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Adaptation of urine source separation in tropical cities: Process optimization and odor mitigation
Jiefeng Zhang1, Apostolos Giannis, Victor W C Chang
1Division of Environmental and Water Resources, School of Civil and Environmental Engineering, Nanyang Technological University, Singapore.
Summary
Source-separating urine in tropical urban areas is feasible, with rapid urea hydrolysis observed. Monitoring conductivity is key, but managing odor emissions from urine hydrolysis is crucial for system success.
Area of Science:
- Environmental Science
- Wastewater Treatment Engineering
- Urban Sustainability
Background:
- Source-separating urine from domestic wastewater offers a sustainable approach to municipal treatment.
- Applying urine source-separation systems in tropical urban settings presents unique challenges and opportunities.
Purpose of the Study:
- To investigate the feasibility and potential issues of urine source-separation in tropical urban environments.
- To identify optimal conditions for urine hydrolysis and explore methods for managing associated emissions.
Main Methods:
- Investigated urea-hydrolysis (ureolysis) rates under various conditions (temperature, dilution, contamination).
- Monitored headspace pressure changes and volatile fatty acid (VFA) production during ureolysis.
- Utilized conductivity measurements as an indicator for the ureolysis process.
Main Results:
- Rapid ureolysis occurred at 34-40°C, with urine ratios >40%, and slight fecal contamination.
- Undiluted or low-diluted urine favored ureolysis, efficiently monitored by conductivity.
- CO2 and NH3 release caused initial pressure increases, followed by negative pressure due to microbial oxygen depletion.
- Significant volatile fatty acid production (acetic, propanoic, butyric acids) contributed to odor.
Conclusions:
- Effective urine source-separation systems are achievable in tropical urban areas.
- Urine stabilization tanks beneath high-rise buildings can mitigate pipe clogging risks.
- Conductivity serves as a reliable indicator for automated urine source-separation systems.
- Odor emission is a significant challenge, necessitating systematic monitoring and control.
- Enhanced ureolysis processes show potential to attenuate odor emissions.
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