Features and Process of Iron and Manganese Removal Equipment for Well Water and Groundwater!

Features and Process of Iron and Manganese Removal Equipment for Well Water and Groundwater!

The well water iron and manganese removal unit is suitable for treating groundwater with iron content below 10 mg/L (maximum 15 mg/L) and a pH value no lower than 5.5. After treatment, the iron content in the water is reduced to less than 0.3 mg/L, meeting the national standard GB5749-85 “Quality Standards for Drinking Water.” It is particularly suitable for iron removal in groundwater sources for water supply in small and medium-sized towns, rural areas, and industrial and mining enterprises, as well as for pre-treatment in industrial water softening and desalination processes.

I. Introduction to Well Water and Groundwater

Well water and groundwater refer to water bodies buried beneath the surface, existing within the pores of rocks and soil and capable of flow. With the accelerating pace of industrialization, environmental pollution has intensified, inevitably contaminating groundwater. In terms of pollution severity, northern cities generally face heavier pollution than southern cities, with more pollutants and higher exceedance rates, particularly in the North China region where pollution is most pronounced. Regarding pollutants, “three nitrogen compounds” contamination is prevalent nationwide. Mineralization and total hardness pollution primarily occur in Northeast, North, Northwest, and Southwest China. Iron and manganese contamination is concentrated in southern regions. Treatment aims to remove harmful substances like iron/manganese, ammonia nitrogen, sediment, and scale, ensuring treated water meets national drinking water standards.

Well water and groundwater treatment primarily focuses on iron and manganese removal, as elevated iron and manganese levels in groundwater are quite common in China. Iron and manganese removal typically employs aeration combined with filtration, using quartz sand or manganese sand as the filtration medium, followed by activated carbon and precision filtration. After treatment, the water quality generally meets national drinking water standards. Ammonia nitrogen is mostly treated using ultrafiltration or reverse osmosis processes, while silt and scale can be filtered using multi-media filtration and ion exchange softening units.

II. Features of Well Water Iron and Manganese Removal Equipment

1. Professionally designed water distribution and collection systems ensure uniform distribution and collection under any inlet conditions. This enhances filtration efficiency within the effective filter bed and guarantees uniform normal filtration and backwashing regeneration without dead zones.

2. High efficiency in iron and manganese removal with stable and reliable treatment results.

3. The entire filtration and backwashing process can be automatically completed under the management of a monitoring system via electric actuators, eliminating manual operation. Application Scope of Well Water Iron and Manganese Removal Equipment: Primarily used for treating iron-exceeding water in food, beverage, paper, and brewing industries; removing iron from groundwater and well water used as drinking water; and meeting the needs of geothermal projects and swimming pool circulating water.

III. Treatment Equipment Process

Raw Water (Groundwater/River Water) → Sedimentation Tank (Aeration (Blower)/Chemical Dosage (Alum, Polyaluminum Chloride)) → Boosting Pump → Multi-Media Filter or Mechanical Filter (Filter Media: Quartz Sand (2-4 mesh/4-6 mesh)/Manganese Sand/SS Filter Media) → Activated Carbon Filter (Filter Media: Coconut Shell Carbon/ nut shell carbon/coal-based carbon) → Point of Use (meets national tap water standards).

Sedimentation Tank

Primarily extends reaction time between iron/manganese ions in water and oxygen ions in air, forming precipitates like iron trioxide/manganese dioxide.

Booster Pump

Main function is pressurizing raw water to provide system power; lightweight horizontal multistage centrifugal pumps feature maintenance-free mechanical seals. All pump wetted parts are constructed from stainless steel (304 or 316), offering low noise, mild corrosion resistance, aesthetic design, compact size, light weight, and extended service life.

Mechanical Filter

Typically equipped with inlet devices and water distribution systems, sometimes including compressed air intake components. Essential piping and valves are installed externally. Mechanical filter tanks are commonly constructed from fiberglass-reinforced plastic (FRP), stainless steel, or carbon steel with anti-corrosion lining. Common filter media include quartz sand, marble, anthracite coal, manganese sand, and dolomite, with particle diameters typically ranging from 0.5 to 1.5 mm. A single type of media may be loaded into the filter, or a combination of two or three types. Filter operation is cyclical, with each cycle comprising three steps: filtration, backwashing, and forward washing.

