ISO 24575:2023

INTERNATIONAL ISO
STANDARD 24575
First edition
2023-05
General principles and guidelines
for cost analysis in planning of
decentralized wastewater treatment
and/or reuse
Principes généraux et lignes directrices pour l'analyse des coûts lors
de la planification du traitement décentralisé et/ou de la réutilisation
des eaux usées
Reference number
© ISO 2023
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Published in Switzerland
ii
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 2
3.1 Terms and definitions . 2
3.2 Symbols and abbreviated terms . 2
4 Description of different degrees of distribution in planning and design .3
5 Generalized elements of wastewater treatment and reuse systems .4
5.1 General . 4
5.2 Collection . 4
5.3 Conveyance . 4
5.4 Treatment . 5
5.5 Effluent reuse management . 7
6 Cost items to be considered in economic life cycle analysis calculations .7
6.1 General . 7
6.2 Investment cost (C ) or CAPEX items . 7
I
6.2.1 General . 7
6.2.2 Sewer collection piping, C . 8
I,A
6.2.3 Pumping stations, C . 8
I,B
6.2.4 The treatment plant, C . 8
I,C
6.2.5 Effluent distribution piping, C . 9
I,D
6.2.6 Effluent pumping stations, C . 9
I,E
6.2.7 Treated water reservoirs, C . 9
I,F
6.3 Operating cost (C ) OPEX items . 9
O
6.3.1 General . 9
6.3.2 Electricity, C . 10
O,A
6.3.3 Labour, C . 10
O,B
6.3.4 Chemicals, C . 10
O,C
6.3.5 Sludge disposal, C . 11
O,D
6.3.6 Services, C . 11
O,E
6.3.7 Others, C . 11
O,F
6.4 Maintenance cost items (C ) . 11
M
6.5 Income or revenue: negative cost items (C ) .12
N
6.5.1 General .12
6.5.2 Income from selling treated water for reuse, I .12
w
6.5.3 Income from biogas and its products, I .12
G
6.5.4 Income from selling recovered products, I .13
S
6.5.5 Other income, I . 13
O
7 Cost calculations, factoring and results integration .14
7.1 General . 14
7.2 Conversion of all costs to present value . 14
7.3 Normalization of all costs per unit . 15
8 Reporting on results of economic life cycle analysis calculations .15
Annex A (informative) Cost calculation example .17
Annex B (informative) Correlations for CAPEX and OPEX of different process units in
a treatment plant for reuse . .19
Annex C (informative) Summary of treatment process units along with their associated
cost items .20
iii
Bibliography .21
iv
Foreword
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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).
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This document was prepared by Technical Committee ISO/TC 282, Water reuse, Subcommittee SC 2,
Water reuse in urban areas, in collaboration with Technical Committee ISO/TC 224 Drinking water,
wastewater and stormwater systems and services.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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v
Introduction
While energy consumption for water and wastewater treatment is significant, up to 80 % of it is used
for conveyance. This includes pumping of wastewater to the treatment facility and pumping the effluent
to its reuse site. In centralized wastewater treatment and reuse system schemes, the long-distance
conveyance through piping systems and pumping stations is also associated with capital investment,
[1],[2]
which would be hard to bear for those people living in areas of low population densities. Thus, a
network of decentralized wastewater treatment and reuse systems will potentially reduce both the
capital expenses (CAPEX) and operating expenses (OPEX) in some cases, compared with conventional
planning of centralized wastewater treatment and reuse systems. Another benefit of decentralized
[3],[4]
treatment is enabling local reuse, mainly for irrigation.
Distributed design is the concept of providing several decentralized wastewater treatment systems
instead of one central plant, as outlined in other International Standards, such as ISO 23056, which
defines and describes different degrees of decentralization of wastewater treatment plants and
discusses considerations that should be taken in the selection of each alternative. Due to development
in automation and telecommunication, as well as in biological wastewater treatment processes, the
distributed design concept has become a viable option. Potential savings in using distributed design
include:
— lower collection and pumping system construction costs;
— lower collection and pumping system operation and maintenance costs;
— lower energy consumption for pumping;
— local availability for reuse in agriculture or industry or landscape irrigation.
However, potential drawbacks include:
— higher specific cost of each plant compared with a centralized wastewater treatment and reuse
system;
— higher operator attention required for many plants compared with one plant.
This document aims to provide guidelines for life cycle cost assessment for any degree of distribution in
th
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