Skip to main content

A Comparison of Municipal Activated Sludge Treatment with Membranes

Buy Article:

$17.50 plus tax (Refund Policy)

Or sign up for a free trial


The use of membranes is growing in popularity as a means of treating municipal wastewater. Typically, membranes are added-on to an existing wastewater treatment process or may be considered in the design of a greenfield plant. In either case, many times the unit processes are designed independent of one another, which can lead to higher costs of ownership.

The most recent improvements to the Fountain Hills Sanitary District WWTP in Fountain Hills, Arizona included, among others, upgrades to the existing activated sludge process, the addition of cloth media filters and a microfiltration system. Each unit process was provided by an independent supplier. Currently, a Multiple Barrier Treatment Process (MBTP) is available that integrates biological treatment with cloth media filtration and membrane separation. This MBTP takes advantage of the intimate knowledge of the interdependence of the unit processes to provide effective treatment at the lowest cost of ownership.

The biological process design of the MBTP can be customized to meet the treatment objectives. The separation of aeration and mixing results in process optimization. Another key aspect of the MBTP is the marriage of cloth media filtration and microfiltration. The pile cloth media has unique characteristics that allow high solids loading while maintaining a consistent effluent quality that is low in TSS and turbidity. Because the effluent from the filter is consistent regardless of fluctuations in influent solids loading, it has proven beneficial to the operation of the hollow fiber microfiltration process as membranes perform optimally on feed streams containing low solids and minimal loading variations. A resultant savings in membrane surface area of 50% to 80% can be realized.

The consistent, high quality feed to the membrane process allows the membranes to operate at flux rates that are much higher than those typically realized on secondary clarified effluent or direct mixed liquor filtration. In addition, because the cloth media filters are able to meet strict effluent reuse objectives as a stand-alone process, they offer additional flexibility to the plant operator in terms of redundancy and point of discharge.

Capital costs are reduced, mainly because of the significant reduction in membrane surface area. The trade-off between cloth media and membrane surface area also serves to dramatically reduce operating costs. Further reductions in operating costs result from the separation of aeration and mixing in the biological reactor portion of the process.

Document Type: Research Article


Publication date: 2003-01-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more