Improvement
of wastewater treatment systems through component redesign to optimize
operational efficiency
Mejora de
sistemas de tratamiento de aguas residuales mediante rediseño de componentes
para optimizar la eficiencia operativa
José Gerardo León Chimbolema1
Published Instituto Tecnológico Superior Edwards Deming. Quito
- Ecuador Periodicity July - September Vol. 1, Num. 26, 2025 pp.
1-16 http://centrosuragraria.com/index.php/revista Dates of receipt Received: May 12, 2025 Approved: June 30, 2025 Correspondence author gerardo.leon@espoch.edu.ec Creative Commons License Creative Commons License,
Attribution-NonCommercial-ShareAlike 4.0
International.https://creativecommons.org/licenses/by-nc-sa/4.0/deed.es
Abstract: Water
is a vital resource for human survival, the development of societies and the
ecological balance of the planet. Its availability in adequate quality and
quantity is essential for the well-being of ecosystems and for sustaining
multiple human activities, such as agriculture, industry, tourism and domestic
supply. However, the increasing pressure exerted on this resource, especially
in urban and rural developing areas, has led to a progressive deterioration of
its quality, compromising its use and natural cycle.
Key words: water, environment, nature
PhD in Chemistry, Master in Environmental
Protection. Research professor. Superior Polytechnic School of Chimborazo. https://orcid.org/0000-0001-9202-8542
Palabras clave: agua, medio ambiente,
naturaleza
Introduction
One of the main
sources of water pollution is the improper discharge of wastewater. These
waters, which come from homes, commercial establishments, industries, and
agricultural activities, contain a high load of organic matter, nutrients,
chemical compounds, and pathogenic microorganisms that, if not properly
treated, can cause severe negative impacts on receiving bodies and human health
(Salazar & Cesar, 2017; Contreras et al., 2021). Globally, it is estimated
that more than 80% of the wastewater generated does not receive any treatment
before final disposal, especially in developing countries (UNESCO, 2020).
In Latin
America, the situation is not encouraging. The region faces significant
challenges in terms of sanitation and wastewater treatment. Although significant
efforts have been made in regulatory and institutional terms, many existing
wastewater treatment plants (WWTPs) operate below capacity or have collapsed
due to lack of maintenance, design deficiencies, hydraulic overloading, or
simply abandonment (Anda Sánchez, 2017; Silva et al., 2020). In Ecuador,
multiple studies have revealed that a large number of WWTPs do not comply with
the parameters established in current environmental regulations, which
contributes to the deterioration of water quality in rivers, lagoons and subway
aquifers (Núñez Collaguazo & López Ramírez, 2014; Morales et al., 2023).
These technical
and structural deficiencies directly affect the ability of plants to remove key
pollutants such as biochemical oxygen demand (BOD), chemical oxygen demand
(COD), total suspended solids (TSS) and nutrients (nitrogen and phosphorus).
Non-compliance with environmental standards established by regulations such as
the Unified Text of Secondary Legislation of the Ministry of Environment
(TULSMA) in Ecuador not only represents a threat to aquatic ecosystems, but
also increases the risk of waterborne diseases in nearby populations (TULSMA,
2015).
Faced with this
problem, it has become imperative to adopt technical strategies that allow for
the rehabilitation and modernization of existing treatment plants. In this
context, the redesign of critical components of WWTPs is presented as a viable
and effective solution. This strategy consists of rethinking the hydraulic
sizing, functional distribution and operability of the treatment units, using
updated technical criteria and technologies appropriate to the context (Allauca
Melena, 2024; Solís Chamorro, 2015; Guzmán Garrido & de la Rosa Luciano,
2015).
Several
investigations have shown that the reconfiguration of elements such as grids,
desander channels, Imhoff tanks, upflow anaerobic filters (AFFA), grease traps
and drying beds can significantly improve system efficiency without the need to
resort to complex or costly solutions (Herrera-Pérez et al., 2022; Ríos-López
& Medina-Flores, 2021). In many cases, these improvements have made it
possible to meet effluent quality requirements, extend the useful life of the
infrastructure and reduce operating costs, especially in community or rural
systems with limited budgets.
