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American Journal of  Medical 
Science and Innovation (AJMSI) 

Evaluation of  Domestic Wastewater Management and the Future Potential for Diverse 
Technologies in Luangprabang City

Sengsavath Sidlakone1*, Atsushi Ichiki2

Volume 4 Issue 2, Year 2025
ISSN: 2836-8509 (Online)

DOI: https://doi.org/10.54536/ajmsi.v4i2.5229
https://journals.e-palli.com/home/index.php/ajmsi

Article Information ABSTRACT

Received: April 30, 2025
Accepted: June 03, 2025
Published: July 08, 2025

Luangprabang City is currently confronting a substantial wastewater management crisis, 
primar-ily due to the lack of  an operational domestic sewage system and insufficient 
wastewater treatment technology. This study aimed to assess the current state of  domestic 
wastewater management and investigate wastewater treatment technologies within a circular 
economic framework that is suitable for local conditions. Data were collected from local 
institutions encompassing local policies, legis-lation, wastewater treatment facilities, site 
visits, and observations. Secondary data were sourced from the literature reviews, technical 
guidelines, and related articles. Three distinct wastewater treatment technologies were 
evaluated to ascertain the optimal feasibility of  the interventions for comparison purposes. 
The technical and treatment efficiencies of  these technologies were also ana-lyzed. The 
financial aspects were assessed, with an assumed affordability rate of  3%, a discount rate 
of  4.5%, and a project period of  10 years. The indicators employed included net present 
value and benefit-cost ratio. Based on the results of  the analysis, the DEWATS Module with 
a constructed wetland was the most suitable option for implementation in the study area.

Keywords
Affordability, Benefit-Cost Ratio, 
Domestic Wastewater, Economic, 
Technologies

1 Department of  Water Supply, Ministry of  Public Works and Transport, Lanexang Avenue, Vientiane Capital, UK
2 Department of  Civil and Environmental Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Shiga 525-8577, Japan
* Corresponding author’s e-mail: vathslk@yahoo.co.uk

INTRODUCTION
The management of  domestic wastewater has become 
a major environmental and public health problem for 
rapidly growing secondary cities in South East Asia, 
such as Luangprabang City, Laos. Under the continuous 
development of  the city based on tourism and urban 
expansion, pressure on out-dated and insufficient 
sanitation infrastructure has increased. There is a lot of  
wastewater from homes that is released either untreated 
or undertreated into the local water supplies, polluting the 
water, dam-aging the ecosystem, and causing waterborne 
dis-eases. Luangprabang is a challenge owing to popu-
lation growth, the expansion of  business entities, and 
the burgeoning tourism sector. These devel-opments 
have placed significant pressure on the urban water 
environment. Consequently, the ex-isting wastewater 
treatment facilities are insuffi-cient for providing the 
domestic wastewater gener-ated. The treatment facilities 
are simple; the tradi-tional pond system intended for 
treating greywater is restricted to the central area of  
Luangprabang and was not designed to process black 
water (pit latrines). Septage is introduced into ponds in 
wetland areas are part of  the treatment system, where 
canals re-ceive wastewater from households, including 
septic tank effluents and gray water. Sewage drainage 
and canals are diverted to ponds and overflow into other 
ponds before flowing into wetland areas, natural rivers, 
and streams. 
Domestic wastewater is channeled through drainage 
systems, with some directed into ponds. Sewage settles 
and the adjacent wetlands absorb effluents before being 
discharged into the Mekong River via drainage outlets. 
The pond-wetland sys-tem has been studied through 

several pilot projects in Luang Prabang, supported by 
development part-ners. This concept utilizes ponds 
and wetlands as natural treatment systems to purify city 
sewagto river discharge. When properly designed and 
main-tained, these systems provide preliminary partial 
treatment of  sewage during dry months, even though 
sewage overflows during rainy periods. A plan to connect 
all ponds and wetlands to capture and treat city sewage 
needs to be developed. As the city progresses towards 
its planning horizon, the development of  wastewater 
treatment systems will be crucial in implementing 
and refining these strategies to ensure long-term 
water environmental sustainability. These systems did 
nottfunction well because they are sewage-contaminated, 
and pollu-tion poses a significant public health risk. Fur-
thermore, there is a limited professional under-standing 
of  the aquatic environment in the context of  planning 
and development. For example, relevant authorities have 
not been able to generate enough revenue to pay for the 
maintenance and operational expenses related to the 
sanitation sector’s service provision. 
According to estimates, Laos’s poor sanitation costs $650 
million a year, or roughly 3.5% of  GDP, in lost productivity 
and associated medical costs. For Luangprabang, this 
amounts to about $10 per person. According to the 
World Health Organization (WHO), a $1 investment in 
improved sanitation yields an economic return of  $5.50, 
which has a positive effect on the city. Although 94% of  
city residents have improved sanitation facilities, one-
third of  the population’s sewage flows through open 
drains and is discharged untreated into natural water 
bodies or agricultural lands. Consequently, the local city 
government has intervened to address this issue.



