The construction of a sand profile sampler: Its use in the study of the Vorticella populations and the general interstitial microfauna of slow sand filters

Abstract A simple and inexpensive method is described by which the component groups of the interstitial fauna can be examined undisturbed by direct microscopy. The method has been developed specifically to locate and enumerate the functional interstitial microfauna of slow sand filters used in water purification and it is designed to demonstrate the spatial relations of the constituent populations as they develop in time in a flowing system. The sampler has been successfully applied to monitoring the development of Protozoa and Rotifera in pilot scale and full scale slow sand filters at the London Metropolitan Water Board's Walton and Ashford Common Treatment Works. Results are presented for the incidence of the general microfauna and for the development, vertical distribution and effect of flow rate on the Vorticella populations.