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Citation: De, I.; Hasan, R.; Iqbal, M.
Natural Treatment Systems and
Importance of Social Cost Benefit
Analysis in Developing Countries: A
Critical Review. Sustainability 2022,
14, 3913. https://doi.org/10.3390/
su14073913
Academic Editor: Andreas
N. Angelakis
Received: 10 February 2022
Accepted: 14 March 2022
Published: 25 March 2022
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sustainability
Review
Natural Treatment Systems and Importance of Social Cost
Benefit Analysis in Developing Countries: A Critical Review
Indranil De 1, * , Rooba Hasan 2and Mubashshir Iqbal 2
1Institute of Rural Management Anand, Anand 388001, Gujarat, India
2Independent Researcher, Anand 388001, Gujarat, India; roobahasan@gmail.com (R.H.);
iqbalmubashshir@gmail.com (M.I.)
*Correspondence: india.indranil@gmail.com or indranil@irma.ac.in
Abstract:
This review article attempts to analyse the social issues that impact the performance of
natural treatment systems (NTSs). An NTS is a decentralised wastewater treatment system found
to be appropriate in developing countries due to its affordability and lower technicity. However, if
socio-economic and institutional issues of community are ignored then NTSs may turn out to be
unsuitable for developing countries. The article also takes a critical view on the extant literature which
ignores the social cost of NTSs. The social cost of NTSs may be high as a decentralised system requires
the engagement of various governmental agencies, research institutes and the community. The cost
of engagement may make NTSs a socio-economically unattractive proposition. The article discusses
the variables to be considered for the social cost-benefit analysis. It also discusses the implications of
social cost-benefit analysis for appreciating the incentives and net benefits for collective actions at the
community level. Social cost-benefit analysis can help overcome the initial difficulty of high financial
cost and usher sustainability.
Keywords: natural treatment systems; social cost-benefit analysis; collective action; sustainability
1. Introduction
Access to safe water is vital to human life, especially for quality of life [
1
]. However,
water goes to waste as nearly 80 per cent of wastewater returns to the ecosystem sans
treatment, irrespective of its vital significance in human life [
2
]. Hence, it is important
to treat and reuse water [
3
]. Furthermore, if wastewater is not treated correctly, it can
pose a serious environmental and health threat [
4
]. The problem is more acute in less
developed countries than in developed countries due to the resource constraints and laxity
in regulation. This article attempts to suggest low-cost alternative wastewater treatment
systems for less developed countries based on the existing literature. Furthermore, it
critically evaluates the notion of a low-cost alternative where unaccounted social costs may
make the apparent low-cost systems unattractive. The cost-benefit analysis of low-cost
alternative systems has been so far limited to financial cost-benefit analysis, where the
social costs and benefits have not been considered explicitly. This review article draws
literature from different domains of knowledge including wastewater management and
social sciences to understand the importance of social cost-benefit analysis for taking
a comprehensive view on low-cost alternatives. In this regard, the social cost-benefit
analysis assumes importance not only for making decisions on technology but also for the
sustainable management of resources through community participation.
A natural treatment system (NTS) is proposed as a low-cost alternative to high-cost
traditional water treatment systems [
5
]. NTSs can be soil-based and aquatic with each
one having different constraints, operating conditions, and design criteria [
6
–
8
]. Soil-based
systems include decentralised wastewater treatment systems (DEWAT), subsurface flow
constructed wetlands (SFCW), rapid infiltration (RI) or soil aquifer treatment, overland flow,
Sustainability 2022,14, 3913. https://doi.org/10.3390/su14073913 https://www.mdpi.com/journal/sustainability
Sustainability 2022,14, 3913 2 of 15
and slow rate systems. Aquatic systems include waste stabilisation ponds (WSP), aquatic
systems with floating plants and wetland systems. NTSs have multi-objective contaminant
targeting processes for the removal of turbidity and suspended solids, biodegradable bulk
organic matter and trace organic compounds, microorganisms and nutrients (N and P) [
9
,
10
].
The systems require simple pumps and piping for wastewater conveyance and distribution.
There are different biological methods for the treatment of greywater including se-
quencing batch reactor (SBR), the membrane bioreactor (MBR), rotating biological contac-
tors (RBCs), the moving bed biofilm reactor (MBBR), and the upflow anaerobic sludge
blanket (UASB) [
11
]. The MBR is one of the most preferred alternatives for wastewater
recycling in high-rise buildings [
12
]. Bacterial enrichment cultures are very useful in de-
grading haloacetic acids (HAAs) frequently detected in surface waters and in drinking
water distribution systems [
13
]. Furthermore, biomass containing denitrifying polyphos-
phate accumulating organisms (DPAOs) may be used efferently to remove COD, nitrogen
and phosphorus [
14
]. Hence, it can be used for the treatment of wastewater containing
high nitrite and nitrate content.
