A warm welcome for two new papers related to the work of EBNet’s Water Biofilms WG and to wider aspects of Theme 2.
The first is a review of factors affecting removal of Cryptosporidium and other protozoal oocysts in slow sand filtration (SSF). Removal rates vary widely, and the review identifies key processes including oocyst degradation or sequestration following by invertebrate ingestion. Integrating physical straining and predation may improve performance, while encouraging selected meio- and microfauna may also help, although the evidence base is still limited. The review concludes that future research should focus on elucidating the fate of excreted oocysts under realistic field conditions, and identifying optimal parameters to maximize net removal.
Dr Francis Hassard, corresponding author on the paper, said “This review provides a valuable underpinning to our ongoing work on SSF”. For more details on this, see the Water Biofilms WG News tag.
The second paper moves on from SSF to a study of a particular variant of the coliform Serratia fonticola which appeared to be adapted to survival within a water treatment works. Findings suggest its persistence was facilitated by physical shielding, rather than any intrinsic chlorine tolerance. The presence of a specific plasmid in nearly all isolates suggested this may confer traits enhancing chlorine resistance and promoting survival within biofilms. The authors suggest that optimising filtration, minimising floc carry-over and appropriate biofilm control or removal strategies may be key to preventing the appearance of this opportunistic organism in treated water.
The paper represents a fascinating piece of detective work, and an excellent contribution to EBNet’s ongoing interest in the interaction between microbial systems and their (engineered) environmental.
The Water Biofilms WG’s activities are now continuing primarily through the Better Water 4 All Network+, and via Seedcorn Funding from the Environmental Biotechnology Innovation Centre (EBIC). Don’t miss the chance to sign up!
Physical and biological fate of protozoan (oo) cysts in slow sand filtration: A review. Bretagne, S.L., Chipps, M., Harris, J. and Hassard, F., 2026. Science of the Total Environment, 1031, p.181810.
Isolation of a single Serratia fonticola strain from interstage samples in a drinking water treatment plant: Genomic insights and floc-shielding effects during chlorination. Exton, B., Gutierrez, V.C., Gave, R., Montgomery, L., Banks, J., Whitehead, N., Jarvis, P. and Hassard, F., 2026. Ecotoxicology and Environmental Safety, 316, p.120147.
