Creating Sustainable Water Recycling in Growing Cities

Jim Crocker
20th February, 2024

Creating Sustainable Water Recycling in Growing Cities

Lima, Peru.

Photo adapted from: European Space Agency, Copernicus Sentinel data / CC BY SA (Source)
Lima, Peru, is facing a growing water crisis driven by population increases, climate change, and aging infrastructure. Traditional wastewater management isn’t equipped to address these challenges, nor does it recover valuable resources. Researchers at Pontificia Universidad Católica del Perú (PUCP) have undertaken a study[1] to identify wastewater treatment options that can simultaneously reduce pollution and create a source of reusable water, moving the city towards a more sustainable, circular economy. The study focused on two primary goals: mitigating eutrophication – the excessive enrichment of water with nutrients, leading to algal blooms and oxygen depletion – and enabling indirect potable reuse (IPR), where treated wastewater is returned to the drinking water supply via an environmental buffer like a river or reservoir. Several treatment technologies were evaluated for each goal. For eutrophication mitigation, the options included MLE, Bardenpho, Step-feed, HF-MBR (Hybrid Fenton Membrane Bioreactor), and FS-MBR (Full Scale Membrane Bioreactor). For IPR, the researchers considered combinations of secondary treatment with ultrafiltration (UF), reverse osmosis (RO), and advanced oxidation processes (AOP), as well as MBR combined with RO and AOP. These systems were envisioned as being implemented at a district level, forming a network of treatment plants. To comprehensively assess these scenarios, the PUCP team employed three key analytical tools: Life Cycle Assessment (LCA), Life Cycle Costing (LCC), and Multi-Criteria Decision Analysis (MCDA). LCA evaluates the environmental impacts of a process, from resource extraction to disposal. LCC determines the overall economic cost. MCDA integrates both quantitative data from LCA and LCC with qualitative factors like social acceptance and operational feasibility. This holistic approach strengthens the decision-making process by considering a wide range of factors. The results revealed that Bardenpho consistently emerged as the preferred option for eutrophication abatement, particularly when environmental and economic considerations were prioritized. This process effectively removes pollutants at a reasonable cost. Global warming impacts associated with Bardenpho ranged from 0.23 to 0.27 kg CO2 equivalent per cubic meter of treated water, while costs were between 0.12 and 0.17 euros per cubic meter. However, when techno-operational and social aspects were given greater weight, HF-MBR proved more suitable. For IPR, HF-MBR combined with RO and AOP demonstrated the best performance. This combination provides a high level of treatment, removing a wide range of contaminants. However, IPR came at a cost: global warming impacts were significantly higher (0.46-0.51 kg CO2eq/m3), and costs increased to approximately 0.44 euros per cubic meter. Despite the higher costs, the IPR scenario achieved over 98% eutrophication abatement. These findings build upon previous research highlighting the benefits of advanced wastewater treatment. For example, studies have shown that advanced treatment trains, including those utilizing ultrafiltration, ozone, and biological activated carbon, can significantly reduce the risk of pathogens like Cryptosporidium, even under suboptimal operating conditions[2]. The PUCP study reinforces this, demonstrating that technologies like RO and AOP are crucial for achieving the high level of purification required for IPR. Furthermore, the study echoes the importance of considering economic factors when implementing advanced wastewater treatment, particularly in developing countries[3]. While tertiary treatment and sludge processing can be costly, the PUCP research demonstrates that water reuse can generate financial profits, offsetting these expenses. The integration of anaerobic digestion, as highlighted in[3], could further enhance the economic viability of the proposed systems by generating biogas for energy production. The PUCP study also acknowledges the complexity of biological nutrient removal processes, building on advancements in modeling these systems[4]. Accurate modeling, like that provided by BNRM2, is essential for optimizing treatment plant performance and predicting outcomes under varying conditions. The research emphasizes the need for a nuanced approach, recognizing that the optimal treatment strategy will depend on specific local conditions and priorities.

EnvironmentSustainabilityBiotech

References

Main Study

1) A multi-criteria decision framework for circular wastewater systems in emerging megacities of the Global South.

Published 20th February, 2024

https://doi.org/10.1016/j.scitotenv.2023.169085

Related Studies

2) Quantifying pathogen risks associated with potable reuse: A risk assessment case study for Cryptosporidium.

https://doi.org/10.1016/j.watres.2017.04.048

3) Environmental and cost life cycle assessment of different alternatives for improvement of wastewater treatment plants in developing countries.

https://doi.org/10.1016/j.scitotenv.2018.12.386

4) Biological Nutrient Removal Model No. 2 (BNRM2): a general model for wastewater treatment plants.

https://doi.org/10.2166/wst.2013.004


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