Use

Secondary treatment of residential black water.

Anaerobic percolating

filters are to be installed downstream of

the Imhoff tank to allow the drain of purified water directly into a

surface watercourse, without the risk of polluting the environment.

Operation

The aerobic percolating filter is a biological treatment system

consisting of a tank containing plastic media for the high specific

surface area. The clari

fied water from the Imhoff tank flow into

the aerobic percolating filter; these filter through the fill media

forming a layer of microbial slime (biofilm). In this way, the contact

surface between the biofilm and the aerobic microorganisms

increases and thus the exposure of the biodegradable material to

microorganisms increases. These aerobic bacteria (that is, which

consume oxygen for growth) adhere to the fill media and feed on

the organic substances contained in the wastewater, purifying it.

Maintenance

For the correct management of the FAE and to achieve the

required purification results, please follow these guidelines:

•

Regularly inspect the FAE to check that there is no gross

material received accidentally to clog the pipes;

•

With the passing of time, the organic substances, some

mineralized, accumulate in the bottom of the tank or between

the interstices of the random fill media, and the functionality

of the system can reduce. It is, therefore, necessary to wash

the random fill media with water under pressure, aspirating

the washing water at the same time. The backwash of the

random fill media and the removal of mineralized sludge

should be carried out at least once every

five years. Such

removal must be carried out by a specialized company;

•

As provided for by the Consolidated Act on Water (Legislative

Decree 152/06 as amended), and suggested by the

normal hygiene practice, periodically inspect and wash the

inspection well.

Specification Item

An aerobic percolating filter manufactured in rotational polyethylene

for secondary treatment of residential black water. Monolithic

structure, free of joints and with reinforcement plate, with entry and

exit hole, with plastic random fill media with a specific surface area of

120 m

2

/m

3

and inspection and sampling lids. Suitable for underground

installation. The aerobic percolating filter is dimensioned according

to the instructions contained in Legislative Decree no. 152/2006 and

summarized below:

RESIDENTIAL WASTEWATER

SECONDARY TREATMENT - DRAIN TO WATERCOURSES

PROJECT PARAMETERS

Water supply per P.E.

lt/d

200

Average flow (Q24) per P.E.

lt/h

8,3

Peak flow (Qp) per P.E.

lt/h

20

Specific organic load

gr BOD

5

/P.E.x d

42

Concentration of the biodegradable fraction

mg/l

240

COD/BOD

5

1,67-2,2

Total daily nitrogen load per P.E.

kg/P.E.x d

<0,012

Total surfactant concentration

mg/l

<15

Concentration of oils and fats

mg/l

<10

Specific surface of the random fill media

m

2

/m

3

120

31

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