More good science, good engineering, and good news coming out of the ongoing programme of work on slow sand filtration (SSF) by Dr Francis Hassard and colleagues at Cranfield and Thames Water. The latest paper on their new underwater cleaning technique reports improved removal of Cryptosporidium oocysts in comparison with conventional ‘dry’ surface cleaning. Quantitative microbial risk assessment also indicates a substantially lower probability of disease from oocyst contamination when the novel cleaning system is used. Combined with the reduced filter downtime, this makes the new technique a significant step towards increasing the performance of the original nature-based technology. The water industry is likely to be paying particularly close attention to the Cryptosporidium results given the recent challenges this pathogen has caused with over 100 cases of Cryptosporidiosis and four people hospitalised in Devon in May 2024.
The WG’s animation on the SSF process is available HERE (subtitled version here). For details of other related publications, and of the WG’s activities to March 2026, see the updated WG Report which is also available on the WG webpage.
Dr Hassard, the WB WG Lead, said: “EBNet’s formal UKRI funding has now ended, but I’m delighted to say that the WG’s activities are now continuing through the Better Water 4 All Network+. EBNet members interested in this area are invited to sign up for the Better Water 4 All mailing list. EBNet will also continue to post occasional News items on new developments in this exciting area”.
Dr Hassard is a Co-Investigator in Better Water 4 All and in the EBIC Hub which is also carrying out ground-breaking work on innovative water biofilm-based treatment technologies.
Evaluating Cryptosporidium oocyst removal in SSF: Impact of underwater skimming and dry skimming. Bretagne, S.L., Chipps, M., Doggett, I., Bradwell, M.C., Hardiman, H., Harris, J. and Hassard, F., 2026. Journal of Environmental Management, 397, p.128062.
https://doi.org/10.1016/j.jenvman.2025.128062
