In industrial production processes, agricultural irrigation, and general water supply, groundwater is the most important alternative source compared to network water. However, the physical, chemical, and...
In industrial production processes, agricultural irrigation, and general water supply, groundwater is the most important alternative source compared to network water. However, the physical, chemical, and microbiological structure of groundwater varies according to the geological conditions of the source. Directly using raw water in the process not only decreases product quality but also leads to irreversible corrosion or clogging damage in the plumbing and equipment.
This is where well water treatment systems come into play, providing solutions that bring raw water to standards suitable for its intended use (pure water, drinking water, process water, boiler feed water, agricultural irrigation water, etc.). The most advanced technology for obtaining water with desired characteristics from well water is Reverse Osmosis systems and complementary pre-treatment units.
Well Water Characteristics
Although groundwater may appear clearer than surface water, it can have higher values in terms of the amount of dissolved substances. Before starting a well water treatment project, the definition of the water must be made. The potential basic contaminants that may be present in the water are as follows:
- Suspended Solids (SS): Sand, silt, and sediment.
- Dissolved Ions: Calcium, magnesium (hardness), sulfate, chloride.
- Heavy Metals: Iron, manganese, arsenic, lead, aluminum.
- Microbiological Load: Bacteria and viruses.
Especially in areas close to the coastline or in basins affected by geothermal sources, high conductivity (TDS) values that necessitate the treatment of saline well water are observed. Conventional filtration is not sufficient to bring these types of waters to industrial standards; it is necessary to use well water treatment systems with membrane technology.
How to Treat Well Water
The design of a treatment facility begins with the examination of the raw water analysis report. The answer to the question of how well water treatment is done can be said to be realized by using multiple treatment systems created according to the analysis values of the water together. The basic process steps are as follows:
Mechanical Pre-Treatment (Filtration Group)
This is the first stage used to protect membrane systems and eliminate physical pollutants.
- Disinfection: Various disinfectants such as chlorine or biocides are applied to well water to both protect the system and extend its lifespan, as well as to ensure the microbiological control of the produced water.
- Ultrafiltration: Although not a very common option for well water, it can be encountered especially in well waters containing high TSS and turbidity. In cases where such well water is present, ultrafiltration systems can also be applied to increase the lifespan and performance of the system.
- Multimedia Filtration (Well Water Filter): Composed of anthracite, quartz sand, glass media, and garnet layers with different granulations. It retains sediments and particles up to 5-20 microns, reducing the SDI (Silt Density Index) value of the water. This unit is generally referred to as a glass media filter or sand filter in the industry.
Well Water Filter and Equipment Selection
The most important factor determining system performance is the correct selection of well water treatment filter. Although there are many different types of filters available in the market, multimedia filters within pressure vessels (FRP tanks) are preferred in industrial applications.
When selecting a well water filter system, the following parameters are considered:
- Filtration Rate: The rate at which water passes through the filter affects the retention efficiency.
- Backwash Period: The duration of backwashing performed with automation valves.
- Micron Sensitivity: Disk filters are used for coarse sediment, while cartridge or bag filters are used for fine sediment.
- Activated Carbon Filtration: Removes organic substances, pesticides, color, and odor parameters present in water. It plays a critical role in retaining free chlorine, which damages the structure of reverse osmosis membranes. In well water treatment systems, coconut carbon, which generally has a high chlorine retention capacity, is commonly used.
(Coconut shell) based variety is used.
- Iron and Manganese Removal: Iron and manganese, commonly found in well water, are removed through oxidation and special mineral filters.
Hardness Removal and Softening
Hard waters cause scaling on membrane surfaces. To prevent this, two methods are applied:
- Fully Automatic Softening Systems: Exchanges calcium and magnesium ions with sodium using resin technology.
- Antiscalant Dosage: In high flow industrial systems, antiscalant chemicals that chemically prevent the formation of scale crystals are dosed.
- Nanofiltration Systems: The working principle is based on membrane technology systems similar to reverse osmosis. Due to the pore size, it has selective removal properties in hardness removal.
Membrane Filtration (Reverse Osmosis - RO)
It is the heart of the system. Well water that has undergone pre-treatment is delivered to semi-permeable membranes with high-pressure pumps.
Reverse Osmosis Technology
Reverse Osmosis is the most sensitive membrane filtration method that separates dissolved inorganic substances, heavy metals, bacteria, and viruses in water at a rate of 95% to 99%.
The system's working principle is based on passing well water through a semi-permeable membrane by creating a resistance (high pressure) against osmotic pressure. The membrane pores are approximately 5 Angstroms in size. Only water molecules can pass through this size, while pollutants are removed from the system via the "concentrate line" (wastewater).