In the 21st century, we still discharge millions of cubic meters of treated water into the environment without any productive use. This is not a technical failure—it is a failure of vision. The water crisis faced by Lima, one of the largest metropolises in Latin America, is emblematic. Located in a watershed that receives only 1.8% of the country’s water but hosts 30% of its population, the city lives with a structural imbalance between water supply and demand. Every drop counts. Yet over 77,000 m³/day of treated water from the La Atarjea WWTP continues to be wasted through direct discharge into the Rímac River.
This project proposes a transformative shift: converting that residual flow into a usable resource for agricultural, industrial, and environmental purposes, creating a new urban cycle of regenerated water. The impact is immediate and tangible: reusing that volume of water is equivalent to the daily consumption of over 300,000 people, or avoiding the pumping of 28 million m³ per year from natural sources. It aims to replace conventional withdrawals with a non-conventional, traceable, and permanent source.
The strategic goal is clear: to break the linear paradigm of “use and discharge” and replace it with a circular and intentional model—one that regenerates water, reduces pressure on the watershed, and creates new productive opportunities. The project is located in the district of El Agustino, Lima Metropolitan Area, and operated by Sedapal, the state-owned water and sanitation utility. The technical proposal includes ultrafiltration units, UV and ozone disinfection systems, regulation tanks, and customized distribution networks for specific end uses, with digital monitoring and real-time alarms.
The project is structured under the Water Positive framework and aligned with the principles of Volumetric Water Benefit Accounting (VWBA 2.0) and Water Quality Benefit Accounting (WQBA), fully complying with the criteria of additionality (the water had no previous use), traceability (digital monitoring by volume and destination), and intentionality (designed from inception for this purpose). Key stakeholders include Sedapal (operator), Aqua Positive (project structurer), end-user companies (industries, agriculture, municipalities), and third-party verification entities (e.g., AWS, Act4Water).
This project is not just an example of efficiency—it is an act of leadership. It transforms waste into resource, the invisible into the visible, and loss into possibility.
The opportunity stems from a longstanding inefficiency: 100% of the effluent treated by La Atarjea WWTP—with over 99% BOD and 97% COD removal—is discharged into the river without any productive use. In a context of structural water stress, this represents both an environmental liability and a strategic loss. The challenge is clear: to harness that regenerated water volume to substitute potable or groundwater withdrawals, reduce discharges, and expand the scope of non-conventional uses in Lima’s urban and industrial zones.
The proposed solution is a robust, modular, and scalable technical intervention. It integrates ultrafiltration and advanced disinfection systems (UV and ozone), enabling water quality that meets the requirements for irrigation, industrial cooling, street cleaning, and even environmental recharge. This additional treatment will gradually transform up to 103,680 m³/day into a safe and traceable resource—positioning the project among the largest urban reuse initiatives in Latin America.
Direct benefits include: decreased potable water consumption by industrial users, reduced organic and thermal loading into the Rímac River, and increased resilience of Lima’s urban water system. Moreover, each cubic meter reused reduces indirect emissions related to pumping and drinking water treatment, contributing to integrated climate action.
The model is led by Sedapal, with technical design and structuring by Aqua Positive, and is open to partnerships with the private sector (food companies, logistics, peri-urban agriculture, local governments). Businesses with ESG targets, water footprint commitments, or regulatory reuse mandates will find in this project a ready-to-implement, verifiable, and replicable solution. It provides a platform for regulatory compliance, reputational leadership, and competitive differentiation in a city where water is no longer abundant—but can be regenerated.
Acting now is not only logical—it is essential. Each day of delay means another 100,000 m³ wasted. Every company that joins multiplies the impact. This project was designed so that the private sector does not remain a spectator but becomes a key player in an inevitable transition.
The project will implement an wastewater system to optimize water quality and promote its application in industrial, agricultural, and aquifer recharge sectors. By integrating advanced treatment technologies, efficient distribution networks, real-time monitoring, and certification processes, the initiative ensures long-term sustainability and compliance with environmental standards.
1. Enhancing Treatment Infrastructure for High-Quality Reuse
To ensure the treated wastewater meets strict reuse standards, the project will upgrade the treatment infrastructure by incorporating ultrafiltration membranes and UV and ozone disinfection systems. These technologies will effectively remove suspended particles, microorganisms, and residual compounds, guaranteeing safe water for various applications. Additionally, pretreatment units will be installed to reduce solid loads and improve overall filtration efficiency, preventing system clogging and ensuring stable operation.
