Environmental Technologies and Eco-innovation in the Czech ...

6.5 | Modern physical methods in the waste
water treatment technology
Filtration is the most-used physical technology in waste water treatment; its
use is possible on several levels. In the final waste water treatment, it is possible to
use both common filtration on sand and mixed filters, as well as pressure filtration
on microstrainers and micro to ultrafiltration on membranes. All the mentioned
technologies are used to remove the residual concentrations of undissolved
substances in the discharge by capture on the filtration medium. Lowering the
concentration of undissolved substances will also cause improved discharge
concentrations of other pollution indicators (total nitrogen, total phosphorus,
COD Cr ). With this technology, it is always necessary to take account of the regeneration
of the filter (the filtration bed) and of the disposal of the water used for this activity.
Sorption, as another method of final tertiary waste water treatment, works on
the principle of accumulating (capture) the dissolved substances on the surface of
the solid phase (adsorbent); the base material. Activated carbon is most often used
as an adsorbent in the technology (powder or granulated). However, other sorption
materials may be used, such as fly-ash, clinker, bentonites and organic polymer
substances (styrene and divinylbenzene copolymers, acrylic acid esters). It is possible
to intensify the filtration process by the adsorbent layer and by filtration bed’s
surface. The sorption process is influenced by a number of factors including the size of
adsorbent particles, the adsorbate concentration, temperature, pH, molecular weight
and other specific properties of the substance being absorbed. Sorption is used to
remove carcinogenic and mutagenic substances, substances that are biologically
degradable with difficulty or malodorous substances. These mainly include residual
concentrations of organic substances (chlorinated aromatic hydrocarbons, pesticides),
heavy metals, free chlorine, etc. The regeneration and removal of exhausted sorbents
may become a problematic issue of this technology.
The technology of electric-impulsion waste water treatment is a less-thanstandard
technology making use of the reaction of water to electric current. This
technology is characterized by high efficiency in reducing carbon pollution,
eliminating nutrients and in removing undesirable substances, such as greases,
degreasing agents, crude oil and oil products. The principle of the operation is that
strong electric and magnetic fields affect the continuous flow of polluted water. In this
process, dissociation of the molecules 19 of the substances contained in the waste water
occurs because of the action of the impulsion electromagnetic field. A consequence is
19 dissociation of molecules – dividing a compound’s molecules into separate ions