9 image scanning apparatus for forming images of micro-organisms, image analysis apparatus for locating micro-organisms in an image analysis, apparatus for identifying micro-organisms in an image, image analysis apparatus for counting micro-organisms in an image, digital cameras, microscopes, computers, computer software for image analysis for locating micro-organisms in an image, computer software for image analysis for identifying micro-organisms in an image, computer software for image analysis for counting micro-organisms in an image; laboratory equipment and supplies, namely microbiological incubators, laboratory apparatus for use in biological or microbiological assays, namely filter membranes, filter support discs of plastics; and sample filtering apparatus comprising filter modules containing a filter membrane and support and bacterial growth medium