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Oil separators

Oil separators

Traidenis produce tanks with inside installation for treatment of surface wastewater contaminated with petroleum products under code name NGP™. Oil separators are used for treatment of surfaces wastewater polluted with oil products and installed in petrol stations, car wash stations, parking lots, garages, industrial companies (for separation of oil products from surface or industrial wastewater), railways, terminals, ports (for collection of oil products leaked from diesel locomotives, tank wagons).

Traidenis produce oil separators of the following modifications for treatment of surfaces wastewater polluted with oil products:

  • NGP and NGP-S;

  • NGP-L and NGP-L-S.

NGP and NGP-S oil- separators with coalescence filter and automatic gate as well as NGP-L and NGP-L-S oil- separators with coalescence filter meet the requirements established by standards LST EN 858-1:2002, LST EN 858-1:2002/A1:2004, LST EN 858-2:2003 and attributed to the coalescing oil separators of I class and have CE marking. 

The diameter of the bodies of NGP and NGP-L (without sand-catcher) as well as NGP-S and NGP-L-S (with integrated sand-catcher) oil- separators can vary from 1,2 to 4 metres, length – from 2 to 16 metres, efficiency – from 1l/s to 100l/s in one tank. With installation of several oil separators the efficiency of treatment plants is increased in parallel.


Main structural parts:       

1. Inlet.
2. Outlet.
3. Lid.
4. Ventilation.
5. Coalescence filter.
6. Automatic protection alarm system
7. Pipe for pumping out oil products

I . Sand catcher
II. Oil products separation chamber
III. Oil products separation chamber 

 1 Fig.  NGP-L-S type oil separator 


The plant consists of two or three chambers. First, surface wastewater passes to the first chamber where the flow of wastewater is settled. If the separator is integrated with sand-catcher, the sand and dirt deposit in the first chamber. From first chamber the wastewater passes to the second chamber with coalescing filter, where oil products bind into larger drops and rise to water surface more quickly. NGP and NGP-S type plants are equipped with absorption filters that keep back fine drops of oil products and partly dissolved organic substances (of surface activity).

The plant is equipped with automatic protection alarm system that gives warning on the accumulated layer of limit thickness of oil products.The installed float gate does not allow the accumulated oil products to pass to the chamber of absorption filters during the accident or service period.

The concentration of oil products does not exceed 5mg/l or 0,05mg/l in the treated surface wastewater depending on the construction of treatment plants.

Oil separators

Oil separator's installation and its functioning ensuring systems shall be carried out in accordance with construction’s technical and/or working project.

Preparation of installation site

We recommend the following:
  1. the site for plant installation shall be selected in such a way that it would not be flooded with surface water;
  2. inspection lid should be available for constant inspection and for proper functioning of the system;
  3. Do maintain a gradient that is required in order to ensure wastewater natural flow to the unit. 
  4. PREPARATION FOR GROUND WORKS: clean a lager site than the treatment plant itself for at least half a metre around it.
  5. GROUND WORKS: ground works are carried out by strictly following the STR 1.07.02:2005 regulation, technical and/or working project and the general construction norms for installation.
In case, when, while ground digging works are performed, units or communications not indicated in the designed drawings are encountered, works shall be immediately stopped and the person performing technical supervision of construction or the authorised person shall be informed. Works in such an area can be continued only after receipt of the permission.
Finishing ground works to the designed altitude, the foundation shall be checked for weak or soaked soil, excavations, etc. Such soil shall be removed to the depth, indicated by the person performing technical supervision of construction and shall be filled with a proper soil by compaction. The site shall be prepared to the altitude indicated in the project, soil shall be compacted (compaction coefficient shall be 0.95÷0.98, compaction layer shall be 200–300mm).

Installation of underground tanks

Tanks shall be mounted based on previously prepared project that is already coordinated with respective institutions. 

ATTENTION: mounting of tank requires special attention as it conditions the further functioning.

