ISO 16075-5:2021

INTERNATIONAL ISO
STANDARD 16075-5
First edition
2021-06
Guidelines for treated wastewater use
for irrigation projects —
Part 5:
Treated wastewater disinfection and
equivalent treatments
Lignes directrices pour l'utilisation des eaux usées traitées dans les
projets d'irrigation —
Partie 5: Désinfection des eaux usées traitées et traitements
équivalents
Reference number
ISO 16075-5:2021(E)
©
ISO 2021

---------------------- Page: 1 ----------------------
ISO 16075-5:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 16075-5:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 3
4 Wastewater pathogenic contaminants and their inactivation or removal .4
4.1 General . 4
4.2 Type and occurrence of pathogens in wastewater . 4
4.3 Reduction of pathogenic microorganisms in various stages of wastewater treatment . 5
4.4 Reduction of pathogenic microorganisms by different disinfection methods . 6
5 Disinfection . 7
6 Chemical disinfection . 8
6.1 General . 8
6.2 Disinfection by chlorine/bromine compounds . 8
6.2.1 General. 8
6.2.2 Reactions of chlorine/bromine with ammonia . 9
6.2.3 Definition of the halogenated disinfection residuals .10
6.2.4 Breakpoint reaction.10
6.2.5 CT values of chlorine/bromide and their compounds .12
6.2.6 Chlorinated compounds for TWW disinfection .12
6.2.7 Advantages, disadvantages and technical considerations of chlorine
biocides-based disinfection method .13
6.2.8 Chlorination process .15
6.2.9 Brominated compounds for TWW disinfection .15
6.2.10 Advantages, disadvantages and technical considerations of brominated
biocides-based disinfection method .17
6.3 Ozone .18
6.3.1 Chemistry of ozone disinfection .18
6.3.2 Direct ozone reaction .18
6.3.3 Indirect ozone reaction .19
6.3.4 Advantages, disadvantages and technical considerations of Ozone
disinfection method .20
6.3.5 System configuration .20
6.3.6 Monitoring of ozonation .21
6.4 Environmental impacts of chemical disinfection .21
6.4.1 Environmental impacts of chlorination/bromination disinfection .21
6.4.2 Environmental impacts of ozonation disinfection .22
7 UV disinfection .22
7.1 General .22
7.2 UV light technologies and how they work .23
7.2.1 General.23
7.2.2 UV disinfection system components .23
7.3 UV source .24
7.3.1 General.24
7.3.2 UV source protector .25
7.4 Disinfection chamber .25
7.5 Sensors .25
7.5.1 UV intensity sensors .25
7.5.2 UV transmittance sensors .26
7.6 Ballasts .27
© ISO 2021 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 16075-5:2021(E)

7.7 UV validation .27
7.8 The effectiveness of a UV disinfection system .29
7.9 Cleaning .29
7.10 Environmental impacts of UV disinfection .29
7.11 Advantages, disadvantages and technical considerations of UV disinfection method .30
8 Removal of pathogens by membrane methods .30
8.1 General .30
8.2 Membrane system .30
8.3 Pathogen removal by membrane filtration .31
8.4 Considerations for operation and maintenance .31
8.5 Monitoring .31
8.6 Environmental impacts of membrane systems.32
8.7 Advantages, disadvantages and technical considerations of pathogens removal by
membrane systems disinfection method .32
Annex A (informative) Infection agents potentially present in untreated (raw) wastewater .33
Annex B (Informative) Microbial removal performance by various membrane filtration .35
Annex C (Informative) Bromine further compounds .36
Annex D (informative) Factors in operation, maintenance and monitoring of membrane system .37
Bibliography .40
iv © ISO 2021 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 16075-5:2021(E)

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 ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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 ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 282, Water reuse, Subcommittee SC 1,
Treated wastewater reuse for irrigation.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2021 – All rights reserved v

---------------------- Page: 5 ----------------------
ISO 16075-5:2021(E)

Introduction
Disinfection of treated wastewater (TWW) is a critical phase in the process of TWW use. Its purpose is
to reduce or eliminate major health risks to the wastewater treatment plant's operators and to anybody
who may come in contact with TWW or with crops that were irrigated with TWW.
This document provides a guideline for the available methods of disinfection, their effectiveness and the
factors impacting those methods, along with their advantages and disadvantages, regarding technical
and environmental aspects and effective inactivation or removal of various pathogens in wastewater
and TWW for use in irrigation.
vi © ISO 2021 – All rights reserved

