This work aims to develop new uses for sewage sludge, which is a byproduct of municipal wastewater treatment plants, by examining the calcination of this waste, the characterization of ashes is obtained, and its use to prepare desulfurant sorbents. Samples of sewage sludge were obtained from a local municipal wastewater treatment plant. This plant applies a pre-treatment followed by a biological treatment, where anaerobic digestion and centrifugation reduces the sludge. Three samples were characterized (in humidity, volatile and fixed solids content), dried, and ignited at two temperatures, 550 and 750°C. The composition of the ash obtained at both ignition temperatures was studied by x-ray fluorescent spectroscopy and the BET specific surface area of the two ashes and of the prepared sorbents was measured. Ash composition was similar for the two temperatures tested, where the components were Si, Ca, Al, Fe, P, S, Mg, K, Cl, Zn and Ti. BET specific surface area values indicate that the lower temperature of calcination produces ash with the highest SSA values (18 m2/g against near 10 m2/g). Preparation of desulfurant sorbents was carried out by mixing the ash with CaO or Ca(OH)2 at room temperature and different experimental conditions. The BET SSA of the prepared desulfurant sorbents showed higher values for the sorbents prepared with the ashes obtained at the lowest temperature. The behaviour of the ash and the prepared sorbents was tested in a fixed bed reactor at 58°C with a flue gas containing 5000 ppm of SO2 with a relative humidity of 55%. Results in the desulfurization process show that the calcium from the sludge seems more efficient than the calcium added as CaO or Ca(OH)2 to prepare the sorbents.

Sulphate-reducing bacteria (SRB) are anaerobic bacteria that couple the oxidation of simple organic compounds to the reduction of sulphate to sulphide. SRB have become important components of bioremediation systems. In this work, a natural SRB sludge was collected in the coastal mud flat of Colindres (Cantabria, Spain) and the removal of soluble cadmium as cadmium sulphide from a synthetic feeding was studied. Discontinuous experiments were performed at room temperature, using four 600 ml reactors. In stage 1, a 250 mL biomass solution (18.16 g/L of volatile matter) was introduced in each reactor and was fed with a solution of cadmium sulphate, sodium sulphate and sucrose as carbon and energy source. The Chemical Oxygen Demand (COD) to SO4-2 ratio (this SO4-2 coming from Na2SO4) was 10 in all the stages of the four reactors, and the different cadmium content tested in each reactor varied from 4 to 12 mg/L. Stages 2, 3, 4 and 5 were performed with the same biomass but with higher initial cadmium amount, from 16 to 300 mg/L, in order to determine the amount of metal causing inhibition of the bacterial activity. Soluble cadmium was analyzed by Atomic Absorption Spectrometry. Additionally in stage 4, the evolution of pH and COD was studied. Results indicated that inhibition of biomass was not found up to a Cd concentration of 300 mg/L. Continuous experiments were performed in an UASB reactor of 1 litter of useful capacity, being the hydraulic residence time 0.833 days and 720 mg of COD/day the organic matter in the influent. After a period of acclimation, biomass was fed with increasing amounts of soluble Cadmium and the specific rate of cadmium elimination was determined.

Simulacion de un proceso industrial de cristalización de Cloruro de Sodio (NaCl) y aplicaciones Resumen La cristalización a partir de disoluciones es importante industrialmente dada la gran variedad de sustancias que se comercializan cristalizadas. Para mejorar la enseñanza aprendizaje de esta Operación Básica, en este trabajo, realizado como Trabajo Fin de Carrera de Ingeniería Química, se ha implementado un programa de simulación de una cristalización, partiendo de los datos de una cristalización industrial de NaCl. El objetivo ha sido manejar herramientas de cálculo para simular y optimizar esta operación, lo que permite conocer más profundamente el proceso de la cristalización y la utilización de las herramientas de cálculo, es decir, utilizar simultáneamente los conocimientos adquiridos en las asignaturas de Operaciones con Sólidos y la de Simulación y Optimización de Procesos.