ISO 9784:2024
(Main)Guidelines for biological filtration of secondary effluent for water reuse
Guidelines for biological filtration of secondary effluent for water reuse
This document provides guidance for biological filtration of secondary effluent for water reuse. It specifies general recommendations, process components and technical recommendations of each component, post-treatment process and water reuse applications. This document is applicable to all types of stakeholders involved in implementing biological filtration for advanced treatment of secondary effluent for water reuse.
Lignes directrices relatives à la filtration biologique de l'effluent secondaire pour la réutilisation de l'eau
General Information
Standards Content (Sample)
International
Standard
ISO 9784
First edition
Guidelines for biological filtration of
2024-10
secondary effluent for water reuse
Lignes directrices relatives à la filtration biologique de l'effluent
secondaire pour la réutilisation de l'eau
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 2
4.1 Overall recommendations .2
4.2 Basic process .3
5 Process components. 4
5.1 Biofilter unit .4
5.2 Mixing unit .4
5.3 Backwashing unit .4
5.4 Controlling unit .4
6 Technical recommendations of the biofilter unit . 4
6.1 Filter media .4
6.2 Water and air distributor zone .5
6.3 Configuration of the biofilter unit .5
7 Technical recommendations of the mixing unit . 6
8 Technical recommendations of the backwashing unit . 6
8.1 Backwashing mode .6
8.2 Equipment .7
9 Technical recommendations of the controlling unit . 7
9.1 M onitoring instrumentation .7
9.2 M onitoring system .7
9.3 Control system .7
10 Post-treatment process . 7
11 Water reuse applications . 8
Annex A (informative) Example structure diagrams of BAF and DNF . 9
Annex B (informative) Cases of water reuse application using biological filtration for secondary
effluent treatment .12
Annex C (informative) Autotrophic denitrification.16
Bibliography . 17
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
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This document was prepared by Technical Committee ISO/TC 282, Water reuse, Subcommittee SC 2, Water
reuse in urban areas.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
Global water consumption has been increasing by approximately 1 % annually since the 1980s, due to
population growth, socio-economic development and changing consumption patterns. It is expected
that global water demand will keep increasing at a similar rate, and that by 2050 the water use will have
[9]
increased by 20 %-30 % compared to the current level . Water reuse is an efficient measure to alleviate
the global water shortage problem and is a common action for many countries in the world. “Fit for purpose”
is a consensus in the field of water reuse, which reduces the demand for fresh water by reusing secondary
effluent in different scenarios, such as urban miscellaneous water, circulating cooling water, process and
product water, etc. Treated secondary effluent acts as an important source of water supply, providing
opportunities to strengthen traditional water supply in some cities, particularly where long-distance
transfers are required to meet water demands. Organics and nitrogen in wastewater are the key indicators
for the management and control of water reuse in various countries.
Biological filtration, as a mainstream technology for wastewater treatment and reuse, is widely used for
advanced treatment of secondary effluent to achieve the effective removal of carbon, nitrogen and solid
substances. However, due to differences in technological, economic, social and environmental conditions,
there is no unified guideline on technical recommendations for biological filtration on a global scale. This
hinders the effective application of biological filtration as a “fit for purpose” practice to treat secondary
effluent.
v
International Standard ISO 9784:2024(en)
Guidelines for biological filtration of secondary effluent for
water reuse
1 Scope
This document provides guidance for biological filtration of secondary effluent for water reuse. It specifies
general recommendations, process components and technical recommendations of each component, post-
treatment process and water reuse applications.
This document is applicable to all types of stakeholders involved in implementing biological filtration for
advanced treatment of secondary effluent for water reuse.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
biological filtration
wastewater treatment process depending on the physical filtration of the filter media (3.7) filled in the
treatment infrastructure and the biochemical action of the biofilm attached to the filter media
3.2
biofilter
bed of inert filter media (3.7) with large holes through which wastewater is caused to percolate for the
purpose of purification by means of an active biological film (bacteria bed) on the inert filter media
Note 1 to entry: Also known as biological filter.
[SOURCE: ISO 6107:2021, 3.72, modified — The preferred term has been changed from “biological filter” to
“biofilter”; Note 1 to entry has been modified.]
3.3
biological aerated filter
BAF
combination of contact oxidation and filtration by means of artificial aeration, intermittent backwashing
and other measures, aiming to remove organic pollutants, ammonium nitrogen and suspended solids
3.4
backwash rate
flow rate of backwashing water or backwashing air passing through filter bed (3.6) per unit area per unit time
3 2
Note 1 to entry: Backwash rate is generally represented as m /(m ·h).
3.5
denitrification filter
DNF
biofilter (3.2) for the purpose of denitrifying nitrate nitrogen in wastewater
3.6
filter bed
filter that consists of layers of filter media (3.7) arranged over one another so that a liquid flowing through
one filter media does not carry it into the next to clog it
Note 1 to entry: Also known as graded filter.
[SOURCE: ISO 6707-1:2020, 3.3.4.45, modified — The preferred term “graded filter” and the admitted term
“leaching field” have been removed; in the definition, “coarse gravel, coarse sand, and fine sand” has been
changed to “filter media”; Note 1 to entry has been ad
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