Guidelines for treated wastewater use for irrigation projects

Lignes directrices pour l'utilisation des eaux usées traitées en irrigation

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Status
Published
Publication Date
23-May-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
02-Apr-2021
Completion Date
02-Apr-2021
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INTERNATIONAL ISO
STANDARD 16075-3
Second edition
Guidelines for treated wastewater use
for irrigation projects —
Part 3:
Components of a reuse project for
irrigation
Lignes directrices pour l'utilisation des eaux usées traitées en
irrigation —
Partie 3: Éléments d'un projet de réutilisation en irrigation
PROOF/ÉPREUVE
Reference number
ISO 16075-3:2021(E)
ISO 2021
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ISO 16075-3:2021(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

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Published in Switzerland
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ISO 16075-3:2021(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 ............................................................................................................................................................................... 2

4 Storage reservoir .................................................................................................................................................................................................. 2

4.1 General ........................................................................................................................................................................................................... 2

4.2 Reservoir types ....................................................................................................................................................................................... 2

4.3 Storage time ............................................................................................................................................................................................... 3

4.4 Problems and strategies.................................................................................................................................................................. 3

5 Additional treatment facilities ............................................................................................................................................................... 5

5.1 General ........................................................................................................................................................................................................... 5

5.2 Filtration ....................................................................................................................................................................................................... 5

5.3 Additional disinfection ..................................................................................................................................................................... 6

6 Distribution systems ........................................................................................................................................................................................ 6

6.1 Pumping stations .................................................................................................................................................................................. 6

6.2 Pipelines ....................................................................................................................................................................................................... 6

6.3 Accessories ................................................................................................................................................................................................. 7

6.3.1 General...................................................................................................................................................................................... 7

6.3.2 Valves ......................................................................................................................................................................................... 7

6.3.3 Blowoffs ................................................................................................................................................................................... 8

6.3.4 Flowmeters ........................................................................................................................................................................... 8

6.3.5 Hydrants .................................................................................................................................................................................. 8

6.4 Resistance of irrigation devices to pH and fertilizers ............................................................................................ 8

6.5 Maintenance of distribution networks to prevent bacterial regrowth ................................................... 9

6.6 Design and operation of distribution network to protect drinking water sources ..................... 9

6.6.1 General...................................................................................................................................................................................... 9

6.6.2 Stipulating a protective radius ..........................................................................................................................10

6.6.3 Principles of TWW irrigation above (underground or surface) drinking

water pipelines ...............................................................................................................................................................10

6.6.4 Principles of cross-connection ..........................................................................................................................10

6.6.5 Principles of painting and marking TWW irrigation pipelines and systems ............11

7 Irrigation systems ............................................................................................................................................................................................12

7.1 Classification ..........................................................................................................................................................................................12

7.2 Pressurized irrigation systems ..............................................................................................................................................13

7.2.1 Sprinkler systems .........................................................................................................................................................13

7.2.2 Micro-irrigation systems ........................................................................................................................................14

7.2.3 Filtration ..............................................................................................................................................................................15

7.2.4 Automation of the irrigation ...............................................................................................................................15

7.3 Preventive treatments, regular maintenance, and handling pressurized irrigation

system failures subject to TWW quality .........................................................................................................................15

7.3.1 General...................................................................................................................................................................................15

7.3.2 Water quality parameters required for the treatment and maintenance of

irrigation systems, for micro-sprinklers and drip irrigation systems ............................15

7.3.3 Equipment and treatments for micro-sprinklers and drip irrigation systems .......16

7.3.4 Restoring working order of an irrigation system after failure ..............................................19

Annex A (informative) Guidelines for injecting chlorine into drip irrigation systems .................................20

Annex B (informative) Guidelines for acid use in drip irrigation systems ................................................................22

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ISO 16075-3:2021(E)

Annex C (informative) Guidelines for injecting hydrogen peroxide into drip irrigation systems .....25

Annex D (informative) Guidelines for sampling drip irrigation pipes ...........................................................................30

Annex E (informative) Appropriated chemicals ....................................................................................................................................32

Annex F (informative) Flushing the drip irrigation pipes ...........................................................................................................34

Bibliography .............................................................................................................................................................................................................................37

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ISO 16075-3:2021(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.

