ISO 23044:2020
(Main)Guidelines for softening and desalination of industrial wastewater for reuse
Guidelines for softening and desalination of industrial wastewater for reuse
This document provides guidance on, the evaluation and comparison of wastewater softening and desalination processes for industrial wastewater reclamation and reuse with specific consideration for the following six: 1) chemical precipitation; 2) ion exchange; 3) nanofiltration (NF); 4) reverse osmosis (RO); 5) electrodialysis (ED) and 6) electrodeionization (EDI). This document provides guidance on the characterisation of both influent and effluent quality (e.g. hardness, alkalinity, etc.) and the effects of these processes on those constituents. The purpose of softening and desalination is only for the reuse usages that have requirements for hardness and salinity, such as cooling circulating water, boiler water, production process water, and cleaning water. This document includes the following sub-processes of wastewater softening and desalination processes: a) wastewater softening processes based on chemical precipitation, ion exchange and NF, which aim to remove hardness ions, such as Mg2+ and Ca2+; b) desalination processes based on ion exchange, RO, ED, EDI and NF, which aim to remove the most of total dissolved solids (TDS). This document is applicable to: a) industrial saline wastewater, which has been pre-treated to remove most of the organic matters if necessary; b) the selection or design of wastewater softening and desalination processes for reuse of wastewater from industries.
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General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 23044
First edition
2020-07
Guidelines for softening and
desalination of industrial wastewater
for reuse
Reference number
©
ISO 2020
© ISO 2020
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ii © ISO 2020 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 2
3.2 Abbreviated terms . 3
4 General . 4
5 Requirements for influent quality . 5
6 Softening process . 7
7 Desalination process . 9
Annex A (informative) Pre-treatment process .12
Annex B (informative) Typical performance of desalination technologies .13
Bibliography .15
Foreword
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This document was prepared by Technical Committee ISO/TC 282, Water reuse, Subcommittee SC 4,
Industrial water reuse.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv © ISO 2020 – All rights reserved
Introduction
With the development of society and economy, the contradiction between water shortage and
industrial growth is becoming increasingly acute. Industrial wastewater reclamation and reuse could
[ ]
be an effective way to alleviate this contradiction by improving the water utilization efficiency 4 .
Industrial processes such as oil extraction, chemicals production, printing and dyeing, pharmaceuticals
[5]
manufacturing and food processing produce the wastewater containing total dissolved solids. In
order to reuse these wastewater, total dissolved solids need to be removed by using water softening
[6]
and desalination technologies .
Currently, wastewater softening and desalination processes are based on chemical precipitation,
ion exchange, nanofiltration (NF), evaporation, reverse osmosis (RO), electrodeionization (EDI),
electrodialysis (ED), membrane distillation (MD), and so on, see References [7] to [10]. Each technology
has different applicable conditions and operational costs. The absence of an international standard to
provide guidance on the selection of wastewater softening and desalination processes makes it difficult
to determine the most appropriate softening or desalination technology for industrial enterprises.
Therefore, it hinders industrial wastewater reclamation and reuse. Six technologies have been selected
for consideration under this document, including chemical precipitation, ion exchange, nanofiltration
(NF), reverse osmosis (RO), electrodialysis (ED), electrodeionization (EDI), and there are other
technologies that could be similarly considered for future updates. It should be noted that mechanical
vapour recompression (MVR) and multi-effect evaporation (MEE) are mainly used for evaporation and
crystallization to acquire salts, not for the purpose of water reuse.
Based on the specific inorganic ion species and their concentration in influent, appropriate effluent
quality can be obtained using the recommended technologies that meets the requirement for hardness,
alkalinity and salinity for potential reuse applications.
This document is an innovative standard in the field of industrial wastewater reclamation and reuse.
It can help enterprises, engineers, operators and other stakeholders, who engage in designing or
operating in industrial saline wastewater reclamation and reuse, choose the technologies applying in
the process, and evaluate the treatment effects. As a result, the reuse of industrial saline wastewater
can be promoted and utilization of water can be improved.
