Challenge update Autumn 2021: A good selection of responses received from enhancements to existing process systems through to new and alternative technologies. In the short term we have agreed to proceed with the adoption of a software monitoring tool to optimise current operation of the ion exchange plant. We will maintain an active watching brief on other proposed solutions including improving efficiencies by trialling different regeneration chemicals, repurposing of existing chemical to provide a reusable waste stream and potential membrane technology as an alternative to ion exchange. All of these suggestions arose from the Marketplace challenge.
*Deadline extended to Friday 18th September*
Are there alternative ways to utilise waste brine from our ion exchange plants?
Wessex Water has three ion exchange plants across our region allowing us to remove nitrates from high nitrate water sources when options such as catchment management or blending aren’t available to us.
One of these sites in the Blandford area has increased its output over the last 2-3 years, and as a result the sewage works that has historically received the waste brine from the plant (a high-salinity plus nitrate liquid stream) is struggling to treat the volume of brine fed to it. We are tankering some of this currently waste liquid away, but the financial cost, as well as the carbon and environmental impact, of this approach has led us to question whether there are alternative options available.
We would therefore like to run a marketplace challenge to understand whether there are any opportunities to either dispose, or make use of, this brine in a more sustainable and efficient way, and invite the market to feedback with any ideas or opportunities they may have.
What are the options?
We think there are three distinct categories of options (but may be surprised – if you think there’s another please let us know!):
- Optimising our current process – On-site salinity reduction – are there treatment processes that we could ‘add on’ to the end of the ion exchange plant that may reduce the salinity of the brine for the sewage works, allow it to be recycled back into the plant itself or creating a useful waste stream?
- Please note circa 10 years ago we looked at on-site options to reduce salinity post ion exchange. At that point in time they weren’t cost effective. We can’t share the technology we reviewed so as not to be disparaging of a particular process, but would be looking for recent innovations in this area rather than a proposal of options that have been around for a while.
- Collaborating more widely – Alternative brine uses – are there opportunities to use this brine rather than dispose of it as a waste product? We can’t share the exact location of the water treatment works, but it is in the Blandford area.
- Building smarter – Future technologies – although this isn’t going to resolve our issue at Blandford in the short term, in the future we may need to look at whether more nitrate removal plants are required at water treatment works. If you have a technology that provides an alternative to ion exchange (or a novel addition to ion exchange that reduces the brine strength) we’d be interested to hear about them so we can factor them into future site considerations.
Ideally we’re looking for something with a relatively low capital investment required (from Wessex Water at least) as we have no capital investment allocated for this site in our investment plan for 2020-25; we are primarily looking to reduce the operating costs. However, that is not to say that we will not consider it should an opportunity present itself with a capital spend element to it, but rather managing expectations that investment upwards of £1m is unlikely to be viable for us without a wider revenue stream to offset the cost (and even at £1m it would need careful consideration and cost benefit review).
The technical details
Our current modelling suggests that the brine waste will have the approximate concentrations shown below:
| Nitrate 19,000 mg/L |
| Sulphate 4,100 mg/L |
| Chloride 47,900 mg/L |
| Bicarbonate 8,700 mg/L |
| Sodium 43,700 mg/L |
The daily volume is typically around 14-18m3 per day depending on the output of the water treatment works.
How to get involved
For this challenge we’re not looking to hold an information session, but are more than happy to answer any queries you may have in order to consider our challenge; please do send queries through by the 11th August and we’ll respond to them all here (unless there are questions that wouldn’t be appropriate to share answers to that may relate to specific IP of an organisation).
*September update* – Query responses now available here, with supporting data in a further PDF file and an Excel file.
We’ll then ask organisations to send in their suggestions by the 18th September, at which point we will review and see if there are any we’d like to discuss further. We’ll then feedback to the companies who submitted options, as well as more generally on the challenge via our blog, and continue to explore any possible opportunities with those who have options we’d like to explore.
We’ll aim to get back to you by mid-October, but as ever with our challenges if we see a particularly high submission rate (it varies across challenges and we have done our best to estimate) we may need to review the time needed; we’ll keep you informed.
What to include when sending in your suggestion?
We ask that submissions are no longer than 8 pages to give our team the ability to review all that come through. Please ensure you cover the following:
- What is your suggestion? An on-site opportunity, collaboration with a local trader, or long term process option?
- Any indicative financial information – capital and operating costs including for example power or chemical use, asset costs, set up costs for collaborations
- Any key operational information – e.g. are there tankering requirements for a collaborative approach or a pipeline connection required?
- If there are examples of it in practice elsewhere in the world
- Your expertise in this area – is this something you’ve delivered before?
Please send your suggestions to marketplace@wessexwater.co.uk. We look forward to hearing from you!