Swine breeding industry has developed rapidly in recent years and generated a sizable quantity of wastewater. Swine wastewater contains high concentration of nitrogen and phosphorus which contributes to widespread eutrophication. Recovery of these nutrients from wastewater has gained interest recently because of the alarming depletion of the phosphate reserves and for their environmental impact. In this study, fluidized-bed crystallization (FBC) was used to treat synthetic swine wastewater by crystallizing struvite or magnesium ammonium phosphate hexahydrate (MgNH4PO4•6H2O) with the same crystal as a seed. The effect of upflow velocity on the phosphate removal was likewise investigated. Fluidized bed crystallization was conducted at phosphate concentration of 150 mg/L, 10.0 g/L seed dose, pH 9.53, Mg/P molar ratio of 1.3, N/P molar ratio of 4 and upflow velocity ranging from 20-50 cm/min. Results show that as the up-flow velocity is increased from 20-35 cm/min the phosphate recovery also increased from 93-95%, however, further increase will lower the recovery to 94%. Ammonium recovery increased from with increasing upflow velocity. Maximum ammonium recovery of 90% was achieved at 50 cm/min upflow velocity. From the sieve analysis, small crystals are of higher quantity than big crystals for all levels, however, the relative amount of small crystals are high for higher upflow velocities.

Effect of upflow velocity on nutrient recovery from swine wastewater by fluidized bed struvite crystallization

249th National Meeting (2015)

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