The NTSs are decentralised systems, as opposed to centralised systems. A centralised
system is less appropriate for low-income areas, rural areas with low population den-
sity [
15
–
18
]. NTSs require lower construction, operation and maintenance costs relative to
traditional wastewater treatment facilities [
19
–
21
]. The contaminant removal procedure
involves no significant quantities of energy and/or chemicals [
22
]. Their simple design and
construction allow for easy replication [23].
These projects can be financed and managed through different arrangements: government-
owned and managed or public–private partnerships (PPPs) [
24
]. The technological choice can be
different depending on the local context. Kalbar et al. [
25
,
26
] propose a scenario-based multiple-
attribute decision-making (MADM) methodology to include regional and local societal priorities
including environmental and economic perspectives to select appropriate technology.
The local communities benefit from NTS projects but at the same time it requires com-
munity or beneficiary participation in operation and maintenance (O&M) and monitoring.
As NTSs are decentralised systems, community participation is essential [
27
]. The cost
of participation increases the indirect or social costs. This may make NTS economically
unviable. Furthermore, making the community participate in collective action is a major
challenge. Business models typically do not take into account social cost, but if commu-
nity participation is one of the requirements or inputs in the management of the systems
then social costs should be taken into account. In this context, this article highlights the
importance of social cost-benefit analysis in developing business models for NTS.
Following Teece [
28
] (p. 179) “a business model describes the design or architecture of
the value creation, delivery and capture mechanisms employed.” However, sustainability
is an important component of the business model. A “sustainable organization expresses
its purpose, vision and/or mission in terms of social, environmental, and economic out-
comes” [
29
] (p. 121). Hence, a business model for sustainability should take into account
natural, social and economic capital beyond its organisational boundaries along with cre-
ating and delivering economic value to itself [
30
]. A similar idea is echoed by interactive
business models where the firm has to combine, integrate and leverage the ecosystem’s
capabilities along with internal resources to create new business opportunities [31].
2. Materials and Methods
The review article includes mostly published peer-reviewed literature emphasising
social cost-benefit, community participation and institutional issues for natural wastewater
treatment systems. We have used some articles and reports published by reputed inter-
national organisations as well. The literature review has been conducted in two stages:
search of published articles, reports, conference proceedings and abstract by keywords,
and thematic selection of articles for peer review.
1.
Search articles, book chapters, conference proceedings, reports and abstract by key-
words: This search was carried out in EBSCOhost, Google Scholar, the Web of
Sustainability 2022,14, 3913 3 of 15
Science database and Scopus. The keywords selected to find the literature were
‘wastewater treatment: developed vs. developing countries’, ‘natural wastewater
treatment’, ‘institutional issues of wastewater treatment’, ‘community participation
and co-production’, ‘wastewater treatment: social cost-benefit analysis’.
As the number of research articles found in the search was very high, we relied on the
Scopus electronic database for systematic selection of articles [
32
]. We have limited the articles
to the social science area. The selection process of the articles is given in Figure 1. We have
finally selected 87 articles for review according to their relevance for the topic of discussion.
Sustainability 2022, 14, x FOR PEER REVIEW 3 of 16
2. Materials and Methods
The review article includes mostly published peer-reviewed literature emphasising
social cost-benefit, community participation and institutional issues for natural
wastewater treatment systems. We have used some articles and reports published by re-
puted international organisations as well. The literature review has been conducted in two
stages: search of published articles, reports, conference proceedings and abstract by key-
words, and thematic selection of articles for peer review.
1. Search articles, book chapters, conference proceedings, reports and abstract by key-
words: This search was carried out in EBSCOhost, Google Scholar, the Web of Science
database and Scopus. The keywords selected to find the literature were ‘wastewater
treatment: developed vs. developing countries’, ‘natural wastewater treatment’, ‘in-
stitutional issues of wastewater treatment’, ‘community participation and co-produc-
tion’, ‘wastewater treatment: social cost-benefit analysis’.
As the number of research articles found in the search was very high, we relied on
the Scopus electronic database for systematic selection of articles [32]. We have limited the
articles to the social science area. The selection process of the articles is given in Figure 1.
We have finally selected 87 articles for review according to their relevance for the topic of
discussion.
Figure 1. Selection of articles through Scopus.
Seven other journal articles and book chapter, two books, three conference proceed-
ings, one published and five unpublished reports from reputed organisations, and one
doctoral thesis was included for review of articles as these were found to be relevant.
