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TitleRecovery of N and P from Urine by Struvite Precipitation Followed by Combined Stripping with Digester Sludge Liquid at Full Scale
Publication TypeJournal Article
Year of Publication2013
AuthorsMorales, N, Boehler, MA, Buettner, S, Liebi, C, Siegrist, H
Paginationp. 1262 - 1278; 6 tab.; 4 fig.
Date Published2013-08-29
PublisherMolecular Diversity Preservation International, Water Editorial Office, MDPI
Place PublishedBasel, Switzerland
Keywordsammonia, chemical analysis, chemical treatment, chemicals, nutrients, urine treatment

A novel ammonia stripping method, including a CO2 pre-stripper was used to treat a mix of supernatant liquor from an anaerobic digester and urine in order to recycle nitrogen as ammonium sulfate at full-scale in the WWTP Kloten/Opfikon. Waste streams
were not generated, since the ammonia was recovered as a marketable nitrogen fertilizer, turning a waste product into a valuable product. The efficiency of this system was increased by means of the addition of pre-treated urine collected separately at EAWAG
building. The separation step was performed by the use of water free urinals and urine diversion flush toilets. An increase of 10% in the liquid flux with the addition of the urine translated into a 40% increase of the ammonia concentration in the inlet of the stripping unit. The achievement of these percentages generated a proportional increase in the fertilizer production. The urine pre- treatment was carried out by adding magnesium to produce a precipitate of struvite. The first experiments with the combined treatment showed the feasibility of the combination of the separation and pre-treatment steps. [authors abstract]

NotesWith 45 references on p. 1276 - 1278
Custom 1114


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