Marine pollution has been considered in increasing problems depending on the increment in sea transportation day by day. Therefore, the large volume of bilge water which contains petroleum, oil and hydrocarbons in high concentrations is generated from all types of ships. In this study, treatment of bilge water by electrocoagulation/electroflotation and nanofiltration integrated process is investigated as a function of voltage, time, and initial pH with aluminum electrode as both anode and cathode. Moreover, commercial NF270 flat-sheet membrane was also used for further purification. Box-Behnken design combined with response surface modeling (RSM) was used to study the response pattern and determined the optimum conditions for maximum chemical oxygen demand (COD) removal and minimum metal ion contents of bilge water. Three independent variables, namely voltage (5–15 V), initial pH (4.5–8.0) and time (30–90 min) were transformed to coded values. The COD removal percent, UV absorbance at 254 nm, pH value (after treatment), the concentration of metal ions (Ti, As, Cu, Cr, Zn, Sr, Mo) was obtained as responses. Analysis of variance results showed that all the models were significant except of Zn (P > 0.05), because of the calculated F values for these models were less than the critical F value for the considered probability (P = 0.05). The obtained R² and R_adj² values signified the correlation between the experimental data and predicted responses showed that except for model of Zn concentration after treatment, the high R² values showed the goodness of the fit model. While the increase in the applied voltage showed negative effects, the increases in time and pH showed a positive effect on COD removal efficiency, also the most effective linear term was found as time. A positive sign of the interactive coefficients of the voltage-time and pH-time systems indicated synergistic effect on COD removal efficiency, when interaction between voltage and pH showed an antagonistic effect.

This work concerns the preparation of a mineral membrane by the slip casting method based on zirconium oxide (ZrO₂) and kaolin. The membrane support is produced from a mixture of clay (kaolin) and calcium carbonate (calcite) powders using heat treatment (sintering). Membrane and support characterization were performed by Scanning Electron Microscopy (SEM), X-ray Fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Raman Spectroscopy. The prepared mineral membrane was tested to treat drinking water obtained from different zones of the El Athmania (Algeria) water station (raw, coagulated, decanted, and bio filtered water). Experimental parameters such as permeate flux, turbidity, and total coliforms were monitored. The results showed that the mineral membrane was mainly composed of SiO₂ and Al₂O₃ and the outer surface, which represented the membrane support, was much more porous than the inner surface where the membrane was deposited. The permeate flux of the raw water decreased with filtration time, due to a rejection of the organic matters contained in the raw water. Moreover, the absence of total coliforms in the filtrate and the increase in concentration in the concentrate indicate that the prepared mineral membrane can be used for drinking water treatment.