2. Review of articles, reports and abstracts: The 106 materials selected for review were
grouped by theme. If any article is spanning several topics, then it is grouped into
more than one group. The articles were reviewed and the succinct knowledge was
presented by themes.
3. Wastewater Treatment: Developed vs. Developing Countries
The practice of wastewater management varies across the globe. Inequality between
the wastewater treatment facilities of developing and developed countries is stark [33].
The wastewater treatment is well established in developed countries but limited in devel-
oping countries [34]. Developed countries mainly use the centralised wastewater treat-
ment system along with onsite wastewater treatment. While around 75% of the popula-
tion in the European Union is connected to the centralised public sewage system, 10%
Figure 1. Selection of articles through Scopus.
Seven other journal articles and book chapter, two books, three conference proceedings,
one published and five unpublished reports from reputed organisations, and one doctoral
thesis was included for review of articles as these were found to be relevant.
2.
Review of articles, reports and abstracts: The 106 materials selected for review were
grouped by theme. If any article is spanning several topics, then it is grouped into
more than one group. The articles were reviewed and the succinct knowledge was
presented by themes.
3. Wastewater Treatment: Developed vs. Developing Countries
The practice of wastewater management varies across the globe. Inequality between
the wastewater treatment facilities of developing and developed countries is stark [
33
]. The
wastewater treatment is well established in developed countries but limited in develop-
ing countries [
34
]. Developed countries mainly use the centralised wastewater treatment
system along with onsite wastewater treatment. While around 75% of the population in
the European Union is connected to the centralised public sewage system, 10% population
in Canada, 12% in Australia and 15% in Germany use onsite wastewater treatment sys-
tems [
35
]. Developing countries either use the decentralised wastewater treatment system
or do not treat wastewater at all [
33
]. In developing countries, discharging untreated water
into sewer systems or public canals is a universal practice [
36
,
37
]. High-income coun-
tries treat about 70 per cent of their wastewater; this proportion drops to 38 per cent for
upper-middle-income countries and further down to 28 per cent for lower-middle-income
countries [2].
The purpose of wastewater treatment also varies between developed and developing
countries. Developed countries seek to eliminate all the pollutants while developing coun-
tries tend to protect public health by controlling pathogens and checking the transmission
of waterborne diseases [38]. Therefore, natural treatment systems (NTSs) like constructed
Sustainability 2022,14, 3913 4 of 15
wetlands (CWs) are suitable for developing countries like India due to their efficiency in
BOD and pathogens removal despite their limitation in nutrient removal [33,39].
Developing countries follow the western nations’ traditional model of centralised wastew-
ater treatment in many places. Yet its implementation has not resulted in the provision of
adequate and universal wastewater treatment services in developing countries [
40
–
42
]. This is
because technologies were transferred from western countries without due consideration of the
systems’ suitability in a different culture, geography and climate [
34
]. As a case in point, lack of
technical, financial and managerial capacity by communities had led to most of the sanitation
treatment plants being non-functional in Ghana [
43
]. The standards of the centralised system
are rendered inappropriate for execution since cost implications are not considered [44–50].
While conventional centralised system such as activated sludge process can produce
good water quality, it is not suitable for developing countries. This is due to the high
operating costs involved and much-needed assured power supply, both of present a major
challenge in developing countries [
33
,
38
,
43
,
51
–
54
]. The conventional centralised tech-
nology also demands the requirement of specialised labour. In conventional systems in
developing countries, domestic wastewater combines with rainwater and generates the
flow of pathogenic wastewater, which causes health problems [
34
]. It also requires a high
amount of water to the tune of 100 litres/cap/day for transporting the waste [15,17].
Owing to their unique configuration, conventional systems have high construction
costs [
18
,
55
]. Therefore, constructing a centralised treatment system for small rural com-
munities or peri-urban areas in low-income countries contribute to the burden of debt on
the population [
56
,
57
]. Restricted local budgets, lack of local expertise and lack of funding
were also observed as the factors responsible for the inadequate operation of centralised
wastewater treatment plants in developing countries [58,59].
In choosing an effective wastewater treatment system for developing countries, the
existing local contexts need to be considered as technologies that function efficiently in
one industrialised country may not function well in a developing country [
37
]. The im-
plementation of low-cost natural treatment systems for waste treatment and conserving
biological communities is warranted in poor nations of the world [
53
,
60
]. The members
of biological communities including aquatic plants like floating, submerged and rooted
macrophytes help absorb pollutants. Gude et al. [
61
] argue that it is possible to introduce
an ecological and low-cost alternative to conventional systems through onsite treatment
and onsite processes.
