Electro‐Oxidation of Pistachio Processing Industry Wastewater Using Graphite Anode

Abstract

In the present study, removal of chemical oxygen demand (COD), total organic carbon (TOC), and total phenols (TP) from pistachio processing industry wastewater was investigated using electro‐oxidation. COD, TOC, and TP removal efficiencies were compared considering stirring speed, support electrolyte types, support electrolyte concentrations, wastewater initial pH, and current density by using stainless steel cathodes and graphite anodes. Results showed that optimum values of operating variables, i.e., processing time, stirring speed, wastewater pH, current density, and support electrolyte (NaCl), were 5 h, 400 rpm, 3, 30 mA/cm2, and 1.25 M, respectively. Removal efficiencies of 99.79, 76.55, and 100% were obtained with these values for COD, TOC, and TP, respectively. Removal of COD, TOC, and TP increased with increased chloride concentration and current density at acidic pH.

Mechanistic Study and Multi‐Response Optimization of the Electrochemical Treatment of Petroleum Refinery Wastewater

“…In the temperatures range of 100–400 °C, weight loss was found to be ≈16.7%. This weight loss was due to the evolution of oxides of carbon . In the temperature range of 400–1012 °C, very marginal weight loss of ≈3.1% was observed due to the oxidation of sludge.…”

“…The SEM image of the fresh SS electrode (Figure a) shows a rough surface. After several EC treatment cycles, SEM of the same electrode (Figure b) shows the loss of electrode material with the formation of dents in the size range of 50–500 μm . SEM images of the dried sludge (Figure c) seem to be crystalline in nature .…”

“…After several EC treatment cycles, SEM of the same electrode (Figure b) shows the loss of electrode material with the formation of dents in the size range of 50–500 μm . SEM images of the dried sludge (Figure c) seem to be crystalline in nature . The presence of different elements in the sludge generated by the EC treatment of the PRW was checked by EDX analysis.…”

“…Five levels, four factors (namely pH o : 2–10; j : 39.06–195.31 A m −2 ; g : 0.5–2.5 cm; and t : 30–150 min), full factorial CCD was used for studying the significance of the parameters affecting the EC treatment. For statistical calculations, the levels for the four parameters ( X i = X 1 (pH 0 ), X 2 ( j ), X 3 ( g), and X 4 ( t )) were coded as x i according to the following relationship: where x i is the coded (dimensionless) value of parameter X i , X o is the value of parameter X i at the center point and δ X represents the step change. Based on this, the levels were designated as −2, −1, 0, +1, and +2.…”

“…EC degradation of wastewaters containing dyes, arsenic, phenolic compounds, poly‐aromatic organic compounds, sulfidic spent caustic, etc. is reported in the literature . Chen reviewed the fundamentals and applications of the EC methods for the treatment of wastewater containing suspended solids, oil and grease and organic and inorganic pollutants.…”