Algerian Journal of Engineering and Technology

Legionella: Health Impacts, Exposure Evaluation, and Hazard Reduction

Djamel Ghernaout, Noureddine Elboughdiri, Ramzi Lajimi — Tue, 28 Jun 2022 00:00:00 +0000

Legionella pneumophila is an intracellular pathogen, omnipresent in the nature and seen as opportunistic. It is the main source of legionellosis that can take place in its nonpneumonic form (Pontiac fever) and acute pneumonic form (Legionnaires’ disease). In the aquatic systems, L. pneumophila can conquer and remain alive intracellularly in different protozoans. The faculty to multiply inside biofilms gives more safeguard from natural stresses like disinfection. Human contagion by L. pneumophila happens following the inhalation or aspiration of aerosols carrying the pathogen. This work defines microbiologically Legionella bacteria and presents a brief history relating to their first discovery and following contagions, a short description relating to their metabolism and physiology, a discussion of their clinical characteristics and their subsistence in the nature and growth in a biofilm, and a general examination of numerous technologies employed for their removal. The spread of opportunistic pathogens (OPs) remains the most significant feature of microbial potable water quality besides the generation of disinfection by-products (DBPs). The (re)growth of OPs and the production of DBPs in urban engineered water systems both closely correlate with the injections or concentrations of disinfectant residuals. Nonetheless, OPs and DBPs respond to disinfectant residuals frequently oppositely. An elevated residual concentration efficiently suppresses the (re)growth of OPs while intensifies the production of DBPs. Oppositely, a low or “detectable” disinfectant residual level decreases the generation of DBPs but could not stop OPs from thriving. To guarantee that the overall or combined health risks of OPs and DBPs are minimum, OP (re)growth and DBP generation must be deeply revised while selecting a practical disinfectant residual dosage or level.

Enhancing Energy Efficiency for Optimal Multiple Photovoltaic DG and DSTATCOM Integration for Techno-Economic and Environmental Analysis: A Case Study of Adrar City Distribution System

Adel Lasmari, Mohamed Zellagui, Rachid Chenni — Tue, 28 Jun 2022 00:00:00 +0000

The insertion of renewable energy resources in existing distribution systems has effectively improved its performance and operation. This paper presents the efficiency of the optimal integration of multiple Photovoltaic DG (PV-DG), and Distribution Static Compensator (DSTATCOM) simultaneously in a practical Power Distribution System (PDS), through the maximization of the Multi-objective function (MOF) based on the Real Power Loss Level (RPLL), the Short Circuit Level (SCL), the Voltage Deviation Level (VDL), the Net Saving Level (NSL), and Environmental Pollution Reduction Level (EPRL) by various Inertia Weight Particle Swarm Optimization (IW-PSO) algorithms. The proposed IW-PSO algorithms applied in the practical Adrar city 205-bus distribution system in Algeria. The obtained results prove the efficiency of the algorithms in terms of achieving the minimum power loss and improvement of the voltage profiles, the EIW-PSO exhibits the best results of MOF compared to other algorithms.

Study and evaluation of electronic transport property for an InAlN based on Monte Carlo

Zakarya Kourdi, Mohammed Khaouani — Tue, 28 Jun 2022 00:00:00 +0000

The emergence of the semiconductors III-N with heterojunction structures has made it possible to study a wide range of two-dimensional phenomena. This paper devotes to simulate the characteristics of the InAlN material, taking into ac-count temperature and doping as dependencies of conduction properties and performance using MOCASIM of the Tcad-Silvaco software. For the electronic transport model analyzing, we adopted most of the predominant mechanisms using various scattering effects including: optical phonon scattering, acoustic phonon scattering through deformation potential and piezoelectric potential, ionized impurity scattering, and grain boundary scattering. As expected, the carrier transports in the GaN layer are affected by the spontaneous polarization of the InAlN layer. To interact that, the diffusion of grain boundaries has been switched from the diffusion of ionized impurities by the deposition of InAlN. In order to achieve the most improvement possible for the electron transferring in terms of thickness and alloy composition related to the improvement of super-deposited layers. The confinement of sub-bands in channel quantum well is also taken into account in the computation of electron mobility. In the end, the adopted electron model is improved by including the effects of deep electron traps.

