Phosphate and Ammonium Removal from Water through Electrochemical and Chemical Precipitation of Struvite

• Main Authors: Kyösti Rajaniemi, Tao Hu, Emma-Tuulia Nurmesniemi, Sari Tuomikoski, Ulla Lassi
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Processes
• Subjects: electrocoagulation; struvite; chemical precipitation; wastewater; ammonium; phosphate
• Online Access: https://www.mdpi.com/2227-9717/9/1/150

Batch electrocoagulation (BEC), continuous electrocoagulation (CEC), and chemical precipitation (CP) were compared in struvite (MgNH₄PO₄·6H₂O) precipitation from synthetic and authentic water. In synthetic water treatment (SWT), struvite yield was in BEC 1.72, CEC 0.61, and CP 1.54 kg/m³. Corresponding values in authentic water treatment (AWT) were 2.55, 3.04, and 2.47 kg/m³. In SWT, 1 kg struvite costs in BEC, CEC, and CP were 0.55, 0.55, and 0.11 €, respectively, for AWT 0.35, 0.22 and 0.07 €. Phosphate removal in SWT was 93.6, 74.5, and 71.6% in BEC, CEC, and CP, respectively, the corresponding rates in AWT were 89.7, 77.8, and 74.4%. Ammonium removal for SWT in BEC, CEC, and CP were 79.4, 51.5, and 62.5%, respectively, rates in AWT 56.1, 64.1, and 60.9%. Efficiency in CEC and BEC are equal in nutrient recovery in SWT, although energy efficiency was better in CEC. CP is cheaper than BEC and CEC.