Mounting schemes of horizontal and vertical underground tanks

We recommend the following:
  1. installation of tank shall be performed following the EN 976-2 standard;
  2. excavation shall be completed to 20–30cm to the designed depth of the excavation. Proceed with manual digging that is dig with the spade. This way, the unit shall rest on a fixed soil by its bottom;
  3. before lowering the plant into the excavation, IT IS NECESSARY TO CHECK, if the depth of the wastewater feeding pipe and the height of the treatment plant inflow coupling, and angles of the inflow and outflow pipes of the treatment plant do match;
  4. the unit shall be lowered to the excavation by using typical lifting mechanisms. After a careful lowering to the excavation, the unit shall be aligned with the help of the lever;
  5. The gap between the edges of the excavation and the tank shall be gradually filled with sand, transported the installation site in advance, which is filled up by layers of thickness of 20–30cm and carefully compacted. Dry sand shall be compacted by watering it.  
  6. during the mounting stage (or in case of high level of ground water), when filling sand into the excavation around the tank, water shall also be filled gradually into the tank at the same time. It shall be performed in the following way: 20–30cm of sand shall be filled into the excavation around the tank and at the same time 20–30cm of water shall be filled into the tank. The procedure shall be repeated further by filling 20–30cm of ground around the tank and 20–30cm of water to the same tank.  
  7. When the tank is covered with sand until the upper part, place the lid, so that the sand would not access the inside of the tank, when performing back-filling works.  
  8. Fill such amount of sand that inspection lid of the tank would be in one level with the cover of the street or the pavement, if the unit is installed on the roadway: 50–70mm from the ground surface – if installed on the green lawn in the residential quarter: 200mm – if the unit is installed in an undeveloped territories (STR 2.07.01:2003, Section 450 ).
  9. When mounting the tank under the roadway, armoured reinforced concrete slab of the thickness of 200mm that distributes the load of transport means from the tank is placed above it.
  10. In case of high ground water level, the tank shall be anchored to the reinforced concrete slab with stainless steel belt.  

Selection of fitting elements and anchoring bolts

Anchoring bolts are necessary for tank for the wind not to roll it over. The highest likelihood for the tank to be rolled over is when strong wind is blowing, it is empty and no snow is present on the top.

Reactions occur in the fitting element due to wind pressure. Vertical reaction is namely the force of pulling out the anchorage bolt. Based on this force, dimensions of anchorage bolt shall be selected. The CUSTOMER presents the construction of fitting elements.  

tvritinim.jpg       tvirtinim2.jpg  

      Example of the fitting element

Note: dimensions of anchorage elements and bolts, their location and quantity are selected individually in each particular case or in accordance to the technical project.  

Oil separators

  1. Company Traidenis (hereinafter - the manufacturer) is fully responsible for the quality of the operation of its equipment and reliability in a particular object, if: 
    • the manufacturer itself selects (designs) wastewater management system for a particular object;
    • the manufacturer itself performs the authorial supervision of construction and installation works or these works are performed by the company, which is suggested by the manufacturer; 
    • the manufacturer itself performs commissioning works; 
    • the owner of plants (hereinafter - the client) performs all conditions of these rules or concludes an agreement on the maintenance of plants with the company, suggested by the manufacturer. 
  2. If the client wishes to maintain the plants on his/her own, he/she (or a person, appointed by him/her to carry out the maintenance of treatment plants) shall hear out the instruction of the maintenance of treatment plant and shall be familiarized with the rules of the maintenance of particular equipment (the client must declare in writing that he/she is familiarized with the rules of maintenance of treatment plants and agrees to follow these rules).
  3. The manufacturer shall carry out the prophylactic and warranty service of plants during the period provided for in the agreement.
  4. In case the alarm of plants goes on and operation disorders are observed visually, the company in charge of technical maintenance or the manufacturer (contact numbers are indicated in the service agreement) shall be called. In some cases (if it is provided for in the rules of maintenance of a particular plant) the water supply to the plant shall be stopped until the elimination of failure.
  5. The client shall ensure the protection of elements of the wastewater management system against the influence of outsiders.
  6. The client or persons in charge of the maintenance shall fill the maintenance register and collect the results of control, carried out by the environment protection institutions. This information shall be periodically (under the agreement) submitted to the manufacturer. 

    Demand for additional technological elements

    Surface wastewater is treated in 100% or only the most polluted part of it is treated. If only the most polluted part of wastewater is treated, the distribution manhole with bypass line shall be installed in front of treatment plants. Such system is usually designed in such a way that 30% of highest instantaneous wastewater flow is treated. 
    NGP type treatment plants are connected to various technological schemes. When treating wastewater from highly polluted territories, sand catchers shall be planned in front of NGP plants. In order to prevent accidental environmental pollution, closed fitting shall be installed behind surface wastewater treatment plants. 

    It is strictly forbidden to do the following:
    • discharge chemical substances to the system, the access of which into sewerage systems is not provided in accordance with the purpose of usage; 

    In case of these and other violations indicated in maintenance instructions, the company shall not be liable for the malfunctions of system operation and consequences thereof. 
    This section provides only the fundamental rules of maintenance of the wastewater treatment system. Detailed rules and instructions are presented to the owner (the client) after the adjustment and start-up of the wastewater treatment system. In addition, the manufacturing company provides training to persons, appointed by the client or, upon the wish of the client, carries out system maintenance by itself. The terms and conditions of warranty service are established in the agreements. 
  1. connect domestic wastewater to the system;
  2. to throw rubbish to the system. 

Oil separators

You will find certificates here.

Oil separators

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