Removal of organic compounds, calcium and strontium from petroleum industry effluent by simultaneous electrocoagulation and adsorption

Abstract

The generation of liquid effluents with high organic and inorganic load in the petroleum industry requires proper treatment in order to prevent environmental pollution. Commonly, refractory organic compounds, which are not easily degraded by conventional methods, require an advanced treatment step. In addition, the inorganic content may negatively interfere with the treatment process due to scaling formation derived from the precipitation of low solubility compounds, primarily strontium and calcium-based salts. The present study aims at the removal of fouling metals such as calcium and strontium and refractory organic matter from the oil industry effluent by electrocoagulation associated with adsorption using coconut husk carbon considering the context of zero liquid discharge. Simultaneous electrocoagulation associated with adsorption presented an economy of the treatment time and capital cost in relation to the process carried out by individual steps of adsorption followed by electrocoagulation, because the efficiencies were similar. The treatment resulted in a residual of 25 mg(O2).L−1 (52 % removal) of organic matter measured as COD, 88 % of calcium removal (residual of 6.0 mg.L−1) and 72 % of strontium removal (residual of 0.4 mg.L–1), which improved the quality of the recovered water. In addition, it is noted that the adsorption process removed the organic compounds preferably while the metals were removed by electrocoagulation.