Alternatives to plastic bead media – can you help?

21 September 2021

Challenge update Spring 2022:  Take a look at our latest blog post for this challenge.

Wessex Water has a number of Biological Aerated Flooded Filter (BAFF) plants that utilise buoyant plastic bead media for wastewater treatment. There is an inherent risk of plastic loss to the environment given the media floats and can be gradually abraded over time. Abraded micro-plastics are able to evade the containment systems installed to prevent plastic loss.

Our long-term strategy is to replace buoyant plastic bead media and we are interested in alternative approaches to facilitate this.


The BAFF process was favoured in the 1990s to early 2000s due to the ability to install high-capacity treatment assets within a small footprint through the use of a single asset to undertake both biological treatment and solids separation.

Our long-term strategy is to replace the plastic bead media used by our BAFF plants.

This Marketplace challenge is a high-level enquiry to help identify any potential options for further consideration. This could be by using an alternative media, or a different treatment process entirely, where possible utilising existing structures.

Identifying an alternative to the BAFF process presents a challenge as most traditional solutions require separate assets for both biological treatment and solids separation. The additional footprint for these assets is difficult to accommodate on existing sites.

As and when the BAFF plants are decommissioned, there will be a significant volume of used media for recycling/disposal. Therefore, we would also be interested in potential applications to recycle used media.

What are we looking for?

We are looking for any ideas that will facilitate us replacing the plastic bead media in our BAFF plants. Submissions may therefore be:

  • Established alternative technologies (high treatment capacity and small footprint)
  • Emerging/innovative technologies for further development (again, high treatment capacity and small footprint)
  • Alternative media for use within a BAFF plant (either proven or requiring further development)
  • Applications for reuse/recycling of waste media

Utilising existing structures would be advantageous.

Given the concern over micro-plastic loss, any submissions should take account of this – i.e. plastic-free, or provide supporting evidence of why micro-plastic loss is not a concern.

Detailed information on individual sites will be provided for a site-by-site evaluation of any submissions taken forward (i.e. at the next stage, not as part of the initial enquiry), but a high-level summary is given below.

Site Max. Flow (l/s) Volume of media (m³) Treatment provided
A 600 2,000 Carbonaceous
B 1,200 1,500 Carbonaceous
C 11 40 Nitrifying

How to get involved

We are very happy to answer any queries you may have in order to consider responding. Please send queries to by Friday 8 October. We will respond to them all here (unless there are questions that wouldn’t be appropriate to share answers to that may relate to the specific IP of an organisation).  (19.10.21. Update: No queries received; we look forward to seeing submitted proposals next month.)

We then ask for interested parties to submit their proposals by Monday 8 November. Please email them to

We ask that submissions are concise at this stage to give our team the ability to review all that come through. Submissions should ideally include the following, where this is available:

  • What is your suggestion – i.e. is it facilitating bead media replacement, or is it recycling used bead media?
  • Details on the technology proposed:
    • Type of technology/media
    • Example details:
      • typical proposal drawing
      • typical Pipeline and Instrumentation Diagram
    • High-level overview of capabilities:
      • Effluent limits achievable
      • Flow rates achievable
  • Indicative costs (e.g. previous schemes/case studies, or typical unit rates)
  • Case studies of any UK/worldwide installations
  • Your expertise in this area
  • Any research and development planned/required to bring to market

We look forward to hearing from you!


Next steps

We will review all the submissions and see if there are any we would like to discuss and explore further, and feed back to companies accordingly. We’ll aim to get back to you by early January but will keep you informed if further time is needed. We also intend to feed back more generally on the challenge via our blog page.

If you want to hear about other Marketplace challenges over a range of areas when they are released you can sign up to our mailing list.

Important points

Taking part in this Marketplace challenge does not guarantee a contract at the end. A tender may be required, and Wessex Water reserves the right to stop the project at any time.