Measurements of non-wetting phase trapping applied to carbon dioxide storage

We measure the trapped non-wetting phase saturation as a function of the initial saturation in sand packs. The application of the work is for CO₂ storage in aquifers where capillary trapping is a rapid and effective mechanism to render injected CO₂ immobile. The CO₂ is injected into the formation followed by chase brine injection, or natural groundwater flow, which displaces and traps CO₂ on the pore scale as a residual immobile phase. Current models to predict the amount of trapping are based on experiments in consolidated media, while CO₂ may be stored in relatively shallow, poorly consolidated systems. We use analogue fluids at ambient conditions. The trapped saturation initially rises linearly with initial saturation to a value of approximately 0.13 for oil/water systems and 0.14 for gas/water systems. There then follows a region where the residual saturation is constant with further increases in initial saturation. This behaviour is not predicted by the traditional literature trapping models, but is physically consistent with unconsolidated media where most of the larger pores can easily be invaded at relatively low saturation and there is, overall, relatively little trapping. A good match to our experimental data was achieved with the trapping model proposed by Aissaoui.     

Development of a waste management protocol based on assessment of knowledge and practice of healthcare personnel in surgical departments

Background:Good healthcare waste management in a hospital depends on a dedicated waste management team, good administration, careful planning, sound organization, underpinning legislation, adequate financing, and full participation by trained staff. Hence, waste management protocols must be convenient and sensible.Aim of study:To assess the knowledge and practice related to waste management among doctors, nurses, and housekeepers in the surgical departments at Al-Mansoura University Hospital, and to design and validate a waste management protocol for the health team in these settings.Subjects and methods:This cross-sectional study was carried out in the eight surgical departments at Al-Mansoura University Hospital. All health care personnel and their assistants were included: 38 doctors, 106 nurses, and 56 housekeepers. Two groups of jury were included for experts’ opinions validation of the developed protocol, one from academia (30 members) and the other from service providers (30 members). Data were collected using a self-administered knowledge questionnaire for nurses and doctors, and an interview questionnaire for housekeepers. Observation checklists were used for assessment of performance. The researchers developed the first draft of the waste management protocol according to the results of the analysis of the data collected in the assessment phase. Then, the protocol was presented to the jury group for validation, and then was implemented.Results:Only 27.4% of the nurses, 32.1% of the housekeepers, and 36.8% of the doctors had satisfactory knowledge. Concerning practice, 18.9% of the nurses, 7.1% of the housekeepers, and none of the doctors had adequate practice. Nurses’ knowledge score had a statistically significant weak positive correlation with the attendance of training courses (r = 0.23, p < 0.05). Validation of the developed protocol was done, and the percent of agreement ranged between 60.0% and 96.7% for the service group, and 60.0% and 90.0% for the academia group.Conclusion and recommendations:The majority of the doctors, nurses, and housekeepers have unsatisfactory knowledge and inadequate practice related to health care waste management. The knowledge among nurses is positively affected by attendance of training programs. Based on the findings, a protocol for healthcare waste management was developed and validated. It is recommended to implement the developed waste management protocol for the surgical departments in the designed hospital, with establishment of waste management audits.     

Identification of source of faecal pollution of Tirumanimuttar River, Tamilnadu, India using microbial source tracking

Efficient management of deteriorating water bodies can be achieved by determining the sources of faecal pollution. Resourceful techniques for discrimination of the sources of Escherichia coli in surface water have recently been developed, including the use of river water to facilitate faecal indicator surveillance, identification of sources of faecal contamination and employing relevant management practices to maintain water quality. This study was conducted to employ microbial source tracking (MST) techniques for the determination of the sources of faecal pollution based on a water quality investigation of the physico-chemical characteristics and coliform count point of the Tirumanimuttar River. To accomplish this, an MST library-based antibiotic resistance analysis, serotyping and the genomic tool rep-PCR techniques were applied, and the obtained results were analysed statistically. Among 135 and 70 E. coli isolates present in the library and water samples collected from the river and nearby well water sources, respectively, most showed intrinsic, high or moderate resistance to antibiotics. Isolates from human and pig faecal sources were 92% homologous with the samples from the river, whereas isolates from sewage and dairy cattle showed 89% and 80% homology, respectively. These findings indicated that the Tirumanimuttar River is subjected to stress from anthropogenic activities and runoff contaminated with agricultural and human faecal contamination. The sources of faecal pollution identified in this study may facilitate the monitoring and management of the Tirumanimuttar River.     

