can interact also with colloidal detrimental substances such as stickies (Fig. 1, center).
Relatively few systematic investigations of such interactions have been reported.
The third possibility is the formation and application of pre-mixed PECs in a first
step, which can then be applied as flocculants (Fig. 1, bottom).This will be described
in Sect. 4.
The use of polymer combinations for the improvement of flocculation efficiency
is not new and was described earlier [1–24]. Two or even more components, added
in sequence as flocculant systems, produce synergistic effects on the flocculation.
Many different systems have been applied in the paper industry, and also in other
fields like peat dewatering [1], flocculation of harbor sediments [2], wastewater [3],
or sugar beet washings [4].
But, in the meantime, the importance of flocculation applications has been growing
because of increasing requirements in several fields, such as for:
The paper industry:
– Excellent dewatering combined with good retention
– Reduction of high anionic trash content in combination with the reduction of
water use in paperprocessing (due to the closure of circuits)
In other fields, flocculation is used in the following processes:
– Separation of ultrafine- or nanoparticles
– Separation of uncharged and/or colored materials
– Purification of fruit and vegetable wash water
– Reduction of the moisture content in separated sludge
– Sorption of low concentrated organic molecules from water, such as enzymes or
hazardous materials
– Removal of humic acid from drinking water
– Preparation of carrier materials with great potential in health care and environmental
sciences
– Splitting of emulsions and the removal of oil from oily sludge
The next three sections show that some of the problems that flocculation is
required to deal with can only be solved with new types of flocculants like polymer
combinations or aggregates.
2 Dual Systems (Step-by-Step Addition)
Flocculants are usually applied to accelerate separation processes, such as the
drainage process during paper making, and to increase the retention of the finely
dispersed material in the paper. Flocculation is one of the most important factors
and influences both the machine runability and paper quality. Many chemical and
physical factors influence flocculation in a complex way.
Usually, cationic polymers of high molar mass are used for flocculating the
anionically charged suspension. However, the improved effect of dual systems is
also appreciated. The application of two or even more components, added in sequence
Polyelectrolyte Complexes in Flocculation Applications
31
Relatively few systematic investigations of such interactions have been reported.
The third possibility is the formation and application of pre-mixed PECs in a first
step, which can then be applied as flocculants (Fig. 1, bottom).This will be described
in Sect. 4.
The use of polymer combinations for the improvement of flocculation efficiency
is not new and was described earlier [1–24]. Two or even more components, added
in sequence as flocculant systems, produce synergistic effects on the flocculation.
Many different systems have been applied in the paper industry, and also in other
fields like peat dewatering [1], flocculation of harbor sediments [2], wastewater [3],
or sugar beet washings [4].
But, in the meantime, the importance of flocculation applications has been growing
because of increasing requirements in several fields, such as for:
The paper industry:
– Excellent dewatering combined with good retention
– Reduction of high anionic trash content in combination with the reduction of
water use in paperprocessing (due to the closure of circuits)
In other fields, flocculation is used in the following processes:
– Separation of ultrafine- or nanoparticles
– Separation of uncharged and/or colored materials
– Purification of fruit and vegetable wash water
– Reduction of the moisture content in separated sludge
– Sorption of low concentrated organic molecules from water, such as enzymes or
hazardous materials
– Removal of humic acid from drinking water
– Preparation of carrier materials with great potential in health care and environmental
sciences
– Splitting of emulsions and the removal of oil from oily sludge
The next three sections show that some of the problems that flocculation is
required to deal with can only be solved with new types of flocculants like polymer
combinations or aggregates.
2 Dual Systems (Step-by-Step Addition)
Flocculants are usually applied to accelerate separation processes, such as the
drainage process during paper making, and to increase the retention of the finely
dispersed material in the paper. Flocculation is one of the most important factors
and influences both the machine runability and paper quality. Many chemical and
physical factors influence flocculation in a complex way.
Usually, cationic polymers of high molar mass are used for flocculating the
anionically charged suspension. However, the improved effect of dual systems is
also appreciated. The application of two or even more components, added in sequence
Polyelectrolyte Complexes in Flocculation Applications
31