Iron, together with manganese, are very common chemical contaminants in drinking water sources. The World Health Organisation sets a limit of 200 µg/L for iron and 50 µg/L for manganese.
The origin of both contaminants in water sources is diverse, but can mostly be from a natural cause. This is because, as water percolates through soil and rocks, it can dissolve these materials and carry them into the groundwater. Iron and manganese are more common in groundwater sources due to lower dissolved oxygen levels, lower pH and higher CO2 concentrations.
In surface water, iron is not only mineral, but may also be linked to organic matter. This is often a seasonal problem. It is important that the water to be treated is correctly characterised in order to implement the best iron removal treatment method for that type of water. However, as a general rule, in these cases it is achieved by removing the organic matter that complexes it.
Likewise, but with less incidence, the origin of such contamination may be anthropogenic pressure, caused by industrial discharges, mining operations or urban runoff.
Iron and manganese problems in drinking water:
These elements are cations that are not dangerous to health but give water an undesirable taste, odour and colour. Iron causes reddish-brown rust stains and manganese brownish-black. In addition, one of the major problems caused by the presence of these pollutants is the clogging and fouling of water distribution networks and outlets.
For example, in a DWTP, equipment can suffer from the accumulation of oxides in its tanks. This results in poor performance, shorter equipment life cycles and poor quality of the output water after treatment.
In water distribution networks, oxides deposited over time lead to reductions in pipe cross-section, corrosion and even leaching of iron pipes, increased head loss or uncontrolled bacterial growth.
The mineral iron found in water is in the form of soluble cations. Concentrations in ground and surface water can be high. Depending on the reduction-oxidation potential and the pH of the water, iron is found in one or the other oxidation state. The most common cation present in drinking water is Fe2+, due to the pH and ORP values of the water.
Manganese is less common and less concentrated than iron ore, but usually occurs together. In these cases, it is usually in low concentrations, above 1 mg/l in surface water (although higher values are possible) and below 0.4 mg/l in groundwater. The most important forms of manganese in water are Mn2+ and Mn4+, and their cations are more stable than iron cations, which makes them more difficult to oxidise or precipitate.
Methods to remove iron and manganese in drinking water
There are different methods for the removal of iron and manganese from drinking water:
Conventional technologies
- Reverse Osmosis: Low material lifetime and high operation and maintenance costs.
- Ion Exchange Resins: Low yield (<50%)
- Chemical precipitation
Tecnología BIOBOX:
- BIOBOX® Iron and Manganese
Conventional technologies are effective treatments for the removal of these compounds, but for medium and large flows they become economically unsustainable.
The BIOBOX Iron and Manganese solution has many advantages and eliminates the limitations and undesirable effects of the traditional approach.
Compact plant for the removal of iron and manganese: BIOBOX Iron and Manganese:
BIOBOX® Iron and Manganese is a technical solution for the effective treatment of iron and manganese removal in a compact plant format in a container or skid format. It uses a much smaller surface area than other technologies on the market. This also leads to lower operating and associated investment costs.
It is a process optimised to the maximum that has a filter medium with a very high specific surface area (>1500 m2/m3). This material used is extremely porous, with very low pressure drop and improved surface characteristics that substantially optimise the process.
Regarding the technology implemented in this solution, there are two possible approaches depending on the iron and manganese concentrations in the water to be treated:
The first is auto-catalytic oxidation, which works best with moderate concentrations of iron and manganese. This treatment is suitable for concentrations of less than 2 mg/l of mineral iron and 0.5 mg/l of manganese.
It is a technology capable of removing these pollutants at very low operating costs and with high efficiency and reliability
The second treatment option consists of a preliminary process of particulation of the iron and manganese present in the water. This is followed by a particular retention process with a specific filter medium. The treatment is suitable for concentrations higher than 2 mg/l of mineral iron and 0.5 mg/l of manganese.
Advantages of technology: remove Iron and Manganese from drinking water
- Less space required.
- Use of specific filter material with Fe2O3 surface and auto-catalytic properties.
- Long service life of the material (+ 10 years).
- High filtration velocities: very compact plants.
- No or very little water pre-conditioning required.
- Optimised, robust and highly competitive design.
- Rapid construction of the BIOBOX Iron and Manganese solution.
- Remote control 4.0
- Plug&Play plant.
- 100% automated.
- Carried out by water treatment experts with more than 25 years of experience in the sector.
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