CEN/TR 12566-5:2008

SLOVENSKI STANDARD
01-januar-2009
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Small wastewater treatment systems up to 50 PT - Part 5: Pre-treated effluent filtration
systems
Kleinkläranlagen für bis zu 50 EW - Teil 5: Filtrationsanlagen für vorbehandeltes
häusliches Schmutzwasser
Petites installations de traitement des eaux usées jusqu'a 50 EH - Partie 5 : Systemes de
filtration d'effluent prétraité
Ta slovenski standard je istoveten z: CEN/TR 12566-5:2008
ICS:
13.060.30 Odpadna voda Sewage water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 12566-5
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
November 2008
ICS 13.060.30
English Version
Small wastewater treatment systems up to 50 PT - Part 5: Pre-
treated Effluent Filtration systems
Petites installations de traitement des eaux usées jusqu'à Kleinkläranlagen für bis zu 50 EW - Teil 5:
50 EH - Partie 5 : Systèmes de filtration d'effluent prétraité Filtrationsanlagen für vorbehandeltes häusliches
Schmutzwasser
This Technical Report was approved by CEN on 7 April 2008. It has been drawn up by the Technical Committee CEN/TC 165.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, 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
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 12566-5:2008: E
worldwide for CEN national Members.

Contents Page
Foreword.3
Introduction .5
1 Scope .6
2 Normative references .6
3 Terms and definitions .6
4 Description of filters.9
5 Design Parameters .9
6 Components.12
7 General requirements for the installation of septic tanks.15
8 Construction.15
9 Filter systems.17
10 Operation and Maintenance.27
Annex A (informative) Preliminary site consideration.29
Annex B (informative) Reeds bed filters comparison.31
Annex C (informative) Selection of suitable sands.33
Annex D (informative) Phosphorus removal .36
Bibliography .37

Foreword
This document (CEN/TR 12566-5:2008) has been prepared by Technical Committee CEN/TC 165
“Wastewater engineering”, the secretariat of which is held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
The standard series EN 12566 "Small wastewater treatment systems for up to 50 PT" contains the following
parts:
 Part 1: Prefabricated septic tanks;
NOTE 1 This part specifies the requirements and test methods for prefabricated septic tank units.
 Part 2: Soil infiltration systems;
NOTE 2 Code of Practice for in-situ constructed soil infiltration systems. No treatment requirements are specified.
 Part 3: Packaged and/or site assembled domestic wastewater treatment plants;
NOTE 3 This part specifies the requirements and test methods used to evaluate packaged wastewater treatment plants
which are required to treat wastewater to a declared quality.
 Part 4: Septic tanks assembled in situ from prefabricated kits;
 Part 5: Pre-treated effluent filtration systems (this Technical Report);
 Part 6: Prefabricated treatment units for septic tank effluent (in preparation);
 Part 7: Prefabricated tertiary treatment units (in preparation).
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Report: Austria, Belgium, Bulgaria, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden,
Switzerland and the United Kingdom.

