The External Principle

Industries worldwide are facing increasing challenges to reduce their environmental impact when it comes to the treatment of industrial process streams and wastewater. Many treatment systems and technologies currently available on the market are incapable of handling fluctuations in volume and concentration of effluent and wastewater streams. In addition, these systems are highly prone to fouling and cleaning is a time-consuming, costly and dirty process.

We at Berghof Membranes believe in external membrane filtration and it is the passion that drives us to “think outside the box”. The Berghof Membranes filtration systems are positioned outside the bioreactor and utilize variable crossflow velocity to keep the membranes working at optimal conditions. If necessary, this process is supported with permeate backwash (temporarily reversed permeate flow) or chemical backwash protocols. Tubular membranes are frequently applied in the external configuration because of the greater ease in cleaning, zero odor emissions and overall superior robustness.

The actual performance of the membranes is dependent on applied crossflow velocity, transmembrane pressure and sludge condition. Healthy sludge and clean biomass result in optimized MBR system performance. In this configuration, the permeate is obtained using pressures of 300-600kPa resulting in permeability between 50 and 150LMH at MLSS up to 30 g/L. Typical removal of COD is above 98%, reaching COD levels of 100ppm and lower. In addition, the Berghof Membranes external filtration systems average a mere 0.2 – 0.8 kWh/m³, thus delivering excellent energy efficiency.

Reducing Operating Costs

Berghof Membranes designed its external membrane filtration systems to help customers reduce costly energy consumption. Available in configurations to suit specific needs, the B-SMART membrane skids are equipped with advanced integrated software that enables the system to automatically adjust to varying feed conditions in order to operate at the lowest possible velocity and minimize energy usage.

The B-SMART system continuously monitors data in real time to control pump speed, backwash and cleaning frequency, thereby minimizing energy consumption, maintenance time and costs.

Minimizing Capital Expenditures

Berghof Membranes also offers simple-to-install and easy-to-operate B-SMART systems that help plant operators minimize upfront capital expenditures while optimizing system performance and operation.

In a typical tubular UF application, fluids (such as pretreated wastewater) flow through the tubular modules at a high velocity, sufficient to maintain a turbulent flow. At a typical transmembrane pressure (TMP) of 2 – 6 bar, the permeate stream is forced through the pores of the membrane while suspended particles remain in the retentate stream. The turbulent flow on the membrane´s surface prevents the build-up of particles on the inner surface of the tube, ensuring high flux and prolonged membrane lifetime.

Industries worldwide are facing increasing challenges in (waste)water treatment to reduce their impact on the environment. In order to stay cost-effective, most companies decide to treat their own wastewater. Therefore, many water treatment plants have been built, not only to reduce discharge costs to municipalities but also to reuse valuable effluent.

To meet these challenges, the interest in using membrane technology has emerged in wastewater treatment and process water production. However, there is the perception that membrane filtration has the disadvantage of membrane fouling and therefore consequently higher operating and membrane replacement costs.

Optimal fouling control with Berghof Membranes technology

Our well-established crossflow filtration technology keeps the membranes working at optimal conditions. The combination of intelligent soft- and hardware, continuously analyses the situation and responds automatically to varying conditions whenever this is required. Water quality and therefore fouling levels are bound to change during the process resulting in increasing Transmembrane Pressure (TMP)-values. The Berghof Membranes technology will respond to these changes automatically to prevent clogging of the membranes.

Automated cleaning

Our intelligent technology enables several cleaning procedures to automatically dissolve membrane fouling. The intelligent combination of variable crossflow velocity, backwashing, chemical enhanced backwash and cleaning in place makes our technology a revolutionary solution for the treatment of any effluent.

The Berghof tubular membranes are known for their rugged construction, long membrane life, high flux rates and easy cleanability. Our membranes are based on the inside-out filtration principle. Wastewater flows in an axial direction inside the tube and penetrates as clean water through the membrane wall to the outside, while the thickened concentrate is separated.

Unlike other wastewater filtration methods, this filtration principle is the single requirement for optimized fouling control. Ultrafiltration processes in industrial applications rely strongly on regular backwashing (outside-in) to maintain their performance. Permeate is used for the backwash in order to keep the membrane free of particles. With permeate the cake is removed from the pores and from the membrane surface.

As result, fouling is eliminated and membrane functionality and – lifespan are assured.

Practice has shown that cleansing of wastewater systems with chemicals that contain high pH values, produces the best results. A major disadvantage is that many polymeric membranes are not sufficiently resistant to highly concentrated alkaline detergents. This generally results in wear and tear of the membrane and associated inferior filtration performance. In addition to lower performance, the same applies at the expense of service life of the membrane.

With this in mind, Berghof Membranes have developed the “Chemical Resistant (CR)” membrane. The resistance to a wide variety of chemicals and pH values (1-13) means that our CR membrane is very suitable for applications with high strength wastewater or process streams. In addition, intensive cleaning with strong alkaline will not affect the quality of the CR membrane. The result is a long service life and optimal filtration results.

Cost-effective solution

The Chemical Resistant membrane of Berghof Membranes will go where no other polymeric membrane has gone. The relatively low costs, in particular, compared to ceramic membranes, means that our CR membrane is a cost-effective solution for high strength wastewaters and applications in which extensive cleaning is needed.

The treatment of wastewater can be very challenging. This is because of the fluctuations in wastewater composition. Traditional wastewater treatment systems are insufficient in handling high variations and peak loads in quality and quantity of industrial effluent.

These unpressurized membrane wastewater treatment systems tend to foul due to the low velocity of the effluent passing through the membranes. As result the membranes get clogged by solids, the result is poorer filtration quality, shorter membrane lifespan and eventually downtime in production due to membrane cleaning or replacement.

External principle

To find a solution for these drawbacks Berghof Membranes developed its external membrane technology, a crossflow filtration based approach.

One of the most important features of this pressurized Berghof Membranes technology is the self-regulating software. The aim of our wastewater treatment technology is to operate under any conditions at the lowest possible velocity, in order to minimize the energy consumption. Under regular flow conditions, the system will operate at a low velocity of 1.0 to 3.0 m/s, with an average energy consumption of only 0.4-1.2 kWh/m³.

Our goal is to treat the wastewater under all circumstances, independently of the feed flow and quality fluctuations resulting in constant permeate flow at any time. In order to achieve this, we have developed an intelligent system which continuously analyses the situation and responds automatically to varying conditions whenever this is required. This reduces the risk of shutdown or capacity-loss.

Less operator attention required

In order to keep filtration running at a low crossflow velocity, advanced self-regulating technology is applied. Each individual transmembrane pressure (TMP) is monitored and if fouling occurs the system automatically starts the cleaning procedure. Depending on the TMP values, the system selects one of the cleaning steps: increased crossflow velocity, backwash, chemical backwash or cleaning-in-place (CIP).

After completion of a cleaning step, the technology checks the TMP values again in order to ensure that the cleaning was successful. Built-in algorithms control and optimize the frequency of the cleanings, which results in reduced chemical costs and system downtime. All these improvements significantly reduce operational costs of running a wastewater treatment system.

In addition, less attention is needed from the plant manager or process operator. The combination of intelligent soft- and hardware makes the system less dependent on human intervention.

 Benefits of the external principle:
  • Easier operation, maintenance and replacement of modules
  • Higher flux rates (50-150 LMH)
  • Lower fouling potential
  • Reduced chemical usage due to extended cleaning periods
  • Modular “plug-and-play” design
  • Quick commissioning and increased flexibility
  • Zero odor emissions

“Our solutions do not only provide the best possible profit for our customers, but also  create a cleaner environment and a better future.”

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