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The Urban Drainage and Sewerage Systems Master Plan 
outlines the development of  primary drainage systems 
to manage stormwater and wastewater, restore wetlands 
for stormwater preservation, and facilitate wastewater 
treatment. The planning horizon extends to 2037. Distinct 
zones encompassing 72 villages were identified, including 
the World Heritage Protection Area, the historic center, 
natural wetlands, and the section within the heritage area 
containing natural wetlands. The Luang Prabang World 
Heritage Office con-ducted an inventory and assessment 
of  106 ponds and the surrounding wetlands. Most ponds 
are pri-vately owned, and regulations prohibit owners 
from backfilling ponds without consent from the City. 
In a study, Starkl et al. (2022) assessed the sustainability 
of  wastewater treatment systems in developing countries. 
Their research examined economic, en-vironmental, 
institutional, and social sustainability, which may have 
various objectives and audiences that require diverse 
approaches. This study evalu-ated the specific aspects of  
sustainability assessment that are relevant to wastewater 
treatment system planners. The criteria included system 
costs and financing; affordability for users; environmental 
impact; health benefits; cultural acceptance of  the system 
and recycled products; technical perfor-mance; and 
administrative, political, and legal frameworks governing 
construction and operation. These findings suggest that 
a multi-criteria ap-proach can identify the most suitable 
system for a given location. 
According to research, Gómez-Román et al. (2020) 
conducted a systematic review of  public perceptions 
concerning the acceptance of  decentralized wastewater 
treatment systems in regions not expe-riencing water 
scarcity. A focus group study was conducted to assess 
whether the identified factors applied to areas in which 
the population was una-ware of  water-related issues. The 
findings indicated that a lack of  awareness regarding water 
issues was a significant factor affecting acceptance. It is 
essential to highlight features like environmental sustaina-
bility in order to highlight the usefulness of  such systems.
Costs, financing, affordability, technical per-formance, 
and legislation are all included in the framework for 
performing a cost-benefit analysis (CBA) of  wastewater 
treatment systems. Further-more, it considers the local 
context and size of  the treatment facility, whereas 
benefits may remain relatively constant. Decision-makers 
can identify the most suitable and sustainable wastewater 
treatment system for a particular location by using this 
all-encompassing approach.
For constructed wetlands, decentralized wastewater 
treatment systems (DEWATS) usually include primary, 
secondary, advanced secondary, and preliminary 
treatments. A sedimentation tank, a primary clarifier, an 
aeration tank, a secondary tank, and a disinfection tank 
make up a conventional activated sludge system (CAS). 
The primary clarifier and secondary clarifier return 
sludge, and simulta-neously control raw sludge exceeding 
the thickener tank and release it for sludge treatment and 
dispos-al. A sedimentation storage tank, an anaerobic 

filter tank, a moving bed biofilm tank, a sedimen-tation 
tank, and a disinfection tank are all included in Johkasou. 
In places where conventional sewage treatment systems 
are impractical, this system pro-vides an inventive 
wastewater solution. 
The technical performances and treatment ca-pabilities of  
the diverse wastewater treatment sys-tems were evaluated. 
Subsequently, a financial analysis was undertaken to 
formulate a strategy that encompassed a comprehensive 
inventory of  all as-sociated costs, including those related 
to sewers, buildings, technical equipment, materials, and 
sys-tem components, all of  which encompassed O&M 
expenses, where land was included as a government 
subsidy for capital costs. The analysis of  net present value 
and benefit-cost ratio offers valuable insights into financial 
viability. By taking into account revenue costs as well as 
capital and operating ex-penditures. Incorporating crucial 
elements like household affordability and discount rates 
guaran-tees that the chosen technologies are both eco-
nomically feasible and technically suitable for the city in 
question. The successful implementation and long-term 
viability of  a system depend on a metic-ulous approach 
to financial planning that strikes a balance between 
economic viability and techno-logical advancements.
In Luangprabang, a significant volume of  un-treated 
domestic wastewater is currently discharged into 
the environment, posing a risk to public health, 
contaminating water supplies, and harming the 
ecosystem. This situation is caused by a number of  
factors, including low community awareness, a lack of  
strict policy enforcement, and financial limita-tions that 
prevent the adoption of  sustainable solu-tions. Despite 
these pressing concerns, empirical studies evaluating the 
present wastewater situation in Luangprabang. Despite 
these pressing concerns, there is still a noticeable lack 
of  empirical research evaluating Luangprabang’s present 
wastewater management procedures and investigating 
alterna-tive, context-appropriate treatment technologies. 
In favor of  an excessively large focus on urban centers, 
most current research overlooks the unique socio-
economic, environmental, and infrastructure con-ditions 
of  medium-sized cities like Luangprabang. Addressing 
these water-related environmental is-sues is essential 
to achieving sustainable develop-ment in the region, 
which necessitates the use of  cutting-edge treatment 
technologies supported by sound research. In addition to 
their engineering design parameters, these technologies 
must be evaluated for technical efficacy, cost-effectiveness, 
environmental impact, and regulatory compliance. 
Therefore, the goal of  this study is to thoroughly evaluate 
the state of  wastewater treatment facilities today and 
investigate a variety of  treatment tech-nologies that are 
appropriate for local needs within a circular economy 
framework. To make sure that wastewater management 
plans are in line with water quality regulations and more 
general sustainability objectives, it looks at the technical, 
environmental, social, and economic aspects of  current 
practices and suggested remedies.



