EN 12255-4:2002

SLOVENSKI STANDARD
01-december-2002
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Wastewater treatment plants - Part 4: Primary settlement
Kläranlagen - Teil 4: Vorklärung
Stations d'épuration - Partie 4: Décantation primaire
Ta slovenski standard je istoveten z: EN 12255-4:2002
ICS:
13.060.30 Odpadna voda Sewage water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 12255-4
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2002
ICS 13.060.30
English version
Wastewater treatment plants - Part 4: Primary settlement
Stations d'épuration - Partie 4: Décantation primaire Kläranlagen - Teil 4: Vorklärung
This European Standard was approved by CEN on 9 November 2001.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2002 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12255-4:2002 E
worldwide for CEN national Members.

Contents
page
Foreword.3
1 Scope .5
2 Normative references .5
3 Terms and definitions.5
4 Requirements .5
4.1 General.5
4.2 Planning.6
4.3 Process .6
4.3.1 General.6
4.3.2 Required Capacity .6
4.3.3 Upward Flow Tanks (including Imhoff Tanks) .6
4.3.4 Horizontal Flow Tanks.7
4.3.5 Lamella Separator.7
4.3.6 Sludge Collection and Removal .7
4.3.7 Scum Removal .8
4.4 Maintenance .8
4.5 Health and Safety.8
Bibliography .9
Foreword
This European Standard has been prepared by Technical Committee CEN/TC 165 "Wastewater engineering", the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical text or
by endorsement, at the latest by July 2002, and conflicting national standards shall be withdrawn at the latest by
December 2002.
It is the fourth part prepared by the Working Groups CEN/TC 165/WG 42 and 43 relating to the general
requirements and processes for treatment plants for a total number of inhabitants and population equivalents (PT)
over 50. The Parts of the series are as follows:

Part 1: General construction principles

Part 3: Preliminary treatment

Part 4: Primary settlement

Part 5: Lagooning processes

Part 6: Activated sludge processes

Part 7: Biological fixed-film reactors

Part 8: Sludge treatment and storage

Part 9: Odour control and ventilation

Part 10: Safety principles

Part 11: General data required

Part 12: Control and automation

Part 13: Chemical treatment – Treatment of wastewater by precipitation/flocculation

Part 14: Disinfection

Part 15: Measurement of the oxygen transfer in clean water in aeration tanks of activated sludge plants
)

Part 16: Physical (mechanical) filtration
NOTE For requirements on pumping installations at wastewater treatment plants, provided initially as part 2 "Pumping
installations for wastewater treatment plants", see EN 752-6 "Drain and sewer systems outside buildings — Part 6: Pumping
installations”.
EN 12255-1, EN 12255-3 to EN 12255-8 and EN 12255-10 and EN 12255-11 were implemented together as a
European package (Resolution BT 152/1998).

)
In preparation.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,
France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain,
Sweden, Switzerland and the United Kingdom.
1 Scope
This European Standard specifies the performance requirements for the primary settlement of wastewater at
wastewater treatment plants for over 50 PT.
The primary application is for wastewater treatment plants designed for the treatment of domestic and municipal
wastewater.
Differences in wastewater treatment throughout Europe have led to a variety of systems being developed. This
standard gives fundamental information about the systems; this standard has not attempted to specify all available
systems.
Detailed information additional to that contained in this standard may be obtained by referring to the Bibliography.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For
dated references, subsequent amendments to or revisions of any of these publications apply to this European
Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies (including amendments).
EN 1085, Wastewater treatment — Vocabulary.
EN 12255-1, Wastewater treatment plants — Part 1: General construction principles.
EN 12255-3, Wastewater treatment plants — Part 3: Preliminary treatment.
EN 12255-10, Wastewater treatment plants — Part 10: Safety principles.
EN 12255-11, Wastewater treatment plants — Part 11: General data required.
EN 12566-1, Small wastewater treatment systems for up to 50 PT — Part 1: Prefabricated septic tanks.
3 Terms and definitions
For the purposes of this European Standard, the following terms and definitions given in EN 1085 and
...