Nitrogen recovery from pig slurry by struvite precipitation using a low-cost magnesium oxide
Ammonia nitrogen management is a recurrent problem in intensive livestock areas. Struvite precipitation stands as a mature technology to recover ammonia nitrogen and prevent associated environmental problems. However, the feasibility of struvite technology to recover ammonia nitrogen from pig manure...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/173111 |
| Acceso en línea: | https://hdl.handle.net/2445/173111 |
| Access Level: | acceso abierto |
| Palabra clave: | Òxid de magnesi Nutrients (Medi ambient) Fosfats Purins Magnesium oxide Nutrients (Ecology) Phosphates Liquid farm manure |
| Sumario: | Ammonia nitrogen management is a recurrent problem in intensive livestock areas. Struvite precipitation stands as a mature technology to recover ammonia nitrogen and prevent associated environmental problems. However, the feasibility of struvite technology to recover ammonia nitrogen from pig manure is limited by the reagents cost. This research aimed to optimise the formulation of a stabilizing agent (SA) synthesised using an industrial low-grade MgO by-product (LG-MgO) and phosphoric acid for efficient TAN recovery via struvite precipitation. Experimental results showed that the H3PO4/LG-MgO ratio controls the magnesium phosphate mineral phase of the SA (bobierrite and/or newberyite). Newberyite-rich SA showed the highest TAN removal efficiency from pig manure (66-73%) compared to the SA formed by a mixture of newberyite and bobierrite (51-59%) and by bobierrite (26%). Particle size reduction of LG-MgO did not improve the SA's TAN removal efficiency, although XRD patterns showed that the precipitates from the TAN removal experiments contained some unreacted newberyite. The economic analysis showed that the higher reactivity of the SA formulated using higher H3PO4/LG-MgO ratios compensated reagent costs. The SA synthesised with a H3PO4/LG-MgO ratio of 0.98 showed the most economical treatment cost, which was estimated at 7.5 ¿ per kg of ammonia nitrogen from pig manure. Finally, the optimum SA was successfully synthesised in a 200-L pilot plant, with a TAN removal capacity only 10% lower than the one synthesised at lab-scale. |
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