Electrocoagulation Process for Nutrient Recovery of Agricultural Wastewater: Effect of Calcium Adding, Voltage, and Time

Abstract Recovery of valuable resources, such as nutrient recovery from wastewater, can help close the nutrient cycle and is interesting to investigate. This study aims to evaluate phosphate recovery and set aside TOC, OC, and IC in agricultural wastewater using electrocoagulation with helix electrode configuration. This study used a Response Surface Methodology (RSM) analysis to perform statistical analysis and modeling using a central composite design (CCD). Variation of calcium concentration, electric voltage, and electrocoagulation time is applied in an electrocoagulation reactor with a helix-shaped stainless steel cathode and a solid cylindrical Mg anode. Based on RSM analysis, calcium concentration, electrical voltage, and electrolysis time significantly affect phosphate recovery and TOC, OC, and IC removal when agricultural wastewater is treated using electrocoagulation with a helical electrode configuration. The lowest phosphate concentration achieved was 0.003 mg/L (99.74% reduction) under operating conditions of 15 V voltage, 15 min time, and two mg/L calcium concentration. The highest TOC allowance is >100% of the initial concentration, TC allowance is 55.79%, and IC allowance is 30.91%. The efficiency of TOC removal in the electrocoagulation process is affected by the formation of metal hydroxides, with higher electrolysis times leading to higher TOC removal efficiency. Higher voltages also improve coagulation and flotation processes in the reactor. Calcium concentration plays a role in enhancing the flocculation process and binding phosphonates from wastewater.