Drying of salted silver jewfish in a hybrid solar drying system and under open sun: Modeling and performance analyses

This study investigated the thin-layer drying kinetics of salted silver jewfish in a hybrid solar drying system and under open sun. Ten drying models were compared with experimental data of salted silver jewfish drying. A new model was introduced, which is an offset linear logarithmic (offset modified Page model). The fit quality of the models was evaluated using the coefficient of determination (R²), root mean square error (RMSE), and sum of squared absolute error (SSAE). The result showed that Midilli et al. model and new model were comparable with two or three-term exponential drying models. This study also analyzed energy and exergy during solar drying of salted silver jewfish. Energy analysis throughout the solar drying process was estimated on the basis of the first law of thermodynamics, whereas exergy analysis during solar drying was determined on the basis of the second law of thermodynamics. At an average solar radiation of 540 W/m² and a mass flow rate of 0.0778 kg/sec, the collector efficiency and drying system efficiency were about 41% and 23%, respectively. Specific energy consumption was 2.92 kWh/kg. Moreover, the exergy efficiency during solar drying process ranged from 17% to 44%, with an average value of 31%. The values of improvement potential varied between 106 and 436 W, with an average of 236 W.     

Air quality in Yanbu,Saudi Arabia

Yanbu, on the Red Sea, is an affluent Saudi Arabian industrial city of modest size. Substantial effort has been spent to balance environmental quality, especially air pollution, and industrial development. We have analyzed six years of observations of criteria pollutants O₃, SO₂, particles (PM_2.5 and PM₁₀) and the known ozone precursors—volatile organic compounds (VOCs) and nitrogen oxides (NO_x). The results suggest frequent VOC-limited conditions in which ozone concentrations increase with decreasing NO_x and with increasing VOCs when NO_x is plentiful. For the remaining circumstances ozone has a complex non-linear relationship with the VOCs. The interactions between these factors at Yanbu cause measurable impacts on air pollution including the weekend effect in which ozone concentrations stay the same or even increase despite significantly lower emissions of the precursors on the weekends. Air pollution was lower during the Eids (al-Fitr and al-Adha), Ramadan and the Hajj periods. During Ramadan, there were substantial night time emissions as the cycle everyday living is almost reversed between night and day. The exceedances of air pollution standards were evaluated using criteria from the U.S. Environmental Protection Agency (EPA), World Health Organization (WHO), the Saudi Presidency of Meteorology and Environment (PME) and the Royal Commission Environmental Regulations (RCER). The latter are stricter standards set just for Yanbu and Jubail. For the fine particles (PM_2.5), an analysis of the winds showed a major impact from desert dust. This effect had to be taken into account but still left many occasions when standards were exceeded. Fewer exceedances were found for SO₂, and fewer still for ozone. The paper presents a comprehensive view of air quality at this isolated desert urban environment.

Implications: Frequent VOC-limited conditions are found at Yanbu in Saudi Arabia that increase ozone pollution if NO_x is are reduced. In this desert environment, increased nightlife produces the highest levels of VOCs and NO_x at night rather than the day. The effects increase during Ramadan. Fine particles peak twice a day—the morning peak is caused by traffic and increases with decreasing wind, potentially representing health concerns, but the larger afternoon peak is caused by the wind, and it increases with increasing wind speeds. These features suggest that exposure to pollutants must be redefined for such an environment.     

