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A pilot scale study of combining struvite precipitation with UniBAR-anammox process as a sustainable unified solution for managing nutrients in centrate

University of British Columbia

Nitrogen (N) and phosphorus (P) from wastewater discharges are the primary causes of eutrophication in receiving water bodies. Removal and recovery of nutrients from wastewater is important, due to their high demand as fertilizer. Two well established technologies, struvite precipitation for P-removal and anammox process for N-removal, are combined in this study to manage both nutrients concurrently. A pilot-scale study was conducted at the Annacis Wastewater Treatment Plant Research Center in Delta, BC, combining Struvite precipitation using the UBC Crystallizer with the UniBAR-anammox process, in two possible combination sequences. In combination 1 (Pre-Anammox-Struvite process), an average combined removal efficiency of 90.8±1.8% P and 79.2 ± 1.9% N was achieved. The anammox process was not affected by the chemical load (caustic and magnesium) from the struvite process. The UniBAR-anammox process showed similar behaviour pattern for both centrate and struvite effluent feed, achieving over 70% N-removal. Batch test results at different temperatures indicated that the anammox process performed better at higher temperature, for both feeds. N-removal efficiency decreased from around 70% to 57%, as the temperature decreased from 34 ̊C to 25 ̊C. In combination 2 (Post-Anammox-Struvite process), the average combined N and P removal efficiencies were 71.0±5.2% and 90.8±1.8 %, respectively. With the change in struvite influent after combination (from centrate to anammox effluent feed), while using the same pH set point of 7.67, P-removal decreased, due to a lower N: P molar ratio. A higher pH set point of 8.30, to maintain desired supersaturation ratio, resulted in 90% removal. However, higher caustic consumption was introduced in combination 2, compared to the negligible amount in combination 1. Pure struvite pellets were recovered from both combinations.

Text

2015-05-11

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/53096

Civil Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/