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Abstract:
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In the present work was evaluated the capacity of natural zeolite for ammonium and phosphorus removal and recovery from residual effluents in tertiary treatments of urban wastewater plants.
Two different natural zeolites were used. One of them was modified with calcium and iron separately for evaluate the possibility of increasing adsorption capacity
The effectiveness of natural, iron and calcium modified zeolite was evaluated through batch studies, where the phosphate and ammonium adsorption was described well by Langmuir isotherm. Ammonium adsorption capacities up to 29 ± 0,4 mg NH4+/g were reported. Also were reported phosphate adsorption capacities up to 5,0 ± 0,1 mg PO34-/g of zeolite
In addition the sorption kinetic for modified zeolite follows a pseudo-second-order reaction model. The most removal percentage was reached for iron modified zeolite with 68% ammonium removal and 45 % phosphate removal respectively.
Besides, the effect of competing anions on the adsorption capacity was evaluated; the selectivity of zeolite onto phosphate was compared with, nitrate, sulphate, bicarbonate and chloride. On the other hand, the selectivity of zeolite onto ammonium was compared with potassium, magnesium, calcium and sodium.
Finally, desorption tests to evaluate the capacity of ammonium and phosphate recovery of iron modified zeolite, was carried out.
Ammonium ad phosphate loaded zeolites were analyzed using SEM/EDS. 35 ± 1% ammonium and 94 ± 2 % phosphate desorption efficiency was reported; as a result, these ammonium and phosphate removable can be evaluated for possible uses in low cost fertilize elaboration. |
