LNAPL Skimming

It is typically composed of:

• 1 DS 500 or DS 100 vacuum pumping unit
• 1 set of SKIM 2 or 4 skimmers immerged in wells and connected to the pumping unit using a flexible hose.
• 1 ST 2500 L or higher capacity storage unit

It is also possible to opt for the purification of pumped effluent, the purification of fumes produced during pumping/storage and the ATEX (Explosion Proof) electrical compliance of the installation.

Skimming is carried out using pump cycles. During each cycle, the supernatant liquid is pumped sequentially and independently in each well while monitoring is carried out by a PLC. The frequency of pumping between two cycles depends on 2 factors:

• The time required to recharge the well with the pollutant.
• The time of suction per well, linked to the quantity of free phase present in the well.

Pumping into the wells is achieved using a SKIM 2 or 4 float connected to the pumping unit with a flexible hose.
The pumped mixture is then transferred automatically to a settling tank. The product is stored in a tank, awaiting removal by a specialised com-pany. The small quantities of effluent are then sent to a coalescence separator.

Following the request from the client, the effluent can then be treated by a small unit of activated carbon before discharge. Similarly, vapours produced during pumping and storage can be purified before discharge by an activated carbon treatment unit. The installation is under continuous monitoring via modem.