Drinking water treatment generates a high amount of pasty by-product known as drinking water treatment sludge (DWTS). The chemical composition, microstructure and rheological behavior of DWTS are of utmost importance in the calculation, design, optimization, commissioning and control of its treatment processes. The purpose of this research was to characterize the DWTS from the drinking water treatment plant of Marrakech (Morocco), aiming to help future researchers and engineers in predicting its hydrodynamic behavior. The first part of this study was devoted to the physical structure and the chemical composition of sludge. The second part was oriented towards the study of the mechanical properties; a penetration test and a rotational rheology test were performed. For the first test, a force–length penetration diagram was plotted in order to calculate the hardness, the cohesiveness and the adhesiveness of DWTS. For the second test, the shear stress and the apparent viscosity were plotted and fitted to five rheological models, as function of the shear rate, aiming to describe the rheological behavior of samples. The obtained results reveal that the drinking water treatment sludge from Marrakech is a porous, amorphous and highly adhesive material, with a shear-thinning (pseudoplastic) rheological behavior that can be described according to the Herschel–Bulkley model (better in low-rate stresses, R² = 0.98) or the Windhad model (better in high shear rates, R² = 0.96) and is mainly composed of silica, aluminum and iron oxides.

The treatment of sludge, which is produced from raw water treatment, has been considered as an ecologically sensitive problem in terms of energy and pollution. In this context, this study presents many series of solar drying tests that were carried on three samples of sludge obtained from several drinking water treatment plants in Marrakech-Safi regions, Morocco. The main aim is to develop further management processes of these wastes such as upgrading or storage. A partially solar indirect convective dryer operating in forced convection was used to run experiment tests. The temperature of air has ranged from 50 to 90°C and the relative humidity from 24% to 46%. The drying airflow was kept at about 0.0833 m3/s. An estimation of the mass diffusion coefficient and the activation energy during vacuum drying besides the characteristic convective drying curve were established. In addition, six semi-theoretical and/or empirical and statistical models were used to predict experimental data. It was found that the temperature was the most important factor during the drying process. Furthermore, the obtained results of mass diffusion coefficient and activation energy were found consistent with those already existing in the literature. The mathematical model called “Midilli–Kucuk” was found to be the most appropriate to describe the drying curves of the three samples. The total energy consumption was also studied. It showed a downward tendency with the increase in temperature. The efficiency of drying energy ranged from 4.89% to 7.5%. Although it was found to be low, it can be improved by increasing the load.

The valorization of the hydroxide sludge, from drinking water treatment plants and solar energy in Morocco, is the main aim of this contribution. In fact, the performance of open and closed solar greenhouse systems were analyzed by comparing with the external and internal meteorological conditions of this greenhouse. The hydroxide sludge from three different sites in the “Marrakech-Safi” region of Morocco was simultaneously dried inside the considered greenhouse. Moreover, the drying kinetic of the samples, during the drying process, was carried out. Based on the drying curves, it was found that the drying time depends on the temperature, higher temperature means shorter time and faster drying speed. In addition, it was revealed that the closed dryer, in the summer season, raises high temperatures and efficiency, and the drying time was reduced compared to the winter season. the moisture content at the end of the process was 71%, the dryness of the sludge was increased from 14.7 to 80%, the characteristic drying curves of the summer and winter periods were made. The cylindrical shape of the samples was constantly measured to follow the shrinkage as well as the geometric reduction of the product.

Water treatment annually produces a huge amount of Drinking Water Treatment Sludge (DWTS) wastes. This latter causes environmental problems in Morroco in terms of energy and pollution. Therefore, cost-effective and eco-friendly solutions for managing them should be proposed in order to reduce the...

The significant production of sewage sludge by wastewater treatment plants on a global scale and the lack of correspondence between housing development and the expansion of sanitation infrastructure indicate a genuine concern regarding environmental preservation. This study addresses the crucial...