Murcia’s LIFE ENRICH project implements a circular economy approach in wastewater treatment. It serves as a bridge between plant operators and the fertilizer industry, by transforming nutrients present in wastewater into fertilizers. The project addresses environmental challenges and validates the efficacy of these alternative fertilizers through crop trials.
Introduction
LIFE ENRICH is a European project funded under the Life programme. The goal of the LIFE ENRICH project is to implement the concept of circular economy, by demonstrating the complete value chain for nutrient recovery in urban wastewater treatment plants (WWTPs). This includes the re-use of these nutrients to produce valuable fertilizers. The project lasted from September 2017 until November 2021.
In modern society, the wastewater treatment and agricultural sectors operate independently of one another. WWTPdischarge nutrients into the environment through rivers, dewatered sludge, and the atmosphere – whilst the fertilizer industry consumes significant amounts of nutrients from natural reserves or complex manufacturing processes. These disconnected processes need to change and LIFE ENRICH has successfully demonstrated the possibility of establishing beneficial synergies between these sectors for the industry, environment, and society.
The LIFE ENRICH project addresses various environmental challenges throughout the process, from upstream raw material recovery to the creation and utilisation of the final agricultural product. Key environmental issues targeted by the project include:
- High energy use in nutrient removal processes: This means finding ways to reduce the amount of energy needed to remove nutrients like nitrogen and phosphorus from wastewater treatment plants (WWTPs).
- Managing sewage sludge: The project aims to reduce the environmental impact of producing and disposing of sewage sludge, a byproduct of wastewater treatment.
- Preventing water pollution: LIFE ENRICH focuses on preventing pollution of water bodies, particularly a problem called 'eutrophication,' which occurs when too many nutrients are released into water and cause excessive plant and algae growth.
- Reducing the environmental impact of chemical fertilizers: The project seeks to lower the environmental harm caused by the production and use of chemical fertilizers.
- Protecting phosphate rock reserves: LIFE ENRICH also aims to address the issue of running out of phosphate rock, a crucial resource used in fertilizers.
Through the implementation of a circular economy model, LIFE ENRICH aims to address these environmental challenges and create a sustainable and efficient nutrient management system for urban wastewater treatment plants.
Description of plan
LIFE ENRICH focuses on the whole value chain, including the recovery of nutrients from WWTPs, the characterisation and optimal blending of these nutrients to create high-value fertilizers, and the validation of their performance in a real-life case study with end-users.
The project primarily concentrates on the recovery of nitrogen (N) and phosphorus (P) from WWTPs. These recovered nutrients are then transformed into alternative fertilizers, struvite and ammonium salts. These fertilizers were utilized in crop trials to assess their effectiveness. To carry out the project, the Murcia Este WWTP was selected as the facility to operate the technological prototypes.
The performance and efficiency of the nutrient recovery process were evaluated in a real-world setting, as horticultural and extensive crops were cultivated in Spanish territories, specifically in Cabrils, Agramunt, and Castelldans soils. These locations served as test sites to validate the effectiveness of the alternative fertilizers and sewage sludge in supporting crop growth.
The LIFE ENRICH project aims to demonstrate the feasibility and efficacy of nutrient recovery from WWTP, the production of high-value fertilizers, and their successful utilisation in crop cultivation.
Challenges
An overarching challenge is the increasing scarcity of phosphorus as a resource globally. Phosphorus is primarily used in the food supply, with more than 80% of the mined product serving the food industry. As living standards rise and the global population continues to grow, the demand for phosphorus is expected to increase. At the same time, the reserves of phosphorus are depleting. Initiatives such as the LIFE Enrich project are now underway to alleviate its scarcity, by focusing on reuse and recovery within the phosphorus cycle.
During the LIFE Enrich project some difficulties were encountered in the production processes. For example, producing ammonia salts (an alternative fertilizer) was difficult, because the WWTP could only be utilised for limited periods due to high energy costs. Additionally, to achieve the required level of purity (a clean product) an extra component had to be added in the production process. This led to higher costs, reducing overall returns. Consequently, establishing the feasibility of the business model was sometimes challenging.
Stakeholders
The project consortium was formed by 7 partners:
- Cetaqua, Water Technology Centre (project coordinator),
- Suez Advanced Solutions,
- Aigües del Segarra Garrigues,
- Aguas de Murcia (EMUASA),
- Instituto de Investigación y Tecnología Agroalimentaria (IRTA),
- Universitat Politècnica de Catalunya (UPC),
- Universitat Politècnica de València (UPV).
Each of the partners contributed to the project by sharing their knowledge and expertise and applying this to the circular model.
Achievements and benefits
Operational: The process implemented by the Murcia Este WWTP is to recover nitrogen and phosphorus from wastewater, transforming them into valuable fertilizer offers several benefits for the WWTP:
- The WWTP’s adaptation enhances the efficiency of water removal from the sludge, resulting in reduced chemical and energy consumption during the dewatering stage.
- The recovery of nitrogen, along with struvite, reduces the nitrogen load in the biological treatment, leading to a lower energy demand.
- The recovery of phosphorus leads to an 85% reduction in the need for antiscaling agents (detergents) to clean the installation.
Additionally, a technical replicability study conducted on three other WWTPs demonstrated that the LIFE ENRICH process is flexible and can be adapted to different WWTP configurations.
Economic and social: The implementation of the LIFE ENRICH value chain reduces the operating expenditures and could create additional jobs. This initiative promotes broader knowledge and the adoption of circular and environmentally friendly strategies. Moreover, nutrient recovery could boost the European agriculture industry by reducing its reliance on mineral fertilizers and their price fluctuations.
Murcia has learned that a WWTP can serve a greater purpose than only treating wastewater. It has the potential to produce high-value products from waste. The operational benefits of the project have exceeded expectations, resulting in improved performance. However, the sales forecasts for the fertilizers and market acceptance have been lower than expected, impacting the business model. The results of the LIFE ENRICH project are also used for further research, specifically in a project called WalNUT, which also aims to close the wastewater cycles for nutrient recovery.
Other cities should consider implementing similar initiatives. This approach offers benefits such as reducing nutrient discharge into watercourses, addressing operational challenges in existing WWTP infrastructure, and ensuring food production by reducing nutrient dependence. It is crucial to involve both producers and consumers in the process to ensure the proper utilisation of the fertilizers. Building consumer confidence and preventing rejection of agricultural products are vital considerations.
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