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In order to enhance the removal of heavy metals such as Ni, Cu, Zn and Cd from wastewater, different cow dung/sewage sludge ratios were tested to assess the effect of these metals on the adaptability of Eisenia fetida earthworms to the treatment process carried out in a typical plant located in Tamaulipas, Mexico. Two experimental water treatment setups were proposed. The first set of experiments was planned to determine the adequate sewage sludge/cow dung ratio(s), whereas the second arrangement was designed to evaluate the growth performance and fecundity of the earthworms under high heavy metal concentrations. To achieve the objectives, the experiments were conducted for 90 days under controlled environmental conditions. Maximum worm biomass and growth rates were attained in samples containing 25 wt.% of sewage sludge. Weight and mortality of worms were significantly affected by the high levels of heavy metals, making difficult the metal accumulation in the worm tissues.

X-ray photoelectron spectroscopy (XPS) was used to analyze the composition of films at different deposition parameters of sputtered Al-Ce coatings on AA6061 aluminum alloys. By means of electrochemical impedance spectroscopy (EIS) measurements, the protective character of these coatings was studied for 21 days of exposure in a 3.5 wt% NaCl solution and an attempt was made to establish the relationship between film thickness and chemical composition (Al/Ce, Ce 3 /Ce 4? ratios) of the surface before and after the electrochemical characterization. XPS studies revealed the presence of the Al o , Al 2 O 3 , CeO 2 and Ce 2 O 3 compounds, confirming that the sputtered Al-Ce films were deposited in the metallic form and thereafter were superficially oxidized under ambient conditions. The Al-Ce bonds were overlapped with the signal of cerium oxides. The transport phenomena in the oxide film or controlled diffusion process are strongly dependent on the deposition parameters and exposure time in the aggressive medium. It was also found that in the deposited samples at p 4 P 200 t 300 , the film was still present after 21 days of exposure, although with visible cracks and erosion areas; however, the Ce 3 /Ce 4? ratio almost remained constant before and after the electrochemical characterization, which explained the barrier properties of these samples as compared with others at different deposition parameters.