Column with CNT/magnesium oxide composite for lead(II) removal from water

Background  

In this study, manganese dioxide-coated multiwall carbon nanotube (MnO₂/CNT) nanocomposite has been successfully synthesized.     

Chemical composition and antimicrobial activities of the essential oil from the seeds of Enterolobium contortisiliquum (leguminosae)

Seeds of Enterolobium contortisiliquum were subjected to steam distillation to obtain a light yellow essential oil in a yield of 3 ml/kg of seeds. The major components of the oil were identified using gas chromatography/mass spectrometry (GC-MS) and were furfural, limonene, linalool, estragole, carvone, and apiole with carvone representing more than 50% of the total composition. Antimicrobial activities of the essential oil were determined against four species of gram positive bacteria (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Micrococcus luteus) and two gram negative bacteria (Klebsiella pneumoniae, Serratia Marcescencs). The essential oil inhibited the growth of all tested bacteria but was most effective against the gram positive bacteria. Chemicals that are responsible for the antibacterial effect of the essential oil were determined using the bio-autography thin layer chromatography (TLC) technique. The active compounds responsible for the activity were found to be carvone and estragole.     

Selection of an effective sludge dewatering system for a small wastewater treatment plant

The Jahra Plant was commissioned in 1981 as a secondary treatment plant employing the extended aeration process. The plant has been upgraded since that time by constructing additional tertiary filtration units to improve effluent quality. The plant has a design capacity of 66 000 m³/d. At present, the daily inflow to the plant is about 47 000 m³/d of domestic sewage. The sludge produced at the Jahra Plant can be classified as excess activated sludge which combines the primary and secondary solids. At present, there are 30 drying beds receiving about 100 m³ of sludge dally. Sewage-sludge production represents about 0.5% of the total flow treated at the plant and is increasing yearly with increases in population and water consumption. Present dewatering systems are not adequate to cope with expansion in sewage treatment. Increasing the capacity of the existing plant would require more drying beds that could exacerbate existing odor problems. Some dewatering systems, such as the belt filter press and the centrifuge, have been tested to determine the most effective one under local conditions. Appropriate polymer doses for thickening have been determined. This paper describes present sludge dewatering units and operating techniques which have been developed during the operation of this facility.     

Immobilization of some metals in contaminated sludge by zeolite prepared from local materials

In this study, zeolite was prepared from cheap local Egyptian clay (kaolin) and characterized by X-ray diffraction, X-ray fluorescence spectroscopy, SEM. The prepared zeolite was used as a binder for immobilization of the metals Cd²⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ in contaminated sewage sludge. Different leaching tests were conducted to determine the efficiency of the prepared zeolite for metal stabilization. The leaching of the metals from stabilized sludge decreased as the zeolite amount increased. It was found that 10% of zeolite is sufficient for the stabilization of all metal ions under investigation. It was suggested that the metal uptake mechanism by zeolite was by an ion-exchange mechanism. Examination of the solidified sample for its compressive strength after curing for 28 days yielded a value of 0.83?MPa, which indicates that the treated sludge was well solidified and safe to be used in a wide variety of applications, for instance as a raw material for pavement blocks.     

Adsorption of cadmium from aqueous solution using Rooibos shoots as adsorbent

The use of Rooibos shoots, a natural adsorbent, for cadmium removal from wastewater is proposed. The effects of initial pH, adsorbent dosage, contact time, and initial concentration were investigated in the batch adsorption mode. The optimum pH was found to be 5.5. Isotherm and kinetic data were modeled; the data fitted best to the Freundlich model, and, kinetically, the adsorption was of pseudo-second order as shown by the high R² value of 0.9928 along with close agreement between the experimental q_e (13.9 mg g^?1) and calculated q_e (14.24 mg g^?1) values. The studied biomass material was found to be effectively used for removal of cadmium from contaminated mine wastewater.