Application of polyvinylpyrrolidone-iodine complex as corrosion inhibitor for carbon steel using an experimental design method

Tue, 28 Jun 2022 00:00:00 +0000

Corrosion processes are responsible for numerous losses, especially in the industrial sector. Inhibitors are commonly used to prevent corrosion in acidic medium. The aim of this study was to apply an experimental design to optimize the influencing parameters such as inhibitor concentration, temperature and immersion time on the corrosion inhibition of polyvinylpyrrolidone-iodine (PVP-I) complexes on carbon steel using the weight loss technique (WL). The parameters of the corrosion protection process were optimized and predictive mathematical models were developed using the Response Surface Methodology (RSM) using the Central Composite Design (CCD). It was also found that the data predicted by the regression analysis had a good agreement with the data obtained from the experiments, with the values R² = 0.999 and Adj. R² = 0.997 for the inhibitory effect. The best efficiencies for experiments that were not performed were determined by experimental design (DOE)

A Laboratory study on water transfer properties of unsaturated compacted lateritic Soil – Bacillus coagulans mixtures

Tue, 28 Jun 2022 00:00:00 +0000

A study on soil water characteristic curves (SWCC) and unsaturated hydraulic conductivity (UHC) of lateritic soil–Bacillus coagulans mixes was done. Three well known models (i.e van Genuchten (VG), Brooks-Corey(BC) and Fredlund-Xing (FX)) were used to predict SWCC and UHC from laboratory test results. Soil samples for the test were admixed with B. coagulans at one-third (1/3) pore in step suspension densities of 0 to 2.4x10⁹cells/ml. Soil samples were then compacted differently with Reduced British Standard light (RBSL), British Standard light(BSL),West African Standard (WAS) and British Standard heavy(BSH) compactive efforts. Cementitious reagent was injected into the compacted soil using gravity up until saturation was attained. Specimens after being compacted were then cored out from the mould using stainless steel cylindrical moulds. The specimens (i.e., inside the stainless steel cylindrical moulds) were then immersed in water chamber till the samples were completely saturated via capillary action and thereafter allowed to undergo a pressure plate drying(PPD) test. Matric suctions of 0, 10, 30, 100, 500, 1000 and 1500kPa, respectively, were used. Result of SWCCs show that with a rise in matric suction, the volumetric water content(θ) declined progressively for all the models (i.e van Genuchten (VG), Brooks-Corey(BC) and Fredlund-Xing(FX)) and the experimental measured values. The UHC slightly reduced with rise in B.coagulans suspension density for VG, BC and FX models. At 500 and 1500kPa matric suctions (MS), BC model documented the least UHC values and satisfied the regulatory lowest hydraulic conductivity value of 1.0×10^-9m/s for use in containment system. Thus, is suggested for modelling the UHC of lateritic soil ̶ B.coagulans mixtures.

Investigation of the mechanical properties of annealing heat treated low carbon steel

Ejiroghene Kelly Orhorhoro, Andrew Amagbon Erameh, Silas Oseme Okuma — Tue, 28 Jun 2022 00:00:00 +0000

The mechanical properties of steel materials usually vary under different conditions, thus choosing the suitable heat treatment is needed to obtain acceptable properties. In this research work, investigation of the mechanical properties of heat treated low carbon steel was determined using tensile tests, and hardness measurements. Also, the microstructure of the samples was characterized by means of optical microscopy. The samples of low carbon steels were sourced at local market in Nigeria. The collected samples were machined using lathe machine to a diameter of 10mm and gauge length of 30 mm. The chemical composition of the steel was determined using X-ray fluorescence spectroscopy. The mechanical properties of the heat treated and untreated samples were investigated at the temperatures of 900 ⁰C, 950 ⁰C, and 1000 ⁰C. The results obtained show that the ultimate tensile strength and percentage elongation of samples increases after heat treatment. Also, yield strength and hardness tend to decrease for all annealed heat treated samples at different temperature as compared to as received samples. The results of the microstructural analyses of the as received samples showed fine dispersion of coalesced pearlite and ferrite grain. For the annealed samples, the steel microstructures compose of martensite distributed in the ferrite matrix. However, with increase in annealing temperature to 1000 ⁰C and 1100 ⁰C cementite and ferrite grain with partial grain boundary were observed.