The experience
documented in different areas of Ecuador reinforces this perspective. In the
case of the Ilapo I treatment plant, located in the parish of the same name in
Guano canton, Chimborazo province, a comprehensive technical redesign was carried
out with the objective of recovering its functionality and ensuring compliance
with the limits established by environmental regulations. This redesign
included the implementation of a FAFA, substantial improvements in the septic
tank, the installation of coarse and fine screens, and the reconfiguration of
the desander channel to optimize the removal of settleable solids (Allauca
Melena, 2024).
Other
experiences, such as that of the Chiquicha Centro community, also in
Chimborazo, have shown positive results. There, the rehabilitation of the WWTP
included the reconstruction of the drying beds, the installation of grease
traps and a new screening system, which allowed a considerable reduction in the
levels of contamination in the final effluent and improved the community's
perception of the sanitation service (Morales et al., 2023).
It should be
noted that, in addition to the technical and environmental benefits, the
redesign of components has a strong social impact. The improvement in the
quality of treated water has a direct impact on public health, the quality of
life of the population and the development of productive activities dependent
on water resources, such as agriculture and aquaculture ( ). Similarly, as they
are technically accessible solutions, they promote community participation,
strengthen local water governance and foster social appropriation of the system
(González-Vargas et al., 2021; Paredes-Herrera & Araujo-Sánchez, 2019).
At the
normative level, compliance with the parameters established by the TULSMA and
other international regulations such as the WHO Guidelines on Water and
Sanitation, represents an indicator of good environmental governance and
institutional responsibility. Therefore, any redesign strategy must be
supported by a rigorous technical evaluation, studies of current and projected
flow rates, effluent characterization, and adequate hydraulic and structural
sizing of each component (UN-Habitat, 2018; PAHO, 2020).
In this sense,
the present article is proposed as a contribution to the technical and
practical knowledge on the redesign of wastewater treatment plant components.
The main objective is to evaluate the impact of the redesign on the operational
efficiency of the WWTP Ilapo I, using a methodological approach based on the
diagnosis of the system, the analysis of its current conditions and the
proposal of solutions adapted to its operational context. The aim is to
demonstrate that it is possible to significantly improve the quality of the
treated effluent through accessible, sustainable and replicable technical
interventions.
The research is
based on a quantitative technical-applied approach, with emphasis on sanitary
engineering and environmental sustainability. It also makes use of empirical
evidence obtained through physicochemical analysis, direct observation and
documentary review, which gives solidity to the conclusions presented. The
relevance of this study lies in its applicability to other similar realities in
the country and the region, where limited resources and complex geographical
conditions make it difficult to implement conventional high-tech treatment
systems.
In sum, the
redesign of wastewater treatment plant components represents an effective,
efficient and sustainable strategy to address sanitation challenges in rural
and semi-urban contexts. Through well-planned and technically sound
interventions, it is possible to optimize the performance of existing systems,
comply with current regulations and contribute to the protection of water
resources as a fundamental axis for sustainable development.
Methodology
The present research adopted a quantitative
approach of a technical-applied type, with the objective of redesigning and
optimizing the Ilapo I Wastewater Treatment Plant (WWTP), located in Ilapo
parish, Guano canton, Chimborazo province, Ecuador. The study was structured in
three main phases: diagnosis, technical analysis and structural redesign,
allowing an integral evaluation of the existing system and the proposal of
specific solutions based on current environmental regulations.
Phase 1: Diagnosis of the current situation
During the first stage, a general diagnosis of
the plant's operational and structural status was carried out. This process
included:
On-site visual inspection, through technical
visits made at different times, to evaluate the physical condition of the
treatment units (grids, desander channel, septic tank, decanters and filters).
Integral cleaning of the plant, essential for
the accurate collection of samples and the detection of obstructions or
invisible faults under normal operating conditions.
Planimetric and topographic survey, using
measuring instruments such as engineer's level, tape measure, theodolite and
drone with camera, which allowed the preparation of updated plans of the
existing units.
Documentary review, in which historical
information available on the WWTP was analyzed, such as original plans,
maintenance reports, operating records and applicable regulations (especially
the TULSMA).
Phase 2: Sampling and physical-chemical
analysis
The diagnosis was complemented by a process of
sampling and analysis of the wastewater, both at the inlet and outlet of the
system. Composite samples (24-hour weighted averages) were taken in sterile
bottles, following the sampling protocol of Technical Standard INEN 2169:2013.
