Sequential struvite precipitation and biological processes for effective removal of ammonium nitrogen from latex concentrate wastewater

Removal of ammonium nitrogen (NH4+-N) from real latex concentrate wastewater using struvite precipitation was investigated. The effect of two operational factors, namely pH and molar ratios for Mg2+:NH4+ and PO43−:NH4+, on struvite formation was investigated. The results revealed that external dosages of Mg2+ and PO43− were required to induce struvite precipitation. Highest NH4+-N removal of 81.7% can be achieved at an optimum pH of 9.5 and Mg2+:NH4+:PO43− molar ratios of 1.4:1:1.4. However, struvite precipitation also showed insignificant chemical oxygen demand (COD) removal. Thereby, an investigation on the incorporation of biological treatment with struvite precipitation in a sequential operation was conducted. The results showed that overall removal efficiencies of 93.1% for COD and 95.8% for NH4+-N were achieved in the sequence of biological treatment – struvite precipitation. This study indicates that the combination of biological methods and struvite precipitation is a feasible treatment option to remove both COD and NH4+ from latex concentrate wastewater.