Decentralised wastewater treatment is a feasible alternative to traditional treatment
in developing countries. In decentralised wastewater management, the wastewater is
managed, collected, treated and disposed of/reused at or near the point of generation [
62
].
At present, decentralised systems have the potential to integrate effectively with water-
carriage waste removal [
63
]. This technology is feasible for low population densities and
industrialised countries [
54
]. Decentralised facilities are more commercially viable than
centralised wastewater treatment systems because of their lower net present value (NPV)
costs [
64
]. NPV costs are a total discounted value of costs spread over the lifetime of the
project. The discount rate captures the time value of money, whereby costs in the future is
discounted more than costs at present.
3.1. Pros and Cons of NTSs
The NTS are simpler and usually reasonably successful in eliminating most pollu-
tants, but they can differ depending on the climate [
49
,
55
,
65
,
66
]. Yet, even under extreme
operating conditions, NTS can work although its efficiency level goes down in cold condi-
tions [
9
,
10
,
53
,
67
,
68
]. An NTS is most competent in warm, sunny climates [
69
,
70
]. Different
natural conditions like sunlight, wind, soil characteristics and geology, hydraulics, health
and sustainability of vegetation and seasonal variations in water surface elevation affect
the treatment capability of NTSs, specifically CWs [
71
]. Warmth and sunlight are freely
available in many developing countries in Asia and Africa and hence these countries can
use the technology at low costs. Furthermore, the contaminant removal procedure involves
Sustainability 2022,14, 3913 5 of 15
no significant quantities of energy and/or chemicals [
22
]. NTSs have lower operational
and maintenance (O&M) costs due to fewer pumping energy needs and less solvent usage
in water acquisition, treatment, and disposal [72,73].
In spite of its advantages, the accessibility and price of the land is the main limiting
factor of NTS, as systems require a significant portion of open space for treatment plants.
Hence, NTS tend to be viable only in the small cities and suburban areas, where land is
not a major constraining factor [
40
,
67
,
74
]. Starkl et al. [
75
] argue that NTS may appear to
be inappropriate in urban and peri-urban areas due to high land prices. Moreover, the
labour cost of NTS may be high, as observed by Sahu and Debey [
76
] in their study on land
spreading wastewater disposal systems in Ethiopia.
The efficiency of the decentralised system over the centralised system depends on
various parameters and external conditions [
77
]. The centralised treatment facility works
better for the inner city, while the decentralised system is more appropriate for the urban
fringe and suburban zones. This is because the city’s wastewater can flow more easily to
the inner city centralised treatment facility as compared to the urban fringe. Decentralised
systems are more appropriate in urban fringe and suburban zones as it requires more
land and space. The removal efficiency of the natural wetland treatment system, an NTS,
depends on other factors including inflow concentration because it is a multifaceted process
with irrigation of a tree farm, percolation ponds and wetland discharge [78].
The NTS’s adaptability is another big problem facing NTS designers and operators.
Disordered vegetation growth, nuisance control (e.g., insect vectors, nuisance animals),
slow treatment rates, wastewater exposure and fast macrophyte growth rate pose a concern
for NTSs [
79
–
81
]. Lack of awareness about tropical wetland ecology and species and lack
of local knowledge about design and management along with the prevalence of mixed
domestic/industrial wastewaters pose problems for embracing NTSs [
38
,
82
]. Routine
maintenance of vegetation is another difficult task for the owner-manager of NTSs in
tropical regions [
83
]. Wetland placement near human settlements presents significant
problems due to disturbances created by bugs, rodents, clogging and foul smells. Due
to operational issues, raw wastewater may reach streets during rainy seasons [
70
]. Post-
construction safeguards like performance bonds, long-term post-supervision contracts and
budget coverage are required to assist the local government in operating and maintaining
the system to avoid risk for humans and the system.
Checking the microbiological content of treated wastewater is important when using
treated water for irrigation. In the Italian study, Cirelli et al. [
84
] observed microbiological
content in fruits product by irrigation water treated partially by CW. Rai and Tripathi [
85
]
also found higher coliform counts in vegetables than the prescribed norm in their Varanasi-
based report.
3.2. NTSs in India
We have looked into the NTSs with a special focus on India because of its geographical
spread and variation. The East Kolkata wetland system, located in eastern India, is one
of the most important NTSs having a waste stabilisation pond (WSP) followed by fish-
pond [
24
]. The WSP generate solar energy, an ecosystem for fishing and discharge irrigation
water. The NTS provides not only sanitation but also food and livelihood to the locals. The
local community is an important stakeholder in operation and management. In return,
they receive the economic benefits of the system. There are other important WSPs in West
Bengal State [
24
]. The wastewater is used for fishing and finally discharged in the Ganga
river. The local community is involved in operation along with the state government. The
community is involved in the cleanup of rivers and lakes in exchange for the benefits of
selling fish. Thus, community engagement developed a sense of ownership which is one of
the important factors of long-term success.
