PhD Research: "Characterising the Functional Microbial Ecology of Slow Sand Filters Through Environmental Genomics



The requirements for energy-efficient water treatment technologies are prompting renewed interest in "biological" water treatment processes such as slow sand filtration. These systems do not require chemicals or electricity to operate and can achieve a high level of treatment mainly attributed to naturally occurring microorganisms within the filter. Several microbiologically mediated purification mechanisms have been hypothesized or assumed to occur within biofilms that form in the filter but have never been comprehensively verified.



Determine the functional microbial ecology of slow sand filters (SSFs) by carrying out both field sampling (at an industrial SSF site) and laboratory experimentation (creation of lab-scale SSFs). In order to answer this complex question my work focussed on:

  1. Sampling full-scale SSFs to determine the spatial and temporal changes in the microbial community, by using qPCR and 16S rRNA gene amplicon sequencing (Illumina and 454).
  2. Identifying and correlating specific microbial groups to water quality parameters and filter performance by using multivariate statistical analysis in combination with molecular data.
  3. Designing, constructing and operating laboratory-scale SSFs to determine if laboratory-scale units accurately mimic the microbial community and water quality performance of full-scale SSFs.
  4. Investigating how SSFs remove pathogens by using DNA-SIP coupled with metagenomics.
  5. Evaluating the potential of SSFs to remove estrogens and determining if removal performance can be improved by bioaugmentation with estrogen metabolizing bacteria.


Supported by:

  1. Lord Kelvin Adam Smith scholarship (44784)
  2. John Robertson Bequest Award
  3. GU68 Trust Award