Septic Tanks – Plastic Sewage Tanks
Building a home requires choosing the right wastewater treatment system, especially in areas without access to the sewer system. Septic tanks are a key component of domestic wastewater treatment systems that serve small households. Understanding their structure and operation is essential to making the right choice, one that is both efficient and economical.
Septic tanks, also known as septic tanks, play a crucial role in the wastewater treatment process in domestic wastewater treatment plants. They are the first phase of the treatment system, where initial sedimentation and biological decomposition of pollutants take place. Below, you’ll find a more detailed explanation of how they work and why they are essential:
The role of septic tanks in domestic sewage treatment plants
Sedimentation:
- When sewage enters the septic tank, heavier solid particles settle at the bottom of the tank, forming sludge.
- Lighter substances, such as fats and oils, float to the surface and form a scum layer.
- Under anaerobic conditions, bacteria naturally present in sewage break down organic matter, reducing the volume of sludge and scum.
- This process leads to partial sewage treatment, reducing the load before the next treatment stage.
- The pre-treated liquid flows out of the septic tank and is directed to subsequent treatment system components, such as drainage fields or biological systems, where it undergoes further treatment.
- Effective pollutant removal: Septic tanks are essential as they remove larger solid particles that could clog or damage other treatment system components.
- Preparation for further treatment: Pre-treatment reduces the biological load in subsequent phases, improving the efficiency of the entire system.
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- Environmental protection: By reducing organic pollutants in wastewater, septic tanks protect local ecosystems from excessive pollution.
- System overflow prevention: Regular emptying of the septic tank ensures proper functioning of the entire sewage treatment system.
- Regular emptying: Septic tanks require regular sludge removal (typically every 1-3 years) to prevent overflow and maintain operational efficiency
- Condition monitoring: Regular inspections allow early detection of potential problems such as leaks or pipe blockages.
Septic tanks are an essential component of domestic wastewater treatment plants, providing pretreatment and enabling the efficient operation of the entire system. By retaining and breaking down larger solids, they help protect both infrastructure and the natural environment.
Furthermore, the distance of the clarifier, which comprises the domestic wastewater treatment plant (for single-family, farm, and individual recreational buildings) from the property boundary and public road should be a minimum of 2 m. From windows and external doors to rooms intended for permanent human occupancy, the distance should be no less than 5 m (in direct proximity to single-family buildings). The location distance of filtration ditches and drainage fields should be 30 m from wells, 2 m from the neighboring property boundary, road (street) or pedestrian walkway. A domestic treatment plant can be built in direct proximity to single-family buildings, provided its ventilation is routed through the sewage system at least 0.6 m above the upper edge of windows and external doors in these buildings.
An important criterion determining the location of a domestic wastewater treatment plant is the distance from water intakes. The treatment plant tank should not be installed at a distance less than 15 m from the nearest well. The distance of the infiltration drainage from water intakes should be at least 30 m, and the groundwater level must be at a depth of 1.5 m below the treated water discharge system. Maintaining such distances is conditioned by the possibility of pathogenic microorganisms penetrating water intakes. Importantly, the above distances apply to all water wells intended for human consumption – both on the property where the domestic wastewater treatment plant is to be located and on neighboring properties.
An important condition for using infiltration drainage is having soil with appropriate permeability and groundwater occurrence at least 1.5 m below the planned position of the wastewater infiltration drainage. Otherwise, it may be necessary to install a sewage pumping station and construct drainage in the form of an embankment.
Note! The treatment plant should be located in non-vehicular terrain with access for sewage trucks.
INSTALLATION OF THE HDPE SETTLER
General rules
To maintain the good condition of the appliance and its operation, follow this instruction manual and its attachments. Incorrect installation may affect the improper operation of the treatment plant. The excavation and installation of the treatment plant should be carried out by a specialized contractor.
Never enter an unventilated tank – LIFE HAZARD!
Make sure that the ground around the treatment plant does not have factors that may have a negative impact during and after installation (guarantee a stable position, keep a safe distance from buildings).
Do not work in heavy rainfall (risk of trench collapse).
Soil subsidence must be taken into account in all assembly work.
After installing the tank and after each service inspection, check that the inspection hatches are closed and properly protected against opening.
We make a trench for a clarifier with dimensions in a floor plan 0.5 – 1.0 m larger than the dimensions of the settling tank. The minimum width of the backfill is 50 cm on each side of the tank.
We make sand ballast with a thickness of min. 30 cm and thicken to at least 85% (according to the Proctor scale).
