The effect of hydraulic jump on the aeration efficiency

One of the most important parameters to determine the quality of water is the amount of the dissolved oxygen (DO) in water body. Microorganisms as bacteria need high concentration of oxygen in water to the able to continue their lives healthfully. In this case, the concentration of the dissolved oxygen in water body should be greater than 5 mg/L. The hydraulic jump is used as an effective natural mechanic mixer for the oxygen transfer from air to water body. This study is aimed to investigate the aeration efficiency created by the water jet vertically on the turbulence shear layer in hydraulic jump. The experiments have been realized in an open channel having a width of 0.4 meters, a height of 0.65 meters and a length of 12 meters. The dissolved oxygen has been measured using by a DO200 hand type oxygen meter. Experiments are taken account five different jet flow rates and Froude numbers with in the range of 1 Fr = 3.55-6.07 in the study

Students' Reluctance to Attend Office Hours: Reasons and Suggested Solutions

This paper focuses on investigating students’ reasons for their reluctance to attend faculty members’ office hours. Study participants included 500 male and female students from the Colleges of Engineering (n = 248) and Arts and Social Sciences (CASS) (n = 252) at Sultan Qaboos University (SQU). The study followed a descriptive-analytical approach, and a questionnaire was utilized to collect people’s views. The results of the study indicate that the rates of SQU students’ attendance to office hours were low, and some students (11.2%) do not attend at all as they consider these office hours a waste of time. The main reasons behind the students’ lack of interest in office hours were busy student timetables, conflicts between faculty office hours and students’ timetables, and easier and faster ways of getting information than visiting faculty members. Additional reasons were related to faculty members’ personalities and their discouraging attitudes toward attending office hours. The researchers recommend that SQU adopt a new strategy for encouraging faculty members to hold office hours, familiarizing students with the importance of office hours and assigning part of a course’s grades to meeting with faculty members’ office hours

Medicinal plants grown in soil amended with struvite recovered from anaerobically pretreated poultry manure wastewater

ABSTRACT 3--P = 1:1:1, pH = 9.0) was tested as a slow release fertilizer on the growth of four medicinal plants including garden rocket (Eruca sativa), dill (Anethum graveolens), fennel (Foeniculum vulgare) and parsley (Petroselinum crispum) in a series of labscale greenhouse experiment. Pot trial tests indicated that rates of increase in fresh weights, dry weights and fresh heights of plants grown in soil fertilized with the recovered struvite were determined as 405%, 488%, and 51% for garden rocket; 154%, 191%, and 44% for dill; 152%, 379%, and 27% for fennel; 141%, 208%, and 22% for parsley, respectively, compared to the control pot. Results of a static bioassay test proved that the use of plants cultivated in MAP pots as the feeding material did not cause any acute toxicity symptoms or mortality in guppy fish (Lebistes reticulatus), and all survived and exhibited normal visual responses at the end of 170-h exposure. Findings of this study confirmed that the recovered struvite from UASB effluent provided a valuable slow release fertilizer for the agricultural use, resulting an edible multi-nutrient animal feed

Assessment of indoor air pollution exposure in urban hospital microenvironments

Hospitals are microenvironments containing populations with potentially enhanced sensitivity to air pollution. The objectives of this study were to characterize the concentration of indoor and outdoor size-fractionated particulate matter (PM) at two urban hospital sites in Kashan, Iran, and to evaluate the relationship between indoor and outdoor PM levels. PM 1.0 , PM 2.5 , and PM 10 concentrations were measured over a 3-month period outside each hospital with parallel sampling at four indoor locations in patient wards. The results indicated that mean indoor concentrations at the sampling sites (PM 1.0 = 17.8 μg/m 3 , PM 2.5 = 45.5 μg/m 3 , and PM 10 = 162.7 μg/m 3 ) were found to be lower than outdoors levels (PM 1.0 = 20.6 μg/m 3 , PM 2.5 = 62.1 μg/m 3 , and PM 10 = 300.6 μg/m 3 ). Outdoor and indoor PM mass concentrations were associated with PM 1.0 , PM 2.5 , and PM 10.0 . Ambient wind speed also influenced the indoor/outdoor relationship for PM 1.0 and PM 2.5 but not for PM 10 . The average I/O ratios for PM 2.5 in the intensive care unit (ICU) and children�s ward at Shahid Beheshti Hospital were close to or above 1.00. Indoor PM 1.0 and PM 2.5 concentrations were found to be positively associated with outdoor PM 1.0 and PM 2.5 concentrations, but no relationship was observed with PM 10 . The present findings may inform policymakers in implementing evidence-based efforts for the aim of improving the indoor air quality in closed and confined spaces. © 2018, Springer Nature B.V

