Intensification of phosphate removal using electrocoagulation treatment by continuous pH adjustment and optimal electrode connection mode

Abstract

International audienceThis paper discusses two possible ways of intensifying the electrocoagulation treatment of water contg. phosphate. The first one consists of controlling the chem. compn. of the water by continuous adjustment of the pH. The second aspect focuses on electrode connection modes, and the four different modes were tested monopolar in series, in parallels and independents, and finally bipolar. Expts. were conducted in a small batch reactor contg. water with 100 mg P​/L using electrodes of aluminum. Several elec. connections were used for the water treatment under favorable operating conditions detd. by a study and presented in a previous paper. The influence of pH adjustment was conducted using different adjustment step times (no adjustment, every 30, 10 and 5 min)​. The kinetics of the treatment was found to be accelerated by continuous adjustment of the pH. The choice of the electrode connection modes was found to strongly affect the efficiency of the treatment, the Faradic yield, and the consumption of energy. The monopolar in parallels connection mode was found to be the most economic, whereas bipolar in parallels was found to favor a higher kinetic rate of treatment

Electrocoagulation as a green technology for phosphate removal from river water

“…As the electric current passes through the Al electrodes, the anode starts the corrosion process producing metal cations that instantly undergo more reactions to form different polymeric metal hydroxides, similar to coagulant salts in traditional chemical coagulation processes (Essadki et al, 2009;Behbahani et al, 2011). These reactions at the Al electrodes and in the solution, can be summarised by the following equations (Behbahani et al, 2011;Tian et al, 2016;Attour et al, 2015):…”

Treatment of wastewaters from food Aromsa and ingredients production by electrocoagulation (EC) treatment aided by mucilage of Opuntia ficus-indica

“…The current density parameter is a significant parameter and the most important variable in electrocoagulation treatments, strongly affecting the yield of these proceedings (Can et al, 2003;Attour et al, 2014;Kobya and Demirbas, 2015;Attour et al, 2016). The bubble formation rate increases at a high current density, with small size that improve turbidity and pollutants elimination of treated wastewater (Merzouk et al, 2009;Adamovic et al, 2016).…”

Treatment and characterization of phosphorus from synthetic wastewater using aluminum plate electrodes in the electrocoagulation process

“…If temperature increases, both rate of Al 3+ hydrolysis to Al(OH) 3 and the diffusivity of Al 3+ increase according to the Stokes–Einstein’s equation with a consequent increase in the rate of mass transfer of Al 3+ from the anode surface to the solution bulk. The phosphorus removal efficiency decreases above 45 °C, this is explained by the fact that higher solution temperatures increase both anode and cathode electrode passivation by the formation of protective aluminum oxide layers, which reduces Al +3 ions dissolution and consequently the electrocoagulation reactor performance [10, 24].

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“…5, 6). According to several authors [10, 15, 22, 28] chemical attack of both anode (pH < 4) and cathode (pH > 10) can occur due to the acidity and alkalinity produced at their vicinity, respectively:…”

“…There have been different studies on various aspects of the phosphate removal from wastewater using electrocoagulation process [2, 6, 9, 10]. However, studies on comparison between the different anode and cathode Al electrode systems in both for the removal of phosphorus from wastewater and the characterization of the electrodes before and after treatments as well as the sludge formed after the treatment using FESEM, EDXS, XRD, FTIR and Raman spectroscopy are very limited.…”