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Along with offering comparative analysis to guide future 
infrastructure planning and policy-making, the study also 
highlights important op-portunities and challenges in 
putting into practice economically feasible and socially 
acceptable treatment systems. This research supports 
the sus-tainable development of  Luangprabang and 
the larger regional conversation on inclusive sanitation 
strategies for secondary cities throughout Southeast Asia 
by providing practical insights into workable, affordable, 
and ecologically friendly wastewater solutions. This 
study is significant because it pro-vides a comprehensive 
assessment of  current do-mestic wastewater practices 
and looks at sustainable treatment options that align with 
the circular economy’s tenets. The results can be used to 
find workable, reasonably priced, and environmentally 
friendly alternatives to assist local policymakers, urban 
planners, and development agencies in cre-ating more 
resilient and inclusive wastewater sys-tems that satisfy the 
demands of  the public.
Ultimately, the study contributes to the broader regional 
discourse on sustainable urban sanitation by offering data 
that other Southeast Asian sec-ondary cities facing similar 
challenges can utilize or adapt.

MATERIALS AND METHODS
The study area, known as the Ban Mano Group, 
encompasses 2,236 ha, 2,100 households, 12,139 
inhabitants, and 3 0 ponds 6. This region is desig-nated 
a World Heritage Site, as shown in Figure 1. The data-
collection methodology integrates both pri-mary and 
secondary data sources.

officials in charge of  domestic wastewater management and 
development, namely, the Department of  Public Works 
and Transport, Luan Prabang City Office of  Management 
and Ser-vice, and Water Supply State Enterprise, focusing 
on local policies related to wastewater development 
initiatives, legislation for wastewater management, 
wastewater treatment facilities, and associated is-sues 
in wastewater management. Interviews were conducted 
with 20 stakeholders. Furthermore, the study included 
site visits to the study area where observations were 
conducted to gather existing phenomena for data analysis, 
specifically in terms of  comparing diverse wastewater 
treatment technology plans conducted in November 
2023. These inter-views explored perspectives on current 
practices, awareness of  wastewater issues, and willingness 
to adopt alternative treatment options. An interview guide 
was used to ensure consistency while allowing flexibility to 
explore emerging topics.
Secondary sourcesincluded project reports, aca-demic 
papers, and relevant articles, which provided a broader 
context and theoretical foundation for the study. By 
synthesizing information from these di-verse sources, this 
study presents a comprehensive analysis of  the current 
sanitation landscape and proposes recommendations for 
future development and policy enhancement. Statistical 
data from mu-nicipal records were also analyzed to 
understand population growth, sanitation coverage, and 
finan-cial allocations for wastewater services.
By exploring these factors, the study offers a thorough 
assessment of  the state of  sanitation today, points out 
possible areas for development, and adds to the continuing 
discussion about appropriate wastewater treatment 
techniques. A thorough ex-amination of  practices and 
policies within the local context, supported by primary 
data obtained from direct interviews with authorities and 
policymakers, provides valuable insight into the current 
state of  wastewater management. This method makes it 
easier to comprehend the difficulties and tactics used for 
local wastewater management.

Data Analysis
To find recurring issues and stakeholder per-ceptions, 
qualitative data from field observations and interviews 
were subjected to thematic analysis. Quantitative 
information was compared between various technologies, 
including treatment capacity and cost estimates. A multi-
criteria assessment framework that considered technical 
feasibility, environmental impact, cost-effectiveness, and 
social acceptance was used to evaluate treatment options.
The Lao National Standard for Wastewater Quality 
Control, which lists the eight main param-eters, is 
displayed in Table 1. The purpose of  this standard was to 
control the wastewater quality that domestic households 
released into the environment. Potential of  hydrogen 
(pH), chemical oxygen de-mand (COD), biochemical 
oxygen demand (BOD5), total suspended solids (TSS), 
total nitrogen, phenol (C6H5OH), fat, oil, and grease 
(FOG), and total dissolved solids (TDS) were among 
these parameters. To guarantee proper wastewater 

Figure 1: Map of  the Study Area

Data Collection
Data collection was conducted with strict ad-herence 
to ethical and legal standards, transparency and 
accountability throughout the study. The ac-quisition 
of  official permission from local authori-ties facilitated 
by a university-issued letter enabled the execution of  
survey interviews and site visits in compliance with local 
regulations. Furthermore, all secondary data sources were 
reviewed, cited, and acknowledged, thus supporting the 
credibility and integrity of  the study methodology.
Primary data were collected through direct in-terviews 
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treatment prior to discharge into watercourses, these 
parameters must be regularly monitored.

Table 4 shows the annual income per capita of  Luang 
Prabang people, as referred to by the local government in 
202510. The assumed wastewater fee was derived from the 
Decree on Water Policy Guidelines, which mandates that 
service providers establish water tariffs or fees for 3-5% 
of  households for affordability of  annual income11). 
This study uses 3% of  the assumed wastewater fee as the 
es-timated operating revenue.