The parameters analyzed were:
Biochemical Oxygen Demand (BOD₅).
Chemical Oxygen Demand (COD)
Total Suspended Solids (TSS)
Fecal coliforms
pH
The tests were performed in certified
laboratory, using standardized techniques according to the Standard Methods for
the Examination of Water and Wastewater (APHA, 2017). The results obtained were
contrasted with the maximum permissible limits established by the Unified Text
of Secondary Legislation of the Ministry of Environment (TULSMA, 2015) for
freshwater bodies.
Phase 3: Hydraulic analysis and sizing
With the data collected, the hydraulic and
structural analysis of the existing units was carried out, considering:
Current and projected population: INEC
population growth rates were applied to determine the future population load.
Average daily flow and peak flow: Estimated
based on average per capita consumption (200 L/inhab/day)
and the daily coefficient of variation (1.5 for rural areas).
Hydraulic retention time (HRT), surface load,
flow velocities, and theoretical efficiency of each treatment unit.
The units with evident deficiencies were
selected for structural intervention. Among these, priority was given to the desander
channel, the septic tank, the grate system, and an upflow
anaerobic filter (AFAF) was incorporated as a secondary treatment technology
adaptable to rural contexts without electricity consumption.
Phase 4: Technical and structural redesign
The redesign was based on the application of
sanitary engineering principles and national and international standards.
Drawings were prepared in AutoCAD Civil 3D and design calculations in Excel
sheets with hydraulic and treatment formulas.
Structural improvements included:
New system of coarse and fine grids in cascade,
to improve the retention of coarse solids from the inlet of the system.
Reconfiguration of the desander channel,
increasing the slope and hydraulic width to optimize sedimentation of heavy
particles.
Redesigned septic tank, with differentiated
compartments, improved ventilation, grease traps and volume adapted to the new
estimated flow.
FAFA installation, which uses existing biomass
for biological treatment without requiring energy inputs.
Inspection chambers and 20-series PVC piping to
facilitate maintenance and operational monitoring.
Phase 5: Operational validation and preparation
of the manual
Following the redesign, an operation and
maintenance (O&M) manual was developed with clear instructions for local
personnel, including inspection frequencies, cleaning procedures, sampling
methods, and preventive routines.
In addition, a community training program was
developed, focusing on operators and community leaders, in order to guarantee social
ownership of the system and ensure its long-term sustainability.
Results
Figure 1 shows
the schematic diagram of the main components of the wastewater treatment system
of the PTAR Ilapo I plant. The influent flow initially enters the overflow box,
where a preliminary separation is performed, followed by a desander channel
that removes heavy solids. Subsequently, the wastewater is directed to the
Imhoff tank, which performs sedimentation and primary digestion, and then
passes to the overflow box, which allows flow monitoring. Finally, the treated
water exits as effluent. The diagram also contemplates a by-pass that connects
the overflow box directly to the review box and the effluent, allowing for an
emergency bypass if necessary.
Figure 1: Diagram of components of the current PTAR Ilapo
I system.
Figure 2 presents
the diagram of the proposed redesign of the wastewater treatment system at PTAR
Ilapo I, which incorporates new stages to optimize the purification process. In
this proposal, the influent flow first enters a screen that retains coarse
solids, then passes to the overflow box and continues to the desander channel,
where heavy particles are removed. The wastewater then enters a septic tank,
which performs primary sedimentation and part of the anaerobic treatment. The
flow is then conveyed to an upflow anaerobic filter, which enhances the
reduction of the organic load. Finally, it passes to the overflow box and exits
as effluent. The scheme also contemplates an emergency by-pass, which connects
the overflow box directly to the overflow box and the effluent, allowing the
flow to be diverted in case of need. This redesign seeks to improve treatment
efficiency and treated water quality.
Figure 2: Diagram of the redesign of the Ilapo I WWTP.
The results
derived from the technical redesign of the Ilapo I
Wastewater Treatment Plant (WWTP) show substantial improvements in all key
operational efficiency indicators. This progress was made possible by a
comprehensive intervention that addressed both structural and functional
aspects of the system. Evaluations following the implementation of the redesign
show that the plant has not only improved the quality of the treated effluent,
but also reduced its environmental impact and optimized its operational
sustainability.
