Membrane Technology in Biological Wastewater Treatment
The high performance of membrane technology has been proven in recent years in
a wide range of fields, such as chemical industry, medical technology, drinking water treatment, biotechnology and environmental technology. The German work
groups of the DWA (ATV-DVWK 2000a, b, 2002a, b; DWA 2005) have provided excellent reports on the application of membranes in the field of wastewater treatment. Also, the Chemical Engineering School at the RWTH Aachen has provided
important knowledge of fundamentals and applications in the whole area of membrane technology (Rautenbach and Albrecht 1981, 1989; Melin and Rautenbach
The continuous development of membrane materials and membrane design on
the one hand and the knowledge of operational management on the other hand
have fostered the growth of membrane technology in wastewater treatment. Many
questions have yet to be answered, however, especially in activated sludge systems:
• How can we best implement membranes in activated sludge systems?
• Do we need primary settlers if we use a membrane activated sludge process?
• Which membrane modules and operating modes are effective and energy efficient?
• Is it possible to perform nitrification and phosphate elimination in combination
with membrane processes?
The number of membrane processes installed for the treatment of municipal
wastewater is rather low but steadily increasing. In Germany, several large membrane processes for wastewater treatment plants (>11 000 inhabitants) are in operation or being planned (MUNLV 2003). The largest one (for 80 000 inhabitants;
about 1900 m3 h–1) has been in operation since 2004 in the wastewater treatment
plant (WWTP) at Nordkanal (DWA 2005). The biggest industrial membrane process in biological wastewater treatment for a flow rate of about 200 m3 h–1 has been
in operation near Dortmund since 2004 for the treatment of wastewater from the
pharmaceutical production plant of Schering AG (Achtabowski and Neuhaus