Quantum leap in energy savings for MBR plants thanks to Membion JetSplash technology
June 20, 2023 – 11:45 a.m., Osnabrück
In recent years, membrane filters have been increasingly used for wastewater treatment in so-called membrane bioreactors (MBR). Compared to conventional wastewater treatment plants, they achieve significantly better water quality while requiring only about half the space. They also offer solutions to current problems in water treatment, such as microplastics, antibiotic-resistant germs, and pathogens in wastewater. However, a significant economic disadvantage of the technology is the high energy requirement for module ventilation to flush the membranes with air.
Basically, two different module designs are used in MBR systems: hollow fiber and plate modules. Both have different operational advantages and disadvantages. Hollow fiber modules require intensive pretreatment with lower energy requirements for membrane aeration. Plate modules require significantly less pretreatment, but generally consume more energy for membrane flushing. To partially compensate for the higher energy consumption, panel modules are often installed on top of each other in so-called double-decker configurations.
The company Membion has developed a novel membrane filter with hollow fiber membranes that combines the advantages of plate and hollow fiber modules through a novel rinsing technique: low energy consumption with minimal pretreatment effort (Vossenkaul et al, 2016), (DBU-VORHABEN, 2019), (DBU-VORHABEN, 2021). An essential component of the new flushing technology is a patented geyser ventilation system with JetSplash® technology. In this process, an air reservoir below the membranes is continuously filled with air and then suddenly emptied after filling. This results in powerful air pulses that are introduced into the module below the membrane bundle. Since the membrane bundles are each surrounded by a rectangular tube that connects directly to the geyser element at the top, the air pulse that suddenly flows out of the geyser element causes the entire liquid column surrounding the hollow fiber membranes to accelerate vertically upward within one and a half seconds. This acceleration has a much more intense and effective flushing effect on the membranes than the air bubbles themselves. This significantly reduces the amount of air required for flushing and thus the energy consumption. Due to the high effectiveness of the rinsing process, the usual backwashing of the membranes with generated filtrate (permeate) is no longer necessary, resulting in higher overall yields and smaller membrane areas.
As part of an SME innovation project funded by the BMBF (Federal Ministry of Education and Research) called “Double Membion” (02WQ1549A-C), the first practical test was carried out on a further development of the single-decker module into a double-decker module configuration. The aim of this project was to replace the existing energy-intensive plate modules at the Konzen wastewater treatment plant with a more energy-efficient and compact solution from Membion in one of the plant’s eight existing streets. In Membion’s patented double-deck module, the advantages of JetSplash® technology are transferred to a concept in which two membrane elements are installed above a geyser element. This allows the existing basin depth of the double-deck slab modules to be fully utilized.
Due to the higher packing density of the Membion modules, only two of the nine membrane stations in the membrane line were needed to install the double-deck modules, resulting in a space saving of more than 75%. If all eight membrane lines were replaced with Membion modules, only two of the existing eight membrane basins would be sufficient for the installation of the entire membrane area (23,200 m²). The membrane basins of the other six streets could then be used to optimize or expand the biological stage.
The Membion modules have been running since spring 2021 without additional pretreatment in normal wastewater treatment plant operation and demonstrate savings in energy consumption for air purging of the membrane modules of up to 90%. Neben dem Vorteil der Energieeinsparung und der damit verbundenen Betriebskosten-Senkung fallen auch die Gebläse und die zu installierenden Rohrleitungen und Aggregate deutlich kleiner aus, was zusätzliche Einsparungen bei den Investitionskosten bedeutet.
Membion’s technology contributes to environmental protection through its significant energy and resource savings, which is becoming increasingly important in light of the law recently passed by the German Bundestag on climate neutrality by the end of 2045. Who, if not the local authorities, could and should have an interest in making progress here?