This second edition cancels and replaces the first edition (ISO 16075-3:2015), which has been

technically revised.
The main changes compared to the previous edition are as follows:
— editorial changes;
— addition of Annex F.
A list of all parts in the ISO 16075 series can be found on the ISO website.

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 PROOF/ÉPREUVE v
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ISO 16075-3:2021(E)
Introduction

The increasing water scarcity and water pollution control efforts in many countries have made treated

municipal and industrial wastewater a suitable economic means of augmenting the existing water

supply, especially when compared to expensive alternatives such as desalination or the development

of new water sources involving dams and reservoirs. Water reuse makes it possible to close the water

cycle at a point closer to cities by producing “new water” from municipal wastewater and reducing

wastewater discharge to the environment.

An important new concept in water reuse is the “fit-to-purpose” approach, which entails the production

of reclaimed water quality that meets the needs of the intended end-users. In the situation of reclaimed

water for irrigation, the reclaimed water quality can induce an adaptation of the type of plant grown.

Thus, the intended water reuse applications are to govern the degree of wastewater treatment required

and inversely, the reliability of wastewater reclamation processes and operation.

Treated wastewater can be used for various non-potable purposes. The dominant applications for the

use of treated wastewater (also referred to as reclaimed water or recycled water) include agricultural

irrigation, landscape irrigation, industrial reuse, and groundwater recharge. More recent and rapidly

growing applications are for various urban, recreational, and environmental uses, and indirect and

direct potable reuse.

Agricultural irrigation was, is, and will likely remain the largest reuse water consumer with recognized

benefits and contribution to food security. Urban water recycling, landscape irrigation in particular,

is characterized by fast development and will play a crucial role for the sustainability of cities in the

future, including energy footprint reduction, human well-being, and environmental restoration.

The suitability of treated wastewater for a given type of reuse depends on the compatibility between

the wastewater availability (volume) and water irrigation demand throughout the year, as well as on

the water quality and the specific use requirements. Water reuse for irrigation can convey some risks

for health and environment depending on the water quality, the irrigation water application method,

the soil characteristics, the climate conditions, and the agronomic practices. Consequently, the public

health and potential agronomic and environmental adverse impacts need to be considered as priority

elements in the successful development of water reuse projects for irrigation. To prevent such potential

adverse impacts, the development and application of international guidelines for the reuse of treated

wastewater is essential.

The main water quality factors that determine the suitability of treated wastewater for irrigation

are pathogen content, salinity, sodicity, specific ion toxicity, other chemical elements, and nutrients.

Local health authorities are responsible for establishing water quality threshold values depending on

authorized uses and they are also responsible for defining practices to ensure health and environmental

protection taking in account local specificities.

From an agronomic point of view, the main limitation in using treated wastewater for irrigation arises

from its quality. Treated wastewater, unlike water supplied for domestic and industrial purposes,

contains higher concentrations of inorganic suspended and dissolved materials (total soluble salts,

sodium, chloride, boron, and heavy metals), which can damage the soil and irrigated crops. Dissolved

salts are not removed by conventional wastewater treatment technologies and appropriate good

management, agronomic, and irrigation practices are intended to be used to avoid or minimize potential

negative impacts.

The presence of nutrients (nitrogen, phosphorus, and potassium) can become an advantage due to

possible saving in fertilizers. However, the amount of nutrients provided by treated wastewater along

the irrigation period is not necessarily synchronized with crop requirements and the availability of

nutrients depends on the chemical forms.

This document provides guidance for healthy, hydrological, environmental and good operation,

monitoring, and maintenance of water reuse projects for unrestricted and restricted irrigation of

agricultural crops, gardens, and landscape areas using treated wastewater. The quality of supplied

treated wastewater should reflect the possible uses according to crop sensitivity (health-wise and

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ISO 16075-3:2021(E)

agronomy-wise), water sources (the hydrologic sensitivity of the project area), the soil, and climate

conditions.

