The plant is designed for the deep biological purification of waste water originated from remote dwellings, motels, resorts, etc.
The technological process is designed for a prolonged aeration and utilises the processes of nitrification and de-nitrification with deep purification in the bio-oxidation unit. The bio-oxidation unit is based on the floating polymer filtering media.
One of the most advantageous and innovative features of the process is a hydraulic automation of the plant operation. The flow of waste water throughout the plant is based on gravity force without a need for transfer pumps. Operational elements of the plant are powered by the difference of water levels.
The plant provides efficient and stable purification of waste water under high fluctuations of waste stream volumes, hydraulic and contamination loads, changes in the composition and properties of waste water.
The after-treatment levels are presented below:
- Suspended particles - below 3 mg/l (ppm)
- Nitrogen as ammonia - below 0.05 mg/l (ppm)
- Nitrogen as nitrite - below 0.02 mg/l (ppm)
- Nitrogen as nitrate - below 9 mg/l (ppm)
- Phosphorus - below 0.1 mg/l (ppm).
As an example, the plant of 12.5 m3/day capacity is designed to receive and treat waste waters from 15 flats/houses. The plant dimensions are: diameter - 1.8 m; height - 2.5 m. Weight of the plant manufactured from steel is approximately 700 kg.
The plant can be manufactured from steel or plastic.
The plant is partitioned into five treatment areas:
- Separation of large-size objects by a grid
- Anaerobic area - area of denitrification
- Aerobic area - area of nitrification
- Sludge separation - clarification area
- Deep purification - area of bio-oxidation in the polymer floating media.
In addition to providing a biological treatment, the anaerobic area also functions as a receiver of waste water overloads and floating contaminants (oil, fat, SAS, etc) from the areas of nitrification and deep purification.
The anaerobic and aerobic areas are interconnected by an airlift, which provides the return of circulating active sludge from nitrification area to denitrification area by gravity flow without enriching it with atmospheric oxygen.
The technological stages of biological treatment in the plant are assisted by one air compressor of membrane type (200 W for the plant of 12.5 m3/day capacity).
The plant can be placed underground and equipped with an inspection hatch.
Maintenance involves periodical (once in two weeks) removal of objects from the grid and removal of excessive active sludge (approximately 100 litres) from the area of nitrification. Active sludge may be processed for organic fertiliser.
The capital, operational and maintenance costs are very low.
Plants of this type have a nine-year operational history without any problems arising.