In Western India, the NTS on Man Sagar Lake in Jaipur is a classic case of NTS being
set up through PPP between the state government and a private company [
24
]. This system
benefits the downstream community by lifting water from the river originating from the
Sustainability 2022,14, 3913 6 of 15
lake. The filth of sewerage coupled with odour and mosquito menace is being reduced
and transformed into a water resource for farmers and a place for tourism. Similarly,
Duckweed Ponds is developed at Wazirabad which combines a duckweed-aquaculture
system producing fish and shrimps along with treated water for irrigation. The system
is operated by Sulabh International, a social service organisation. Duckweed ponds were
constructed in of Punjab state of India [
86
]. However, most village ponds were constructed
without proper location, planning and drainage systems. It was observed that the wetlands
in the centre of the populated part of the village are hard to drain.
In central India, there is a CW in Bhopal. It made the lives of neighbouring slum
residents stressful, owing to inadequate maintenance [
87
]. Despite CWs’ issues, they can
be effective in developing countries like India. For instance, the constructed wasteland at
Sainik School, Bhubaneshwar, Orissa has been working efficiently and cost-effectively [
88
].
On an experimental basis, NEERI India, an environmental research institute in India, has
developed phytorid technology [
89
]. The technology is very simple in design and operation,
requires no skilled manpower for operation and maintenance and consumption of electric
power is negligible.
In the northern part of India, up-flow anaerobic sludge blanket (UASB) reactor, final
polishing unit (FPU) and down-flow hanging sponge (DHS) systems treating municipal
wastewater located at Dhandhupura, Agra, Uttar Pradesh outperforms many other con-
temporary NTS technologies [
90
]. The treated water may be considered for cultivation, and
safely discharged into water bodies. To improve the efficiency of wastewater treatment,
Kalbar [
91
] suggest involving hybrid treatment systems (HTSs) in India. It is a combina-
tion of natural and mechanised treatment approaches that will save energy and deliver
environmental benefits.
4. Institutional Issues
Decentralised processes are well established and are able to match low-income rural
communities. However decentralised processes can be developed, operated and main-
tained only through community participation. The level of community participation should
provide the community with the power to control the projects or institutions, instead of
just placing people in rubberstamp advisory committees or advisory boards [92].
Community participation is required to understand the local context and design struc-
tures appropriately [
49
]. The process of community participation involving several steps or
activities such as building institutional commitment and partnership for planning, under-
standing existing context and defining priorities, developing systems and implementation
is required for the community to understand their own problem and trigger actions as
illustrated by Parkinson et al. [
93
] for implementation of community-led total sanitation.
Government and non-government organisations (NGOs) are entrusted to create favourable
conditions and support ignition and lateral spread. In other words, programmes need to
be co-produced and co-managed by the community, scientists, NGOs and government.
In a study on DEWATS in Nepal, Bright-Davies et al. [
94
] argue that technically and fi-
nancially more sustainable systems may have better O&M and user ownership through
community-led urban environmental sanitation (CLUES) planning. Studies have delineated
the institutional and technical feasibility as well as business models for NTS in developing
countries, but none of them has considered problems and cost of community participation
explicitly [
95
–
98
]. However, these studies have cautioned about lack of awareness and
capacity, lack of financial incentives, and unwillingness to comply with regulations as major
constraints in wastewater treatment and reuse.
4.1. Community Participation and Co-Production
The efficiency of the decentralised system depends on the local context, and com-
munity participation is essential for NTS. Engagement with the community is one of the
mechanisms to understand the economic, socio-cultural and local context [
99
]. This can
be achieved through co-production, which is the process where inputs are contributed by
Sustainability 2022,14, 3913 7 of 15
individuals and citizens can play an active role in the production of public goods and ser-
vices [
100
]. The larger needs of the community should be better integrated while designing
wastewater management systems [
101
]. The benefits of co-production, especially in water
and sanitation, are the development of hybrid and/or decentralised systems rendering
service and resources accessible, where large, centralised and standardised techno-scientific
systems fail [102].
Community participation in NTS is essential at all stages including technology selection
and O&M [
103
]. The community needs to be informed about the O&M and management
requirement of the technology. Non-governmental organisations (NGOs), consulting firms
and universities may provide technical support during the initial phase. The cost of these
interventions should be taken into account explicitly. The study by Muga and Mihelcic [
101
]
takes into account indicators of public participation in the technology section and cultural
acceptance of the technology but does not estimate the cost of public participation explicitly.
