Removal of iron ions from water by aeration. Different methods are used to
remove iron ions form underground waters; aeration is the simplest method. It consists
in saturation of water with oxygen for the oxidation of iron (II) compounds and the
conversion of them into hard-soluble iron hydroxide (III). The alkalinity of water
should be not less than 2 mg-eqv/l, and pH> 7 (Table 4).
Table 4 Basic methods of iron removal from water
Method
Characteristics of
the solution
Advantages
Disadvantages
Maximal
concentration
Fe
2+
, mg/l
рН
Ozonization
10
6,8 –
8,5
High efficiency; Removal
of organic Fe; Removal of
Mn
High cost; High energy
consumption; Corrosive
activity; Toxicity
Chlorination
5
6,8 –
8,5
Simultaneous disinfection
of water
The complexity of technology;
Toxicity
Catalytic
oxidation
with
filtration
10
6,2 –
8,5
Efficiency; Economy
The need for prior aeration;
Wear (rubbing) fillings; Low
efficiency of removal of organic
Fe
Industrial
precipitation
5
6,8 –
8,0
Productivity; Economy
Slow process speed; Need for
coagulants; Low efficiency of
removal of organicFe
Ion exchange
50
5,0 –
7,0
High degree of cleaning;
Simultaneous water
softening
Overgrowth of cationite;
Inability to remove Fe
3+
Membrane
filtration
0,5
6,8 –
7,5
High degree of purification;
Ability to remove colloidal
and bacterial Fe
Low initial concentration of
iron; High cost; Rapid
overgrown and clogged
membranes
Biological
50
6,0 –
7,5
Simultaneous removal of
hydrogen sulfide
Further sorption purification and
decontamination are required
Simplified
aeration
5
6,0 –
9,0
Productivity; Economy
Low efficiency of removal of
organic Fe
Forced
aeration
10
6,8 –
8,5
Productivity; Economy
Low efficiency of removal of
organic Fe
Enhanced
aeration
100
4,0 –
9,0
Productivity; Economy;
High initial concentration of
iron; Wide range of pH;
Simultaneous removal of
excess СО
2
Low efficiency of removal of
organic Fe
Sorption on
natural
materials
100
6,0-
8,5
Economy; Availability of
the raw material base;
Reuse of waste
Low efficiency of removal of
organic Fe; The need for sorbent
modification
Electro-
coagulation
method
100
6,0-
8,5
Simple equipment and
operation; Efficiency; Low
energy consumption
Electrodes dissolving
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