Electrocoagulation of yogurt industry wastewater and the production of ceramic pigments from the sludge

The treatment of chromium containing wastewater using electrocoagulation and the production of ceramic pigments from the resulting sludge

This research experimentally investigates the treatment of authentic electroplating wastewater with high Cr(VI) content by electrocoagulation with the obtained sludge being reused as a raw material to produce inorganic pigments. A zero waste process is introduced to help conserve resources and to minimize environmental effects. The effects of operational parameters on electrocoagulation are determined in a batch stirred reactor using an iron electrode. The best performance was observed when a current density 20 mA/cm², pH 2.4 and 0.05 M NaCl electrolyte were maintained. The initial Cr(VI) concentration of 1000 mg/L was almost completely abated (∼100%) at an energy cost of 2.68 kWh/m³, fulfilling the EPA guideline of 2.77 mg/L within a single step process. The sludge was characterized using XRD and XRF showing that the sludge is a rich source of iron and chromium and can be reused to produce value added ceramic pigments. Pigments prepared in this way appeared to be reddish brown and black color in transparent glaze and were also characterized using XRD and XRF. In this study, a zero waste process is successfully introduced with ∼100% Cr(VI) removal, with subsequent reuse of the resulting sludge.

Continuous flow electrocoagulation in the treatment of wastewater from dairy industries

Dairy industry wastewater contains high levels of organic matter, consisting mainly of fat, protein and products of their partial microbial decomposition. In the present study, the use of continuous electrocoagulation is proposed for the primary treatment of dairy wastewater. The electrochemical treatment was carried out in a continuous flow cell with aluminum electrodes. The influence of the voltage, the distance between the electrodes and the hydraulic residence time (HRT) on the process performance was assessed, by measuring the removal of color, turbidity, total organic carbon (TOC) and chemical oxygen demand (COD). The optimum voltage, distance between the electrodes and HRT were 10 V, 1 cm and 90 min, respectively, yielding a current density of 13.3 A.m(-2). Under these conditions, removal of color, turbidity, TOC and COD were 94%, 93%, 65% and 69%, respectively, after a steady state was reached in the continuous flow reactor.

Continuous electrocoagulation of cheese whey wastewater: an application of Response Surface Methodology

In this study, treatment of cheese whey wastewater was performed using a uniquely-designed continuous electrocoagulation reactor, not previously encountered in the literature. An iron horizontal rotating screw type anode was used in the continuous mode. An empirical model, in terms of effective operational factors, such as current density (40, 50, 60 mA/cm(2)), pH (3, 5, 7) and retention time (20, 40, 60 min), was developed through Response Surface Methodology. An optimal region characterized by low values of Chemical Oxygen Demand (COD) was determined. As a result of experiments, a linear effect in the removal efficiency of COD was obtained for current density and retention time, while the initial pH of the wastewater was found to have a quadratic effect in the removal efficiency of COD. The best fit nonlinear mathematical model, with a coefficient of determination value (R(2)) of 85%, was defined. An initial COD concentration of 15.500 mg/L was reduced to 2112 mg/L with a removal efficiency of 86.4%. In conclusion, it can be said that electrocoagulation was successfully applied for the treatment of cheese whey wastewater.