If the citizens are not involved from the outset of the projects, then co-production may
end up passing on the cost to the poor [
104
]. Understanding the complexity of the O&M
of the system and bearing the cost may become an unwanted burden for the poor if they
are not consulted before entrusting the responsibility of O&M on them. To develop an
accountable system users’ perspectives should be combined with institutional commitment
from the formal urban institutions, as observed by Iribarnegaray et al. [
105
] after studying
decentralised domestic wastewater treatment systems (DWWTS) systems in Argentina.
In this context, Joshi and Moore [
106
] suggest institutionalised co-production to include
regular, long-term relationships between state agencies and organised groups of citizens
for public service provision. The Participatory Action Planning Project (PAPP) is a useful
means for institutionalised co-production [107].
4.2. Social Cost-Benefit Analysis
Financing and managing the NTS projects is one of the biggest challenges, especially from
the standpoint of replication and scaling. There are models whereby international organisations,
central, state and local governments have funded NTS projects. The problem with such
financing is that they often do not have a sound business plan from the applicants before the
release of funds. Alternatively, there could be an incentive-based financing model supported
by grants and subsidies, community-based loans, revolving funds and microcredits [
24
]. A
microcredit is a small loan taken from own saving group (also known as a self-help group) or
loans disbursed by venture capitalists known as microcredit organisations.
Cost-benefit analysis is a standard tool to analyse the economic viability of a project.
However, as NTS projects involve the environment and society, mere accounting profitabil-
ity may not make the projects sustainable. It is important to take into account the intangible
costs and benefits of the project through social cost-benefit analysis [
108
]. Social cost-benefit
is a more holistic analysis encompassing financial cost-benefit analysis, economic cost-
benefit analysis and distributional cost-benefit analysis [
109
]. Balkema et al. [
110
] have
detailed the list of indicators to be considered for sustainability analysis of wastewater
treatment. However, to assess a social enterprise like an NTS, it is also important to un-
derstand economic and distributional problems along with financial and environmental
costs and benefits. Moller et al. [
111
] found that in Thailand the sustainability of CWs is
determined by socio-cultural dimension; public perception, awareness and knowledge,
local expertise and institutional clarity of roles.
Net present value (NPV) and benefit-cost ratio (BCR) are calculated for the social cost-
benefit analysis of an environmental project [
112
,
113
]. The costs include initial investment
and incremental operating and maintenance costs. The benefits are measured through
willingness to pay (WTP) surveys following the contingent valuation method (CVM).
The CVM is a survey-based elicitation method to estimate the WTP of goods or services
not traded in the market. A hypothetical market scenario is formulated and described
to the survey respondents to elicit their WTP for the good or service. This process of
eliciting WTP is called the stated preference method. Eggimann et al. [
114
] take into
Sustainability 2022,14, 3913 8 of 15
account settlement distribution and topography into the calculation of the cost efficiency of
sewer systems. Kihila et al. [
115
] have suggested considering employment gains in cost-
benefit analysis. Nevertheless, these approaches do not consider the cost of community
participation explicitly.
The cost of community participation may be accounted as the transaction cost of NTS.
Transaction costs are comparative costs incurred by agents or stakeholders for planning,
adapting and monitoring of the task under alternative governing structures [
116
] and
therefore the function of institutional designs [
117
]. Transaction costs may also be defined
as costs associated with defining, establishing and maintaining property rights [118].
In estimating transaction costs, financial and non-financial costs of collecting informa-
tion, time spent and documentation for submission and service can be considered [
119
,
120
].
Bostedt et al. [
121
] calculated transaction costs involved in the negotiations between two
contestant parties. These calculations are essential in order to understand why community
participation fails.
A few studies on NTS have examined the risk associated with the systems and social
acceptability along with technical and financial feasibility [
75
,
122
]. Although they took
information regarding social acceptance or receptivity in the assessment, they did not
calculate the transaction cost of acceptability or monitoring costs of potential health issues
explicitly. There is a need for training and capacity building to increase wiliness to pay and
community participation [
123
,
124
]. The costs for these activities need to be accounted for
in a cost-benefit analysis.
The variables to be considered to assess the social cost-benefit of the NTS project
have been depicted in Figure 2. It includes measures for both direct and indirect costs
and benefits. It would be difficult to measure people’s perceived risk, hesitancy and
discomfort for NTA projects or reuse of treated water in terms of monetary or economic
value. However, there are techniques through which the economic value of perceived risk,
hesitancy and discomfort can be measured. These techniques are averting expenses or WTP
calculated through the revealed preference method (as opposed to the stated preference
method). Averting expenses are the expenditure made to avert the ill effect of bad odour or
nuisances [
125
]. The additional expense people are willing to incur to use water other than
that supplied through NTS is the WTP for getting rid of the hesitancy of using NTS treated
water. The averting expenditure reveals the WTP for having an environment free from the
perception of risks and discomfort and therefore being less hesitant to use treated water.
