Synthesis, characterization and application of iron oxide nanoparticles have received much attention in recent years due to their interesting chemical and physics properties. Magnetite (Fe3O4) nanoparticles were synthesed by chemical co-precipitation and characterized using X ray diffraction (XDR), Fourier transmission spectroscopy (FT-IR), dynamic light scattering and (DLS). Fe3O4 nanoparticles were successfully removed humic acid (HA) from water. The influence of pH, contact time, adsorbent nanoparticle doses and HA concentrations were analyzed. Maximum HA removal occurred at pH 6 (89.63%), 40 mg.L-1 of Magnetite (88.8%), 0.03g of HA (96.64%) and contact time of 20 min (94.37%). Sorption data fit pseudo-second order kinetics, indicated a chemical adsorption process. The Langmuir, Freundlich and Temkin adsorption isotherm models were applied to describe equilibrium data. Adsorption of HA on magnetite nanoparticles was well described by Temkin model. The maximum adsorption capacity was 128.23 mg.g-1. Fe3O4 nanoparticles were promising potential adsorbents for HA removal from water.

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Thiols represent a source of environmental pollution especially wastewater. The present work aims to evaluate the degradation of sulfur in two biological treatment plants in Tunisia: conventional plant of Rades Malienne, and vertical and horizontal flow from the Grombalia plant. We analyzed (1) wastewater properties, (2) the hydrosulfur (thiol) group, (3) membrane processes ultrafiltration technique and (4) characterization of the quality of wastewater from different plants. We used ultrafiltration membrane assisted ZnO and TiO2 NPs application on real effluents from different biological treatment plants. STEP1 is found to be more loaded with sulphur. Application of AC-ZnO membrane gives 99.07% and 99.55% of sulfur removal from wastewater of STEP1 and STEP3. STEP3 is 50 times less charged on sulfur than STEP1. We suggested that when the sulphur content is high, this leads to an increase in mineral elements. This could be explained by the interactions between thiols and the major elements that cause mineral pollution.

The application of chemical dispersants aims to stimulate microbial oil degradation by increasing the bioavailability of oil compounds. Overall, nine microcosms were prepared (three for each treatment) using treated sediment with (i) dispersant (d: 25 ppm), (ii) oil (500 ppm), and (iii) with oil + dispersant (500: 25 ppm), respectively. There are also three control microcosms containing only water and sediment without petroleum. Then, we analyzed bacterial abundance, total hydrocarbon, biological oxygen demand (BOD5), and chemical oxygen demand (COD) in each microcosm. Bacterial response density was significantly affected after 40 days of exposure; it was higher in the control microcosm and d (> 24.103 cell/l) than in the other treatments. The index of total hydrocarbons was equal to 53 mg/kg dw in oil and 56 mg/kg dw in oil + dispersant. The higher BOD5 found in oil and in oil + d shows the increased amount of oxygen consumed, which indicates enhanced bacterial activity. Microcosms treated with dispersant had higher COD than the others, but the dispersant did not stimulate microbial hydrocarbon degradation.