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Design optimization of a mixing reactor for close to source urine stabilization
What happens when you flush the toilet? Together with urine and feces, valuable nutrients are lost. Recovering nutrients such as nitrogen and phosphorus from urine is crucial for agriculture and environmental protection while potentially offering financial value through fertilizer sales. The separation of human excreta offers a resource-efficient wastewater treatment alternative not only for fast-growing cities and low-income countries, but also for the industrialized parts of the world. During onsite treatment, stabilizing urine is key to prevent ammonia volatilization causing nitrogen loss and environmental harm. A promising method to stabilize urine is to increase the pH-value (alkaline stabilization), whereby urea breakdown and thereby ammonia release is inhibited at high pH levels using basic salts like calcium hydroxide (Ca(OH)2). When efficiently mixed with fresh urine, Ca(OH)2 not only stabilizes urine but also aids in phosphate separation and reduces the risk by pathogens.
At Eawag (Dept. of Process Engineering), an onsite urine treatment prototype is currently developed, employing a two-step process: initial alkaline stabilization using Ca(OH)2 followed by evaporation for volume reduction. Proximity of the stabilization step to the source, i.e. the toilet, is critical. We are looking for a student who will design and test a mixing reactor that can be installed at the source allowing transporting urine through pipes and reaching the evaporation reactor. In doing so, a set of requirements related to the available space, mixing performance, solid separation options, and inflow and outflow conditions must be met.
At Eawag (Dept. of Process Engineering), an onsite urine treatment prototype is currently developed, employing a two-step process: initial alkaline stabilization using Ca(OH)2 followed by evaporation for volume reduction. Proximity of the stabilization step to the source, i.e. the toilet, is critical. We are looking for a student who will design and test a mixing reactor that can be installed at the source allowing transporting urine through pipes and reaching the evaporation reactor. In doing so, a set of requirements related to the available space, mixing performance, solid separation options, and inflow and outflow conditions must be met.
In the course of the project, the student will be responsible for:
- Understanding the technology and design of the current urine treatment system.
- Conceptualizing mixing mechanisms.
- Selection of the most promising design configuration(s).
- CAD design, building and commissioning of the mixing reactor.
- Experimental investigation under different mixing regimes (with powdered and granular Ca(OH)2).
An iterative design process is envisaged.
In the course of the project, the student will be responsible for: - Understanding the technology and design of the current urine treatment system. - Conceptualizing mixing mechanisms. - Selection of the most promising design configuration(s). - CAD design, building and commissioning of the mixing reactor. - Experimental investigation under different mixing regimes (with powdered and granular Ca(OH)2).
An iterative design process is envisaged.
This research looks for a master-level mechanical engineering/environmental engineering student with skills in conceptual design, CAD design, experimental measurements. The described project will be fully conducted at Eawag.
Interested and qualified candidates are invited to contact Prof. Dr. Kai Udert (kai.udert@eawag.ch).
This research looks for a master-level mechanical engineering/environmental engineering student with skills in conceptual design, CAD design, experimental measurements. The described project will be fully conducted at Eawag.
Interested and qualified candidates are invited to contact Prof. Dr. Kai Udert (kai.udert@eawag.ch).