Water Infrastructure Ressources (Institute)

EVEREST

EVEREST: Evaluation of a nature-based, resource-efficient process for the treatment of household wastewater streams

 

Project duration: 06/2024 - 02/2025

Project execution: rewa 

Staff (RPTU) :

Funding:

  • Willy Hager Foundation

Project partners:

  • Universidade Federal do Mato Grosso do Sul,  Research group “Saneamento Focado em Recursos” 

Project description:
Starting Point: Decentralized Sanitation Concepts for the Future

In light of global challenges such as climate change, water scarcity, and the need to establish circular economies, innovative approaches in urban water management are essential. The system implemented at the rural Reinighof site in Rhineland-Palatinate is one such forward-looking, resource-oriented sanitation concept. It is based on the separation of domestic wastewater streams (greywater, urine, feces) and combines technical with nature-based processes. While valuable phosphorus is recovered from urine in a reactor in the form of struvite fertilizer, a specialized soil filter (SSF) and a downstream constructed wetland (CW) treat the wastewater. An evaporation pond ensures a zero-discharge solution that protects groundwater bodies.

Research Focus: Resilience and Optimization after Long-Term Operation

After more than six years of successful operation, seasonal overload with up to 100 users instead of the originally planned 16 led to the irreversible clogging of the SSF. This event offered the opportunity to investigate the system's long-term stability and loading limits under real-world conditions. Within the research project, running from June 2024 to February 2025, the system was refurbished with new filter material. The scientific focus was now on the evaluation of the performance of the refurbished system, the detailed analysis of the causes of the previous clogging, and the development of optimization strategies for future, resilient operation.

Key Results and Findings

The investigations demonstrated the impressive robustness of the overall system. Even extremely high total nitrogen (TN) concentrations in the urine supernatant of up to 5,420 mg/L were reduced to an average of just 10.7 mg/L in the final effluent. Ammonium nitrogen (NH4​-N) removal was also excellent, with a reduction from values as high as 4,774 mg/L to 0.7 mg/L. Residual phosphorus (TP) and chemical oxygen demand (COD) were also reliably reduced to very low levels. The analysis of the microbiological water quality revealed that the concentrations of E. coli and enterococci in the final pond met the standards of the EU Bathing Water Directive for "excellent quality". The investigation of the old filter material confirmed that the clogging was caused by a combination of mineral precipitation and the accumulation of fine particles.

Impact and Outlook

The project provides valuable, practical data on the performance, loading limits, and optimization potential of nature-based processes for wastewater treatment and resource recovery. The findings contribute significantly to the development of more robust and efficient decentralized sanitation solutions. The close cooperation with the Federal University of Mato Grosso do Sul (UFMS) also ensured knowledge transfer and the investigation of the transferability of such concepts to other climatic and socio-economic contexts, such as Brazil.

The project report can be downloaded here.