In nature, whether groundwater or surface water contains a certain amount of iron. Iron contaminated water significantly affects the daily life of everyone, directly affecting health. So how to recognize iron contaminated water, what is the cause of iron contaminated water and how to treat iron contaminated water?
Cause iron contaminated water
For groundwater, wastewater from mineral mining projects, this wastewater during the extraction process will seep into the surrounding groundwater. The indiscriminate burying of waste and improperly handled wastes causes pollutants including iron to be absorbed into the groundwater.
For surface water, iron contamination originates from indiscriminate disposal, indiscriminate and untreated garbage disposal. Long after the rains, these contaminants are absorbed into the soil by water, partly by water flowing into lakes, rivers and streams leading to heavy iron contamination of water.
In addition, more and more factories, untreated water from reservoirs will leak into rivers, streams, ponds, huge domestic wastewater, untreated. It is also exposed to the environment as a heavily polluted water source, especially iron pollution. Besides, water from railway works, roads, transportation routes is also one of the causes of iron-contaminated water.
Signs of iron contaminated water
Iron contaminated water significantly affects daily activities and the health of users. So how to recognize iron contaminated water is also a question that many people are concerned about. To recognize iron contaminated water is not too difficult. Here are a few ways you can identify iron-contaminated water:
- Identify by taste: Iron dissolved in water is iron 2 (Fe2 +), which will cause the water to have a very unpleasant fishy smell.
- Identified by color: Iron contaminated water is usually still pumped to the storage tank, when left in the air for a while, iron 2 (Fe2 +) will transform into iron 3 (Fe3 +), precipitating to create reddish brown color to make water. turbid.
- Identify items commonly used in the home: Iron contaminated water will stain clothing, floors, tools stained reddish brown. Metal tools can rust from this water source.
- Recognize through meals: Iron contaminated water makes the dish lose its natural taste and loss of appetite. Cooking rice will make the rice gray, the taste is difficult to eat. If you use iron-contaminated water to make tea, it will lose the flavor of the tea.
Effective methods of treating iron contaminated water
1. Treatment of iron contaminated water with filter material
Currently on the market there are a number of special filter materials used to remove iron (treatment of iron contaminated water) such as Manganese Sand, Birm and Pyrolox. These materials are used in the column system and other filter materials such as gravel support, quartz sand, activated carbon, Cation, ODM, Corosex …
Manganese sand has its basic chemical composition as Mn (OH) 4 or KMnO4, which is a specialized material for treating water contaminated with manganese, iron, hydrogen sulfide, and arsenic. Manganese sand also removes fishy odors by oxidizing directly through contact with the sand surface, precipitation and the filtration capacity of the grain layer.
Birm is a specialized water filtration material to remove iron and manganese compounds dissolved in groundwater. Birm acts as an insoluble catalyst to enhance the oxidation reactions of Fe 2+ to Fe 3+ in the form of precipitated iron hydroxide and can be easily removed by backwashing.
Pyrolox is the leading manganese dioxide filter material used by water treatment specialists to remove iron, manganese, hydrogen sulfide and arsenic from groundwater. The manganese dioxide coating acts strongly as a catalyst to oxidize dissolved iron, manganese, and hydrogen sulphide from solution in the form of a precipitate.
2. Treatment of iron contaminated water by filter tank system
Build tanks with cement, sand, including 3 compartments: sedimentation, filtering and storage, the area of each compartment is 0.35 – 0.49 m³. For the settling compartment, we will install a rain spraying rig consisting of a number of perforated pipes or plastic showerheads available on the market. For the filter compartment, we use l support gravel layer of size 5 – 10 cm, thickness 10 cm, above is a layer of filtered sand of 0.4 – 0.85 mm, 40 cm thick and the top is sand layer. smooth (0.15 – 0.3 mm) 20 cm thick.
In addition, we can add a layer of coal on the gravel, to remove the fishy smell of the water. We proceed to install a plastic tube from the bottom up and the outlet is higher than the top layer of sand so that when the water flows through the product compartment until it is exhausted, it does not expose the sand surface. Note that the finished product compartment must have a lid. Water is pumped up from the well and flows through the shower to the settling tank. When exposed to air, the iron in the water is oxidized. The water is partly sedimented, to the filter compartment, the water is filtered to remove the suspended residue, becoming clear, following the pipe leading to the finished water compartment.
With this system it is possible to filter 4 – 5 m3 of water / day. The cost to build the system costs about 3 to 4 million.
3. Treatment of iron contaminated water by ventilation method
The essence of this iron-contaminated water treatment method is to de-iron by ventilating and enrich the water for oxygen, enabling Fe2 + to oxidize to Fe3 + to conduct hydrolysis to form low-soluble Fe (OH) compounds 3 then use the filter to keep.
4. Treatment of iron contaminated water with lime
Proceed to add lime to the water, the pH of the water increases. Under conditions of rich OH- ions, Fe2 + ions rapidly hydrolyze to partially deposited Fe (OH) 2, replacing the standard redox of the Fe (OH) 2 / Fe (OH) 3 system. create favorable conditions for iron (II) to convert to iron (III). Iron (III) hydroxide and agglomerated into cotton residue, deposited in sedimentation tanks and separated from the water.
This lime fermentation method is applicable to water plants with both surface water and groundwater. If this method is used, it is necessary to use bulky dispensing equipment with a complex level of management.
5. Chemical treatment of iron contaminated water
Reducing iron with strong oxidizing agents
The strong oxidizing agents commonly used to reduce iron are: Cl2, KMnO4, O3 …
- 2Fe2 + + Cl2 + 6H2O → 2Fe (OH) 3 ↓ + 2Cl- + 6H +
- 3Fe2 + + KMnO4 + 7H2O → 3Fe (OH) 3 ↓ + MnO2 + K + + 5H +
For this reaction to oxidize 1 mg Fe2 + requires 0.64 mg Cl2 or 0.9 4 mg KMnO4 and at this time the alkalinity of the water is reduced by 0.018 meq / l.
Reducing iron with lime
Lime-iron treatments are not usually stand-alone, but incorporate water stabilization or softening processes. The reaction was conducted according to 2 schemes as follows:
There is dissolved oxygen
- 4Fe (HCO3) 2 + O2 + 2H2O + 4Ca (OH) 2 → 4Fe (OH) 3 ↓ + 4Ca (HCO3) 2
- When iron (III) hydroxide is formed, it will be retained in the sedimentation tank and completely lie in the filter tank
There is no dissolved oxygen
- Fe (HCO3) 2 + Ca (OH) 2 → FeCO3 + CaCO3 + 2H2O
- When the reaction occurs iron is reduced as FeCO3
6. Treatment of iron contaminated water with kitchen ash
Using this method is simple, the materials are easy to find, you can take advantage of kitchen ash as household waste, friendly with the environment. This method of treating iron contaminated water can be applied to a household scale using well water. We proceed to put kitchen ash into a water sample with a dosage of 5 to 10g / l and then let it settle for 15 minutes. Chemical reactions take place and the insoluble iron is removed through filtration.
Sunil Trivedi is the Managing Director of Aqua Drink. With 15 years of experience in the water purification industry, Sunil and his team have been ensuring that his clients consume 100% potable water to lead a healthy life and keeping water-borne diseases miles away.