Filtration Media for Simultaneous Removal of Iron, Manganese, Arsenic, and Heavy Metals from Water

DMI-65 is a catalytic oxidation filtration medium based on silica sand, with high-valent manganese oxides "injected" into its surface through a proprietary process. In scenarios requiring "simultaneous removal of iron, manganese, arsenic, and multiple heavy metals," its value lies in three major advantages: "multi-effect capability, no need for regeneration, and high flow rate."

By maintaining 0.1–0.3 ppm NaClO and a pH of 5.8–8.6, DMI-65 can reduce iron, manganese, arsenic, and various heavy metals to trace levels in a single filter vessel, with no need for regeneration or media replacement for 5–10 years.

Key points are as follows:

1. Target Contaminants and Ultimate Precision

2. Iron: ≤0.001 mg/L

3. Manganese: ≤0.001 mg/L

4. Arsenic: Can be reduced below the WHO guideline of 10 μg/L. The mechanism utilizes Fe-As complex co-precipitation—when the raw water contains sufficient iron, DMI-65 removes arsenic through co-precipitation during iron removal. If the raw water is iron-deficient, FeCl? can be added as a co-precipitant.

5. Other Heavy Metals: Al, Pb, Zn, Cu, Cd, Cr, Sb, Ni, etc., as long as they can form hydroxide or carbonate precipitates under oxidizing conditions, can be effectively retained.

• Process Conditions (Chemical Requirements)
  

1. pH: 5.8–8.6 (peak treatment capacity at pH 7.0–7.5); pH <5.8 may dissolve the catalytic layer, while pH >8.6 inhibits manganese oxidation.

2. Oxidant: Continuous dosing of NaClO to maintain free chlorine at 0.1–0.3 mg/L.

3. Temperature: ≤45 °C.

4. Initial Operation: Soak in a 12.5% NaClO solution for 4–6 hours to complete "activation."

System-Level Advantages

Only backwashing is required, no acid/alkali regeneration: The media itself is not consumed or depleted, with a lifespan of 5–10 years. Performance is restored solely through periodic backwashing.

Strong compatibility: Can be "plug-and-play" replacement for quartz sand or manganese sand in existing sand filters, without altering the hydraulic configuration.

Low cost: No need for KMnO? or additional aeration. Chemical dosing is only about 1/10 of traditional processes.

High flow rate: Linear filtration velocity can be twice that of traditional quartz sand or manganese sand, allowing for smaller vessels and less space for the same effluent quality.

• Typical Integrated Process (Example for Arsenic Removal)

1.  Pretreatment: If the raw water is iron-deficient, add FeCl? to achieve an Fe/As mass ratio ≥ 20:1;

2. DMI-65 catalytic oxidation + filtration: Fe2?→Fe3?, Mn2?→Mn??, As(III)→As(V) with co-precipitation;

3. Post-treatment: Use a 5 μm precision filter cartridge or UF as a safety barrier to ensure no leakage;

4.  Backwashing: Intensity of 25–80 m3/m2·h, expansion ≥40%, cycle every 24–72 hours depending on influent turbidity.

• Applicable Water Quality

1. Groundwater, well water, mine drainage, RO pretreatment water, drinking water plant upgrades, process water for beverage/food processing, etc.

2. For raw water containing oil, high NH??, or high H?S, pre-treatment for oil removal, ammonia removal, or stripping is required to prevent catalytic layer contamination or excessive chlorine consumption.