Local treatment plants BioLOS

The homogenizer is designed to equalize the inflow of wastewater in terms of flow rate and composition. Wastewater enters the homogenizer at varying hourly flow rates depending on the population’s water usage schedule. From the homogenizer, water is supplied at a constant flow rate equal to the average hourly flow. The presence of a homogenizer ensures the most stable possible pumping of water to biological treatment, thereby improving the overall quality of biological purification. A trash-retaining basket with a smaller opening than in the SPS is also installed at the inlet of the homogenizer. This basket serves as a mechanical pre-treatment unit for debris removal.

After the homogenizer, wastewater enters the denitrifier, where a recirculation flow from the nitrifier and activated sludge from the secondary settling tank are added. Continuous mixing of wastewater and sludge takes place in the denitrifier to create optimal conditions for the denitrification process.

From the denitrifier, the wastewater mixture flows into the nitrifier, where purification with activated sludge occurs. Air is supplied to this compartment to support the activity of aerobic bacteria. A recirculation pump with a constant flow rate is installed at the outlet section of the nitrifier.

After the nitrifier, water enters the secondary settling tank. Due to the design of the tank, the flow direction changes: water first moves downward and then upward, which allows activated sludge to separate and settle at the bottom of the tank. The settled sludge is pumped back to the denitrifier, while the clarified water is directed to post-treatment.

In BioLOS-5, 10, 15, 20, and 30 units, a sand filter is used for post-treatment. Water passes through a sand layer and is freed from fine suspended contaminants. Air is supplied periodically to loosen the sand. In the BioLOS-50 unit, a drum microfilter is used. The operating principle of mesh drum filters is as follows: treated water continuously flows through the inlet pipe into the drum, is filtered through mesh filter elements, and enters the installation chamber, from where it flows over a weir into the discharge channel for purified water. The drum is not fully submerged in water; its upper section (approximately 0.15 of the diameter) remains above water. When the filter element reaches the upper position, contaminants are washed off by water jets from the flushing device into hoppers inside the drum, then discharged into the sewer system. The mesh drums are washed periodically depending on the level of contamination.

The main method of disinfecting biologically treated water in BioLOS systems is UV disinfection. After post-treatment, purified water passes through a UV disinfection unit, where bacteria are destroyed through exposure to ultraviolet radiation. If deeper disinfection is required, water after UV treatment is directed to a contact tank, where a hypochlorite solution is dosed. Each disinfection method fully meets the required standards, so simultaneous use of both methods is generally unnecessary. However, under increased disinfection requirements or in case of risk of failure of one method, both can be used.

The sludge stabilizer is designed for storage and stabilization of excess sludge. It is a tank equipped with internal aerators. If necessary, sludge stored in the stabilizer can help restart the treatment plant without importing sludge from another facility. Stabilized sludge is more suitable for dewatering processes, making stabilization an important stage before sludge dewatering.

The sludge dewatering unit is designed to separate water from stabilized sludge. For treatment facilities with a capacity of up to 100 m³/day, a bag-type dewatering system can be used. It consists of a metal frame with attached bags made of non-woven filter material. As sludge passes through the material, water drains out, leaving partially dewatered sludge inside the bag. The dewatered sludge is then disposed of in accordance with the approved project requirements. The design allows for repeated replacement of filled sludge bags with new ones. To accelerate the process and increase water removal efficiency, the use of a flocculant dosing system is recommended. For higher dewatering requirements, a screw-type sludge dewatering unit can be applied, which is more efficient in terms of water removal and final sludge moisture content compared to the bag-type system.