RECENT ADVANCES IN USING ELECTROCOAGULATION AS A WASTEWATER TREATMENT TECHNIQUE
Water shortage is one of the biggest problems confronting humanity as the world’s population and water demand continue to climb. There is a need to create cost-effective, safe, and environmentally sustainable wastewater treatment systems to recover the large quantities of wastewater produced by numerous industries. Moreover, the effl uents from many industries contain hazardous contaminants that are toxic to aquatic life and need to treat before discharging in water bodies. The conventional techniques to treat wastewater consists of a combination of physical, chemical, and biological process. A relatively new promising technology that utilizes the concepts of electrochemistry to treat wastewater is known as Electrocoagulation (EC). It has gained popularity in recent years due to its simple operation, high removal effi ciency, and reduced sludge production.
As shown in Figure 1, the EC process involves applying an electric current to a pair of electrodes termed as anode and Cathode. Typically, anode being a sacrifi cial electrode, it is made up of mostly iron and aluminum. In presence of a hydroxide the application of electric potentials produces coagulant agents (Fe+3
or Al+3 ) from
the electrode material (Fe or Al). In presence of hydroxide medium, Fe(OH)3
is formed which interacts with the dissolved pollutants by agglomeration and forms fl ocs. These fl ocs begin to precipitate at the bottom of the tank and can be removed out through fi ltration. Alternatively, fl ocs can attach to the bubbles of H2
(gas) evolved
at the cathode and transported to the top of the solution, thereby removing the turbidity, suspended and dissolved particles in the wastewater.
The effectiveness of the EC process depends on the following variables: electrolyte concentration, type of wastewater, pH, current density, applied voltage, operating temperature, electrode material (Aluminum, Stainless Steel, Iron), number of electrodes, size of electrodes, and electrode confi gurations. These variables would affect the overall removal effi ciency, reaction kinetics, and treatment time.
The different types of wastewater shown to be treated by EC include: Tannery and textile industry wastewater, Food industry wastewater, Refi nery wastewater, Paper industry wastewater, Oil and gas industry wastewater, Brewery industry wastewater, Dairy effl uent, and Municipal wastewater. For example, there are many investigations of EC for the treatment of tannery and textile industry wastewater. Usually, effl uent from the textile industry is highly contaminated with high concentrations of chlorides, aliphatic sulfonates, phenols, surfactants and pesticides, sulfates, organic matter, and chromium. Chromium alone is a major hazard it may oxidize to Cr6+
which is carcinogenic. The dyes are also
known to be highly stable, toxic, and may resist chemical and biological degradation. One research treated tannery wastewater by an integrated process of electrocoagulation and Biological Fungal Treatment as they are referred (BFT) using aluminum anode and iron cathode. The main chemicals in the tanning process
are the “tanning agents” as they referred to as the process of leather production as the operating cost of the combined process was calculated as 1.73 $/m3 COD (96%) and Cr6+
. The maximum removal effi ciency of (97%) removal was achieved by combined
EC and BFT system. The optimum condition for EC was pH 8.0, 60 min reaction time, and 0.81A current. The optimum condition of BFT for pH 5.0, 36hr reaction time, and 2% inoculum rate [2]. Another research employed EC for the treatment of textile dyeing effl uent using aluminum electrodes. the study found that at the optimum condition of pH 6 and current density 53 A/m2 in maximum COD removal 82.5% [3]. Some scientists studied
resulted
the electrocoagulation-electrofl otation process to evaluate the treatment of laundry wastewater using an aluminum electrode. Current density value as 5.26 mA/cm2
, pH as 5.5, and 5 min
processing time was found to be an optimum condition for the experiment. The consumption of electrical energy, in this case, amounted to 1.25 kW h/m3
[4]. . Maximum percent removal
for Methylene Blue Active Substances (MBAS) was 97%. The maximum color removal is achieved (98%) at 7.89 mA/cm2 the maximum turbidity removal (99%) is at 5.26 mA/cm2
while
The Pulp and Paper Industry is another major contributor to wastewater as it relies mostly on water, forest, and agricultural
WWW.ENVIROTECH-ONLINE.COM AET ANNUAL BUYERS’ GUIDE 2021
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72