Effect of selected oven drying temperatures on the quality of Tiger Nut (Cyperus Esculentus) and Ginger Nut (Zingiber Officinale)

Abdulaziz Nuhu Jibril, Abubakar Aliyu Ishaq — Tue, 28 Jun 2022 00:00:00 +0000

The present study was to evaluate the effect of selected drying temperatures on the quality of tiger nut (Cyperus Esculentus) and ginger (Zingiber Officinale). The temperatures used were 25, 50, and 75°C for 4 hours. The quality composition determined were moisture content, crude protein, crude fiber, crude fat, ash content, and carbohydrate. From the results, the tiger nut parameters that show significant difference at the three drying temperatures 25, 50, and 75°C with their mean values were moisture content 0.05, 0.20, and 1.05%, crude protein 8.75, 6.56, and 5.47%, and crude fat 10.28, 14.60 and 12.65%. For ginger nuts were moisture content was 1.25, 2.15, and 2.60%, and crude protein was 15.31, 14.22, and 17.50%. While the parameters that show no significant difference at the three drying temperatures 25, 50, and 75°C with their mean values were crude fiber 1.26, 1.27, and 1.28%, ash content 2.95, 3.95, and 4.90%, and carbohydrate 76.75, 74.62, and 75.72. For gingers were ash content 8.7, 6.50, and 7.35%, crude fat 8.72, 10.43 and 9.20%, crude fiber 1.42, 1.23 and 1.28%, and carbohydrate 65.84, 67.63, and 64.67. Drying temperatures are crucial in affecting food internal structure, composition and widely practiced as a method of preserving agricultural products because of its ease and affordability.

Transient electron transport in the ternary alloys AlxGa1-xN, InxGa1-xN, AlxIn1-xN using the Monte Carlo method of simulation.

Nadia BACHIR, Nasr Eddine Chabane Sari — Tue, 28 Jun 2022 00:00:00 +0000

The transient electron transport and overspeed phenomenon in the binary cubic compounds GaN, InN and AlN and their ternary alloys AlGaN, InGaN and InAlN are examined and compared. For all these alloys, the overspeed phenomenon occurs beyond the critical field at which electrons can pass from the valence band to the conduction band. This field is relatively large for these alloys, particularly when the molar fraction of aluminum is large in the InAlN and AlGaN alloys. This field can reach 500 kV/cm for AlN and it is smaller in alloys with high indium concentration. It is 70 kV/cm for InN. Thus, the critical field for these alloys can vary from kV/cm to 500 kV/cm, including 150 KV/cm for GaN. The overspeed phenomenon becomes greater in the presence of Indium and it is less important in the presence of Aluminum. The present work focuses on the electronic transport in the alloys AlxGa1-xN, In_xGa_1-xN and In_xAl_1-xN in the transitional mode by using the Monte Carlo method of simulation which is the most appropriate.

Graphitization of lignin-modified phenolic resins: role of lignin pretreatments

Segun Talabi — Tue, 28 Jun 2022 00:00:00 +0000

Aiming at the generation of graphitic carbon from low-cost phenolic resins, this study investigated the role of lignin pretreatments on the amount of crystalline carbon generated from lignin-phenol-formaldehyde resins containing boron oxide, boric acid and ferrocene as graphitizing additives. Kraft lignin used to synthesize the resins was initially subjected to thermal and thermomechanical treatments to improve processability and promote greater mobility for ease of graphitization during carbonization. The results showed that the characteristics of lignin used to prepare the thermosetting resins affect the quantity of graphitic carbon that was generated during pyrolysis. The lignin-modified resin prepared using Kraft lignin, which has the lowest molecular weight and polydispersivity values produced the highest amount of graphitic carbon. This formulation containing 10 wt.% boric acid presents a graphitization level value of 73%. In addition, limited amounts of crystalline carbon were generated when boron oxide and ferrocene were used as graphitizing additives.

Improving biogas production from animal manure by batch anaerobic digestion

Tue, 28 Jun 2022 00:00:00 +0000

In Libya, even if the production of biogas started in the last years, still there is too much need to optimize the biogas resources. This paper examined improving cow, sheep, and poultry manure in two phases. The experiment was carried out in a 2000 mL digester put in bath water at 37 °C. The mixing ratio of animal manure and water used was 1:1 in 12 days of Hydraulic Retention Time (HRT). The produced gas was measured by the volumetric water replacement method. In the first phase, the best pH was chosen in the experimental test with different pH ranges. Three set-ups were prepared with different pHs (6.5, 7, 7.5). The results showed that the pH had significant effects on biogas yield, where pH 7 had the highest biogas production and pH 6.5 had the lowest. In the second phase, the effect of insulation of digester on the biogas yield of cow, sheep, and poultry manure was investigated. The experiments showed that the biogas produced from an insulated digester was higher than the transparent digester. Therefore, it is assumed that the study, which gives a maximum yield of biogas production from the batch digestion process, might meet future energy demand.