Prior to the
redesign, the contamination levels present in the treated water far exceeded
the limits established by the Unified Text of Secondary Legislation of the
Ministry of the Environment (TULSMA). In particular, the BOD₅, COD and
TSS values evidenced that the system did not meet the minimum treatment
requirements.
Another relevant
aspect was the pH behavior. Although this parameter did not represent a
critical problem before the redesign (7.2), the intervention allowed stabilizing
it even closer to neutrality, with a post-redesign value of 7.0. This is
important because it ensures that no corrosive or toxic conditions are
generated for the receiving aquatic ecosystems, which complements the benefits
achieved in terms of organic matter and solids removal.
Beyond the
numbers, the results obtained have a concrete impact on the quality of the
environment and public health. The improvement in BOD₅ removal efficiency
translates into a decrease in the organic load discharged to water bodies,
which in turn implies a lower demand for dissolved oxygen by degrading
microorganisms in the environment. This is crucial to avoid anoxic conditions
affecting aquatic fauna.
Reducing TSS also
has obvious benefits, as it limits water turbidity and reduces sedimentation of
organic and inorganic materials in riverbeds or canals. This helps maintain
water transparency and improves conditions for aquatic life. pH stabilization,
on the other hand, minimizes the risks of physiological stress in sensitive
species, especially in reproductive stages.
The key to these
improvements lies in the redesign of critical plant components. Elements such
as the desander channel, which was resized and its slope increased to improve
the settling of heavy solids, and the septic tank, which was rebuilt with a new
operating volume and an improved sealing and ventilation system; the upflow anaerobic filter (AFAF), which was designed and
implemented to increase biological efficiency without the need for additional
energy inputs; and finally, the screen system, which was replaced with a
cascading set of coarse and fine screens, improving the retention of solids
from the system inlet.
Each of these
improvements not only contributed individually, but worked synergistically with
the rest of the system. For example, the FAFA allowed for more effective
reduction of BOD₅, but its efficiency depended on adequate solids removal
previously achieved in the desander channel and grates. Also, the improved
septic tank facilitated a more uniform and stable process, which in turn
optimized the operation of the downstream units.
In addition, the
operational stability of the system was improved. The redesign reduced the
frequency of corrective maintenance, while simplifying daily operational tasks.
This translates into lower long-term costs and greater financial sustainability
for the system. In social terms, the redesigned system generates greater
confidence in the local community, which now perceives water treatment as an
effective and tangible action to improve the quality of the environment.
As shown in Table
1, biochemical oxygen demand (BOD₅) was 150 mg/L, chemical oxygen demand
(COD) reached 280 mg/L, and total suspended solids (TSS) were as high as 200
mg/L. These figures were alarming, considering that the permissible limits
established by environmental regulations are 50 mg/L for BOD₅, 150 mg/L
for COD and 100 mg/L for TSS.
After the
redesign, the figures changed drastically. BOD₅ was reduced to 40 mg/L,
COD dropped to 90 mg/L and TSS stood at 60 mg/L. These values are not only
below legal limits, but also reflect an optimized system that has recovered its
functionality and pollutant removal capacity. The efficiency of the system can
be seen in the reduction percentages: BOD₅ was reduced by 73.3%, COD by
67.9% and TSS by 70%. These removal rates place the plant in an optimal
operating range, comparable to modern treatment systems.
Table 1. Comparison of water quality parameters before
and after the redesign of the Ilapo I WWTP.
|
Parameter |
Before redesign |
After redesign |
Allowable limit (TULSMA) |
|
BOD₅ (mg/L) |
150 |
40 |
50 |
|
COD (mg/L) |
280 |
90 |
150 |
|
TSS (mg/L) |
200 |
60 |
100 |
|
pH |
7.2 |
7.0 |
6.5-8.5 |
As can be seen,
the redesign made it possible to reduce BOD₅ by 73.3%, going from 150
mg/L to 40 mg/L, thus complying with current regulations. Likewise, COD was
reduced from 280 mg/L to 90 mg/L, representing an improvement of 67.9%. Total
suspended solids decreased by 70%, reaching an average value of 60 mg/L after
the intervention. The pH remained stable within the permitted range, reflecting
good regulation of the treatment system.
Figure 1. Graphical comparison of BOD₅, COD and
TSS parameters before and after the redesign of the Ilapo
I WWTP.
