Biology Reference
In-Depth Information
Raw Water
⇩
Preozonation
⇩
Remineralization (when necessary)
⇩
Other chemicals:
-Coagulants (all cases)
-Flocculants (optional)
-pH adjustment
Powdered Activated Carbon (optional)
⇩
Coagulant-Flocculation settlig or Flotation
⇩
First stage filtration on sand (or Dual-Media filter)
⇩
Disinfection by means of O
3
Oxidation by free radicals
⇩
Second stage Filtration on GAC
⇩
Final disinfection by Cl
2 or
ClO
2
pH Adjustment (Optional)
Figure 28:
Typical water treatment line for surface waters in the 90s.
subjected to ozonation followed by carbon and sand fi ltration steps. Ozone concentrations of 1.5
mg L
-1
were required to destroy 5 x 10
5
Microcystis
cells ml
-1
(equivalent to total organic carbon
of 1.56 mg L
-1
) (Hoeger
et al
., 2002). They suggested that for effective treatment of surface waters
containing cyanobacterial blooms the regular monitoring of total organic carbon with cyanobacterial
cell densities, ozonation combined with effi cient fi ltration steps are required to provide safe drinking
water. An immunoaffi nity column (IAC) for the determination of MCs to the level of pg to µg L
-1
in tap waters has been designed by Tsutsumi
et al
. (2000). The mean recovery level as determined
by HPLC with UV detection or ELISA revealed MC-LR, MC-RR and MC-YR to be 91.8%, 77.3%
and 86.4% respectively, in the range of 2.5-100 µg L
-1
. The tap water cleaned up with IAC rendered
effective elimination of the toxins when compared to octadecyl silanized catridge.
