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C. Wallis and J.L. Melnick
water then passes through the second polyester clarifier (3), a 1 μ unit.
By way of a 3/4 inch jumper, the test water is passed through the next unit (4), which
contains a 1 μ Tween-treated cotton filter, which removes complexed metals but not
virus. Depending upon the water under test, this filter should be changed when a rust film
forms on the surface of the filter, since virus will be removed by this metallic surface
(Wallis, Homma, and Melnick, 1971). To change filters, the multiport valve is switched
and the water directed to the effluent (7). A jumper is inserted at the outlet of the cotton
unit (4) and connected to this effluent QD (7). There are three QDs on the effluent (7),
two 3/4" and one 1/4", each containing a check valve to drive water only in one
direction. A 1/4" jumper is attached between the nitrogen tank and to the nitrogen inlet
(E). The nitrogen pressure is used to empty the water from the filter holder system so
that filters can be changed.
After the water passes the cotton filter it is passed through the mixer (5) via a long
3/4" jumper. The mixer is a T-shaped tube containing QDs on each of the three ends of
the T. Water passes into one 3/4" QD and meets salts and dyes directed into the T
through a 1/4" QD. The salt is required for virus adsorption. The water-salt-dye mixture
exits through the third QD, which contains a long jumper, and enters the virus adsorbent
(6) through a thick-walled glass tubing. The adsorbent is a fibreglass or cellulose acetate
unit which avidly adsorbs viruses in the presence of small amounts of salts. Attached to
the glass tubing which leads into the virus concentrator is a sight glass (I); this allows one
to maintain the desired molarity of salts injected into the water. This glass tubing is
shown in Fig. 2 above the nitrogen tank.
The sight glass consists of a test tube; the desired color is achieved by making a known
1:100 dilution of the salt-dye stock (4 M MgCl 2 - 0.4% neutral red) in the water under
test. Thus, a standard for colorimetric comparison was provided to ensure that the salt
was present in the test water at the desired 0.04 M level. If the dilution of the salt in the
test water became too great, 1:200 or more, the dye color was barely detectable; if it was
too low, 1:50 or less, the color was a deep red. By using the colorimetric sight glass,
nitrogen pressure can easily be regulated with the aid of the metering device (G) to keep
the concentration of salts within 50% of the desired level.
The water passing the virus adsorbent is discarded via a jumper to the main outlet (7).
When the total volume of water is processed, the jumper to the virus adsorbent is
disconnected, and the one from the nitrogen tank is connected to drive the excess water
from the filter unit. When the filter holder containing the virus adsorbent is free of excess
water, the virus adsorbent is washed with 4 liters of saline. The virus is then eluted from
the virus adsorbent with 1 liter of pH 11.5 Ca-Mg-free phosphate-buffered saline (PBS).
This saline is stored in the eluent container (8), which consists of a filter holder, but
without a filter, swiveled with a male-female QD pair, held between 2 flat steel bars (Fig.
3). A jumper is placed between the eluent container and the virus adsorbent, and another
jumper between the nitrogen tank and the other side of the eluent container.
C. Wallis and J.L. Melnick
water then passes through the second polyester clarifier (3), a 1 μ unit.
By way of a 3/4 inch jumper, the test water is passed through the next unit (4), which
contains a 1 μ Tween-treated cotton filter, which removes complexed metals but not
virus. Depending upon the water under test, this filter should be changed when a rust film
forms on the surface of the filter, since virus will be removed by this metallic surface
(Wallis, Homma, and Melnick, 1971). To change filters, the multiport valve is switched
and the water directed to the effluent (7). A jumper is inserted at the outlet of the cotton
unit (4) and connected to this effluent QD (7). There are three QDs on the effluent (7),
two 3/4" and one 1/4", each containing a check valve to drive water only in one
direction. A 1/4" jumper is attached between the nitrogen tank and to the nitrogen inlet
(E). The nitrogen pressure is used to empty the water from the filter holder system so
that filters can be changed.
After the water passes the cotton filter it is passed through the mixer (5) via a long
3/4" jumper. The mixer is a T-shaped tube containing QDs on each of the three ends of
the T. Water passes into one 3/4" QD and meets salts and dyes directed into the T
through a 1/4" QD. The salt is required for virus adsorption. The water-salt-dye mixture
exits through the third QD, which contains a long jumper, and enters the virus adsorbent
(6) through a thick-walled glass tubing. The adsorbent is a fibreglass or cellulose acetate
unit which avidly adsorbs viruses in the presence of small amounts of salts. Attached to
the glass tubing which leads into the virus concentrator is a sight glass (I); this allows one
to maintain the desired molarity of salts injected into the water. This glass tubing is
shown in Fig. 2 above the nitrogen tank.
The sight glass consists of a test tube; the desired color is achieved by making a known
1:100 dilution of the salt-dye stock (4 M MgCl 2 - 0.4% neutral red) in the water under
test. Thus, a standard for colorimetric comparison was provided to ensure that the salt
was present in the test water at the desired 0.04 M level. If the dilution of the salt in the
test water became too great, 1:200 or more, the dye color was barely detectable; if it was
too low, 1:50 or less, the color was a deep red. By using the colorimetric sight glass,
nitrogen pressure can easily be regulated with the aid of the metering device (G) to keep
the concentration of salts within 50% of the desired level.
The water passing the virus adsorbent is discarded via a jumper to the main outlet (7).
When the total volume of water is processed, the jumper to the virus adsorbent is
disconnected, and the one from the nitrogen tank is connected to drive the excess water
from the filter unit. When the filter holder containing the virus adsorbent is free of excess
water, the virus adsorbent is washed with 4 liters of saline. The virus is then eluted from
the virus adsorbent with 1 liter of pH 11.5 Ca-Mg-free phosphate-buffered saline (PBS).
This saline is stored in the eluent container (8), which consists of a filter holder, but
without a filter, swiveled with a male-female QD pair, held between 2 flat steel bars (Fig.
3). A jumper is placed between the eluent container and the virus adsorbent, and another
jumper between the nitrogen tank and the other side of the eluent container.