Finally, the net present value (NPV) or benefit-cost ratio (BCR) of the social cost-benefit can
be calculated.
Sustainability 2022,14, 3913 9 of 15
Sustainability 2022, 14, x FOR PEER REVIEW 9 of 16
water. Finally, the net present value (NPV) or benefit-cost ratio (BCR) of the social cost-
benefit can be calculated.
Figure 2. Calculation of social cost-benefit of NTS.
It is also important to conduct a distributional analysis of NPV or net benefits of the
project. Due to the political and economic factors, the net benefits would vary across eco-
nomic classes. Some stakeholders may incur a negative NPV or net loss in the project
while others may have positive NPV or net gain. To make those with negative NPV par-
ticipate, stakeholders having positive NPV need to compensate stakeholders having neg-
ative NPV. If the compensation is possible then the business model would be sustainable.
The Kaldor-Hicks Criteria of distribution would be satisfied if stakeholders with negative
NPVs can be compensated by stakeholders with positive NPVs [126]. In an ideal situation,
no one should receive any negative NPV, which refers to the Pareto Criteria of distribu-
tional analysis. Distributional analysis of NPV amongst stakeholders should be consid-
ered after the overall NPV of the project is calculated as indicated in Figure 2.
4.3. Implications for Sustainability
Social cost-benefit analysis has implications for social entrepreneurship or commu-
nity participation for sustainable management of resources through NTSs. Entrepreneurs
and the community would be interested to participate and manage an NTS system if they
find that their present value of financial benefits is higher than the costs. PPP arrange-
ments and social organisations managing NTSs [24] are possible if net financial benefits
are positive. These individual incentives may lead to sustainable environmental manage-
ment. According to UNFCCC, the incentives may be market (creating a market for envi-
ronmental good) and non-market-based (technology support, financial support, ecolabels,
etc.) [127] (https://unfccc.int/topics/what-are-market-and-non-market-mechanisms, ac-
cessed on 1 March 2022). In the short run, if the economic returns are lower than the costs
then perceived long-run social benefits may incentivise them for sustainable ventures.
Figure 2. Calculation of social cost-benefit of NTS.
It is also important to conduct a distributional analysis of NPV or net benefits of
the project. Due to the political and economic factors, the net benefits would vary across
economic classes. Some stakeholders may incur a negative NPV or net loss in the project
while others may have positive NPV or net gain. To make those with negative NPV
participate, stakeholders having positive NPV need to compensate stakeholders having
negative NPV. If the compensation is possible then the business model would be sustainable.
The Kaldor-Hicks Criteria of distribution would be satisfied if stakeholders with negative
NPVs can be compensated by stakeholders with positive NPVs [
126
]. In an ideal situation,
no one should receive any negative NPV, which refers to the Pareto Criteria of distributional
analysis. Distributional analysis of NPV amongst stakeholders should be considered after
the overall NPV of the project is calculated as indicated in Figure 2.
4.3. Implications for Sustainability
Social cost-benefit analysis has implications for social entrepreneurship or community
participation for sustainable management of resources through NTSs. Entrepreneurs and
the community would be interested to participate and manage an NTS system if they find
that their present value of financial benefits is higher than the costs. PPP arrangements
and social organisations managing NTSs [
24
] are possible if net financial benefits are
positive. These individual incentives may lead to sustainable environmental management.
According to UNFCCC, the incentives may be market (creating a market for environmental
good) and non-market-based (technology support, financial support, ecolabels, etc.) [
127
]
(https://unfccc.int/topics/what-are-market-and-non-market-mechanisms, accessed on
1 March 2022). In the short run, if the economic returns are lower than the costs then
perceived long-run social benefits may incentivise them for sustainable ventures. Subsidy
or credit support in the short run may incentivise them. The social cost-benefit analysis
assumes importance in this regard to assess the social sustainability of the NTS projects.
Sustainability 2022,14, 3913 10 of 15
The community may participate in O&M of the NTS projects due to long-run incen-
tives of adaption of sustainable practices. Local community participation is one of the key
elements of WSPs in East Kolkata and other parts of the West Bengal state in India [
24
].
In this regard, the incentive-driven mechanism should be directed to more vulnerable
communities, whose short-term costs are much higher [
128
]. Incentives could be voluntary
such as certification of water footprint or carbon footprint under Clean Development Mech-
anism of UN. Environmental regulation can be construed as involuntary incentives. The
success of voluntary incentives depends on the community’s ability to organise collective
action. Involuntary incentives may play a more certain role if the cost of monitoring is low.
