376
I. Licsko et al.
direct physicochemical methods (Karlsson 1985; Sagberg et al. 1998). The wide
application of chemical wastewater treatment in Norway is partly due to the fact
that the high dissolved oxygen content of the Norwegian water bodies (fjords,
lakes) allows the application of wastewater-treatment technologies with lower
organic matter removal efficiency. At the same time, chemical treatment methods
are very effective in phosphorus removal, and thus are able to satisfy the strict
effluent standards concerning phosphorus. Climatic conditions in Norway also
indicated the widespread application of chemical methods, being more reliable
than biological treatment in cold weather (Sagberg et al. 1998). Solving the
removal of nitrogen, chemical treatment is often supplemented by nitrifying and
denitrifying biofilters (Biofor).
In the USA there are several examples for chemically enhanced primary
treatment (CEPT) systems. Based on the early experiments, aluminum or ferric
salts (often in combination with polymers) are applied into the primary settling
tanks (Morrissey and Harleman, 1992).
Applying the combination of chemical-biological processes in municipal
wastewater treatment is also well known from the literature (Karlsson 1985; Hahn
et al. 1990; Henze and 0degaard 1994). Chemical treatment can be introduced to
the biological treatment in three ways: pre-, simultaneous, and postprecipitation.
Chemical pretreatment (i.e., preprecipitation) is one of the most effective (in terms
of both pollutant removal efficiency and cost) among the possible upgrading
methods (Karlsson 1988). Chemical dosing prior to the primary settling tank
enhances the removal of organic substances - mainly particulate matter - and
phosphorus. As a consequence, the downstream biological stage will receive a
lower organic load, and, as chemical treatment removes the particulate organic
substances, pretreated sewage contains organic matter mostly in dissolved form.
Due to this phenomenon, the efficiency of the biological reactor will improve and,
in many cases, nitrification occurs where ammonium conversion has never been
observed before (Karlsson 1985; Andersson et al. 1992; Henze and Harremoes
1992).
For chemical upgrading of existing facilities, Hungarian approaches are also
found (Murcott and Harleman 1994; Somly6dy and Knolmar 1997). The
experiments concerning the introduction of chemical treatment showed that,
besides increased BOD, COD, TSS and TP removal, a significant increase in the
plant capacity can be achieved.
4 Materials and Methods
Coagulation-flocculation laboratory Jar tests were carried out to gain data about
the pollutant removal efficiency of coagulants. The aim was to compare the
efficiency of different coagulants and to determine the optimal dosage of
application concerning primarily organic matter (CODe" BODs) and phosphorus
(total phosphorus and ortho-phosphate) removal.
I. Licsko et al.
direct physicochemical methods (Karlsson 1985; Sagberg et al. 1998). The wide
application of chemical wastewater treatment in Norway is partly due to the fact
that the high dissolved oxygen content of the Norwegian water bodies (fjords,
lakes) allows the application of wastewater-treatment technologies with lower
organic matter removal efficiency. At the same time, chemical treatment methods
are very effective in phosphorus removal, and thus are able to satisfy the strict
effluent standards concerning phosphorus. Climatic conditions in Norway also
indicated the widespread application of chemical methods, being more reliable
than biological treatment in cold weather (Sagberg et al. 1998). Solving the
removal of nitrogen, chemical treatment is often supplemented by nitrifying and
denitrifying biofilters (Biofor).
In the USA there are several examples for chemically enhanced primary
treatment (CEPT) systems. Based on the early experiments, aluminum or ferric
salts (often in combination with polymers) are applied into the primary settling
tanks (Morrissey and Harleman, 1992).
Applying the combination of chemical-biological processes in municipal
wastewater treatment is also well known from the literature (Karlsson 1985; Hahn
et al. 1990; Henze and 0degaard 1994). Chemical treatment can be introduced to
the biological treatment in three ways: pre-, simultaneous, and postprecipitation.
Chemical pretreatment (i.e., preprecipitation) is one of the most effective (in terms
of both pollutant removal efficiency and cost) among the possible upgrading
methods (Karlsson 1988). Chemical dosing prior to the primary settling tank
enhances the removal of organic substances - mainly particulate matter - and
phosphorus. As a consequence, the downstream biological stage will receive a
lower organic load, and, as chemical treatment removes the particulate organic
substances, pretreated sewage contains organic matter mostly in dissolved form.
Due to this phenomenon, the efficiency of the biological reactor will improve and,
in many cases, nitrification occurs where ammonium conversion has never been
observed before (Karlsson 1985; Andersson et al. 1992; Henze and Harremoes
1992).
For chemical upgrading of existing facilities, Hungarian approaches are also
found (Murcott and Harleman 1994; Somly6dy and Knolmar 1997). The
experiments concerning the introduction of chemical treatment showed that,
besides increased BOD, COD, TSS and TP removal, a significant increase in the
plant capacity can be achieved.
4 Materials and Methods
Coagulation-flocculation laboratory Jar tests were carried out to gain data about
the pollutant removal efficiency of coagulants. The aim was to compare the
efficiency of different coagulants and to determine the optimal dosage of
application concerning primarily organic matter (CODe" BODs) and phosphorus
(total phosphorus and ortho-phosphate) removal.