Related Experiment Video
Updated: Aug 8, 2025
06:18
High-Throughput Protein Crystallization via Microdialysis
Published on: March 3, 2023
2.4K
Concentrating stabilized human urine using eutectic freeze crystallization for liquid fertilizer production
Caitlin Courtney1, Dyllon G Randall1
1Civil Engineering Department & Future Water Institute, University of Cape Town, 7700 Cape Town, South Africa.
Water Research
|February 27, 2023
Summary
A new hybrid reverse osmosis (RO) and eutectic freeze crystallization (EFC) system effectively concentrates human urine for fertilizer production. This sustainable method recovers valuable nutrients like nitrogen and potassium while minimizing energy consumption.
Area of Science:
- Environmental Science
- Chemical Engineering
- Sustainable Resource Management
Background:
- Source-separated urine is a valuable resource for fertilizer production, offering a sustainable alternative to mineral fertilizers.
- Conventional methods like reverse osmosis (RO) face limitations in water removal due to membrane scaling and operational constraints.
- Further water removal is crucial for efficient nutrient concentration and fertilizer production from urine.
Purpose of the Study:
- To investigate a novel hybrid eutectic freeze crystallization (EFC) and RO system for concentrating human urine.
- To assess the simultaneous crystallization of salt and ice under EFC conditions for enhanced water removal.
- To evaluate the potential for producing a concentrated liquid fertilizer from treated human urine.
Main Methods:
- A hybrid system combining RO with EFC was designed and investigated.
- A thermodynamic model was employed to predict salt crystallization and eutectic conditions.
- Real and synthetic urine samples were used to validate the EFC process.
- Mass balance calculations were performed for a hybrid RO-EFC process, including ice washing and recycle streams.
Main Results:
- Eutectic conditions allowed for the simultaneous crystallization of sodium sulfate decahydrate (Na2SO4∙10H2O) and ice.
- The hybrid RO-EFC process achieved 95% water removal from urine.
- High recovery rates were achieved: 77% for urea and 96% for potassium.
- Over 98% of phosphorus was recovered as calcium phosphate during initial urine stabilization.
Conclusions:
- The hybrid RO-EFC system offers an innovative and effective method for concentrating human urine for liquid fertilizer production.
- This approach enables significant recovery of key nutrients (N, K, P) and valuable salts.
- The process demonstrates substantial energy savings compared to other urine concentration methods, with an estimated requirement of 60 kWh m⁻³.
Related Concept Videos
01:23Formation of Concentrated Urine
1.9K
There is a gradient of solutes in the interstitial fluid from the renal cortex through the medulla, known as the medullary osmotic gradient. The juxtamedullary nephrons establish and maintain this gradient using countercurrent mechanisms with loops extending deep into the medulla. These nephrons also use countercurrent mechanisms to regulate urine volume and concentration. The interaction between the descending and ascending limbs of the nephron loop creates an osmotic gradient through...
1.9K
01:12Precipitation Processes
514
The experimental conditions in a gravimetric analysis should be optimized to maximize the particle size and purity of the obtained precipitate. Ideally, the concentration of the precipitating reagent should be low with effective stirring to maintain low relative supersaturation for the growth of large crystals. In homogeneous precipitation, the precipitant is slowly generated by a chemical reaction in the solution to avoid local reagent excesses. For example, urea decomposes gradually to...
514
01:10Recrystallization: Solid–Solution Equilibria
1.2K
Recrystallization is a purification technique used to separate impurities from solid compounds. In this technique, no chemical reactions occur. Instead, it exploits physical properties only, specifically, the solubility differences between the desired compound and impurities, either at a single temperature or at different temperatures, and under other selected conditions. The solid-solution equilibrium (solubility equilibrium) of each component in the solution represents a binary phase...
1.2K
01:20Formation of Dilute Urine
1.7K
The formation of dilute urine is a critical renal adaptation that maintains fluid balance, particularly during periods of high fluid intake. This process primarily involves the juxtamedullary nephrons. By adjusting the permeability of water and ions in response to physiological conditions, the kidneys can either conserve or excrete water, resulting in concentrated or dilute urine.
Filtrate Osmolarity in the PCT
Initially, as the filtrate passes through the proximal convoluted tubule (PCT), its...
Filtrate Osmolarity in the PCT
Initially, as the filtrate passes through the proximal convoluted tubule (PCT), its...
1.7K
01:25Crystal Growth: Principles of Crystallization
2.2K
Crystallization is a phase transformation process in which crystals are precipitated from a supersaturated solution or formed from other sources. During crystallization, atoms or molecules arrange themselves into a well-defined, rigid crystal lattice to minimize energy.
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent...
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent...
2.2K