34
J. 1. SHELBOURNE
tank were continuously pumped through two ultra-violet boxes at a
total rate of 2000 l./h ; a further 300 l./h passed through a glass-wool
filter. Water samples were withdrawn at frequent intervals, and bacterial populations assessed by mixing 1-ml volumes with ZoBell’s
2216 medium, using the standard pour-plate method. Plates were
incubated for 24 h at 26°C. Duplicate bacterial counts were also
derived from a modification of the dropping technique of Miles and
Misra (1938).
Iinqd with ’
epoxy resin
F I ~ .
8. Sea-water eterilieing box,
Even at a flow of 1000 l./h/box, water leaving the outlets was
virtually sterile after irradiation. Within 0 h, the originally high
bacterial counts characteristic of inshore water (ZoBell, 1946) had
dropped to a level closer to that of the open sea (Fig. 9). The treatment
was continued overnight and sampling resumed the following morning.
By this time the sea water in the reservoir wm perfectly clear? and the
filters coated with estuarine debris. The filter by-pam was then CIosed,
and the whole flow directed through the ultra-violet boxes alone.
Fig. 9 demonstrates (a) the bactericidal efficiency of these units at a
high rate of flow and (b) the re-contaminating infiuence of dirty
filters in a by-paas circuit.
J. 1. SHELBOURNE
tank were continuously pumped through two ultra-violet boxes at a
total rate of 2000 l./h ; a further 300 l./h passed through a glass-wool
filter. Water samples were withdrawn at frequent intervals, and bacterial populations assessed by mixing 1-ml volumes with ZoBell’s
2216 medium, using the standard pour-plate method. Plates were
incubated for 24 h at 26°C. Duplicate bacterial counts were also
derived from a modification of the dropping technique of Miles and
Misra (1938).
Iinqd with ’
epoxy resin
F I ~ .
8. Sea-water eterilieing box,
Even at a flow of 1000 l./h/box, water leaving the outlets was
virtually sterile after irradiation. Within 0 h, the originally high
bacterial counts characteristic of inshore water (ZoBell, 1946) had
dropped to a level closer to that of the open sea (Fig. 9). The treatment
was continued overnight and sampling resumed the following morning.
By this time the sea water in the reservoir wm perfectly clear? and the
filters coated with estuarine debris. The filter by-pam was then CIosed,
and the whole flow directed through the ultra-violet boxes alone.
Fig. 9 demonstrates (a) the bactericidal efficiency of these units at a
high rate of flow and (b) the re-contaminating infiuence of dirty
filters in a by-paas circuit.