Domestic greywater treatment using electrocoagulation-electrooxidation process: optimisation and experimental approaches

Abstract

A synergistic combination of electrocoagulation-electrooxidation (EC-EO) process was used in the current study to treat domestic greywater. The EC process consisted of an aluminium (Al) anode and an iron (Fe) cathode, and the EO process consisted of titanium with platinum coating mesh (Ti/Pt) as an anode and stainless steel as a cathode. The effect of operative variables, namely current density, pH, EC time and EO time, on the removal of chemical oxygen demand (COD), colour, turbidity, and total organic carbon (TOC) was studied and optimised using Response Surface Methodology (RSM). The results showed that although the pH affected the removal of all studied pollutants, it had more effect on turbidity removal with a contribution of 88.44%, while the current density had the main dominant effect on colour removal with a contribution of 73.59%. It was also found that at optimal operation conditions for a current density of 2.6 A, an initial pH of 4.67, an EC time of 31.67 min, and an EO time of 93.28 min led to a COD, colour, turbidity, and TOC removal rates of 96.1%, 97.5%, 90.9%, and 98%, respectively, which were close to the predicted results. The average operating cost and energy consumption for the removal of COD, colour, turbidity, and TOC were 0.014 $/m3 and 0.01 kWh/kg, 0.083 $/m3 and 0.008 kWh/kg, 0.075 $/m3 and 0.062 kWh/kg, and 0.105 $/m3 and 0.079 kWh/kg, respectively.

Optimization of iron electrocoagulation parameters for enhanced turbidity and chemical oxygen demand removal from laundry greywater

“…Mousazadeh et al reported an optimum turbidity removal of 90.9% using aluminum and iron electrodes, across a wide range of initial concentrations (150–500 NTU) and achieved a COD removal efficiency of 96.1% with initial concentrations ranging from 1300 to 2000 mg/L 41 . Additionally, the studies by Shakeri et al 44 and Çalışkan et al 45 underscored the high efficacy of aluminum and iron electrodes, achieving optimum turbidity removals of 97–99% and 55–98.75%, respectively, and COD removal efficiencies ranging from 49.94 to 94.99%.…”

“…The negative impact might be due to over-oxidation leading to inefficient use of energy, excessive generation of metal ions leading to saturation and ineffective flocculation, or the formation of complex organo-metallic compounds that are difficult to degrade. In practice, to optimize COD removal, it's crucial to find the balance point where the rate of reaction and time of exposure minimize energy use while maximizing pollutant removal 57 – 59 . This is a classic case where operational efficiency needs to be balanced against chemical kinetics, and understanding the interaction helps in setting these operational parameters optimally.…”

Catalysts Based on Iron Oxides for Wastewater Purification from Phenolic Compounds: Synthesis, Physicochemical Analysis, Determination of Catalytic Activity

“…The main share of pollution of water bodies comes from emissions of industrial untreated wastewater from industrial, agricultural, storm water and municipal enterprises [1][2][3][4][5][6][7][8][9][10][11][12]. One of the urgent problems of environmental protection is the neutralization of wastewater from dissolved organic pollutants.…”