In order to enhance the efficiency of anaerobic digestion, the effects of ultrasounds, ozonation and thermal pre-treatment have been studied on waste activated sludge. The feature of this study was to carry out the comparison of the three pre-treatments in the same conditions and on the same sludge sample. Each treatment was tested in two conditions close to optimum conditions to maximise batch anaerobic sludge biodegradability. All treatments led to chemical oxygen demand and matter solubilisation and had little influence on mineral matter. In terms of solubilisation thermal pre-treatment was better than sonication or ozonation. But, in terms of batch anaerobic biodegradability, best results were obtained with ultrasounds with an energy of 6250 or 9350 kJ/kg TS and a thermal treatment at 170 or 190 • C. Moreover, treatments had effects on physicochemical characteristics of sludge samples: apparent viscosity decreased after all treatments but the reduction was more important with thermal treatment. Median diameter of sludge flocs were reduced after sonication, increased after thermal treatment and did not change after ozonation. Finally, capillary suction time (CST) increased after ozonation, increased highly after sonication and was reduced after thermal treatment.

Critical fouling conditions were studied during wine cross-flow microfiltration using a multichannel ceramic membrane (0.2 m). The aim was to determine critical operating conditions in order to limit fouling caused by wine colloids (tannins, pectin and mannoproteins) and enhance process performances. The method used is a square wave filtration based on the determination of the reversibility and irreversibility of fouling. Filtrations were performed with filtered red wine (FW) added with different concentrations of colloids. Considering FW, critical flux for irreversibility was beyond the studied range of pressure (≥1.4 × 10 −4 m/s). No clear critical flux could be determined for any of the tested molecules in the studied range of pressure. On the other hand, an upper limit of fluxes range has been identified (below which critical flux could be found). Irreversible fouling always takes place from the beginning of the filtrations and even at low pressures. For FW containing 0.2 g/l mannoprotein and 0.5 g/l pectin, a loss of average fluxes is observed beyond a given limit of transmembrane pressure. This fact was attributed to the compaction of a gel layer. Finally, a criterion (R if /R m ≤ 1) has been suggested to determine the so-called "threshold flux" below it, fouling remains acceptable.