Electrochemical Pre-Treatment Combined with Biological Treatment for the Degradation of Methylene Blue Dye: Pb/PbO₂ Electrode and Modeling-Optimization through Central Composite Design

Abstract

Electrochemical pretreatment of wastewater containing methylene blue was studied on an Pb/PbO2 electrode and showed enhancement of the color removal efficiency for increasing current density and decreasing dye concentration. The effect of the temperature was more pronounced at a high initial dye concentration (134 mg L–1) compared to a low initial concentration (12 mg L–1), whereas it was the opposite for the agitation speed. The model obtained by central composite design led to the following optimal conditions for MB degradation: 41 ≤ T ≤ 60 °C, 10.66 ≤ i ≤ 25 mA cm–2, [MB]0 = 134 mg L–1, and ω = 720 rpm, which gave 95.61% degradation efficiency. Electrolysis improved biodegradability from 0.034 to 0.54 for the BOD5/COD ratio, indicating the feasibility of a biological treatment combined to an electrochemical pretreatment process. The degradation of the generated intermediate compounds was performed using activated sludge and led to 92.03% mineralization (overall DOC removal).

Punica granatum husk (PGH), a powdered biowaste material for the adsorption of methylene blue dye from aqueous solution

“…(2014) [1][2][3][4][5][6][7][8][9][10][11] www.deswater.com doi: 10.1080/19443994.2014.984344 ability of activated carbon for dye removal is well known and undisputed, but its high cost precludes the practical use [11]. In this way, the search for cheaper and efficient adsorbents, such as, low-cost agricultural wastes, to replace activated carbon has gained attention in recent years [12].…”

“…Several traditional treatment processes have been applied for the removal of MB dye from waters and wastewaters in order to decrease their impact on the environment. The processes developed consist basically in decolorizing by electrochemical combined with biological treatment [4], photocatalytic oxidation [5], Fenton treatment [6], nanofiltration [7], sonocatalytic degradation [8], biological treatment [9], and adsorption on activated carbon [10]. Activated carbon is most popular adsorbent used for metals, pesticide, and dye removal.…”

Purification treatment of dyes wastewater with a novel micro-electrolysis reactor

“…Some technologies have been developed for the potential application in the pretreatment of poor biodegradable and even toxic wastewater [17,19,20]. Electrochemistry has been used to pretreat the wastewater containing methylene blue with its BI improved by 16 times [21].…”

Increase of the anaerobic biodegradability of olive mill wastewaters through a pre-treatment with hydrogen peroxide in alkaline conditions

“…However, the acidic pH, high salinity, lack of nutrients, low biodegradability and elevated polyphenols concentrations make it necessary to perform an adequate pre-treatment [1][2][3][4]. For the removal of phyto-toxic and low-biodegradable compounds, many advanced oxidation techniques have been proposed [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Some of these, such as ultrasonic irradiation, photo-catalysis and electrochemical processes are quite profitable because there is no need for the addition of chemical reagents.…”