2. Developing Efficient Distribution and Storage Systems
To facilitate safe and equitable water distribution, the project will establish dedicated pipelines, control valves, and storage tanks that minimize losses due to evaporation and leaks. The storage tanks will be equipped with level sensors and recirculation systems, preventing bacterial growth and ensuring a continuous and reliable water supply for industrial and agricultural users.
3. Implementing Real-Time Monitoring for System Optimization
A real-time monitoring system will be deployed, utilizing strategically placed sensors to measure flow rates, water quality parameters, and treatment system performance. Automated control mechanisms will trigger alerts in case of deviations, allowing for rapid corrective actions. The continuous collection of data will provide valuable insights into efficiency, compliance with regulations, and long-term environmental benefits.
4. Ensuring Compliance Through External Certification and Auditing
To validate the system’s sustainability and compliance with global standards, the project will undergo external certification and auditing under recognized frameworks such as AWS (Alliance for Water Stewardship) and SBTs for Water (Science-Based Targets for Water). These certifications will ensure traceability, verify additional environmental benefits, and position the project as a replicable model for similar regions seeking efficient wastewaterreuse solutions.
✅ SDG 1 – No Poverty:
Access to treated water for industrial and agricultural use reduces operational costs and fosters employment opportunities, supporting local livelihoods. Reduced dependency on potable water alleviates pressure on urban supply, indirectly benefiting underserved communities.
✅ SDG 2 – Zero Hunger:
Treated water reuse supports sustainable irrigation, increasing food production without additional freshwater withdrawal.
✅ SDG 6 – Clean Water and Sanitation:
This is the central goal addressed by the project. Enhanced treatment, reuse, distribution, and real-time water quality monitoring directly improve water availability and sanitation. The project aligns strongly with SDG 6 Targets 6.3, 6.4, and 6.5.
✅ SDG 8 – Decent Work and Economic Growth:
The project creates jobs in wastewater treatment, infrastructure development, operation, and monitoring. It also supports water-intensive industries and agriculture sustainably, fostering economic activity and aligning with green growth models through efficient water resource use.
✅ SDG 9 – Industry, Innovation and Infrastructure:
The project promotes infrastructure upgrades (ultrafiltration, disinfection, monitoring) that foster innovation in wastewater reuse and sustainable industrial development. It also supports resilient infrastructure in a climate-sensitive context.
✅ SDG 11 – Sustainable Cities and Communities:
The project reduces environmental pressure on urban water systems and contributes to urban resilience through sustainable water reuse systems.
✅ SDG 12 – Responsible Consumption and Production:
Efficient water reuse aligns with sustainable resource management and promotes circular economy through reduced waste discharge and resource recirculation. Monitoring and reporting practices align with CSRD/CSDDD transparency requirements.
✅ SDG 13 – Climate Action:
The project reduces the carbon footprint by optimizing water reuse and decreasing freshwater extraction energy demands. Reuse strategies enhance climate resilience of agriculture and industry.
✅ SDG 14 – Life Below Water:
The reduction of wastewater discharge into the Rímac River minimizes aquatic ecosystem degradation. Advanced treatment reduces chemical and nutrient pollution, preserving downstream aquatic health.
✅ SDG 15 – Life on Land:
Treated water for irrigation improves soil health, supports vegetation, and prevents land degradation. It also reduces freshwater extraction from aquifers, preserving terrestrial ecosystems.
✅ SDG 17 – Partnerships for the Goals:
The project promotes external certification (AWS, SBT for Water) and fosters multi-sectoral cooperation. It encourages collaboration between public, private, and civil society sectors for responsible water stewardship and sets a replicable model for other regions.
The project will be executed in several strategic phases, ensuring effectiveness, sustainability, and regulatory compliance. Each step is designed to optimize the wastewater plant , guaranteeing high water quality and long-term operational efficiency.
1. Initial Diagnosis
The first phase of the project focuses on conducting a comprehensive assessment of the quality and potential applications of treated wastewater. This includes a detailed physicochemical and microbiological evaluation to determine critical parameters such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), nitrogen, phosphorus, and fecal coliform concentrations. These indicators provide a clear understanding of water composition, helping define necessary treatment adjustments to ensure it meets reuse standards.
In parallel, an analysis of water demand from potential users will be carried out. This step identifies key sectors—such as agriculture, industry, or municipal services—that could benefit from treated wastewater, establishing the required volumes and specific quality criteria for each use. Additionally, this phase will include a regulatory compliance review, ensuring that all water reuse activities align with national and international wastewater treatment standards. By defining these requirements early on, the project can be structured to meet environmental and legal obligations effectively.