We lower the tank into the trench, level and make the first layer of 30 cm of sand backfill in order to stabilize it and compact it to min. 85% according to the Proctor scale.
Check the position of the aeration diffusers. They should lie flat on the bottom of the tank.
After leveling and stabilizing the tank, we make backfilling in layers every 30 cm with its simultaneous compaction to the level of the drain spigot according to the proportions and degree of compaction as above. In each layer of filling, the clarifier should be filled with water to the level of backfilling. Particular attention must be paid to the thorough filling of all the cavities of the tank with material and the strong compaction of the layers, so that there are no voids in the backfill, which will guarantee the stability of the tank.
After making the backfill and compacting it, connect the inlet and drain ports, connecting it simultaneously with the distribution manhole.
We install the DN 650 extension, adjusting the height to the expected level of the ground (terrain) and finish the backfill with compaction. When installing the extension, it is imperative to seal the connection point with a special tank designed for this purpose with glue (e.g. Wurth glue + sealant) or another suitable sealant and then screw it with screws (e.g. Farmer type). The tank cover should not exceed 120 cm.
After the installation of the clarifier is completed, a leak test must be carried out.
After completing the above-mentioned works, we proceed to the installation of the drainage.
10. After the excavation is made, depending on the type of soil, we make a protective layer with simultaneous installation of drainage pipes and, if necessary, a supporting layer and covering it with geotextile.
After installing the device and putting it into operation, it is very important to check the correct arrangement of the diffusers located in the biological treatment zone. The biological reactor hatch must be opened and, if necessary, the diffuser should be lifted and laid flat on the bottom, which will ensure that the wastewater is aerated evenly.
Compliance with the manufacturer's guidelines will ensure the stability and functionality of the treatment plant tank and its proper behavior in the trench. Slight deformations of the tank result from the properties of the material used and do not affect the proper operation of the treatment plant. A deformation of the tank of not more than 5% is allowed.
- installation depth 55 - 110 cm
- maximum line length - 24.0 m
- distance between lines 1.0 - 3.0 m depending on soil category
- drainage slope 0.5 - 1.0%
- excavation width at bottom min. 0.5 m
- groundwater level min. 1.5 m below drainage bottom
INSTALLATION VENTILATION
- To ensure proper operation of the treatment plant, the building should have high ventilation of at least DN 110 as sewerage ventilation.
- The outlet of the ventilation pipe removing vapors should be routed above the building roof.
- Ventilation should run in a straight line, without bends or constrictions, taking into account and sealing all inspection objects to enable proper and effective operation.
- In case of installing the system at a greater distance from the building, or in case of lack of high ventilation in the building, additional ventilation should be installed on the building facade and routed to a height of at least 50 cm above the roof ridge.
- If installing additional external ventilation on a residential building is impossible for various reasons, neighboring buildings or other structures should be used.
- Infiltration drainage should be ventilated using an exhaust vent at the end of each drainage line - so-called low ventilation.
Safe device construction has been achieved by eliminating moving parts. Therefore, electric pumps are not used in SBR construction, and a monolithic tank made of polyethylene (PE) ensures device tightness.
The SBR biological treatment plant has CE marking – It has been tested by a notified testing body for compliance with PN-EN 12566-3+A2:2013-10 – therefore our treatment plants ensure high treatment efficiency confirmed by testing.
Low sensitivity to power supply interruptions – In case of power failure, the control system adapts treatment phases to the amount of wastewater flowing to the treatment plant and activates the appropriate phase depending on accumulated wastewater.
The treatment process is automated – Allowing control over the treatment cycle, additionally the control system automatically adapts to the amount of wastewater inflow.
Ability to set the treatment plant to standby mode – Allows maintaining the treatment process even without wastewater inflow for up to 2 weeks.
Easy and inexpensive expansion – Thanks to modular construction, expansion involves adding an additional tank without the need to replace all treatment plant components.
Treatment in the SBR biological wastewater treatment plant occurs without the need to use biopreparations.
Long service life and reliability – PE tanks are made monolithically, additionally reinforced inside the tank with steel reinforcement.
The treatment plant does not require a large land area for installation.
The tanks of the SBR biological treatment plant and the elements inside them are 100% recyclable for used products and raw material reuse.
The device is energy-efficient – allows saving money and protecting the environment.
By treating wastewater, we protect the valuable resource that is water.
- Single and multi-family homes,
- Holiday resorts,
- Small businesses
Product data SETTLEMANS
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