■Is it dissolved or in particle form? The method of treatment changes depending on whether iron and manganese are dissolved in water or have already formed undissolved particles. 1. Undissolved particles: Remove directly by filtration. 2. Dissolved: Oxidize to convert into particles, then remove by filtration. ■Combination of chlorine and manganese sand A typical method is to pass water through a filter filled with manganese sand immediately after adding chlorine. When water passes through manganese sand in the presence of free chlorine, the dissolved manganese is oxidized on the surface of the sand and removed. This process is called contact oxidation. ■Filtration sand also works like manganese sand! Continuing manganese removal with chlorine causes the filtration sand to become covered with manganese oxides, turning it black and allowing it to function like manganese sand. The presence of manganese oxides acts as a catalyst, promoting oxidation even around pH 7. ■How to choose a removal method? If the groundwater is clear and contains manganese, coagulation and sedimentation are unnecessary, and contact filtration with manganese sand is suitable. After oxidizing to form particles, either combine coagulation and sedimentation with filtration or remove it using only filtration.

■Can water turn black even at 0.02 mg/L?! Even at around 0.02 mg/L of manganese, a film can form on the inside of the pipes, which may peel off and appear as black sediment. Fine black oxides that precipitate can adhere to the inside of the pipes, causing black water. The standard for manganese in drinking water is below 0.05 mg/L, so it's important to note that issues can arise even at lower concentrations. Even if the levels are below the standard, manganese can gradually accumulate inside the pipes. ■It tends to remain in normal water purification processes! In typical water purification processes, manganese is hardly removed. Therefore, when there is a risk of problems, effective manganese removal treatment is necessary. ■Things to check first Whether you need iron removal equipment should be decided based on the following points: 1. The amount of iron present 2. The state of existence, whether dissolved or particulate 3. The situation of the facility using the water Additionally, consider whether manganese removal is also necessary. Since iron and manganese are often found together, it is reassuring to check both values. Please feel free to consult with us first.