Optimization of oil extraction from olive pomace using response surface methodology
A statistical methodology, combining Plackett–Burman design with Box–Behnken design, was applied to optimize the oil extraction process from olive pomace using hexane as solvent. Plackett–Burman design was used in the first step to evaluate the effects of five independent variables on the oil extraction yield. Temperature of extraction, time of contact, solvent-to-solids ratio and moisture content of the olive pomace were identified as significant independent variables and were further optimized by using response surface methodology based on Box–Behnken design. The optimized conditions to maximize the yield were as follows: extraction temperature at 33 ℃, contact time at 10 min, solvent-to-solids ratio at 3.5 mL/g and moisture content at 13%. The experimental value of the yield (5.98%) at these optimum conditions was found in perfect agreement with the value predicted by model (5.80%).
Treatment and disposal of olive mill effluents
Abstract Olive mill wastewaters constitute a serious pollution problem, especially in Mediterranean countries. In this paper the peculiar problems related to their treatment and disposal are described. The most interesting processes, either physico-chemical or biological, tested on pilot scale or in industrial plants, for the treatment of these effluents, are presented. It is shown that pollution abatement due to olive mill effluents is a complex problem which has different optimal solutions according to local factors such as the oil extraction process, the possibility to store the wastes and the ratio between the load due to the mills and the one related to the local population.
Impact of Mining Wastes on the Physicochemical and Biological Characteristics of Groundwater in a Mining Area in Marrakech (Morocco)
Metal sulphide tailings represent a potential risk basically for the environment and particularly for water resources, because of their natural oxidisability which leads to the production of acid/neutral mine drainage. The prospected site close to Marrakech includes zinc, lead and copper sulphide deposits. This site is located in an agricultural area where ground water is used both for irrigation and drinking. Eco-toxicological investigations have been undertaken in order to asses the tailings impact on water quality in nearby wells. These investigations include physico-chemical characterization of the groundwaters as well as faunistic population determination. As compared to standard wells, waters from the wells located downstream of the mining site, have high electrical conductivities and high major ions contents, which can reach : 755 mg l−1 in SO4 2−, 1670 mg l−1in Ca2+, 528 mg l−1 in Mg2+, 2289 mg l−1 in Na+ and 14981 mg l−1 in Cl−. The fauna distribution analysis carried out around the studied wells shows qualitative and quantitative differences according to the flow gradient of the groundwaters. Areas located upstream of the mine tailings site are richer in stygobite species (Type and quantity) than those located downstream or close to it. It is likely that these biological differences are due to water quality alteration induced by the mining activity.