Table 1: Lao PDR’s standard limits for the quality 
parameters of  domestic wastewater
Symbol Standard Value Unit
pH 6-9 Not defined
BOD5 30 mg/L
COD 125 mg/L
TSS 50 mg/L
TN 10 mg/L
C6H5OH 2 mg/L
FOG 5 mg/L
TDS 400 MPN/ml

Table 2 lists the key factors that have a major impact on 
water quality and human health: total suspended solids 
(TSS), total Kjeldahl nitrogen (TKN), chemical oxygen 
demand (COD), bio-chemical oxygen demand (BOD5), 
and total phos-phorus (TP). Different wastewater 
treatment sys-tems in the study area are compared using 
the es-timated pollution load per capita. These parameters 
are important markers of  possible health hazards and 
water quality. Elevated levels of  BOD5, COD, TSS, TN, 
and TP can cause eutrophication, algal blooms, decreased 
light penetration, and oxygen depletion, all of  which are 
harmful to aquatic ecosystems and human health.

Table 2: Parameters Pollution Load Assumptions
Parameters Units Average Range
BOD5 g/cap/d 60 40-60
COD g/cap/d 130 25-200
TSS g/cap/d 50 35-70
TN g/cap/d 14 2-15
TP g/cap/d 2.4 1-3

Table 3 shows the main parameters used to es-timate the 
dDesign capacity of  wastewater treat-ment technologies 
derived from the national soci-oeconomic statistics of  
the province. Water usage per capita was obtained from 
the Water Supply State Enterprise ReportReport. And 
wastewater was es-timated according to the guideline. 
Three diverse wastewater treatment systems were 
assumed to have equal capacities of  1,000 m3/d.

Table 3: Main Parameters for Design Capacity
Indicators Unit Values
No. of  Household Unit 2,100
Household Size Persons 6
Population Persons 12,139
Assumed water usage per capita Liter/day 150
Assumed wastewater produced % 60%
Total daily water usage amount Liter/ca 1,820,850
Total daily wastewater produced Liter/ca 1,092,510
Assume the total design capacity m3/d 1,000

Table 4: Household socioeconomic data
Socioeconomic data (USD)
Income per capita 1,752
Income per household 
(Average 6 persons) 10,512
The annual income of  a household in 
the study area

22,075,200

Affordability of  wastewater fee (3%) 662,256
Operating revenue for evaluation 662,256

Equation for Financial Aspects Evaluation
The net present value measures the viability of  projects 
by calculating the difference between discounted benefits 
and costs12). 
NPV=∑n

(t=1) ((Bt - Ct))/((1+r)t)  
NPV= Net Present Value; Bt = amount of  net benefit in 
year t; Ct = operating costs, including O&M costs); r = 
discount rate; n = project period. 
The benefit-cost ratio is the ratio of  the sum of  the present 
value of  the project benefits to  the total project costs12). 
BCR=∑n

(t=1) Bt/(1+r)t ÷ ∑n
(t=1) Ct/(1+r)t

Where BCR Benefit Cost Ratio (BCR), Bt = amount of  
net benefits in year t, Ct = operating cost including O & 
M cosr interest rate, and n project period.  
Figure 2 presents the DEWATS with constructed 
wetlands encompassing preliminary, primary, secondary, 
and tertiary advanced treatment processes. In the primary 
treatment phase, a settler, specifically a septic tank, 
was used. The majority of  solids were processed in the 
initial chamber, whereas the second chamber facilitated 
the smooth flow of  water. This system incorporates 
mechanical treatment via sedimentation and biological 
treatment via sludge digestion. Anaerobic baffled reactors 
and anaerobic filters are commonly used as backup 

Figure 2: Schematic of  DEWATS with constructed 
wetlands treatment process



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treatments. Constructed wetlands use soil, vegetation, 
and microorganisms to remove pollutants naturally.
Both the secondary (post-initial) and tertiary (post-
polishing) treatments use these systems. Wastewater 
traverses wetlands, where plants, soil, and microorganisms 
remove contaminants, such as organic matter, nutrients 
(nitrogen and phosphorus), and pathogens. Constructed 
wetlands represent a low-energy and l operationally 
demanding alternative to conventional treatment systems. 
The systems demonstrated efficiency in pollutant removal, 
achieving reductions exceeding 70% for BOD5, 46% for 
COD, 46% for TSS, and 45% for both TN and TP13.
Figure 3 shows that the conventional activated 
sludge process is fundamental to the activated sludge 
processes. A Conventional Activated Sludge system 
(CAS) comprises a sedimentation tank, primary clarifier, 
aeration tank, secondary tank, and disinfection tank. 
The primary and secondary clari-fiers return sludge, 
allowing the raw sludge to ex-ceed the thickener tank 
for treatment and disposal. However, this requires strict 
operating conditions, the outputs are affected by load 
fluctuations, and the nitrogen and phosphorus removal 
ratios are low. Other processes have been developed 
to solve these problems and improve the conventional 
activated sludge processes. A sedimentation tank treats 
the initial wastewater by removing the grit and garbage 
through settling. The primary clarifier settles small 
particles that cannot be removed from a sedimenta-tion 
tank. The primary sludge was placed in a sludge thickener 
tank with excess sludge. The activated sludge multiplied 
as the wastewater received oxygen from the aeration 
tank. By breaking down organic materials in wastewater, 
this activated sludge puri-fies the water.. The secondary 
clarifier was activated sludge, which became lump-shaped 
and heavier than the water. After settling, the clean water 
was removed from the top layer. The settled sludge 
was treated after being transported to a thickener tank. 
Some of  the precipitated activated sludge was re-turned 
to the aeration tank. The disinfection facility sterilizes 
the water removed from the secondary clarifier before 
discharge into the receiving water-course. The systems 
demonstrated treatment effi-ciencies exceeding 80% for 
removing pollutants such as BOD5, COD, and TSS, while 
achieving over 70% efficiency for removing TN and  TP.