This document refers to factors involved in water reuse projects for irrigation regardless of size,

location, and complexity. It is applicable to intended uses of treated wastewater in a given project even

if such uses will change during the project’s lifetime as a result of changes in the project itself or in the

applicable legislation.

The key factors in assuring the health, environmental, and safety of water reuse projects in irrigation

are the following:

— adequate monitoring of TWW quality to ensure the system functions as planned and designed;

— design and maintenance instructions of the irrigation systems to ensure their proper long-term

operation;

— compatibility between the TWW quality, the distribution method, and the intended soil and crops

to ensure a viable use of the soil and undamaged crop growth;

— compatibility between the TWW quality and its use to prevent or minimize possible contamination

of groundwater or surface water sources.

This document is not intended to prevent the creation of more specific standards or guides which are

better adapted to specific regions, countries, areas, or organizations. If such documents are published,

it is recommended to reference this document to ensure uniformity throughout the treated wastewater

use community.
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INTERNATIONAL STANDARD ISO 16075-3:2021(E)
Guidelines for treated wastewater use for irrigation
projects —
Part 3:
Components of a reuse project for irrigation
1 Scope

This document covers the system's components needed for the use of treated wastewater (TWW) for

irrigation. Emphasis is placed on irrigation methods, mainly drip irrigation, as this method represents

an efficient method of irrigation and water saving, while reducing the pollution of the crops. Despite

the fact that water quality and filtration of treated wastewater (herein TWW) using drip irrigation are

critical, open irrigation systems are more popular and are frequently used for irrigation with TWW

and therefore are covered in this document.

This document covers issues related to the main components of a TWW irrigation project, including the

following:
— pumping stations;
— storage reservoirs;
— treatment facilities (for irrigation purposes);
— filtration and disinfection;
— distribution pipeline networks;
— water application devices: irrigation system components and treatment.
This document is not intended to be used for certification purposes.
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

ISO 16075-1, Guidelines for treated wastewater use for irrigation projects — Part 1: The basis of a reuse

project for irrigation
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 ISO 16075-1 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/
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ISO 16075-3:2021(E)
3.2 Abbreviated terms
BOD biochemical oxygen demand
COD chemical oxygen demand
HDPE high-density polyethylene
NPW non-potable water
PE polyethylene
PVC polyvinyl chloride
TWW treated wastewater
WW wastewater
WWTP wastewater treatment plant
4 Storage reservoir
4.1 General

TWW is sent by a transmission pipeline to the distribution centre where water is distributed to

agricultural or other users.

Operational and seasonal storage facilities should be placed downstream the wastewater treatment plant

to equalize daily and seasonal variations in flow from the WWTP to the distribution centre, so as to:

— meet peek irrigation demands;

— store excess of TWW entering the irrigation system in relation to irrigation demands (including

winter storage);

— minimize the consequences of a disruptive operation of WWTP or temporary flow of unsuitable

quality of TWW to the operation of the irrigation system.

Storage reservoirs can also be used to provide additional treatment to the TWW when managers of

irrigation systems need to control changes of wastewater quality that can affect the operation of the

irrigation system or to increase the TWW quality.
4.2 Reservoir types
Storage facilities can be open reservoirs or ponds or closed reservoirs.

Closed reservoirs can be fixed roof reservoirs including underground reservoirs or reservoirs with

removable floating cover (partial or full covered).
Closed reservoirs are more expensive, but can have several advantages:
— reduced evaporation;
— lower potential for algal growth;
— no possibility of contact of wastewater with people or animals;
— protection of stored wastewater from rainfall runoff.
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ISO 16075-3:2021(E)

The disadvantage of these reservoirs is that they require periodic cleaning due to biofilm formation

and biofouling, and due to the lack of photosynthesis there is greater potential for the development of

anaerobic conditions and therefore odour emission.
4.3 Storage time

According to the requirements of the irrigation project, there are two main types of storage, the short-

term and the long-term storage.

Short-term storage is needed in most irrigation systems for equalizing and balancing TWW supply and

application that occur during one or more days (according to the needs of the irrigation system).

Short-term storage is usually provided by concrete or plastic tanks and small ponds while long-term

storage is usually provided by dams, large ponds, lakes, or aquifer storage and recovery.