Figure 1 presents
a graphical comparison of BOD₅, COD and total suspended solids (TSS)
values measured before and after the redesign of the Ilapo
I WWTP. A significant reduction is observed in all three parameters, evidencing
a substantial improvement in the quality of the treated effluent. In the case
of BOD₅, the value decreased from 150 mg/L to 40 mg/L; COD went from 280
mg/L to 90 mg/L; and TSS decreased from 200 mg/L to 60 mg/L. These results
reflect considerable efficiency in the removal of organic matter and solids,
far exceeding compliance with the limits established by environmental
regulations. The graph visually demonstrates the positive impact of the
technical redesign on the operational optimization of the plant.
Therefore, the
redesign of the Ilapo I WWTP demonstrates the
effectiveness of this strategy to improve deteriorated treatment systems. Not
only was it possible to comply with current environmental standards, but the
operational capacity was improved, the ecological impact was reduced and the
sustainability of the system was strengthened. This experience is a replicable
example for other communities with similar conditions, where technical and
economic limitations make it difficult to implement higher-cost conventional
solutions.
The results
obtained after the redesign of the Ilapo I wastewater
treatment plant show a significant improvement in the efficiency of the system.
The reduction of key parameters such as BOD₅ (73.3%), COD (67.9%) and
total suspended solids (70%) not only reflects the correct hydraulic sizing of
the new components, but also the effectiveness of the structural redesign in
the purification process.
These findings
are consistent with previous studies conducted in Ecuador and other Latin
American countries, where the redesign of deteriorated WWTPs has proven to be
an effective strategy to recover operational capacity and comply with
regulatory requirements (Morales et al., 2023; Solís Chamorro, 2015). In
particular, the incorporation of appropriate technologies such as the upflow anaerobic filter (AFAF), the redesign of the
desander and the implementation of an improved grid system allowed optimizing
the physical and biological processes without resorting to high-cost or
technically complex solutions.
It should be
noted that the pH stability within the permissible range (7.0) confirms that
the redesigned system does not generate extreme conditions in the effluent, which
is fundamental to prevent adverse impacts on the receiving bodies. In addition,
the comparison of the results obtained with the limits established by TULSMA
shows that the new design complies with national environmental quality
standards, which validates its applicability in rural and semi-urban contexts
with limited resources.
On the other
hand, it is important to point out that the success of this intervention does
not depend only on the technical redesign, but also on the correct operation
and maintenance of the system. In this sense, the preparation of a specific
operating manual for the Ilapo I WWTP is a crucial
contribution to ensure its long-term sustainability. The continuous monitoring,
the training of local personnel and the institutionalization of control
routines should be considered strategic factors to avoid the progressive
deterioration of the plant.
Conclusions
The redesign of
the Ilapo I Wastewater Treatment Plant (WWTP) proved
to be an effective technical strategy to optimize the operational efficiency of
the system and ensure compliance with current environmental regulations. From
the analysis of the results obtained, the following conclusions can be drawn:
Significant
improvement in effluent quality: The intervention allowed reducing the levels
of BOD₅, COD and total suspended solids by more than 65%, reaching values
that are below the limits established by the TULSMA, which evidences an
efficient wastewater treatment.
Efficiency of
component redesign: The resizing of the desander channel, the redesign of the
septic tank, the installation of an upflow anaerobic
filter (FAFA) and the implementation of improved grids were decisive in
improving the performance of the system. These structural elements made it
possible to optimize the solids, grease and organic matter separation process.
Adaptability of
the design to rural contexts: The technical proposal was characterized by its
operational simplicity and economic viability, making it a replicable solution
in other communities with similar conditions, where access to advanced
technologies is limited.
Importance of
maintenance and operational management: The success of the system depends not
only on the physical redesign, but also on technical follow-up, periodic
maintenance and training of the personnel in charge. The development of an
operation and maintenance manual is a key tool for the sustainability of the
system.
Positive
environmental and social impact: The redesign of the WWTP contributes to the
protection of the receiving water sources, reduces the risk of waterborne
diseases and improves the quality of life of the local population, promoting
access to a healthier and safer environment.
Based on the
above, it is recommended to promote the evaluation and redesign of other
deteriorated treatment plants at the national level, prioritizing technical
approaches adapted to the context and sustainable in the long term.
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