Environmental Engineering Reference
In-Depth Information
With the Watreco VPT, this is achieved in a similar device as in the “ice case.” The only
difference is that a small hose is connecting the vacuum in the center of the vortex with
the air at the surface of the water, in this case, a pond. When the water is run through the
vortex generator, the vacuum created literally sucks the air into the vortex cavity chamber
from a suitably placed hose and further into the vortex. Here, it is ripped apart by the
strong shear forces inside the vortex and at the end very ine bubbles down to nanoscale
are injected into the surrounding pond water.
The result is a very eficient aerator that makes it possible to keep the oxygen levels at the
top, even in harsh conditions. In this way, very little energy is needed in order to keep the
ish in ish tanks alive or as in the pond case, to control algae growth by no other means
than the oxygen in the air that surrounds us. Not only gas can be introduced in the bulk
water, as the unit is actually a very good mixer. Various other substances can be used, even
solids in powder form. However, it is preferred that the solids are dissolved or at least are
in a liquid state to start, as the power has a tendency to clog the inside of an inlet tube.
6.7.9 Ice Fabrication
There are several applications where extremely small bubbles in water can either be
removed or introduced depending on the actual need. One such need is to increase the
lowing properties of water on artiicially made ice. The idea here is to let the water low
out on the ice and into cracks and pores so the ice can be “healed” during maintenance.
Today this is achieved by using hot (40°C-60°C) water that loats very smoothly; however, it
also costs a lot of money because of the energy required for heating. A signiicant increase
of pressure is required to lower the melting point of ordinary ice; for example, the pres-
sure exerted by an ice skater on the ice reduces the melting point by approximately 0.09°C.
Using Watreco's Vortex removes the nanoscale bubbles altering the properties of the
water and can achieve the same loating properties with 17°C-18°C water instead of using
40°C-60°C, saving a lot of energy in this way. Also, as the water contains fewer bubbles, the
ice also does. Therefore, the ice gets stronger (fewer weak points from bubbles) but also the
optical transparence gets better, making the messages from the advertisers more visible
but also gives an opportunity to increase the set temperature of the ice, saving even more
energy in the process.
Another use for the VPT is also in an ice arena, when the ice is built for the irst time.
Here, water is sprayed through a hose and a nozzle. In this case, the Watreco nozzle is
shaped like a ball where the water comes out through a rather small hole. The very edge
of the hole is a bit rounded and when the water runs over the rounded edge, it is exposed
to Coanda forces that rip the water apart into extremely small drops, which slowly fall to
the concrete piste where they freeze into thin layers of ice. In this way, the ice is “built” in
thin layers, creating a very dense and strong ice. Work done with professional ice skaters
by Watreco shows a hardening of the ice, improving performance for skaters, making the
surface “quicker,” but at the same time reducing the energy costs to make it.
6.8 SonoPhotoCatalytic Cavitation or SPCC
The combined effects of SPCC with AOP appear to offer a good solution leveraging
the advantages of each individual processes to the treatment of water for the various