Modeling the adsorption of benzeneacetic acid on CaO2 nanoparticles using artificial neural network

AbstractThe present work reported a method for removal of benzeneacetic acid from water solution using CaO2 nanoparticle as adsorbent and modeling the adsorption process using artificial neural network (ANN). CaO2 nanoparticles were synthesized by a chemical precipitation technique. The characterization and confirmation of nanoparticles have been done by using different techniques such as X-ray powder diffraction (XRD), high resolution field emission scanning electron microscope (HR-FESEM),transmittance electron microscopy (TEM) and high-resolution TEM (HRTEM) analysis. ANN model was developed by using elite-ANN software. The network was trained using experimental data at optimum temperature and time with different CaO2 nanoparticle dosage (0.002–0.05 g) and initial benzeneacetic acid concentration (0.03–0.099 mol/L). Root mean square error (RMS) of 3.432, average percentage error (APE) of 5.813 and coefficient of determination (R2) of 0.989 were found for prediction and modeling of benzeneacetic acid removal. The trained artificial neural network is employed to predict the output of the given set of input parameters. The single-stage batch adsorber design of the adsorption of benzeneacetic acid onto CaO2 nanoparticles has been studied with well fitted Langmuir isotherm equation which is homogeneous and has monolayer sorption capacity

Preparation and optimization of macroalgae-derived solid acid catalysts

Solid acid catalysts were synthesized from macroalgae Sargassum horneri via hydrothermal carbonization followed by sulfuric acid sulfonation. A three-variable Box-Behnken design and optimization was used to maximize surface acidity. The optimal preparation conditions were found to be at the carbonization temperature of 217 °C, the carbonization time of 4.6 h and the sulfonation temperature of 108.5 °C. Under these conditions, the highest surface acidity achieved was 1.62 mmol g−1. Physical and chemical properties of prepared solid acid catalyst were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, and elemental analysis. The results proved the grafting of –SO3H groups on an amorphous carbon structure. The catalyst activity was evaluated by the esterification of oleic acid with methanol. The sample prepared achieved 96.6% esterification yield, which was higher than the 86.7% yield achieved by commercial Ambersyst-15 under the same reaction conditions

Enhanced MFC power production and struvite recovery by the addition of sea salts to urine

© 2016 The Authors Urine is an excellent fuel for electricity generation in Microbial Fuel Cells (MFCs), especially with practical implementations in mind. Moreover, urine has a high content in nutrients which can be easily recovered. Struvite (MgNH4PO4·6H2O) crystals naturally precipitate in urine, but this reaction can be enhanced by the introduction of additional magnesium. In this work, the effect of magnesium additives on the power output of the MFCs and on the catholyte generation is evaluated. Several magnesium sources including MgCl2, artificial sea water and a commercially available sea salts mixture for seawater preparation (SeaMix) were mixed with real fresh human urine in order to enhance struvite precipitation. The supernatant of each mixture was tested as a feedstock for the MFCs and it was evaluated in terms of power output and catholyte generation. The commercial SeaMix showed the best performance in terms of struvite precipitation, increasing the amount of struvite in the solid collected from 21% to 94%. Moreover, the SeaMix increased the maximum power performance of the MFCs by over 10% and it also changed the properties of the catholyte collected by increasing the pH, conductivity and the concentration of chloride ions. These results demonstrate that the addition of sea-salts to real urine is beneficial for both struvite recovery and electricity generation in MFCs

Phosphorus recovery as struvite from farm, municipal and industrial waste: feedstock suitability, methods and pre-treatments

Global population growth requires intensification of agriculture, for which a sustainable supply of phosphorus (P) is essential. Since natural P reserves are diminishing, recovering P from wastes and residues is an increasingly attractive prospect, particularly as technical and economic potential in the area is growing. In addition to providing phosphorus for agricultural use, precipitation of P from waste residues and effluents lessens their nutrient loading prior to disposal. This paper critically reviews published methods for P recovery from waste streams (municipal, farm and industrial) with emphasis on struvite (MgNH4PO46H2O) crystallisation, including pre-treatments to maximise recovery. Based on compositional parameters of a range of wastes, a Feedstock Suitability Index (FSI) was developed as a guide to inform researchers and operators of the relative potential for struvite production from each waste