A Question to ... Experts Answer Current Issues in Filtration Technology
You need a technology that filters highly and low-viscous media or removes pharmaceutical residues in drinking water? You want to know, how to reduce the energy consumption of membrane bioreactors in wastewater treatment? Prior to this year’s Filtech (October 22–24, Wiesbaden/Germany), the largest filtration event worldwide, PROCESS asked manufacturers of filtration technologies.
Mr. Lamparter, in wastewater treatment the energy demand and susceptibility of membrane bioreactors are higher compared to sedimentation. How can plant operators handle these problems?
“The best way to reduce the energy consumption is to use the membrane bioreactor system only when needed. This fits perfectly with the modular structure of MBR systems. With an intelligent control system a MBR plant is able to operate only as many lines as needed according to the actual inflow. Then every line can be operated on high flux rates and will relax when the next line takes the load. Only in cases of peak flow all the lines have to be in operation.
Additionally higher flux rates can be achieved with more sophisticated methods of cleaning. Microdyn-Nadir developed the patented Mechanical Cleaning Process for Bio-Cel. Applying this the performance is on a constant high level, because of no fouling on the membrane. This again reduces the energy demand. These actions also reduce the risk of scaling.”
Mr. Strasser, which technology is the most appropriate filtration method for highly viscous media?
“We recommend filters of the Lenzing Viscofil series. These are specifically designed for the usage of a metal fiber fleece, which consists of a multi-layer structure of sintered 2 µm stainless steel fibers. Especially suited for retaining soft gel particles with low pressure losses, this filter material is also characterized by high separation rates and an enormous dirt holding capacity. The filter reaches absolute filtration rates of up to 3 µm. The metal fiber fleeces can be cleaned as much as 100 000 times by a fully-automatic backwash procedure with internal process medium.“
Is it possible to use these filters for medium to low-viscous media?
“For those applications we have developed the patented Lenzing Optifil. At first glance, this filter system operates similarly — but it differs in detail. The automatic cleaning processes are executed in such little time, that the filter area is regenerated only after 3 seconds. Both filter types require small backwash quantities while achieving fine filtration rates — in individual cases even down to 1 µm. This saves money by either lower product losses of easier reject recovery if needed. By the high degree of specialization, we reach a filter fineness of 10 µm of less than 90 % of our applications.”