Bsi bs en 12255 5 1999 (2004)

/home/gencode/cen/w12255p5/122 1 28314 BRITISH STANDARD BS EN 12255 5 1999 Incorporating Corrigendum No 1 Wastewater treatment plants — Part 5 Lagooning processes The European Standard EN 12255 5 1999[.]

BRITISH STANDARD BS EN

12255-5:1999

Incorporating Corrigendum No.1

Wastewater treatment

plants —

Part 5: Lagooning processes

The European Standard EN 12255-5:1999 has the status of a

British Standard

ICS 13.060.30

12&23<,1*:,7+287%6,3(50,66,21(;&(37$63(50,77('%<&23<5,*+7/$:

BS EN 12255-5:1999

This British Standard, was

published under the authority

of the Standards Policy and

Strategy Committee on

15 December 1999

© BSI 27 July 2004

ISBN 0 580 35056 8

National foreword

This British Standard is the official English language version of

EN 12255-5:1999

The UK participation in its preparation was entrusted by Technical Committee B/505, Wastewater engineering, to Subcommittee B/505/40, Wastewater treatment plants, which has the responsibility to:

A list of organizations represented on this subcommittee can be obtained on request to its secretary

This standard is published with a national annex, which provides further information for the UK user on polishing ponds

Cross-references

The British Standards which implement international or European

publications referred to in this document may be found in the BSI Catalogue

under the section entitled “International Standards Correspondence Index”, or

by using the “Search” facility of the BSI Electronic Catalogue or of British

Standards Online

This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application

Compliance with a British Standard does not of itself confer immunity from legal obligations.

— aid enquirers to understand the text;

— present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the

UK interests informed;

— monitor related international and European developments and promulgate them in the UK

Summary of pages

This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 9 and a back cover

The BSI copyright notice displayed in this document indicates when the document was last issued

Amendments issued since publication

15266 Corrigendum No.1 27 July 2004 Addition of national annex

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National annex NA (informative)

Design and loading data

NA.1 Introduction

Clause 4 of the standard gives guidance on the different types of lagoon system which are in

use in Europe In the UK, lagoon treatment is limited mainly to polishing ponds This

national annex gives more detailed information on the typical surface loading rates, and

retention times for polishing ponds

Further information may be obtained from the Handbook of UK Wastewater Practice on

Tertiary Treatment [1] The design of polishing ponds to serve population equivalents of

1 000 or less is considered in more detail by BS 6297

The surface loading rates and retention times are based on treatment of secondary effluent

from a typical works treating mainly domestic wastewater Additional treatment or extra

capacity may be required, if wastewater:

— is subject to wide variations in diurnal flow, e.g at small works;

— has a warm temperature and generates density gradients within the lagoon

NA.2 Polishing ponds

Table NA.1 — Typical surface loading rates for polishing ponds

Treatment

required

Type of process Number of

lagoons

Surface loading ratea

Retention time

series

Phosphate

removal

a Based on typical depth of 1 to 1.5 m

b To minimize algal growth which increase effluent suspended solids

c To promote algal growth which assimilates phosphate and must be subsequently removed

National bibliography

Standards publications

BS 6297, Code of practice for design and installation of small sewage and treatment works

and cesspools

Other publications

[1] The Chartered Institution of Water and Environmental Management Handbook of UK

Wastewater Practice, Tertiary Treatment (second edition) CIWEM: 1994

Page 9

BS EN 12255−5:1999