tank, a sedimentation tank, and a disinfection tank. 
During the treatment process, influents are stored in a 
sedimentation tank, large amounts of  solid matter are 
separated, and the sludge is stored. The solid matter 
was separated when the wastewater flowed through the 
filter. Anaerobic bacteria decompose organic matter and 
remove nitrogen via denitrification. Aerobic bacteria 
decompose organic matter. Ammonia was oxidized, 
and nitrification proceeded. The suspended matter was 
precipitated in the treated water, a clean su-pernatant 
was sent to the disinfection tank, and the effluent was 
discharged after disinfection with chlorine. The Johkasou 
Module integrates domestic wastewater treatment with an 
efficiency rate of  90%, achieving BOD5 concentrations 
below 60 mg/L, COD at 20 mg/L, and a TSS removal 
ratio of  90%.  The TN and TP concentrations were less 
than 20 mg/L or a removal ratio of  70%14),15).

Figure 3: Systematic of  the Conventional Activation 
Sludge Process

Figure 4 shows the Johkasou (an advanced Septic Tank). 
The Johkasou system comprises a sedimen-tation storage 
tank, an anaerobic filter tank, a moving bed biofilm 

Figure 4: Systematic of  the Johkasou Process

Table 5 presents a comparative analysis that of-fers 
valuable insight into the performance of  the three 
wastewater treatment technologies. By uti-lizing 
standardized metrics and drawing from es-tablished 
research, this study provides a robust framework for 
evaluating and comparing these systems. Quantifiable 
data on removal efficiencies and rates enable stakeholders 
to make informed decisions when selecting appropriate 
wastewater treatment solutions. This approach not only 
facili-tates a clear understanding of  each technology’s 
strengths but also contributes to the broader goal of  
improving water quality management.

Table 5: Parameters of  Comparison 

Po
llu

tio
n 

R
em

ov
al

 
(%

)

U
ni

t

D
E

W
A

T
S

C
A

S

Jo
hk

as
ou

BOD5 mg/cap/d 73.6 80 90
COD mg/cap/d 46.10 80 80
TSS mg/cap/d 75.20 90 90
TN mg/cap/d 45 70 90
TP mg/cap/d 45 70 90

Statistical Analysis
To evaluate and contrast wastewater treatment 
performance and financial viability, the study mostly used 
descriptive statistical techniques. Im-portant parameters, 
such as the removal efficiencies of  BOD₅, COD, 



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TSS, TN, and TP, were summarized using percentage 
reduction values. The Bene-fit-Cost Ratio (BCR) and 
Net Present Value (NPV) were computed as part of  
financial analyses to evaluate the economic feasibility of  
each treat-ment system. Design capacities were estimated 
us-ing population, water use, and wastewater genera-tion 
data. Since the study concentrated on compar-ative and 
economic evaluation using primary and secondary data, 
no inferential statistical tests were conducted.
During the data collection process, local authorities 
were unable to provide a complete set of  technical 
and financial data. Limited availability of  technical and 
financial data from local authorities impedes the analysis 
of  wastewater treatment options. Previous research on 
the Lao PDR constrains the under-standing of  suitable 
technologies in the study area. The absence of  specific 
data and insufficient tech-nical information complicates 
the development of  effective solutions. Consequently, 
inadequate local data and narrow research scope restrict 
the identi-fication of  cost-effective treatment options for 
cit-ies.

