Electrochemically Induced Precipitation Enables Fresh Urine Stabilization and Facilitates Source Separation

Source separation of urine can enable nutrient recycling, facilitate wastewater management, and conserve water. Without stabilization of the urine, urea is quickly hydrolyzed into ammonia and (bi)­carbonate, causing nutrient loss, clogging of collection systems, ammonia volatilization, and odor nuis...

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Bibliographic Details
Published in:Environmental science & technology 2020-03, Vol.54 (6), p.3618-3627
Main Authors: De Paepe, Jolien, De Pryck, Laurens, Verliefde, Arne R. D, Rabaey, Korneel, Clauwaert, Peter
Format: Article
Language:English
Subjects:
Ammonia
Anion exchange
Anion exchanging
Bathroom Equipment
Calcium
Cation exchange
Cation exchanging
Chemical Precipitation
Chemical treatment
Clogging
Collection
Electrochemical cells
Electrochemistry
Hydrolysis
Hydroxyl ions
Magnesium
Membranes
Nutrient loss
Nutrients
Odor
Odors
pH effects
Recycling
Separation
Stabilization
Storage
Urea
Ureas
Urine
Volatilization
Waste management
Waste Water
Wastewater
Wastewater management
Water conservation
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Summary:Source separation of urine can enable nutrient recycling, facilitate wastewater management, and conserve water. Without stabilization of the urine, urea is quickly hydrolyzed into ammonia and (bi)­carbonate, causing nutrient loss, clogging of collection systems, ammonia volatilization, and odor nuisance. In this study, electrochemically induced precipitation and stabilization of fresh urine was successfully demonstrated. By recirculating the urine over the cathodic compartment of an electrochemical cell, the pH was increased due to the production of hydroxyl ions at the cathode. The pH increased to 11–12, decreasing calcium and magnesium concentrations by >80%, and minimizing scaling and clogging during downstream processing. At pH 11, urine could be stabilized for one week, while an increase to pH 12 allowed urine storage without urea hydrolysis for >18 months. By a smart selection of membranes [anion exchange membrane (AEM) with a cation exchange membrane (CEM) or a bipolar membrane (BPM)], no chemical input was required in the electrochemical cell and an acidic stream was produced that can be used to periodically rinse the electrochemical cell and toilet. On-site electrochemical treatment, close to the toilet, is a promising new concept to minimize clogging in collection systems by forcing controlled precipitation and to inhibit urea hydrolysis during storage until further treatment in more centralized nutrient recovery plants.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.9b06804