Replacement equipment for 1/6 and 7/12 wastewater treatment plants, or for converting 3500 and 5000 septic tanks into treatment plants. The treatment unit consists of: – 1 pontoon-type polyethylene support with chains – 1 aeration pump that ensures air bubbling and dissolution of oxygen necessary for the microorganism population that decomposes organic substances into primary components, – 1 feed pump that transfers sludge from the treatment compartment to the first compartment and, through its body, ensures water transfer to the treatment compartment based on the principle of communicating vessels, – 1 treated water discharge pump. The minimum and maximum flotation height of the pontoon with pumps are set to cover the calculated water flow. The entire process is controlled and supervised by a microprocessor, mounted in a control panel. The panel features a display with process parameters, a cycle reset button, and an RS232 connector for PC or programming console connection. The display shows the current phase and equipment status. Self-diagnosis functions for equipment status and automatic recovery from operating errors are implemented. Installed power 300 W, Energy consumption – depending on load 500 – 2000 W/day. The treatment plant operates on the SBR (sequencing batch reactor) principle, using a combination of activated sludge treatment and physical separation by decantation. This is achieved in 4 operating cycles/24 hours, each in 4 stages: 1 – Feeding – Domestic wastewater is transferred from the first compartment based on the principle of communicating vessels. 2 – Treatment – Concurrently with feeding, the aeration pump begins operation. Thus, the air necessary for biological purification is introduced into the wastewater. Due to the pontoon system, water homogenization is also ensured. Aeration stages are alternated with pauses to ensure optimal nitrification-denitrification. 3 – Sedimentation – Aeration is stopped, allowing solid suspensions to settle at the bottom of the basin. Only clarified water remains in the upper zone. 4 – Discharge – The clarified water is discharged from the plant using the discharge pump. After the discharge operation is completed, the feed pump will transfer sludge from the treatment compartment to the first compartment, after which the treatment cycle resumes. Vacation mode: If no water input from the first compartment is detected during the feeding stage, the plant switches to vacation mode. Aeration occurs in shorter and more frequent cycles to keep bacteria alive. No water is discharged from the system. The plant automatically switches to normal operating mode as soon as water input from the first compartment is detected. ATTENTION! The treatment plant can only treat domestic wastewater. Water accumulated in the plant must not contain chemicals that can harm the bacterial population. Feeding the plant with the following is not permitted: industrial wastewater, rainwater or recirculated pool water, water containing aggressive chemical agents, petroleum residues, oils, etc.