---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 16075-5:2021(E)
Guidelines for treated wastewater use for irrigation
projects —
Part 5:
Treated wastewater disinfection and equivalent
treatments
1 Scope
This document provides a guideline for the application of various available methods of treated
wastewater (TWW) disinfection for an effective inactivation or removal of pathogens from TWW,
which is intended for irrigation purposes.
This document deals with:
— chemical and physical technologies, principles of operation, and establishment of effective doses to
be applied, possible interferences, and technical guidance for design and monitoring;
— comparison of the advantages and disadvantages of various disinfection methods suitable for TWW;
— potential environmental effects of the disinfection methodologies and ways to minimize those
impacts;
— disinfection at different locations in the TWW use system, including in the wastewater treatment
plant, within the distribution system and at the point of use.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
ISO 20670, Water reuse — Vocabulary
3 Terms, definitions, and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 20670 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1.1
advanced oxidation process
AOP
process that generates hydroxyl radicals in sufficient quantity to remove organics by oxidation
© ISO 2021 – All rights reserved 1

---------------------- Page: 7 ----------------------
ISO 16075-5:2021(E)

3.1.2
ballast
unit inserted between the supply and one or more discharge lamps, which by means of inductance,
capacitance, or a combination of inductance and capacitance, serves mainly to limit the current of the
lamp(s) to the required value so as to convert and regulate incoming power to UV lamps to produce UV
light
Note 1 to entry: The ballast provides the proper voltage and current required to initiate and generate UV photons.
3.1.3
fouling
process leading to deterioration of membrane flux due to surface or internal blockage of the membrane
[1]
Note 1 to entry: See AWWA B130-13 .
3.1.4
pore size
size of the opening in a porous membrane
Note 1 to entry: Pore sizes are expressed either as nominal (average) or absolute (maximum), typically in terms
of μm.
[1]
Note 2 to entry: See in AWWA B130-13 .
3.1.5
reduction equivalent dose
RED
dose of UV in a given device which is determined by biodosimetry
Note 1 to entry: See UV dose (3.1.9) and “biodosimetry”
Note 2 to entry: This UV dose (3.1.9) is determined by measuring the inactivation of a challenge microorganism
after exposure to UV light in a UV unit and comparing the results to the known UV dose response curve of the
same challenge organism determined via Bench scale collimated beam testing.
3.1.6
ultrafiltration
UF
Note 1 to entry: pressure driven process employing semipermeable membrane under hydraulic pressure gradient
for the separation components in a solution
Note 2 to entry: The pores of the membrane are of a size smaller than 0.1μm, which allows passage of the
solvent(s) but will retain non-ionic solutes based primarily on physical size, not chemical potential.
Note 3 to entry: See in ASTM D6161-10.
3.1.7
UV disinfection system
combination of UV disinfection units (3.1.8) with associated controls and instrumentation
3.1.8
UV disinfection unit
independent combination of single or multiple bank(s) in series with a common mode of failure (e.g.,
electrical, cooling, cleaning system, etc.)
3.1.9
UV dose
UV fluence
2
amount of UV energy given as the time integral of the fluence rate or irradiance (W/m )
2 2
Note 1 to entry: This is given in units of mJ/cm or J/m
2 © ISO 2021 – All rights reserved

---------------------- Page: 8 ----------------------
ISO 16075-5:2021(E)

