| Title |
Recovery of phosphates as struvite from urine-diverting toilets: optimization of pH, Mg:PO4 ratio and contact time to improve precipitation yield and crystal morphology |
| ID_Doc |
10062 |
| Authors |
Rodrigues, DM; Fragoso, RD; Carvalho, AP; Hein, T; de Brito, AG |
| Title |
Recovery of phosphates as struvite from urine-diverting toilets: optimization of pH, Mg:PO4 ratio and contact time to improve precipitation yield and crystal morphology |
| Year |
2019 |
| Published |
Water Science And Technology, 80.0, 7 |
| DOI |
10.2166/wst.2019.371 |
| Abstract |
Phosphate (P) recovery from urban wastewaters is an effective strategy to address environmental protection and resource conservation, aiming at an effective circular economy. Off-grid wastewater treatment systems like urine-diverting toilets (UDT) can contribute to source separation towards nutrient recovery, namely phosphorus recovery. Effectiveness of P precipitation requires a process-based knowledge regarding pH, Mg:PO4, contact time and their interactions in P recovery and crystal morphology. Several studies failed to see the process as a whole and how factors influence both morphology and P recovery for UDT hydrolysed urine. This study addressed the above-mentioned factors and their interactions, and results showed that pH and Mg:PO4 ratio are the key factors for struvite precipitation, whereas contact time is relevant for crystal growth. The recommended set of factors proposed (pH 8.5, Mg:PO4 ratio of 1.2:1 and 30 minutes contact time) not only promotes a high precipitation yield - 99% of P with co-precipitation of at least 21% of ammonium (NH4+) - but also leads to larger crystals with lower water solubility (10% less crystals dissolved in water after 3 days). The obtained outcome facilitates the downstream process and leads to a more efficient slow-release fertiliser, as less P is wasted to receiving waters by leaching, minimising eutrophication processes. |
| Author Keywords |
hydrolysed urine; nutrients recovery; phosphates; struvite; urine-diverting toilets |
| Index Keywords |
Index Keywords |
| Document Type |
Other |
| Open Access |
Open Access |
| Source |
Science Citation Index Expanded (SCI-EXPANDED) |
| EID |
WOS:000503485300007 |
| WoS Category |
Engineering, Environmental; Environmental Sciences; Water Resources |
| Research Area |
Engineering; Environmental Sciences & Ecology; Water Resources |
| PDF |
https://iwaponline.com/wst/article-pdf/80/7/1276/637311/wst080071276.pdf
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