Information on both financial and social costs and benefits is essential for the community
to assess and realise these incentives. Without clear prospects of adaptation of sustainable
practices communities may not participate as they might not have any previous knowledge
about long-run benefits. Initial knowledge about long-run social benefits may entice them
to cooperate at the beginning and then cooperation would gradually built-up in the long
run if they realise current cooperation is beneficial and other members are reliable [129].
Communities can participate not only because they have individual incentives but
shared goal of sustainable development. Ostrom [
130
] suggested a mutually agreed binding
constraint amongst the members to refrain from free riding and manage common resources
for ecological and social sustainability. Communities would agree upon the binding
constraining only when they find that the benefits of cooperation are higher than that of
defection. A social cost-benefit analysis would enable them to appreciate the net social
benefits of cooperation for NTS.
Blomquist and Ostrom [
131
] and Ostrom [
130
] argued that participants may not
have information concerning the resource such as its capacity and growth for making
decisions to participate in collective actions. This information must be gathered and
disseminated amongst all the users. This information includes identification of users
or participants, the capacity of the resource and its use. The systems should be able to
formulate a communication strategy amongst the participants. The net benefit sharing
amongst the participants should be equitable. The participants should be able to establish
an enforceable and contingent contract with an effective monitoring system. As monitoring
is not costless, the cost of it should be accounted for. The information on the capacity of
resources, their use and monitoring cost should be accounted for through social cost-benefit
analysis.
5. Summary and Conclusions
A centralised system is more appropriate in developed countries as compared to
developing countries. Developing countries face challenges of cost overruns and operation
and maintenance. The natural treatment system (NTS) is a feasible option in developing
nations. It is a decentralised structure based on simple technologies which are less expensive
to run and maintain. There are different types of NTSs, both soil-based and aquatic.
In spite of the benefits, an NTS has many other shortcomings. NTSs require large open
space and the efficiency of an NTS is strongly dependent on the external environment. This
study highlights that another major input of decentralised production is efforts made by
beneficiaries in O&M including monitoring of the system, failure of which may lead to
inefficient functioning of the system.
Community participation is required to co-produce the service in coordination with
various actors: local and central governments, hydraulics institutes and the community.
This can be achieved through a process of participatory planning that empowers the
community to manage or even rectify the faults or deficiencies of the system. However,
collective engagement costs can be high. This cost of community participation may reflect
as the project’s transaction cost.
Projects may fail—even when costs of technology, material and operations are low—if
the transaction costs are high. Time spent in the process of negotiations, planning, and other
activities of community participation, along with other indirect costs must be included in
Sustainability 2022,14, 3913 11 of 15
the cost-benefit analysis of NTS projects. It is also very important to conduct a distributional
analysis of the net benefits and compensate the net losers.
The knowledge of the costs and benefits of the project is important for decision-making
as it has implications for individual and collective actions. Thus, it has implications on the
ecological and social sustainability of low-cost alternative wastewater treatment. Higher
financial costs may discourage the poor in the short run. In this regard, long-run social
benefits may encourage them if they are successful in organising collective action. This is
possible if information about long-run social costs and benefits are available. Hence, the
social cost-benefit analysis can have a direct impact on environmental sustainability.
The NTS projects can be a low-cost solution for wastewater treatment in developing
countries. It may help more efficient use of natural resources. The social and environmental
costs of NTSs may be low due to the minimal use of electricity. The beneficiaries can
manage and operate the NTS as the requirement of skills is low. Finally, it may benefit the
poorest who cannot afford irrigation water or treat wastewater on their own. All these
are possible if the beneficiaries find it economically beneficial considering both direct and
indirect costs and benefits. In this regard, the social cost-benefit analysis of NTSs may
directly contribute towards the economic and ecological sustainability of poor communities
as well as reduce inequality.
Author Contributions:
Conceptualization, I.D.; Methodology, I.D.; formal analysis, I.D.; investiga-
tion, I.D., R.H. and M.I.; writing—original draft preparation, I.D., R.H. and M.I.; writing—review and
editing, original draft preparation, I.D., R.H. and M.I.; funding acquisition, I.D. All authors have read
and agreed to the published version of the manuscript.
Funding:
This research was funded by Department of Science and Technology (DST), Government of
India under project entitled “Innovation Centre For Eco-Prudent Wastewater Solutions (IC-ECOWS)”.
IC-ECOWS is hosted by National Institute of Hydrology, Roorkee.
Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.
Data Availability Statement: Not applicable.
Conflicts of Interest: The authors declare no conflict of interest.
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