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Nitrogen recovery from municipal wastewater through newberyite to struvite crystallization process

University of British Columbia

The present study evaluated the feasibility of using newberyite (MgHPO₄.6H₂O), a thermal decomposition product of struvite, as an inexpensive source of magnesium and phosphate to achieve high nitrogen removal efficiency from domestic wastewater, through struvite recrystallization. Several bench scale and pilot scale experiments were performed with a different combination of synthetic wastewater, real centrate from the municipal post digestion wastewater stream, synthetic newberyite powder and actual newberyite pellets, derived from thermally decomposing struvite. Ammonia removal efficiency as high as 94% was achieved in bench scale experiments for dewatering centrate from Annacis wastewater treatment plant at pH 8.5. Orthophosphate residual resulting from newberyite dissolution can be kept as low 23.8 mg/l. The recrystallized product was found to be a mixture of newberyite and struvite. Further experiments were carried out to solubilized newberyite, prior to providing a favorable condition for struvite formation. Although no struvite was formed at this stage, the orthophosphate release was lower, compared to model prediction. The reduction in orthophosphate dissolution is potentially due to low hydraulic retention time. The pilot scale experiment in the UBC fluidized bed reactor was inconclusive, due to an inability to continuously produce struvite pellets, instead of fines. The present study illustrates the potential for newberyite to struvite recrystallization technology. However, it is recommended to carry out further research on newberyite solubilization and newberyite to struvite, pelletization kinetics.

Text

2018-03-21

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/64870

Civil Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/