Investigation of soundness and erosion rate of rocks used for strengths the bank river in southern Iraq

Haider Hadi Jasim — Tue, 28 Jun 2022 00:00:00 +0000

Rocks are the basic materials that are used to strengthen the banks of rivers. Their properties and characteristics play an important role in controlling erosion problems. This paper compares and studies the soundness and erosion rates of several types of rocks collected from four locations in Muthanna Province, southern Iraq. Soundness testing is performed using two experimental approaches (ASTM C88 method and EN 1367-2 (Annex B) approaches). To perform the erosion test, a rotating erosion testing apparatus (RETA) was built in the laboratory. Soundness tests indicated that the rock of South Muthanna sites (SRM2) had a lower resistance to degradation, whereas the rock of West Muthanna sites (WMA1) had a higher resistance. Both ASTM C88 and EN 1367-2 techniques yield similar results, but the EN 1367-2 method yields greater mass loss than ASTM C88. As well, it was discovered that the porosity of the rock and its capacity to absorb water directly affect the soundness test results. Tests conducted with the erosion function apparatus (EFA) indicated that the erosion rate value is higher than those obtained from the rotating erosion testing apparatus (RETA). High water salinity decreases erosion rates; whereas higher water velocity leads to increase it.

Causes of pavement failure of Edunabon – Sekona road, Osun State, Nigeria

Hussein Mohammed — Tue, 28 Jun 2022 00:00:00 +0000

The study investigated Edunabon-Sekona road, Osun State, in Southwest Nigeria, with a view to determining the causes of its failure. Condition survey of a five kilometre stretch of the road was carried out to visually assess and characterise the pavement distresses. In situ density tests were conducted using the core cutter method at intervals of 500 m along the route. Soil samples were collected at these intervals for laboratory tests and selected engineering properties determined, using standard procedures. Deflection at every point as well the representative rebound deflection was determined using standard equations. The condition survey showed wide spread distresses. The average in-situ density (IDD) value was 1.55 g/cm³, while the maximum dry density (MDD), relative density (RD) and deflection (δ) mean values were, 1.94 g/cm³, 80 % and 0.66 mm, respectively. The representative rebound deflection (δ_rrd) was 0.66 mm. The study concluded that the pavement failed due to the low relative density and representative rebound deflection values of the subgrade.

Effect of selected admixtures on the geotechnical properties of black cotton soil

Tue, 28 Jun 2022 00:00:00 +0000

The effect locust bean waste ash (LBWA) and cement kiln dust (CKD) on black cotton soil (BCS) was studied. BCS was modified with 0, 2, 4, 6, 8 and 10 % LBWA and 0, 1, 2, 3 and 4 %CKD in relation to the soil dry weight. Test carried out include cation exchange capacity (CEC), Atterberg limits, compaction and shear strength test. Results show that a combination of LBWA and CKD have negative effect on the geotechnical properties of soil with exception in few cases. The CEC increased with increase in both the LBWA and CKD contents with deviations in few cases. Values of 21.9, 24, 34.1, 33.5, 32.1 and 33.8 Cmol/Kg were recorded at 0, 2, 4, 6, 8 and 10% LBWA content. Similar trend was observed for 1, 2, 3 and 4% CKD. Liquid limit generally increased with increase in LBWA content while plastic limit generally decreased. In the case of plasticity index, values increased with increase in LBWA content. Peak values were recorded at 6%LBWA content. Maximum dry density (MDD) decreased with increase in LBWA content. MDD values of 1.68, 1.67, 1.66, 1.65, 1.63 and 1.61 were recorded at 0, 2, 4, 6, 8 and 10% LBWA content. Similar trend was observed for 1, 2, 3 and 4% CKD. Optimum moisture content (OMC) increased with increase in LBWA content. Cohesion of soil decreased with increase in LBWA content. Values of 140, 110, 95, 60, 120 and 180 kN/m² was recorded at 0, 2, 4, 6, 8 and 10% LBWA content, while angle of internal friction improved from its natural value up to 10% LBWA content. Statistical studies by means of two–way analysis of variance (ANOVA) reveal that LBWA and CKD have significant effect on the soil properties. Although the modified soil did not effectively improve the consistency and shear strength parameters of BCS, an optimal blend of 2% CKD/10% LBWA blend slightly improved the soil properties. The optimally modified soil could be utilised for lightly trafficked roads construction as sub-base materials.