Long-term storage can be divided to:

— Seasonal storage, that accumulate water during long periods of treatment plant discharge higher

than irrigation demand. The stored TWW may be used when the irrigation demands are higher

than the treatment plant discharge. This storage is generally used in open large reservoirs. The

residence time is generally months.

— Aquifer storage, which is commonly combined with soil aquifer treatment (by means of infiltration

basins). The residence time may be months or years.
4.4 Problems and strategies

During the storage period, wastewater is subject to changes that affect its physical, chemical,

and biological quality. Bacterial regrowth and/or entering from the surroundings, nitrification,

algae growth, and production of H S (responsible for odour emission and risk of corrosion to metal

components in the irrigation system) are the main biological processes affecting the quality of stored

TWW. Increase in suspended solids sediments and dissolved oxygen, modification of pH, decrease of

nutrients concentration (particularly nitrogen), and residual disinfectant are also effects that result

from storage. Natural decay of microorganisms (especially pathogenic microorganisms) during storage

depends on the water retention time and operation conditions of the reservoir.

Due to the high dependency of chemical and biological reactions with the temperature and the pH of

the wastewater, climate conditions and type of reservoir (open or closed) considerably affect the TWW

quality during storage. Temperature, particularly in warm regions, and rainfall are important factors

for stored water quality particularly in open reservoirs.

Management strategies that should be adopted to reduce physical, chemical, and biological problems

associated with wastewater storage in open and closed reservoirs are indicated in Table 1 and Table 2.

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ISO 16075-3:2021(E)

Table 1 — Problems associated with wastewater storage in open reservoirs and management

strategies
Problems Management strategies

— Temperature stratification — Installation of aeration facilities – submerged or surface mixers

or recirculating pumps
— Low content of dissolved oxygen
— Maintaining elevated oxygen concentrations (positive redox)
— Release of odours
through the water column and mainly at the sediment water
interface to prevent phosphorus from entering the water
column and keep it in the sediment
— Sediments — Periodic mechanical or hydraulic dredging of accumulated
sediments at an interval according with the particular local
conditions (five years is considered an acceptable period)

— Excessive growth of algae and — Proper mixing of wastewater in order to improve the photo-

zooplankton oxidation of organic matter induced by the sunlight

— Reduction of internal recycling of — Addition of chemical algaecides. Copper sulfate can have

phosphorous toxicity effects associated with copper accumulation
(overdosing has adverse impacts on reservoir ecosystem).
According to this: caution is required when using copper
sulfate and quantities should be reduced as much as possible
— Maintenance of fish that eat algae and zooplankton. Addition
of chemical dyes to reduce sunlight penetration as well as the
growth of algae. Chemical dyes should be such as do not harm
health, plant or the environment
— Biomanipulation of zooplankton (in shallow reservoirs)
— Ultrasonic emissions placed into the open reservoir

— High content of suspended solids — As suspended solids removal depends on particle size and

residence time, consideration should be given to these factors
when designing the storage reservoirs
— Microorganisms regrowth — Increasing disinfectant residual
— Disinfecting the TWW that enter the irrigation system
— Increasing residence time
— Improving storage quality and facilities
— Isolating and disinfecting problematic sites in pipelines
— Increase of insects namely — Spraying of adequate insecticides
mosquitoes
— Mechanical methods such as keeping the water moving
— Biological controls such as natural larvicides and use of larvae
eating fish
— Keeping banks trimmed

According to the surface area and depth of the reservoir and the accumulation of the sediments.

Sometime there can be an increase in contaminants, due to the increase in residence time, because of secondary

contamination.
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ISO 16075-3:2021(E)

Table 2 — Problems associated with wastewater storage in closed reservoirs and management

strategies
Problems Management strategies

— Wastewater stagnation Recirculation of wastewater (pumping and configuration of inlet

and outlet piping promoting water recirculation)
Maintaining elevated oxygen concentrations (positive redox)
through the water column and especially at the sediment water
interface, to help prevent phosphorus from entering the water col-
umn and keep it locked in the sediment
— Low content of dissolved oxygen Aeration (aeration devices)
— Release of odours
— Loss of d
...

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