Technological project for 15–20 equivalent inhabitants
GENERAL INFORMATION AND PROJECT OBJECTIVE
The objective of the implemented project in Perushtitsa is the introduction of a modern, compact and sustainable solution for treatment of domestic wastewater from 15 to 20 equivalent inhabitants (EI). The project is developed with a focus on achieving a balanced living environment, environmental protection and full compliance with
Technological project for 15–20 equivalent inhabitants
GENERAL INFORMATION AND PROJECT OBJECTIVE
The objective of the implemented project in Perushtitsa is the introduction of a modern, compact and sustainable solution for treatment of domestic wastewater from 15 to 20 equivalent inhabitants (EI). The project is developed with a focus on achieving a balanced living environment, environmental protection and full compliance with the requirements of Bulgarian and European environmental legislation.
The proposed technology is suitable for single-family and small residential facilities, tourist buildings and complexes, located outside the scope of the central sewerage network.
TECHNOLOGICAL CONCEPT
The treatment plant is designed as a compact modular facility, made of high-quality polypropylene (PP), with a fully closed process and minimal operating costs. Biological treatment is carried out through active sludge in an aerobic environment, with gravitational recirculation of biomass.
The technology ensures effective removal of:
- Organic pollution (BOD₅)
- Suspended solids
- Partial nitrogen and phosphorus compounds
MAIN ELEMENTS OF WWTP
Reception shaft (if necessary)
In the presence of a difference in elevation between the incoming channel and the treatment facility, a polypropylene reception shaft is provided, which serves as an equalization reservoir and ensures uniform supply of wastewater to the station.
Pump-grinder (optional)
For certain configurations, an automated pump-grinder is provided, which crushes incoming solid impurities and protects subsequent technological stages from clogging.
Coarse screen
Fixed basket screen with manual cleaning, designed to retain large impurities (toilet paper, food waste, etc.). Its compact design allows easy maintenance and reliable operation.
Biological stage
Biological treatment is carried out in an aerobic zone with continuous aeration through fine tubular diffusers. The built-in volumetric settler ensures effective separation of active biomass and its gravitational return to the process, without the need for additional pumps for recirculation.
Sludge treatment stage
The project provides:
- Aerobic stabilizer for biological stabilization of excess sludge
- Possibility for gravitational compaction
- Optional dewatering through a geotextile membrane module, without the need for frequent removal with vacuum truck
The dewatered sludge is removed periodically – approximately once every three months.
CONSTRUCTIVE AND OPERATIONAL ADVANTAGES
- Manufactured from high-strength polymeric materials (PP)
- Resistance to corrosion and aggressive environment
- No additional thermal insulation required in winter conditions
- Possibility for installation in ground excavation without concreting
- Flexible arrangement – above ground, underground or in existing septic tank
- Low operating and energy costs
RESULT
The implementation of the project in Perushtitsa provides an effective, environmentally friendly and long-term solution for treatment of domestic wastewater with a small equivalent number of inhabitants. The project is an example of sustainable engineering, combining modern technologies, compactness and reliable operation in accordance with European environmental standards.
