Water & Wastewater Asia September/October 2019

38 | INSIGHT
Using the vortex layer of
ferromagnetic particles
in wastewater treatment
By Frank May, GlobeCore GmbH, Oldenburg, Germany
Part one of this two-part series explored how the electromagnetic vortex layer device works in intensifying
wastewater treatment, making the process more efficient. Part two discusses how vortex layer devices
can be effectively used in the treatment of chemical wastewater.
REMOVAL OF PHENOL FROM WASTEWATER
Vortex layer devices can be applied for efficient treatment of
wastewater from the production of phenol formaldehyde resins, coking,
wood processing etc, which contain phenol, methanol, formaldehyde
and other contaminants. The process of phenol removal involves
oxidation of phenol (at 0.5-10 g/litre concentrations) in acidic
environment.
Some of the oxidants are manganese dioxide, potassium or sodium
dichromate, ozone, calcium hypochlorite or potassium permanganate.
Of the listed agents, it is recommended to use potassium or sodium
dichromate in the amount of 2.5–3.3 grams per one gram of phenol.
In practice, it is recommended to use a 50–200 g/litre water
solution of Na2Cr2O7 depending on phenol concentration, with a
30–50 per cent sulfuric acid solution.
Phenol is removed from wastewater by mechanical agitator reactors,
where the oxidation reaction takes 3-4 hours at 95–100°C. A vortex
layer device significantly simplifies this process, reducing oxidation
temperature to 20–40°C and minimising process duration, making a
continuous process possible.
Wastewater continuously processed with the vortex layer device
must be:
• equalised in terms of contaminant composition and concentrations;
• purified to remove particulate matter;
• without resins and petrochemical substances.
The processing of wastewater is as follows (Figure 6).
Wastewater enters the accumulator tank for equalisation. If the amount
of acid in the wastewater is insufficient, the portioning device supplies
the required amount of sulfuric acid from tank number two.
The pump feeds the wastewater from the accumulator tank into the
vortex layer device at the rate of up to 15 m 3 /hour. 150-200 grams
of 1.2-1.8mm-long cylindrical ferromagnetic particles with l/d ratio
of 10 are used. These particles last four to six hours, with subsequent
replacement or loading more particles by an automatic loader. Oxidiser
is fed into the device at the same time; the ingredients are intensively
mixed, phenol and other organic substances (methanol, formaldehyde)
are oxidised to form water and carbon gas.
After phenol is removed, the wastewater undergoes reduction of
hexavalent chrome formed in the process of phenol oxidation, as well
as neutralisation in another vortex layer device (pos. 8 in Figure 6).
To reduce Cr+6 to Cr+3, iron sulphide is used, and the wastewater is
neutralised with lime milk.
FIGURE 6:
Removal of phenol from industrial wastewater using vortex layer devices:
1 – wastewater accumulator and equalisation tank;
2 – H2SO4 tank;
3 – oxidiser tank;
4, 8 – vortex layer device;
5, 6 – portioning devices;
7 – pump
CYANIDE REMOVAL FROM WASTEWATER
Application of vortex layer devices for removal of cyanide wastewater
allows to oxidise cyanides to cyanates, forming non-toxic carbonates
and ammonia. The process occurs in basic environment at
рН = 9–10. Lime milk or five to 10 per cent water solution of soda is
Water & Wastewater Asia • September / October 2019