LOCAL WATER-TREATMENT PLANTS
Local wastewater-treatment plants ensure high treatment efficiency combined with reasonable production cost and minor operational expenses. They are used in areas having no central sewerage systems and are intended for servicing one-family houses and small public sites. The main facility is a septic tank with integrated filter and filter draining system for final treatment. During the wastewater flow through the septic tank the wastewater is subjected to the following technological processes: settlement (sedimentation) of easily sinkable fractions; gravity flotation of floating solids, mostly kitchen waste; oxygen stabilizing (psychrophilic fermentation) of the sludge and its biological treatment.
Treatment efficiency in local water-treatment plants is established by comparing the parameters characterizing the wastewater pollution at the inlet and outlet of the septic tank.
TECHNO-PLAST manufactures two types of septic tanks:
2000L, Up to 4 resident people
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3200L, 6-8 people |
Septic tanks are equipped with PVC elements, filter chamber, filter container, reservoir lid, distribution box with a lid and leveling ring.
Up to 3 tanks can be connected in a sequence for servicing more users.
The retention period of the water flowing through the septic tank is from 2 to 4 hours and the period for sludge fermentation is at least 180 days. The maximum filling of the tank with sludge is up to 50% of its volume and the tank should be emptied from sludge every two or three years. Bacterial activators are added into the septic tank (through the toilets) which facilitate natural biological processes, eliminate smells, destroy pathogenic bacteria and help the disintegration of oils and the liquefying of solid sediments.
The wastewater going out of a properly selected and operated septic tank is clean and its quality enables its further ground clarification in a filter draining network.
FUNCTIONING OF THE SYSTEM
The household and fecal wastewater is transported through the sewer to the septic tank. A process of anaerobic bacterial treatment of the water takes place in the tank and the end product is decontaminated filtered liquid mass overflowing to the underground draining network and sinking into the earth thus irrigating and fertilizing the soil. The draining network is made of perforated PVC pipes which are laid in the draining branches located at a distance of ~2 m from each other. There is an 80 l polyethylene distribution box in the starting section of the draining network to which the main pipes (PVC 0110 mm) are connected. The draining pipes are placed in pits of different depth depending on the land specifics and the underground water level.
The bottom of the pit is covered with about 20 cm of sand and then about 30 cm of rubble, on top of which the pre-perforated PVC pipes are installed; the pipes are covered with about 10 cm of rubble which is then covered with geotextile fabric protecting the draining system from contamination. Backfilling is then performed on top of the fabric until the pit levels with the land and this is finally followed by greening.
MAIN RULES FOR IMPLEMENTING THE SYSTEM
- The building to be serviced by the water-treatment plant should have air vents with outlets on the roof through a chimney.
- The underground water level and the soil permeability should be taken into account when installing the draining system. The system should be installed at a depth not greater than 2 m.
- The draining system should be sloping at 1.5% (1.5 cm per 1 m length).
- The draining branches should end with air vents.
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