Experiences with rotating ultrafiltration membranes in MBR-applications in Germany and Indonesia

Abstract

Submerged Membrane Bioreactor Systems convince clients all around the world with their outstanding effluent quality (outflow is nearly free of all bacteria and germs), the compact design and the opportunity to realize the waste-water-treatment at very limited space. One of the latest developments in the MBR market is a technique with rotating flat-sheet-ultrafiltration-membranes − a unique design which focuses especially on reducing energy and overall operation costs. This system − called VacuumRotationMembrane − consists of trapezoidal membrane plates which are arranged around a hollow shaft. Within this hollow shaft the membrane scouring system is located. The scouring air demand (flow) and the introduction depth of the air is significantly reduced, the key to realize economic MBR-systems. This system has meanwhile been implemented in more than fifty installations world-wide, both in field of municipal waste-water-treatment and various industrial applications, e. g. in meat processing, textile- and beverage-industry, mostly with downstream recycling of the treated waste-water. One of the biggest installations so far is the municipal waste-water-treatment plant in Hutthurm, a small city in the eastern part of Bavaria. Since mid of 2008 there are 3 membrane-units with nearly 10.000 m² membrane area installed, treating max. throughputs of 220 m³ per hour at minimum water temperatures around 5 °C. As there are big breweries connected to the sewer-system the waste-water-composition is characterized by big variations especially between workdays and weekends. Therefore the design and operation requires special attendance. This special characteristic implicates impacts both on the biological system and the membrane filtration, what leads to temporary deterioration of the biological- and in follow also the membrane-performance. Therefore intensive research- and optimisation time followed after the initial start-up of the system. During this period the quality of the biological system was monitored continuously and the significant correlation between deterioration of the membrane performance and the upcoming of increased SMP's (soluble microbial products) in the supernatant of the mixed liquor was proven. Actually the special meaning of Ca/Na-ratio in the activated sludge, it's variation during different inflow scenarios and the consequences for the membrane-performance is under investigation. First results will be available end of this year. Since mid of 2009 a waste-water-recycling-plant is installed at a shopping-mall in Jakarta/Indonesia. This plant treats the waste-water of the shopping-complex and a decicated Hyatt-Hotel and produces service-water for the cooling of the air-con-towers. The two membrane units with a total membrane-area of nearly 4.500 m² membrane area are treating the waste-water, up to a quality which is free of particles, bacteria and nearly all viruses. The plant is dimensioned for daily throughput of 2.200 m³. During the meanwhile more than two years of operation-time the plant shows continuously perfect effluent-quality and simple operation. Beside this plant, there are another four MBR-plants established in Indonesia (municipal and industrial), each plant serving both waste-water-treatment and service-water for different purposes. Nearly all worldwide MBR-installations show, that the special focus and attendance on the biological-process and the overall plant-concept is extremely important for the successful realization of MBR-applications. If the complete process will not be paid deep attention during design, the consequence is always a malfunction of the membranes and therefore of the complete system. Where conventional-treatments systems ‘react’ only with worse effluent quality, MBR-systems can fail completely. Thus the consideration of the complete and exact plant-lay-out is a matter of extreme importance and must be supported either by the membrane-manufacturer or the project-consultant. During the conference the experience of mentioned plants in this matter will be given.