3.1.10
UV intensity sensor
UV irradiance meter or radiometer instrument to measure UV irradiance
3.1.11
UV transmittance
fraction of photons in the UV spectrum transmitted through a material such as water or quartz
Note 1 to entry: It is preferable that an online UVT sensor be installed and used to verify UVT.
Note 2 to entry: The wavelength of the UVT (%) should be specified, often using a path length of 1 cm. The
measurement is calibrated compared to ultra pure water (ISO 3696 grade 1 or equivalent).
Note 3 to entry: UVT is related to the UV absorbance (A) by the following formula (for a 1 cm path length): % UVT
-A
= 100 × 10 .
3.2 Abbreviated terms
A254 absorbance at 254
CT product of the total residual chlorine and contact time
DBP disinfection by-products
EPA Environmental protection agency
DOC dissolved organic carbon
DVGM German Technical and Scientific Association for Gas and Water (deutsher veriein des gas-
und wasserfaches e.v.)
LP low pressure
LPHO low pressure high output
LRV log removal value
MF microfiltration
MP medium pressure
MWCO molecular weight cut off
NOM natural organic matter
ONORM Austrian Standard (Österreichisches Normungsinstitut)
QA/QC quality assurance/quality control
RED reduction equivalent dose
RO reverse osmosis
TDS total dissolved solids
THM trihalomethanes
TMP trans membrane pressure
TOC total organic carbon
© ISO 2021 – All rights reserved 3

---------------------- Page: 9 ----------------------
ISO 16075-5:2021(E)

TWW treated wastewater
UF ultra-filtration
UV ultraviolet
UVT ultraviolet transmittance
WW wastewater
4 Wastewater pathogenic contaminants and their inactivation or removal
4.1 General
The most critical objective in a TWW reuse programme should be public health.
To achieve the main objective, other equally important objectives should be considered, including:
— environmental protection,
— aesthetics (odour and colour); and
— ability to meet irrigation requirements.
To protect public health and prevent environmental degradation, the TWW quality characteristics and
pathogenic microorganisms contained in the wastewater should be assessed and consideration given
to appropriate treatment to reduce the risk of negative impacts.
There are a wide range of technology options available to meet the water quality goals and to reduce
the risk of disease transmission from pathogenic microorganisms that can be present in TWW and to
meet the water quality goals.
In regular wastewater treatment plants, the two main processes that reduce the concentrations of
pathogenic microorganisms in the water should be:
— the wastewater treatment process itself, which is intended mainly to reduce concentrations of
suspended and dissolved organic matter;
— the process of disinfection of the TWW.
4.2 Type and occurrence of pathogens in wastewater
Urban wastewater intended for agricultural irrigation or for other purposes contains a variety of
pathogenic microbial contaminants that can pose a risk to public health.
The type and number of pathogenic microorganisms in urban wastewater varies between countries
and cities and with time/season (wet and dry), epidemics etc. When selecting disinfection method(s) the
range of microorganisms that can be present should be considered, including parasites eggs, bacteria,
amoebas and other protozoa, Giardia and viruses. Common infectious agents, associated diseases, and
[2]
potential numbers of microorganisms found in domestic wastewater are shown in Table 1 (for the
complete table see Table A.1).
[2]
Table 1 — Infectious agents potentially present in untreated (raw) wastewater
Numbers in
Pathogen Disease raw wastewa-
ter (per litre)
4
Shigella` Shigellosis (bacillary dysentery) Up to 10
4 © ISO 2021 – All rights reserved

---------------------- Page: 10 ----------------------
ISO 16075-5:2021(E)

Table 1 (continued)
Numbers in
Pathogen Disease raw wastewa-
ter (per litre)
Salmonellosis, gastroenteritis (diarrhoea, vomiting, fever), reactive
5
Salmonella Up to 10
arthritis, typhoid fever
5
Vibro cholera Cholera Up to 10
4
Campylobacter Gastroenteritis, reactive arthritis, Guillain-Barré syndrome Up to 10
Enteroviruses (polio,
echo, coxsackie, new Gastroenteritis, heart anomalies, meningitis, respiratory illness, nerv-
6
Up to 10
enteroviruses, sero- ous disorders, others
type 68 to 71)
Respiratory disease, eye infections, gastroenteritis (serotype 40 and
6
Adenovirus Up to 10
41)
5
Rotavirus Gastroenteritis Up to 10
2
Entamoeba Amebiasis (amebic dysentery) Up to 10
5
Giardia Giardiasis (gastroenteritis) Up to 10
4
Cryptosporidium Cryptosporidiosis, diarrhoea, fever Up to 10
3
Ascaris Ascariasis (roundworm infection) Up to 10
3
Ancylostoma Ancylostomiasis (hookworm infection) Up to 10
2
Trichuris Trichuriasis (whipworm infection) Up to 10
The practical measurement of all pathogenic pollutants in TWW is almost impossible.
The main reasons are:
— low concentrations of the pathogenic contaminants in the TWW;
— limitation of present technology, to detect pathogens when they are present in low numbers;
— testing for pathogenic contaminants in the laboratory is lengthy and expensive.
Consequently, the control and monitoring of pathogenic microorganisms should be done by testing for
indicator microorganisms, which are feasible and simple to measure as a result of their much larger
numbers, and based on the premise that factors and treatment affecting their removal similarly affect
the pathogens of interest.
4.3 covers the effect of the first process (WW treatment and the reduction of the concentration of
contaminants). 4.4 covers the effects of the disinfection of the TWW.
4.3 Reduction of pathogenic microorganisms in various stages of wastewater treatment
Although wastewater treatment is mainly intended to eliminate suspended and dissolved organic
matter, independent of disinfection, the treatment process can reduce the number of pathogenic and
indicator microorganisms present in the wastewater. The degree of removal can depend (in part) on
[2]
the type of treatment process, as illustrated in Table 2 .
© ISO 2021 – All rights reserved 5

