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Understanding the sanitising efficacy of a new, environmentally friendly hot tub water treatment product, eco3pa

Key Information

Supervisors: Dr Geertje van Keulen, Dr Chedly Tizaoui, and Dr Chris O. Phillips

Industry Supervisors: Mrs Anne Knight and Mr Andre Knight (SureSpa Ltd)

Surespa Ltd launched an innovative, active oxygen based hot tub water treatment product, eco3spa, onto the market in February 2019. Since the product launch online sales have increased very rapidly and dealers have been recruited throughout the UK, France and now Germany. The popularity of the product stems from the fact that it is free of both chlorine and bromine, which are bad for the environment and frequently cause unpleasant odour and skin irritation. Additionally, there is no need to continuously test the water and balance the total alkalinity and pH, as is required when using chlorine, thus making the hot tub significantly easier to maintain.

Domestic hot tub water typically remains in the tub for 3 months, so adequate and ongoing sanitation is crucial. It is important that independent and validated test data is available to prove that a product is effective and safe for use.

eco3spa comprises three components:

  1. A non-hazardous, environmentally friendly Step 1 Cleaner which removes biofilm from the pipework prior to initial use.
  2. A Step 2 Conditioner, which contains surfactants, coconut extract, a pH stabiliser and enzymes. This is added to the hot tub monthly to soften the water and maintain water clarity.
  3. Step 3 Active Oxygen Sanitiser Tablets which are added to the water when the tub is initially filled and prior to each use to kill harmful bacteria.

An MSc research project was conducted at Swansea University during 2019/2020 to look at the sanitising and biofilm control efficacy of eco3spa with positive results. This  research confirmed that the Step 3 Active Oxygen Tablets perform at least as well as chlorine in killing common contaminants, Escherichia coli and Pseudomonas aeruginosa, at a range of relevant water temperatures and pH values, validating the assertion that constant pH balancing is not required when using the product. The study also looked at the effect of the Step 2 Conditioner on the performance of the active oxygen and appeared to show that, although the Conditioner didn’t reduce live bacterial replication it did appear to make the cells clump and switch to a viable but non-culturable state.

This new study will build on the previous research to further study the performance of active oxygen as an effective sanitiser over a period of time after it is added to the water and to look in much more detail at the role the Water Conditioner plays in the sanitation process.

Project Aims:

  1. To determine the time dependency of how quickly the Step 3 Active Oxygen Tablets kills/inactivates living bacteria and how long after first and follow-on applications the active oxygen remains active in the water.
  2. To benchmark time dependency and residual activity of the product against chlorine.
  3. To (bio)chemically and microscopically analyse the Step 2 Water Conditioner to clarify the constituent parts and the effect (if any) of each of these chemical and enzyme components on the efficacy of the active oxygen in both killing/loss of viability of bacteria and preventing biofilm formation at a range of pH values and temperatures, as well as determine their effect on cell clumping and water clarification.

The Materials and Manufacturing Academy (M2A) in the College of Engineering is a Swansea University initiative which provides postgraduate research training in partnership with industry; providing access to world-class laboratories and a wealth of academic and industry expertise. 

The M2A is committed to providing top quality research opportunities within an inclusive environment, funded by the Welsh European Funding Office (WEFO), the Engineering and Physical Sciences Research Council (EPSRC), Swansea University and Industry partners. 

Sponsoring Company SureSpa Ltd
Company Website Eligibility

We welcome applications from candidates with an honours degree in biochemical engineering, biochemistry or microbiology (minimum level 2:1), or a combination of degree and equivalent experience to the same level.
Normally, we would expect candidates to have met the University’s English Language requirements (e.g. IELTS 6.5 overall with 5.5+ in each component) by point of application.
Full eligibility can be found at https://www.materials-academy.co.uk/eligibility



Fees at Home / EU rate and Stipend £12500, both for the period of one year.
For full details on funding eligibility, please refer to the Materials and Manufacturing Academy (M2A) Website.
Due to funding restrictions, this scholarship is not open to ‘International’ candidates.

Closing Date 29 January 2021

Start Date October 2021

Apply Now

Informal enquiries about this studentship are welcome and may be directed by email to: M2A@swansea.ac.uk