RESULTS AND DISCUSSION
Local Authorities 
Local municipal organizations have reported that the 
existing wastewater treatment facilities are in-adequate 
for processing domestic wastewater. This region is prone 
to natural disasters, which worsen residents’ lack of  
access to sanitation facilities and hinder basic needs. The 
sanitation sector requires cost recovery strategies that 
consider residents’ low-income status and willingness 
to pay for im-provements. Sanitation services fail to 
adequately serve urban populations, leading to poor 
health, a reduced quality of  life, and impeded economic 
de-velopment. Failure to implement master plans has 
resulted in a lack of  urbanization benefits. The city 
employs strategies to guide investment and sanita-tion 
infrastructure expansion, influenced by social, cultural, 
economic, and environmental factors. Defective sewer 
systems that link pipes to septic tanks have been found 
during site inspections, re-sulting in wastewater being 
released into wetlands, rivers, and streams. There are two 
kinds of  sewage collection systems: separate systems that 
collect sewage and stormwater separately, and combined 
systems that collect both. This indicates the need for 
individual water flow systems, as stormwater must be 
diverted during rainfalls. The three primary sewerage 
collection systems were conventional sewerage with 
centrally installed sewer pipes, sim-plified sewerage with 
pipes installed at the rear and sides of  the properties 
requiring the owner’s consent for maintenance, and 
established systems of  gravity collection networks with 
interceptor septic tanks and small-diameter pipelines. 
Settled effluent wastewater enters small-diameter pipes 
for treat-ment. Septic tanks near wetlands are connected 
to these areas through discharge pipes. Individual wa-ter-
flow systems are essential for stormwater man-agement 
during rainfall events. However, popula-tion growth and 

tourism have increased wastewater beyond the capacity 
of  existing wetlands, which are affected by excessive 
wastewater inflow. Addition-ally, authorities have been 
deficient in maintenance, resulting in noncompliance with 
LENS standards. Authorities cannot generate sufficient 
revenue from user charges to cover O&M costs because 
of  low wastewater tariffs, high technical standards, com-
mercial losses, and poor collection efforts. 

Site and Observations
Luang Prabang lacks centralized sewage, with residences 
that use individual on-site treatment systems with septic 
tanks. However, domestic wastewater has only been 
partially treated. Before entering the Nam and Mekong 
Rivers, septic tank effluents and household wastewater 
from kitchens, bathrooms, laundry, and cleaning (gray 
water) exit through drainage canals or pond-wetland 
systems. This presents health hazards, especially during 
rainy seasons when floodwater tainted with sewerage 
overflows drainage systems, ponds, and wetlands. Recent 
comprehensive studies on urban sewage systems are 
lacking. Current efforts have focused on decentralized 
systems and pond rehabilitation for preliminary treatment. 
Local authorities, initially hesitant about centralized 
wastewater systems be-cause of  spatial constraints, now 
prioritize city cleanliness and aesthetics, particularly in 
tourist areas. The existing decentralized wastewater treat-
ment system demonstrates a typical non-mechanized 
treatment flow. Similar low-cost systems globally have 
reduced organic pollution from domestic wastewater, but 
show limited ca-pacity to remove nutrients and coliforms 
from sewage.

Comparison of  Technical Aspects
Table 6 presents the results of  wastewater treatment 
systems that vary in effectiveness in eliminating pollutants, 
such as BOD5, COD, TSS, TN, and TP. Decentralized 
wastewater module combustion showed less than ideal 
results, remov-ing only 73.6% of  BOD5 and 46.1% of  
COD, with BOD5 levels of  60 mg per capita per day, and 
a 46.10% increase in COD. The TSS and TP removal rates 
were 75.2% and 45%, respectively. However, conventional 
activated sludge systems performed better, efficiently 
reducing BOD, COD, TSS, TN, and TP to meet the 
discharge standards. The Johkasou system has emerged 
as the most effective treatment method, surpassing other 
technologies in terms of  all the parameters. Different 
treatment methods have shown varying efficiencies for 
spe-cific pollutants, which has implications for water 
quality management and environmental protection.
The poor performance of  the decentralized 
wastewater module combination highlights the need 
for improvements to meet the acceptable dis-charge 
standards. In contrast, the superior perfor-mance of  
conventional activated sludge systems and the Johkasou 
system suggests their potential as the preferred methods 
for wastewater treatment. These findings emphasize 
the importance of  selecting appropriate treatment 



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technologies based on pollu-tant removal capabilities 
to ensure optimal water quality. The effectiveness of  
wastewater treatment systems varies across technologies. 
While the de-centralized wastewater module showed 
suboptimal performance, conventional activated sludge 

systems demonstrated superior efficiency. Johkasou 
systems have emerged as one of  the most effective 
methods. These findings highlight the importance of  
selecting appropriate treatment technologies based on 
pollu-tant removal capabilities. 

Table 6: Comparison of  pollution removal efficiency
Pollution Removal (%) DEWATS CAS Johkasou
Parameters Unit Pollution (103) 

Load/ca/d
(%) (103) (%) (103) (%) (103)

BOD5 mg/cap/d 728 73.6 536 80 582 90 655
COD mg/cap/d 1,578 46.10 727 80 1,262 80 1,262
TSS mg/cap/d 606 75.20 456 90 546 90 546
TN mg/cap/d 169 45 76 70 118 90 152
TP mg/cap/d 29 45 13 70 20 90 26

Comparison of  the Financial Aspects
Table 7 presents the primary values for comparison 
within the wastewater treatment system encom-passing 
both capital expenditure (CAPEX) and op-erational 
expenditure (OPEX). OPEX includes the costs related 
to administration and maintenance. Revenue costs 
were evaluated by examining household contributions 
to wastewater fees. By the Decree on Water Supply 
Tariffs Policy 11), service providers are authorized to 
receive 3-5% of  house-hold income. This study utilized 

a conservative estimate of  3% for household income 
contribution. Affordability is the principal factor that 
influences household contributions to wastewater fees. 
The assessment methodology balances system costs by 
considering household affordability. This study advocates 
a prudent approach to revenue projections. The system 
prioritizes affordability while also aim-ing for financial 
sustainability. The balance between cost and affordability 
may influence the treatment service quality and long-term 
system sustainability.