2. Design of the Reuse System
Once the diagnosis is completed, the project will move on to designing an advanced reuse system that integrates high-efficiency filtration and disinfection technologies. The selection of these technologies will be based on the findings from the previous phase, ensuring that water meets the highest safety and quality standards. Key processes will include ultrafiltration, which effectively removes suspended particles and microorganisms, followed by UV disinfection and ozonation, which provide additional microbiological protection and improve overall water clarity.
Beyond treatment, this phase will also address storage and distribution planning. Large-capacity storage tanks will be strategically placed to maintain a stable and continuous supply of treated water, ensuring its availability even during peak demand periods. A well-designed pumping and pipeline system will be established, allowing for efficient distribution to different end-users. This infrastructure will be carefully planned to optimize energy use and reduce operational costs, ensuring a sustainable and cost-effective delivery system.
3. Construction and Infrastructure Installation
With the system design finalized, the project will move into the construction phase, where the necessary infrastructure will be installed to ensure proper treatment and distribution of the reused water. The ultrafiltration system will be deployed first, ensuring the removal of suspended solids and microorganisms before further disinfection. This will be followed by the installation of UV and ozonation units, guaranteeing that the water meets strict microbiological safety standards before distribution.
A robust distribution network will also be developed, incorporating pumping stations, storage tanks, and high-capacity pipelines. These components will ensure an efficient and uninterrupted flow of treated water to beneficiary sectors, optimizing its use in industrial processes, irrigation systems, or municipal services. The construction process will adhere to environmental best practices, minimizing energy consumption and material waste while ensuring long-term infrastructure durability.
4. Monitoring and Control
To ensure ongoing performance and compliance, an advanced real-time monitoring system will be implemented. This system will be equipped with strategically placed sensors that will continuously measure critical water quality parameters, including flow rates, microbial contamination, and chemical composition. These sensors will allow operators to track system efficiency in real time, enabling immediate response to any deviations from expected standards.
Additionally, an automated control system will be integrated, featuring alerts and early warning mechanisms to notify operators of any issues in the treatment process. This will allow for rapid intervention, reducing the risk of system malfunctions and ensuring that treated water consistently meets reuse requirements. The data collected from this monitoring system will be analyzed regularly to identify potential areas for optimization, ensuring that the system remains efficient, reliable, and adaptable to changing conditions.
5. Evaluation and Certification
To validate the project’s success and ensure transparency, an external audit and certification process will be conducted. Independent evaluators will assess the system’s performance, measuring its impact on water conservation, pollution reduction, and operational efficiency. The project will also undergo certification under internationally recognized sustainability frameworks, such as the Alliance for Water Stewardship (AWS) and Science-Based Targets for Water (SBTs for Water), ensuring that all reported benefits are measurable and verifiable.
Through this certification process, the project will gain credibility as a model for sustainable water reuse, demonstrating its effectiveness in reducing demand for freshwater sources and improving overall environmental resilience. The evaluation process will also provide valuable insights that can be used to enhance future system expansions or adaptations.
The Wastewater Reuse Project at PTAR La Atarjea seeks to leverage the plant’s existing treatment capacity to provide an alternative source of treated water, reducing pressure on conventional sources and promoting a circular water economy model. Currently, treated wastewater are discharged into the Rímac River without further use, representing a wasted opportunity. With this project, treated wastewater will be allocated to strategic uses in sectors with high water demand.
Treated Water Applications
The recovered water can be utilized in various strategic sectors, contributing to regional water resource optimization:
Agricultural irrigation: A portion of the treated water will be allocated to irrigation systems in nearby agricultural areas, ensuring compliance with sanitary standards for low-risk crops.
Industrial processes: Companies in nearby industrial zones will use treated water for cooling towers, boilers, equipment washing, and manufacturing processes, reducing dependence on potable water.
Aquifer recharge: Using controlled infiltration techniques, treated water can contribute to aquifer recharge in strategic areas, helping mitigate groundwater overexploitation.
Municipal and recreational uses: The recovered water will be used for street cleaning, park irrigation, and urban green spaces, promoting potable water conservation in these sectors.
Ecological restoration: Improved water quality will allow its use in wetland rehabilitation and riparian ecosystem restoration, benefiting biodiversity and regional water resilience.
Project Impact: The implementation of the reuse system at PTAR La Atarjea will reduce potable water consumption in key sectors, easing pressure on conventional water sources. It will also improve Rímac River water quality by reducing pollutant loads, aligning with environmental regulations and international certifications that guarantee project sustainability. Through efficient and sustainable water management, this project represents a significant step toward greater regional water security, ensuring both environmental and economic benefits in the long term.
