existing water treatment plant. The RO unit is a fully automated unit, can be monitored and controlled remotely.

Process water degassing – water degassing – liquid degassing

Membranes can also be used for the degassing of water and liquids. The oxygen content of various process waters can thus be reduced to ppb level. In a degassing installation, the gases dissolved in the liquid are removed from the liquid by means of so-called membrane contactors. The gases that can be removed are not only oxygen but also CO2 and NH3. The degassing takes place under vacuum, with or without a stripping gas. 

Liquid degassing with membranes allows for a very compact installation, without major adjustment costs and/or space requirements for the client. Considerable savings can be made on operational costs. For example, an industrial nitrogen quality can be used instead of a pure (and more expensive) variant. This can save you a lot of money on an annual basis!

In an industrial environment, degassing membranes are mainly used in the following applications:

  • O2 removal in process water down to ppb level
  • CO2 removal from various process waters
  • Ammonia removal from various process waters
  • Removal of gases from beverages/liquids in the food industry
  • Corrosion control in industrial environments
  • Controlled carbonic acid and nitrogen addition to beverages

Projects