Use

Parking apron water treatment (such as parking garages, car

washes, service stations, etc.) and rainwater.

The coalescing oil trap, defined by class I according to UNI EN

858-1, are setting tanks that separate mixtures with petrol, oils,

mineral fats and other light fractions of petroleum products

that are highly polluting and are not biodegradable. Coalescing

filters contained in the tank improve the effectiveness of the

system allowing the drain into watercourses. They are installed

in places such as parking areas, service stations, car parks, car

washes, etc. to avoid that oil-based residues flow into drains or the

environment, polluting the territory after a rainfall.

Operation

The process of oil extraction uses the principles of settling by

coalescence process. Coalescence is the process by which two

or more droplets of oil merge during contact. When they collide,

they join together to form larger drops. When the drops of oily

substances become too big, they begin to float on the surface,

while all solid particles that are heavier than water are deposited

on the bottom of the tank. The oil trap should be selected based

on the drainage area that can be covered (covered car park) or

uncovered (uncovered square) and the maximum drainage

capacity.

Maintenance

To maintain the proper operation of the plant the flowing controls

must be carried out every six months:

•

the level of the inert substances in the grease separator;

•

the level of oil/hydrocarbons in the grease separator;

If an excessive amount of sludge (inert) is found in the grease

separator, proceed to its removal.

If an excessive amount of oil/hydrocarbons are found in the

grease separator, proceed to their elimination.

In case the coalescing filter is particularly dirty, proceed to its

removal, cleaning and reinsertion.

PROJECT PARAMETERS

Type of oil/hydrocarbons (specific weight)

Retention time in the treatment stage

Rainfall for the calculation

of absorbing surface

g/cm

3

min

l/s m

2

0.85

approx. 4

5,5 l/s x 1000 m

2

Example of installation

INSPECTION

WELL

COVERED AND UNCOVERED

PRIMARY TREATMENT - DRAIN TO WATERCOURSES

Specification Item

Grease separator/sand trap suitable to separate by gravity the non-

emulsified oil/hydrocarbons lighter than 0.85 g/cm

3

from the drained

wastewater through static separation and coalescing filtration with

efficiency increased by 95%.

Grease separators/sand traps manufactured in rotational

polyethylene, in a single structure free of joints and reinforcement

plating, equipped with inlet and outlet holes, and inspection and

sampling lids. Suitable for underground installation. The plant has

been designed with the following parameters:

R

a

i

n

w

a

t

e

r

t

r

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a

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m

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59

OIL-C