Backwashing aims to remove accumulated contaminants from the filter bed, restoring its contaminant retention capacity. This is a critical step in filter operation. To enhance backwashing effectiveness, compressed air is typically introduced during the process. Standard filter operating flow rates are approximately 8–10 m/h. When the pressure drop across the filter bed reaches the permissible limit, filtration ceases and backwashing commences. At this point, water within the filter is drained until it reaches the upper edge of the filter bed. Compressed air at an intensity of 18–25 L/(m²·s) is then introduced. After 3–5 minutes of air blowing, backwash water is introduced into the filter while continuing air supply. The intensity should cause the filter bed expansion rate to reach approximately 40%–50%. Finally, water is used for forward washing until the effluent meets quality standards before formal filtration operation can resume. For this type of filter, cleaning can be determined not only by the pressure drop across the filter bed but also based on a set operating time. The permissible operating cycle should be determined through adjustment tests. Cleaning should not be performed only when suspended solids are about to pass through; it should be done slightly earlier. Otherwise, the filter bed may not be thoroughly cleaned, and prolonged neglect may cause the filter media to form clumps. The generally permissible pressure drop is approximately 0.5 bar.

Activated Carbon Filter

The primary function of activated carbon filters is to remove organic compounds and residual chlorine from water, while also eliminating odors, color, and other undesirable characteristics. Typically, high-quality shell-based activated carbon is preferred to ensure good mechanical strength, rapid adsorption rates, and high adsorption capacity. Activated carbon performs dual roles: adsorption; and second, filtration. The surface of activated carbon contains numerous functional groups such as hydroxyl and hydroxyl groups, enabling it to chemically adsorb organic substances of various properties through electrostatic attraction. Therefore, activated carbon can remove organic substances such as humic acid, fulvic acid, and lignin sulfonic acid from water; organic pollutants (e.g., phenolic compounds); it also eliminates residual oxidants, free residual chlorine, odors, and harmful gases from water. Activated carbon also removes heavy metal ions like mercury (Hg), cadmium (Cd), and chromium (Cr) from water. Activated carbon filters typically operate at flow rates of 10-20 m/h. Due to the porous structure of the filter media and the accumulation of organic matter adsorbed by activated carbon, which provides a breeding environment for bacteria, activated carbon filters require regular sterilization or chemical treatment. Backwashing Method: Employ combined air and water backwashing at an intensity of 0.5 m³/(m²·s) for 10-15 minutes (or at a backwash velocity of 20-30 m/h for 4-10 minutes, with backwashing every 3-6 days and a bed expansion rate of 30%-50%).

Activated Carbon Service Life: Typically 2-3 years. Saturated carbon can be regenerated or replaced. Newly installed activated carbon must first be fully submerged in water for over 24 hours to ensure thorough wetting. This expels air trapped within the carbon particles and their internal pores, preventing the carbon from floating. Subsequently, seal the inlet port, conduct a pressure test, and perform a forward wash to remove anthracite dust from the activated carbon. Continue washing until the effluent becomes transparent and colorless, with no fine particles present, before putting it into service.

Precision Filters (Microfiltration) Also commonly referred to as security filters, these serve as the final pretreatment stage preceding reverse osmosis (or nanofiltration) systems. Precision filters utilize molded filter media such as filter cloth, mesh, discs, membranes, or cartridges. The filtration rating is determined by the specific media and its precision, typically ranging from 0.01-1μm; 5-20μm; 20-100μm; Precision filters are often installed after pressure filters to remove fine particles with turbidity below 0.4 NTU, meeting subsequent process requirements for feedwater. They may also be placed at the end of the entire water treatment system to prevent fine particles from entering the finished water. The filter media (cartridges) in precision filters are consumable materials and require replacement when the operating differential pressure reaches 0.1 MPa.

IV. Technical Specifications

1. This series of iron removal units offers treatment capacities ranging from 120 to 2400 t/d. Capacity can be appropriately increased to 2500 t/d based on production requirements.

2. When raw water iron content is below 15 mg/l, treated effluent iron levels meet national drinking water standards. For industrial production water with specific iron content requirements, our company can provide customized designs.

3. This unit supports both continuous and intermittent operation.

4. Filtration rate: 8–12 m/h; Backwash intensity: 15 l/cm².