Table 7: Result of  CAPEX, OPEX, and Revenue 
Type of   Technologies Unit Data Total (103USD)
DEWATS
CAPEX/cap (USD) 150 12,139 1,820
OPEX /cap (USD) 5.16 12,139 62
Affordability to pay 3% 21,267,528 638
CAS
CAPEX/cap (USD) 100 12,139 1,213
OPEX /cap (USD) 9.78 12,139 118
Affordability to pay 3% 21,267,528 638
Johkasou
CAPEX/cap (USD) 800 12,139 9,711
OPEX /cap (USD) 98 12,139 1,189
Affordability to pay 3% 21,267,528 638

Table 8 provides a comparative analysis of  the various 
wastewater treatment technologies. Under the constraints 
of  a specified project duration of  10 years, discount rate 
of  4.5% based on the wastewater treatment project in Lao 
PDR16), and capacity, it was assumed that the operational 
and benefit costs re-mained constant throughout the 
project. The results indicate that the net present value 
(NPV) of  the benefits is uniform across technologies. 
However, because each wastewater treatment technology 
has different operating and maintenance costs, differ-
ences in the net present value (NPV) of  the costs were 
noted. Critical values, like those found in cost-benefit 

analyses, must be taken into account. The analysis 
demonstrates that the benefit-cost ratio of  the DEWATS 
Module Combination yields the highest benefits, followed 
by the CAS, whereas the Johkasou case does not achieve a 
benefit-cost ratio of  one. According to economic theory, 
a bene-fit-cost ratio below one suggests that the project is 
unlikely to be profitable because of  elevated opera-tional 
costs and insufficient benefits.
Specifically, the Johkasou technology’s benefit-cost 
ratio falling below one indicates potential economic 
unsustain-ability in the long term. These findings can 
guide policymakers and project planners in prioritizing 



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and allocating resources towards more cost-effective and 
sustainable wastewater treatment technologies, thereby 

potentially enhancing sanitation outcomes and optimizing 
the use of  public funds.

Table 8: Results of  Net Present Value and Net Benefit
Year CAPEX &OPEX

(103USD)
Benefit (103USD) Discount 

Factor (4.5%)
Net Value Benefit 
(103 USD)

Net Present Value 
Cost (103 USD)

1) DEWATS Module Combination
0 (1,820) - 1 - (1,820)
1 62 638 0.96 610 59
15 62 638 0.63 410 40
Benefit Cost Ratio 10.25
2) Conventional Activated Sludge
0 (1,213) - 1 - -
1 118 638 0.96 610 113
15 118 638 0.63 410 76
Benefit Cost Ratio 5.39
3) Johkasou
0 (9,711) - 1 -
1 1,189 638 0.96 610 1,138
15 1,189 638 0.63 410 766
Benefit Cost Ratio (BCR) 0.53

Decentralized Wastewater Treatment Systems (DEWATS) 
that use constructed wetlands offer cost-effective 
solutions. The system provides ad-vantages such as low 
construction and operational cost and the possibility 
of  resource recovery. How-ever, these methods require 
sufficient space, pose odor issues, and require optimal 
treatment.  The treated effluent can be used for irrigation 
or aqua-culture, and nutrients can be recovered. The 
system adapts to various scales using local materials and 
labor for community participation. Constructed wetlands 
improve water quality and reduce flood risk. However, 
they require large areas, which limits their use in densely 
populated areas. Treatment effectiveness varies with the 
wastewater composi-tion, climate, and wetland design. 
Maintenance included solid removal and water quality 
monitoring. Conventional activated sludge (CAS) systems 
have the advantages of  low installation cost and high 
effluent quality. However, they have high opera-tional 
costs, require space for sludge disposal, and require skilled 
supervision. Effluent quality can be inconsistent. These 
systems handle various wastewater loads with lower 
energy demands for aeration than Johkasou systems. 
However, aeration, sludge recycling, and maintenance 
costs are also high. The effluent quality varied and did not 
meet the clarity levels. This process is time-consuming 
and sensitive to fluctuations in wastewater. There-fore, 
CAS systemsmay be unsuitable for wastewater with 
high pollutant concentrations. The Johkasou system 
offers an alternative that balances cost-effectiveness 
and environmental benefits. De-spite their high initial 
costs and maintenance needs, their long-term benefits 
often outweigh their drawbacks. Their adaptability, 
pollutant removal efficiency, and water reuse potential 

