Towards the sustainable powering of the electrocoagulation of wastewater through the use of solar-vanadium redox flow battery: A first approach

Abstract

Electrocoagulation (EC) of wastewater polluted with 100 mg dm -3 of oxyfluorfen (OFF) has been studied in cells with iron anodes and aluminum cathodes. Solar power combined with energy storage in a vanadium redox flow battery (VRFB) has been used to electrically power a continuous EC process. Three scenarios have been evaluated.Firstly, a constant current was applied to the EC reactor. Secondly, a solar energy profile was applied to the EC reactor and the RFB. Finally, the EC process was operated in the same way as the second scenario except that the RFB was powered with double the current charge than in the second scenario. The results show that electrocoagulation is not suitable for the complete removal of oxyfluorfen from wastewater, although it attained a significant pollutant accumulation into the flocs of 25%, showing potential as a pretreatment for this kind of waste. Likewise, results obtained pointed out that electrocoagulation can be powered directly with solar energy and this energy can also be regulated by VRFB, although, in the latter case, to attain the same treatment efficiency, around 1/3 more energy is required during energy storage. In addition, the higher the energy provided by the VRFB is, the lower the Fe/Al ratio produced during the electrocoagulation is.

Environmental and Preliminary Cost Assessments of Redox Flow Batteries for Renewable Energy Storage

“…This FU value (1 kWh) can be applied in electrochemical processes for wastewater treatment powered with renewable energy and batteries at pilot plant scale which is one of the research line of our group. [4,9] Moreover, it is interested to point out that VRFBs have a life span of 20 years; however, ZCBs are still at an experimental stage, and only 57 operating cycles of charge/discharge [10] have been demonstrated. System boundaries of both redox batteries are shown in Figure 1.…”

“…[6,7] There are different types of RFBs according to the different electrolytes that can be used. [8,9] Among the huge amount of RFBs, the present work is focused on the vanadium redox flow batteries (VRFBs) and the zinc/cerium batteries (ZCBs). The last ones use salts of zinc and cerium in an organic solution as negative and positive electrolytes, respectively.…”

Electrocoagulation coupled adsorption for anaerobic wastewater post-treatment and reuse purposes

“…During coagulation, aluminum ions produce hydroxide ions and hydroxides of neutral metals [17,20,26,41]. These aluminum hydroxides (coagulating agent) are responsible for increasing the pH during the removal process and for the neutralization of electrostatic charges of dispersed particles (reducing the repulsion between the particles and favoring the Van der Waals attractions), facilitating the agglomeration and separation of particles in the wastewater [16,42].…”

“…Several mechanisms of removal and degradation may exist simultaneously in the electrochemical reactor [11][12][13]16]. It has been successfully applied in the treatment of water for reuse purposes [11][12][13], including post-treatment of UASB effluent [17,18], especially when there is the option of replacing energy matrices with renewable sources [19,20].…”

Electrocoagulation/Electroflotation Process for Removal of Organics and Microplastics in Laundry Wastewater

“…So far, the EC/EF process has been used for the removal of pesticides, [26] drugs, [27] heavy metals, [28][29][30][31] organics, [32][33][34] and inorganics [35,36] from wastewater. Although some researchers have already tried to remove organics from LWW by the EC process, [37,38] a full-scale optimization study has to be carried out, including the adsorption kinetics, operating cost, and removal efficiency of microplastics via response surface methodology (RSM).…”