Remove Iron from Water

I. Sources and hazards of iron in water

1. Sources of iron

 ● Natural existence: groundwater dissolves divalent iron (Fe²⁺) in the soil, and oxidizes to trivalent iron (Fe³⁺) after contacting the air to form a precipitate.

 ● Industrial pollution: iron and steel, electroplating, mining and other industries wastewater containing iron up to hundreds of mg / L, often accompanied by the coexistence of heavy metals.

2. Hazards of Iron Pollution

 ● Equipment Damage: Formation of iron scale in reverse osmosis (RO) membranes, boilers, heat exchangers, reducing efficiency and increasing energy consumption.

 ● Product Risks: Excessive iron in the food and beverage industry can lead to discoloration, off-flavors, and even violation of food safety standards.

 ● Health impact: Long-term consumption of high iron water may cause gastrointestinal discomfort, and iron bacterial growth exacerbates pipeline corrosion.

II. 5 kinds of mainstream iron removal technology comparison

Ⅲ. Industrial Scenario: Iron Removal Case for Iron and Steel Plant Wastewater

 Problem: The iron content of circulating cooling water in an iron and steel plant reaches 15mg/L, which leads to an increase in the frequency of membrane contamination in the RO system by 30%.

Solution:

1. Pre-treatment stage:

 ● Installation of aeration tower to oxidize Fe²⁺, together with pH adjustment to 6.5-7.5, to promote Fe(OH)₃ precipitation.

 ● Multi-media filter is used to remove suspended solids and reduce SDI value (<5).

2. Deep treatment stage:

 ● Select anti-pollution type RO membrane with scale inhibitor to prevent iron scale deposition.

 ● Implement regular chemical cleaning (citric acid + EDTA solution) to restore membrane flux.

Effect: RO system water conductivity stabilized at <10μS/cm, membrane life extended to more than 5 years.

IV. Home Scenarios: A DIY Guide to Iron Removal from Groundwater

Step 1: Test for Iron Levels

 ● Use an iron test kit (e.g. Hach brand) or send it to a professional organization to distinguish between dissolved iron (clear) and particulate iron (cloudy).

Step 2: Choose Iron Removal Equipment

Step 3: Maintenance points

 ● Manganese sand filter needs to be replaced every 2 years to avoid the decline of catalytic activity.

 ● RO membrane every 6-12 months to detect a desalination rate, below 90% timely replacement.

V. Iron removal technology selection principles

1. Concentration priority:

 ● Low concentration (<5mg/L): ion exchange or catalytic oxidation filtration.

 ● High concentration (> 10mg / L): reverse osmosis or chemical oxidation.

2. Cost Orientation:

 ● Operating cost ranking: chemical oxidation > reverse osmosis > ion exchange > catalytic oxidation > oxidative precipitation.

3. Sustainability:

 ● Priority is given to technologies without chemical additives (e.g. catalytic oxidation, RO) to reduce secondary pollution.

VI. Frequently Asked Questions

Q1: The water is still yellow after iron removal, why?

 ● Possible reasons: iron bacteria breeding or incomplete removal of colloidal iron, need to cooperate with biocides (such as chlorine) or ultrafiltration treatment.

Q2: Can RO system directly treat high iron water?

 ● No. It is not possible to treat directly! Pre-treatment is required to reduce the iron content to <0.1mg/L, otherwise the risk of membrane contamination is extremely high.

Q3：How to judge the failure of home iron removal equipment?

 ● Observe the color and odor of the water or test the TDS value, if the iron content rises back to more than 50% of the initial value, the filter media needs to be replaced.

 Conclusion: Removing iron from water requires a customized solution based on water quality, volume and usage. Industrial scenarios suggest commissioning a professional water treatment company to design the system, home users can choose modular equipment and regular maintenance. For specific equipment selection or case study, please contact our technical team for free consultation!