Ammonium removal from waters by chemical precipitation method

One of the essential nutrients for living and growth of organisms is nitrogen, which presents in aquatic environment as ammonium (NH4+) form. Ammonium, which is toxic effect on aquatic organisms even at low concentrations, could lead to eutrophication, transformed into forms that algae can benefit as a result of various processes. Therefore, ammonium input at certain levels in receiving environment should be prevented. Ammonium removal from waters using chemical precipitation is the preferred method when taking into consideration economic return of products obtained (MAP; Magnesium Ammonium Phosphate; Struvite) after removal process.In this study, physical and chemical parameters, which are effective in MAP precipitation, were investigated. Removal of ammonium at high concentrations (Cmean=348 mg NH4+/L ± 38,1; n=25) taking place as a result of urea hydrolysis in the Biocatalytic Calcification Reactor (BCR) was carried out in the form of MAP precipitation. Magnesium and phosphate required for precipitation were provided from MgCl2.6H2O as solid form and H3PO4 as liquid form, respectively. Optimum molar ratio of Mg:NH4:PO4 was determined as 1,25:1:1. Different pH ranges (7?10) studies with used that molar ratio, ammonium removal of approximately 96% reached at pH value of 9,36. It was seen that rapid mixing (200 rpm) of 30 s. and slow mixing (30 rpm) of 2 min. periods were sufficient for MAP precipitation. Struvite obtained after precipitation was used as fertilizer and it was observed that struvite supported to development of plant.