| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4481385 | Water Research | 2014 | 10 Pages |
•The ureolysis can largely assist the P recovery efficiency in SUPR system.•40% of ureolysis is adequate for achieving >90% P recovery efficiency within 10 min.•The precipitates from SUPR can be directly applied as fertilizer with abundant N&P.
Phosphorus (P) is a crucial and non-renewable resource, while it is excessively discharged via sewage, significant amounts originating from human urine. Recovery of P from source-separated urine presents an opportunity not only to recover this precious resource but also to improve downstream sewage treatment works. This paper proposes a simple and economic method to recover urine derived P by using seawater as a low-cost precipitant to form struvite, as Hong Kong has practised seawater toilet flushing as an alternative water resource since 1958. Chemical reactions, process conditions and precipitate composition for P precipitation in urine have been investigated to develop this new urine P recovery approach. This study concluded that ureolysis extent in a urine-seawater mixture determines the reaction pH that in turn influences the P recovery efficiency significantly; 98% of urine P can precipitate with seawater within 10 min when 40–75% of the urea in urine is ureolysed; the urine to seawater ratio alters the composition of the precipitates. The P content in the precipitates was found to be more than 9% when the urine fraction was 40% or higher. Magnesium ammonium phosphate (MAP) was confirmed to be the predominant component of the precipitates.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (242 K)Download as PowerPoint slide
