Self-Cleaning Screen Filter FMA 7000 uv


STF’s FMA 7000 filter is an automatic, electrically operated mesh filter with disinfection treatment by ultraviolet lamps, specially designed for filtration at small filtration sizes with disinfection treatment for low flows in municipal and industrial applications.

By adapting our designs to the new legislation, STF meets the requirements of Royal Decree 1620/2007 on Reusing Treated Water, with a device which combines filtration action and disinfection in one single unit, thus achieving smaller sized facilities and increased system simplicity.

The washing is automatically performed with no need to interrupt fluid filtration operation, and is also capable of disinfecting the liquid without having to add any chemicals to the water with the goal of minimizing the impact on the environment.

The FMA-7000-UV filter consists of a water inlet for the water to be treated, an outlet for treated water and a drain outlet for equipment cleaning. When water enters the interior of the first chamber (filtration), it reduces its speed and all the partciles are retained as a filter cake on the filtration mesh of the selected size.

Once the fluid has passed through the first stage, it proceeds towards the top of the filter through a duct inside the cartridge. At the end of the duct, the fluid reaches some interleaved ultraviolet lamps which are capable of destroying bacteria and virus DNA by emitting type C ultraviolet light at 254 nm.

The germicidal action starts when the fluid begins to proceed toward the device outlet. The fluid flows at a speed which is suitable so that the dose recommended for each application can be applied.

The FMA-7000-UV device is fully automatic, and is equipped with two washing systems for both the filter mesh and the ultraviolet lamps.

As dirt builds up on the filter mesh, a pressure differential is created. When a preset differential pressure is reached, which is detected by analog pressure transducers, the device initiates a wash cycle which consists of opening the drain valve and rotation of a nozzle system with nylon bristles which suck dirt that has been retained in the filter mesh. The backwash cycles of the filter mesh can also be initiated manually or by means of a timer.

The ultraviolet lamps are equipped with an automatic cleaning system for the quartz glass that protects the lamp, in order to maintain the effectiveness of the system during the lifetime of the lamps. Their cleaning is initiated by time or when a sensor indicates a reduction in radiation.

In recent years the disinfection technology by means of ultraviolet light has been implemented as an alternative to chemical disinfection, as it  is more respectful of the environment and has a smaller environmental impact on water courses. But this system has not always been implemented correctly, since water must be pretreated so that it reaches the disinfection system in ideal conditions in order to ensure the correct operation of the system.

One of the problems that decrease disinfection performance is the so-called "shadow effect", which occurs when water entering the UV disinfection system contains a high concentration of suspended solids of a size which is sufficient for these solids to prevent radiation from reaching the organic matter to be degraded. To avoid this effect it is advisable to perform filtration as a complement to the disinfection system.

The treatment equipment proposed by STF combines both treatments in one device, thus ensuring the proper operation of the disinfection system and further reducing the concentration of suspended solids in water reuse systems.

Thanks to its configuration, the FMA-7000-UV filter is ideal for installation in sewage treatment plants, cooling systems and industrial systems, since as well as ensuring water quality parameters, it reduces both implementation and maintenance economic costs, and significantly reduces the space required for installation.