Key Engineering Materials Vol. 954

Abstract: Moroccan industry, like most industries around the world, today faces a water scarcity. Water is one of the basic utilities for all kinds of production, especially in the agro-food sector. Morocco, a country of bioclimatic and ecological transition with fragile resources, is threatened with rapid degradation in the event of overexploitation of underground water reserves. Indeed, the evolution of the water supply over the last decade already testifies to the irregularity of the outlook and confirms climate failure. “From 1990 to 2000, the resources in m³ per inhabitant per year fell from 1200 to 950. In 2020 the water resources are only around 600m³ / inhabitant / year, at a time when the demand for water total has reached the ceiling of 20 to 21km³ of water that can be mobilized. The country will drop to the shortage threshold for 500m³ / inhabitant / year around the year 2030".In fact, Morocco has launched programs to save water and review some resource allocations in order to meet growing needs. One of these programs is the launch of 10-95 law. It about the regulation of water discharges by establishing a financing instrument based on “the polluter pays” principle. This law has forced several industries, to install wastewater treatment plants (WWTP) for their water discharges to the extent that they meet the standards defined by Law 10-95. On this work, we will present an analysis of the operation of a wastewater treatment plant in a Moroccan dairy, the issues that have arisen and the solutions that have been provided. The analysis of the influential of the WWTP during the different phases of treatment gave results, which allowed us to optimize the performance of each phase and reduce the cost of running the WWTP.

Abstract: A simple and efficient method for the synthesis of an heterostructure of Ag-ZnO composite alone and impregnated with activated carbon (AC) prepared from almond shells has been developed. The structural, morphological, compositional and optical properties of the synthesized composites were examined respectively by X-ray Diffraction, Scanning Electron Microscopy Coupled to EDS, Infrared Spectroscopy and Diffuse Reflectance Ultraviolet-Visible. The use of this prepared these materials allows to degrade up to 99.9% of MR by photocatalysis in visible light at a pH of 6 and a H₂O₂ concentration of 0.1 M. This efficiency of these composites developed is attributed to their homogeneous structural and functional composition, to the fineness of the particles, to their wide bandgap of 2,487 eV for Ag-ZnO and 1,856 eV for Ag-ZnO/CA and to the high thermal resistance of Ag-ZnO. This type of composite seems to be effective for the depollution of organic effluents.

Abstract: The main purpose of this study is to investigate the effect of operating conditions on the performance of two methods used for dairy wastewater treatment. First, a treatment that combined both physic-chemical and conventional activated sludge. Second, the conventional activated sludge alone. On one side, the study included the comparison of parameters of each system, and on the other side, it studied the economic impact on the dairy industry the subject of the study. The waste water treatment plant was modified in order to study the differences between the two options and to come up with the different possibilities. The comparison takes into consideration different parameters: temperature, pH, SS, COD. The dairy waste water was used with characterisation of COD: 4000mg/l, Suspended sludge: 425 mg/l, temperature: 27 °C, pH: 7.5. In this study we will see the different conditions to use one or another process. The studies come for many reasons, the most of them was the maintenance of the physic-chemical station. In order to let the system running the industrial decided to try the feeding the biological tank directly and see if it’s going to work. This is what will present this article in two parts; the first one showing the parameters and results of using the both process and the second one will show the parameters and results of using just the biological treatment.

Abstract: The present study aims to evaluate the possibility of using low-cost adsorbents based on Cardoon waste for the depollution of industrial effluents. After characterization of the raw cardoon waste [1], the carbonization was carried out at 350 °C in a muffle furnace. In order to show the performance of the method used to prepare this activated carbon (PC), a comparative study with a commercial carbon (CC) is performed. The obtained activated carbon and the commercial carbon were characterized by thermogravimetric analysis, scanning electron microscopy coupled with EDX, X-ray diffraction, Fourier transform infrared absorption spectroscopy and inductively coupled plasma atomic emission spectroscopy. Approximate analyses of moisture content, volatile matter content, ash content and fixed carbon content, acid-base surface functions, pH at zero charge and iodine value were performed. The obtained results indicate that the main characteristics of the activated carbon prepared at 350 °C are practically similar to those of the commercial carbon; a homogeneous porous surface, an interesting percentage of carbon, a high thermal stability and a disorganized graphitic crystalline structure, the iodine adsorption values on the two carbons are 409.887 mg/g for PC and 430.191 mg/g for CC. The adsorption of methylene blue (MB) on both carbons was performed. The kinetics and isotherms of MB adsorption on the two carbons were evaluated. According to the obtained results, the use of the prepared carbon in effluent treatment can be put into perspective.