render them suitable for dense areas. In recent years, 
wastewater management has changed. Johkasou systems 
are a sustainable solution, but in order to optimize their 
efficacy, local conditions must be taken into ac-count. 
A wastewater treatment system’s selection is influenced 
by a number of  variables, including local conditions, 
environmental impact, and cost effec-tiveness. DEWATS 
with artificial wetlands provide an inexpensive, natural 
solution, but they need a large amount of  land and 
careful planning. Even though they are well-known and 
efficient, conven-tional activated sludge systems have 
problems with consistency and operating costs. Johkasou 
systems have become viable substitutes for balancing 
envi-ronmental advantages with cost-effectiveness. De-
spite their high initial costs, they are appropriate for 
densely populated areas due to their long-term benefits, 
adaptability, and efficacy in pollutant re-moval. To ensure 
sustainable wastewater manage-ment, local conditions 
and requirements must be taken into account when 
choosing treatment sys-tems.
In order to achieve environmental sustainability, 
community involvement in wastewater treatment systems 
is essential. Focusing on a number of  im-portant areas is 
necessary for effective community involvement, such as 
the effects of  wastewater management on environmental 
quality, public health, and economic stability, as these 
factors can raise community members’ awareness and 
interest. Communities can gain a better understanding of  
their role in supporting sustainable wastewater treatment 
systems by educating the public. The many advantages 
of  sustainable methods for in-volving the community 
in wastewater treatment systems must be emphasized. 
Presenting wastewater treatment as a crucial component 



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of  sustainable urban development and circular econ-
omy principles can encourage participation in deci-
sion-making and support creative, environmentally 
friendly solutions by emphasizing the economic and 
environmental benefits, such as the mitigation of  water 
pollution and the preservation of  ecosystems.
Based on these results, we draw the conclusion that 
decentralized wastewater treatment systems provide 
significant benefits, such as lower pollution and better 
investment costs, in local economic and environmental 
contexts. These systems offer bene-fits through lower 
investment and operating ex-penses than centralized 
systems. However, com-paring these systems is 
complicated by the diverse contexts and priorities under 
varying circular eco-nomic conditions. 
Comparative analyses of  wastewater treatment systems 
have significantly contributed to water management 
and sustainability. Such methodolo-gies are essential for 
the selection of  suitable treatment technologies. These 
approaches evaluate sustainability across economic, 
environmental, so-cial, and technical dimensions and 
offer a compre-hensive assessment of  options. There 
is an in-creasing focus on decentralized strategies and 
nat-ural systems such as constructed wetlands. These 
systems are often favored over conventional acti-vated 
sludge treatments and Johkasou systems, owing to their 
lower energy use and environmental impact. However, 
an analysis of  land suitability is required to identify 
appropriate locations. This highlights the need to 
consider the technological and geographical factors when 
selecting treatment systems. The comparative evaluation 
of  wastewater treatment systems facilitates informed 
decisions, promotes sustainable solutions, and addresses 
water management challenges. This approach supports 
the development of  efficient strategies that can con-
tribute to improved public health and environmen-tal 
protection. 
A significant limitation of  this study was the absence 
of  standardized monitoring protocols for wastewater 
treatment systems. Current systems focus on conventional 
pollutants and lack effective standards for monitoring 
the pollution loads from household sources. This 
deficiency complicates the assessment of  decentralized 
systems. Decentralized wastewater treatment systems 
can contribute to optimal household wastewater fees. 
Limitations in data collection, standardization, and con-
text-specific factors impede comprehensive com-parison. 
Future research should prioritize the de-velopment 
of  cost-effective technologies tailored to site-specific 
conditions to facilitate accurate com-parisons.

Practical Implications
For policymakers looking to enhance wastewater 
management in Luang Prabang, this study offers several 
practical insights. According to a comparative study 
of  treatment technologies, in-tegrating low-energy, 
decentralized systems like DEWATS with artificial 
wetlands may provide sustainable and affordable solutions. 

Taking into account local socioeconomic conditions 
and af-fordability, policymakers should give capaci-ty-
building top priority and offer incentives to promote the 
adoption of  such technologies. Addi-tionally, improved 
data collection and financial and technical information 
transparency will facilitate long-term planning and better 
informed deci-sion-making. These actions are essential 
to im-proving the region’s public health, environmental 
protection, and sanitation coverage.

CONCLUSION
This study looked into the current wastewater fa-cilities in 
Luang Prabang and compared three dif-ferent treatment 
technologies to see which would work best locally. 
The evaluation took into account technical needs, site 
characteristics, what house-holds can afford, and national 
water quality stand-ards. Key factors analyzed included 
wastewater volume, treatment efficiency, and economic 
feasi-bility—covering everything from initial investment 
to operational and maintenance costs—within the 
context of  local policies.
The findings indicated that the DEWATS system 
combined with a constructed wetland stands out as the 
optimal choice for larger areas, thanks to its low operating 
costs, sustainability, and eco-friendliness, making it well-
suited to local budgets and land availability. Although 
Johkasou comes with higher setup and running expenses, 
it’s a good option for areas at high risk for organic 
waste, like factories or hospitals. On the other hand, the 
conventional ac-tivated sludge system could still be an 
option in some cases, despite its higher operational costs. 
This thorough evaluation lays a strong groundwork for 
picking the right wastewater treatment technologies that 
strike a balance between technical efficiency, economic 
soundness, and policy needs for sustain-able wastewater 
management in Luang Prabang City.

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