Settling tanks are devices used in pre-treatment of wastewater and settleable solids of density higher than 1 kg/dm3.
Ecol-Unicon settling tanks provide:
- efficient wastewater pre-treatment from suspended solids up to 100 mg/dm3 according to Polish Minister of Environment regulation
- protection for excessive amount of solids flowing into other devices (e.g. before separators or wastewater treatment plants)
- efficient separation of petroleum derivates in the system integrated with lamella section (EOW-2L).
Despite using the force of gravity vortex settling tanks use centrifugal force. In consequence, there is high efficiency of suspended solids separation at high hydraulic load, which significantly reduces the required size of a vortex settling tank in the design.
The rotary movement of wastewater coming into the device is caused by a directional deflector. The outlet from the vortex chamber is in the middle part of the tank (central pipe).
Inside an EOW vortex settling tank
In a double-chamber vortex settling tank the second chamber is divided into two parts the first of which catches all particles, which are lighter than water including petroleum derivatives, while the second is an outflow chamber.
In a vortex settling tank with lamella section the second chamber has the lamella section and functions as petroleum derivatives separator.
Any petroleum derivatives and other light impurities are caught, depending on settling tank type, in:
- the second part of the chamber (EOW-1 fitted with a deflector)
- the second chamber (EOW-2)
- petroleum derivatives separator in the second chamber (EOW-2L integrated with lamella section)
Settling tanks have a watertight concrete chamber of the diameter of EU chambers or are made of DZB modular reinforced concrete retention tanks or can be installed as a separate chamber in a DZB chamber with pre-treatment system. Depending on the location of the device there are different cast iron or cast iron concrete manholes used in A15, B125 and C250 classes. When used in overrun areas (road, car park, maneuver area etc.) heavy manholes class D400 are used.
In order to adjust the location of the settling tank slab to ground elevation, there is an additional top element used made of concrete rings corresponding to the diameter of the settling tank’s chamber. When the sewer system is located deep in the ground, a reduction-slab and a chimney made of ID 1000 rings can be used.
The inlet and outlet are located in the axis of a settling tank. In certain types of settling tanks it is possible to deviate inlet and outlet axes (consult the catalogue for details).
In order to inform about the amount of sediment collected in a tank, alerting installations are used such as sediment level sensor (Fig. 1) which informs about the need to clean the settling tank. This solution significantly reduces operating costs.
Technical solutions for settling tanks designed by Ecol-Unicon are characterised by high pre-treatment efficiency, low operating costs and easy access while cleaning.