Abstract: This article discusses the use of solar dryers as a method for stabilizing and reducing the volume of residual sludge produced by wastewater treatment facilities. The study focused on the convective drying behavior of sewage sludge produced by the wastewater treatment plant of Meknes City under convective solar drying. The study aimed to investigate the drying kinetics of sewage sludge and emphasize the effect of temperature and water content on the evolution of the drying rate. The measured water content values showed a decrease as drying time increased. The results revealed the presence of phase II, which characterizes the decreasing rate drying period, and the absence of phase I, which describes the constant rate drying period.The study developed an empirical model to describe the kinetic behavior of convective solar drying of Moroccan domestic sludge. The model can be used to predict the shape of a drying curve under other aerothermal conditions. Additionally, the study analyzed the thermal diffusivity and activation energy of sewage sludge using an experimental macroscopic method based on Fick's diffusion model and the Arrhenius equation. The measured diffusion coefficient values range from 0,71 10^-9 m².s^-1 to 1,47 10^-9 m².s^-1, and the value of activation energy was evaluated at 17.54 kJ/mol.

Abstract: Methylene blue, a synthetic organic dye commonly used in industries, poses health and environmental concerns. In the current study, activated carbon derived from wheat straw was used as an adsorbent for removing methylene blue dye from water. The effects of various operating parameters, such as pH, contact time, temperature, mass of adsorbent, and initial concentration of the pollutant, were investigated to understand the adsorption mechanism. The results showed that the activated carbon prepared from wheat straw through a chemical activation with H₃PO₄ was highly effective in adsorbing methylene blue. The Langmuir isotherm provided the best fit to the experimental data, indicating favorable adsorption with a maximum adsorption capacity of 5.2548 mg/g. The kinetic study revealed that the adsorption process followed a pseudo second-order model with significant intraparticle diffusion. The process was found to be spontaneous and endothermic. The activated carbon derived from wheat straw exhibited comparable or even greater adsorption capacity compared to other agricultural by-products and commercial activated carbons. Overall, these findings suggest that wheat straw-derived activated carbon has promising potential as a low-cost adsorbent for removing methylene blue and other organic pollutants from water

Abstract: Renewable energy is a very minor percentage of energy consumed in the world. Fossil fuels still dominate despite their drawbacks (degradation of the environment). Renewable energy is not yet cost competitive with fossil fuels. The conversion of energy from renewable sources, especially for inexhaustible and clean energy sources (solar cells), must be efficient to be viable for large scale use. Single junction cells (SJC) have a theoretical efficiency limit of 33.7%, called Shockley-Queisser limit (SQ). Because the cost of electricity produced from solar cells depends on their efficiency, improving their conversion efficiency is a key way to make them cost-competitive. The two most important efficiency losses in SJC are the inability to convert photons with energies below the band gap energy (E_g) into electricity and the thermalization of photon energies exceeding E_g. Dual Junction Solar Cells (DJSC) was proposed to avoid the efficiency losses and to overcome the SQ limit. Our simulation model, presented in a previous work, was used to calculate solar cells efficiency and to plot the current-voltage (I-V) characteristics and the power-voltage (P-V) characteristics curves. Our simulation results show that high conversion efficiencies can be achieved by DJSC, more than 43.5%.

Abstract: Desert locations are of great interest for photovoltaic applications due to their high solar availability. However, in these regions, harsh climatic conditions can have a significant impact on the performance and reliability of photovoltaic panels. In the present study, the effect of temperature on the performance of the two PV technologies, Polycrystalline Silicon (pc-Si) and thin film Cadmium Telluride (CdTe), in a hot desert climate was investigated. To accomplish this, one module from each technology was installed in Benguerir city and exposed to outdoor conditions during the hot season of the year (May to October). Results indicate that although pc-Si exhibits higher module efficiency than CdTe, the latter was less temperature-sensitive under high ambient temperature values. In fact, during the monitoring period, CdTe technology demonstrated lower module temperatures than pc-Si, with a daily average temperature deviation of 1.75°C. In addition, the performance ratio and conversion efficiency for pc-Si were reduced by 8.7% and 1.35%, respectively, when the daily average ambient temperature increased from 25°C to 40°C. While with the thin film CdTe technology, the decline in these performance parameters did not exceed 6.8% and 1.05%, respectively.

Abstract: The thermodynamic model of work of the loaded cable line is presented. The received mathematical ratio allows to define the maximum allowed current loadings of the cable line in the form of a single-core cable product with the single-layer isolation depending on material and thickness of layer of isolation. It is constructed dependences of the maximum allowed current for a single-core wire of a certain section with one layer rubber (or polyvinilchloride) isolation from insulation layer thickness at various temperatures of the environment and the coefficients of the heat conductivity.