INTERNATIONAL STANDARD ISO 23044:2020(E)
Guidelines for softening and desalination of industrial
wastewater for reuse
1 Scope
This document provides guidance on, the evaluation and comparison of wastewater softening and
desalination processes for industrial wastewater reclamation and reuse with specific consideration for
the following six: 1) chemical precipitation; 2) ion exchange; 3) nanofiltration (NF); 4) reverse osmosis
(RO); 5) electrodialysis (ED) and 6) electrodeionization (EDI). This document provides guidance on the
characterisation of both influent and effluent quality (e.g. hardness, alkalinity, etc.) and the effects of
these processes on those constituents. The purpose of softening and desalination is only for the reuse
usages that have requirements for hardness and salinity, such as cooling circulating water, boiler water,
production process water, and cleaning water.
This document includes the following sub-processes of wastewater softening and desalination
processes:
a) wastewater softening processes based on chemical precipitation, ion exchange and NF, which aim
2+ 2+
to remove hardness ions, such as Mg and Ca ;
b) desalination processes based on ion exchange, RO, ED, EDI and NF, which aim to remove the most of
total dissolved solids (TDS).
This document is applicable to:
a) industrial saline wastewater, which has been pre-treated to remove most of the organic matters if
necessary;
b) the selection or design of wastewater softening and desalination processes for reuse of wastewater
from industries.
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
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 http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 Terms and definitions
3.1.1
regeneration
process of restoring an ion-exchange resin after use to its operationally effective state
Note 1 to entry: Two types of generation can occur: co-current regeneration and counter-current regeneration.
Co-current regeneration is original downflow process where both input water and regeneration chemicals flow
in the same direction, while counter-current regeneration is upflow process where input water and regeneration
chemicals flow in different directions.
3.1.2
electrodeionization
method for removing ions by combination of mixed bed ion exchange and electrodialysis in an
electrodialyser, where the fresh water chamber is filled with mixed bed ion exchange resin, and the ion
exchange resin can be electrochemically regenerated by polarization during the electrodialysis process
Note 1 to entry: Generally, it is a polishing process for production of ultrapure reclaimed water and used after
reverse osmosis.
3.1.3
electrodialysis
process used for the deionization of water in which ions are removed, under the influence of an electric
field, from one body of water and transferred to another across an ion-exchange membrane
[SOURCE: ISO 6107-1:2004, 32]
3.1.4
industrial saline wastewater
industrial wastewater that contains high concentration of inorganic ions
3.1.5
ion exchange
process by which certain anions or cations in water are replaced by other ions by passage through a
bed of ion-exchange material
[SOURCE: ISO 6107-1:2004, 46]
3.1.6
mechanical vapour recompression
use of the heat of the secondary steam as a heat source instead of fresh steam by raising its temperature,
with a part of the compressor working to achieve cyclic evaporation
3.1.7
membrane distillation
separation process where a micro-porous hydrophobic membrane separates two aqueous solutions at
different temperatures
3.1.8
microfiltration
type of physical filtration process by pressure driven where a contaminated liquid is passed through
a special pore-sized membrane (0,1-1 µm) to separate microorganisms and suspended particles from
process liquid
3.1.9
multi-effect evaporation
use of microporous membranes with a filtration accuracy of 0,01-0,1 μm for the separation of
microorganisms, large molecules or very finely divided suspended matter from water by filtration,
often by means of applied differential pressure
2 © ISO 2020 – All rights reserved
3.1.10
nanofiltration
membrane separation technology with a filtration accuracy of 0,001-0,01 μm to separate proteins and
low molecular organic compounds
3.1.11
precipitation
chemical reaction in solution resulting in the formation of a solid product
[SOURCE: ISO 11074:2015, 6.4.30]
3.1.12
pre-treatment
treatment process or processes carried out before the softening and desalination processes
3.1.13
reverse osmosis
flow of water through a membrane with a filtration accuracy of 0,000 1-0,001 μm, from a more
concentrated to a less concentrated solution, as a result of applying pressure to the more concentrated
solution in excess of the normal osmotic pressure
Note 1 to entry: The filtration accuracy of membrane is added.
[SOURCE: ISO 6107-1:2004, 61]
3.1.14
softening
partial or complete removal from water of calcium and magnesium ions which are responsible for
hardness
Note 1 to entry: In this context, not only calcium and magnesium ions are removed, other inorganic ions and
cations are also included.
[SOURCE: ISO 6107-1:2004, 68]
3.1.15
ultrafiltration
us
...
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