---------------------- Page: 11 ----------------------
ISO 16075-5:2021(E)

Table 2 — Indicative log removals of indicator microorganisms and enteric pathogens during
[2]
various stages of wastewater treatment
Indicator microorganisms Pathogenic microorganisms
Escheri- Phage
Clostrid- Enteric bacteria Crypto-
chia coli (indi- Enteric Giardia Hel-
ium per- (e.g., Campylo- sporidium
(indicator cator viruses lamblia minths
fringens bacter) parvum
bacteria) virus)
Bacteria X X X
Protozoa
and hel- X X X
minths
Viruses X X
Indicative log reductions in various stages of wastewater treatment
Secondary 0,5 to
1 to 3 0,5 to 1 0,5 to 2,5 1 to 3 0,5 to 2 0,5 to 1 0 to 2
treatment 1,5
Dual media
0 to1 0 to 1 1 to 4 0 to 1 0,5 to 3 1 to 3 1,5 to 2,5 2 to 3
a
filtration
Reservoir
1 to 5 N/A 1 to 4 1 to 5 1 to 4 3 to 4 1 to 3,5 1,5 to >3
storage
Key
N/A not available
NOTE 1 Reduction rates depend on specific operating conditions, such as retention time, contact time and concentrations
of chemicals used, pore size, filter depths, pretreatment, and other factors. Ranges given should not be used as design or
regulatory bases—they are meant to show relative comparisons only.
NOTE 2 See Table 3.
a
Including coagulation.
As the reduction presented in the table for each type of treatment is only indicative, the exact values
of pathogen reduction should be determined for each situation taking into account both the type of
treatment and the environmental and operating conditions such as temperature, organic matter,
turbidity, pH, ammonia, alkalinity, of each system.
4.4 Reduction of pathogenic microorganisms by different disinfection methods
The purpose of disinfecting TWW should be to remove or inactivate pathogenic microorganisms
that remain in the TWW at the end of the standard treatment process. As complete inactivation is
not always feasible or involves investment in methods which could make the required treatment
unpractical, pathogenic microorganisms should be brought to low levels that will not cause significant
health damage when the wastewater is used for irrigation. Reduction of pathogenic microorganism
concentrations may be integrated with additional control strategies that can prevent health impact
such as setting limitations to irrigation with TWW based on the quality achieved.
The practical measurement of all pathogenic microorganisms in TWW is almost impossible for reasons,
and indicator microorganisms are used (see 4.2).
The reduction of indicator and pathogenic microorganisms in TWW by different disinfection methods
[2]
is indicated in Table 3 .
6 © ISO 2021 – All rights reserved

---------------------- Page: 12 ----------------------
ISO 16075-5:2021(E)

Table 3 — Indicative log reductions of indicator microorganisms and enteric pathogens by
[2]
various methods of disinfecting TWW
Indicator microorganisms Pathogenic microorganisms
Enteric
Crypto-
Escherichia Phage bacteria
Clostridium Enteric Giardia sporidi-
coli (indica- (indicator (e.g., Cam- Helminths
perfringens viruses lamblia um par-
tor bacteria) virus) py
...