Key
A: Raw domestic wastewater 1: Prefabricated septic tank
B: Septic tank effluent 2: Soil infiltration system
C: Treated infiltrated effluent 3: Packaged and/or site assembled domestic wastewater treatment plant
D: Treated wastewater 4: Septic tank assembled in situ from prefabricated kit
E: Tertiary treated wastewater 5: Pre-treated effluent filtration system
6: Prefabricated treatment unit used for septic tank effluent
7: Prefabricated tertiary treatment unit
Figure 1 – Scheme related to the arrangement of the parts of EN 12566
Introduction
Filtration systems have effluent collection systems and the effluent quality can be measured. The systems
described are intended to illustrate the main principles of construction and are subject to variation. The
regulatory authorities shall be consulted for suitability. All filtration systems shall be designed to accept the
total daily flow from at least one house.
No treatment efficiencies are indicated in this document for any particular system.
The dimensional values and ranges given in the document were agreed as sufficient to provide acceptable
treatment for basic parameters in the majority of simple situations.
Some specific dimensional values and ranges can be found in country’s codes of practice and regulations
given in the bibliography.
1 Scope
This Technical Report provides details of filtration systems used for applications ranging from a single house
up to and included 50 PT. The filtration systems receive domestic wastewater from septic tanks manufactured
according to the requirements given in EN 12566-1 and EN 12566-4.
This document is a code of practice and gives design parameters, construction details, installation and
component requirements for constructed sand filters and subsurface flow sand or gravel reed beds.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 1085:2007, Wastewater treatment – Vocabulary
EN 12050-2, Wastewater lifting plants for buildings and sites - Principles of construction and testing - Part 2:
Lifting plants for faecal-free wastewater
EN 13252, Geotextiles and geotextile-related products — Required characteristics for use in drainage
systems
3 Terms and definitions
For the purposes of this Technical Report, the terms and definitions given in EN 1085:2007 and the following
apply.
3.1
biological layer
biological film which grows on the top of the filter material when pre-treated effluent from the septic tank
infiltrates the filter material
3.2
buried filter
filter covered with a layer of soil
3.3
collection layer
layer in which collection pipes collect treated waste water that has passed through the filter
3.4
collection pipe
perforated pipe placed at the bottom within the collection layer connected to the collection chamber
3.5
collection chamber
chamber receiving treated waste water from the collection layer and discharging through the pipe to the outfall
NOTE It is designed to enable effluent sampling.
3.6
collection trench
mound of granular fill material on the base of the excavation at the outlet side, in which a collection pipe
collects water which has passed through the filter
3.7
covered filter
filter usually covered with pebbles or gravel
3.8
connection pipe
non-perforated pipe used to connect the septic tank to the distribution chamber or the collection pipe(s) to an
external collection chamber
3.9
distribution chamber
chamber allowing even gravity distribution of septic tank effluent via the distribution pipes
3.10
distribution layer
layer of the system composed of granular fill material in which pre-treated effluent from the septic tank is
discharged through infiltration pipes
3.11
distribution pipe
non-perforated pipe used to connect the distribution chamber to a single infiltration pipe
3.12
dosing chamber
small tank receiving pre-treated effluent from the septic tank and containing a dosing device (e.g. a pump, a
hydraulic siphon or a tipping trough) which automatically discharges the desired volume
3.13
end connections
perforated and non-perforated pipes and fittings that connect the lower ends of infiltration pipes, and can
enable airflow between infiltration pipes
NOTE The connecting fittings may incorporate ventilation and access provision.
3.14
filter area
surface area of the filter material
3.15
filter material
inert material with various particle or pore sizes used for filtration
NOTE This material, often sand, placed beneath the distribution layer provides both an area for biological growth and
a degree of filtration for the pre-treated effluent from the septic tank.
3.16
filtration system
construction of infiltration pipes, filter material and a collection system used for treating pre-treated effluent
NOTE The infiltration pipes may be located either in trenches or beds which can be singular or multiple.
3.17
granular fill material
inert material in which the infiltration pipes are placed in the distribution or collection layers
Note It may also be used to replace native soil when used as backfill.
3.18
gravel filter
constructed filter using gravel as the filter material
3.19
horizontal reed bed
open gravel filter planted with macrophytes where the effluent is treated by flowing horizontally from the
distribution to the collection point
NOTE Local practice may dictate the use of specific macrophytes, reeds or plants.
3.20
horizontal filter
filter where the effluent is treated by flowing horizontally from the distribution to the collection point
3.21
impermeable film
inert membrane, which is impermeable to liquid
3.22
infiltration pipe
perforated pipe through which the pre-treated effluent from the septic tank is discharged into the treatment
installation
3.23
installation area
area of septic tank and filtration system excluding the outfall
3.24
land drain
surface or subsurface channel for the transportation of rainwater
NOTE They are used to dewater ground and divert the natural flow of surface and subsurface water away from the
filtration system.
3.25
lining
material used to form a container within an excavation
3.26
mesh
fabric, resistant to decomposition with hole diameters approximately 1 mm, which is permeable to liquid and
air but prevents solid particles from passing through it
3.27
open filter
uncovered filter
3.28
prefilter
device used to protect the treatment system (to prevent clogging of the filtration system, particularly the
infiltration pipes)
3.29
reed bed
open filter planted with macrophytes
NOTE Local practice may dictate the use of specific macrophytes, reeds or plants.
3.30
sand filter
constructed filter using sand as the filter material
3.31
vertical reed bed
open sand or gravel filter planted with macrophytes where the effluent is treated by flowing vertically
NOTE Local practice may dictate the use of specific macrophytes, reeds or plants.
3.32
vertical filter
filter where the effluent is treated by flowing vertically between the distribution and collection layer
3.33
water table
level below which the ground is saturated with water
4 Description of filters
The systems described in this document are:
 Buried vertical sand filter;
 Covered vertical sand filter;
 Open vertical sand filter with reeds;
NOTE 1 This system
...