Full paper/M emoire Hydrogen sulphide removal from the effluents of a phosphoric acid production unit by absorption into chlorinated seawater under alkaline conditions Elimination du sulfure d'hydrogene de l'effluent de l'unit e de production d'acide phosphorique par absorption avec une solution chlor ee et basifi ee d'eau de mer

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The aim of this work is to optimize the drying process through the reduction of energy consumption and the improvement of the dried product quality using tempering or intermittent drying. The effectiveness of intermittent drying was evaluated by the determination of the sensible, latent and total energies necessary to perform the drying process. The results show that tempering drying is more effective than continuous drying. This effectiveness was qualified by the energy consumption. A reduction of energy consumption varying from 13% to 67% was achieved. The drying time, energy consumption and product quality were improved when using temporary drying. The decrease of the gradient of moisture content in the material during the period of no heating is considered as the main factor that increases the rate of moisture removal when the heating is resumed.

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Earlier research suggested using ash to substitute cement, whereas other studies looked at the possibility of using plant-derived agricultural wastes as fiber reinforcement in cement applications. This study offered an environmentally friendly option to change traditional mortars by replacing cement with fly bottom ash (FBA) waste at 10, 20, 30, and 40 wt %. Likewise, Arundo donax leaves (ADL) were employed to reinforce the modified cement mortars at 0.4, 2, 5, and 7 wt %. X-ray diffraction analysis of used materials was performed. The morphology of composites made with FBA and ADL was investigated using scanning electron microscopy. Moreover, the density, water uptake, thermal conductivity, energy gain, and carbon dioxide (CO2) emissions of the prepared composites were discussed. Their flexural strength, compressive strength, and displacement were also compared. Results revealed that the addition of FBA in the mortar matrix has a positive effect on decreasing the thermal conductivity and lightness of the mortar. In addition, 20 wt % of cement replacement by FBA guarantees simultaneously moderate mechanical properties, nearly 51% of energy gain, and 20% of total CO2 emission reduction. In the same, adding ADL to the 20wt %FBA mortar reduced the thermal conductivity and the lightness of the mortar. The 0.4 wt % ADL reinforcement ensured 59% energy gain and 6% of total CO2 emission reduction. A major amelioration was observed in the compressive strength (an increase of 14%) and in the plasticity (an increase of 27%) of the considered composite materials. In conclusion, using FBA as a cement replacement with low ADL content inclusion results in a thermal-resistant composite with reasonable durability and strength.

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