45 research outputs found
Optimized biological nitrogen removal of high-strength ammonium wastewater by activated sludge modeling
No full textAbstract
Wastewater containing high ammonium concentrations is produced from various industrial activities. In this study, the author used a complex activated sludge model, improved by utilizing BioWin© (EnviroSim, Hamilton, Canada) simulation software, to gain understanding of the problem of instability in biological nitrogen removal (BNR). Specifically, the study focused on BNR in an industrial wastewater treatment plant that receives high-strength ammonium wastewater. Using the data obtained from a nine-day sampling campaign and routinely measured data, the model was successfully calibrated and validated, with modifications to the sensitive stoichiometric and kinetic parameters. Subsequently, the calibrated model was employed to study various operating conditions in order to optimize the BNR. These operating conditions include alkalinity addition, sludge retention time, and the COD/N ratio. The addition of a stripping step and modifications to the configuration of the aerators are suggested by the author to increase the COD/N ratio and therefore enhance denitrification. It was found that the calibrated model could successfully represent and optimize the treatment of the high-strength ammonium wastewater.</jats:p
Optimized biological nitrogen removal of high-strength ammonium wastewater by activated sludge modeling
No full textWastewater containing high ammonium concentrations is produced from various industrial activities. In this study, the author used a complex activated sludge model, improved by utilizing BioWin© (EnviroSim, Hamilton, Canada) simulation software, to gain understanding of the problem of instability in biological nitrogen removal (BNR). Specifically, the study focused on BNR in an industrial wastewater treatment plant that receives high-strength ammonium wastewater. Using the data obtained from a nine-day sampling campaign and routinely measured data, the model was successfully calibrated and validated, with modifications to the sensitive stoichiometric and kinetic parameters. Subsequently, the calibrated model was employed to study various operating conditions in order to optimize the BNR. These operating conditions include alkalinity addition, sludge retention time, and the COD/N ratio. The addition of a stripping step and modifications to the configuration of the aerators are suggested by the author to increase the COD/N ratio and therefore enhance denitrification. It was found that the calibrated model could successfully represent and optimize the treatment of the high-strength ammonium wastewater
Action research for the development and integration of child protection policies and practices at private schools in Egypt
No full textViolence against children is a widespread phenomenon in Egypt. The education sector has a large role to play in preventing violence and promoting child-wellbeing inside and outside schools. This study reviews the literature, assesses the current status and attitudes regarding School-Based Child Protection and documents a nine-month action research project conducted with International British Schools. Data is collected via six school visits, a baseline questionnaire administered to 60 respondents from 44 schools, field notes, participant feedback and participant reflections. The paper discusses lessons learned on the school’s needs, challenges and opportunities, as well as culture-specific aspects and contextual factors that need to be taken into consideration. The author then draws implications for policy development and implementation and capacity building on both the state level and the school level and identifies topics requiring further research. Findings show that there is a substantial lack in child protection policies and practices and that child-centered thinking is overpowered by the dominant focus on child disciplining and educator authority, reflected especially in the shortcomings of state policy and services and the limited scope of educator training. Capacity building efforts in Child Protection require trust-building efforts, reflective practice on underlying assumptions (e.g. regarding authority, confidentiality and sexuality), the establishment of preventive measures and responsive mechanisms, as well as increased child participation and empowerment, staff accountability and monitoring
Recent Trends in Computational Fluid Dynamics
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Recent Trends in Computational Fluid Dynamics
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
STUDY OF FULLY-MIXED HYBRID THERMAL ENERGY STORAGE WITH PHASE CHANGE MATERIALS FOR SOLAR HEATING APPLICATIONS
No full textA novel design of hybrid thermal energy storage (HTES) using Phase Change Material (PCM) was evaluated using a mathematical model. Both single and multi-tank (cascaded) storage were explored to span small to large-scale applications (200-1600 litres). The storage element was based on the concept of a fully-mixed modular tank which is charged and discharged indirectly using two immersed coil heat exchangers situated at the bottom and top of the tank. A three-node model was developed to simulate different thermal behaviors during the operation of the storage element. Experiments were conducted on full-scale 200-l single-tank sensible heat storage (SHS) and hybrid thermal energy storage (HTES) to provide validation for the mathematical model. The HTES incorporated rectangular PCM modules submerged in the water tank. Satisfactory agreement was found between the numerical results and the experimental results obtained by Mather (2000) on single and multi-tank SHS. In addition, good agreement was noticed with the experiments performed by the author on single-tank SHS and HTES at McMaster University. The developed model was found to provide high levels of accuracy in simulating different operation conditions of the proposed design of storage element as well as computational efficiency.
A parametric study was undertaken to investigate the potential benefits of the HTES over the SHS, operating under idealistic conditions. The HTES can perform at least two times better than the SHS with the same volume. The PCM volume fraction, melting temperature and properties were found to have critical impact on the storage gains of the HTES. All the parameters must be adjusted such that: (1) the thermal resistance of the storage element is minimized, and (2) most of the energy exchange with the storage element takes place in the latent heat form.
The performance of the single-tank HTES was evaluated numerically while operating in a solar thermal domestic hot water (DHW) system for a single-family residence. The PCM parameters were selected to maximize the solar fraction during the operation on a typical spring day in Toronto. The use of the HTES can reduce the tank volume by 50% compared to the matched size of the SHS tank. However, the HTES was found to underperform the SHS when the system was operated in different days with different solar irradiation intensities. The effect of different draw patterns was also investigated. The results indicated that thermal storage is needed only when the energy demand is out-of-phase with the energy supply. For the same daily hot water demand, different consumption profiles; ex. dominant morning, dominant evening, dominant night and dispersed consumptions, showed slight impact on the performance of the system.
The concept of multi-tank (cascaded) HTES storage was explored for medium/large scale solar heating applications such as for restaurants, motels, and multi-family residences. The design was based on the series connection of modular tanks through the bottom and top heat exchangers. Each individual tank had a PCM with different melting temperature. The results showed that the cascaded storage system outperformed the single-tank system with the same total volume as a result of the high levels of sequential or tank-to-tank stratification. The use of the cascaded HTES resulted in slight improvement in the solar fraction of the system.ThesisDoctor of Philosophy (PhD
Maintaining Quality of Service for Adaptive Mobile Map Clients
No full textI hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Mobile devices must deal with limited and dynamically varying resources, in particular, the network quality of service (QoS). In addition, wireless devices have other constraints such as limited memory, battery power, and physical dimensions. Applications that execute in such environments need to adapt to the dynamic operating conditions in order to preserve an acceptable level of service as close to 100 % of the time as possible. Viewing and downloading digital spatial data on mobile devices has become more popular, especially with the availability of “location-aware ” applications that exploit GPS (Global Positioning System) receivers integrated in many of today’s mobile devices. Map client applications face many challenges in accessing data across a wireless network. Vector spatial data files tend to be large, and file sizes tend to increase unpredictably depending on th
Assessment of Some Dietary Elements and Serum Minerals in Asthmatic Children Attending the Outpatient Clinic of National Nutrition Institute
No full textEffect of Different Techniques of Cervical Immobilization on Intracranial Pressure in Healthy Volunteers: Observational Study
No full textBackground: Cervical immobilization is crucial for preventing further injury in spinal trauma. However, cervical immobilization may increase intracranial pressure (ICP), which results in a reduction in cerebral blood flow and a subsequent decline in neurological function. Optic nerve sheath diameter (ONSD) measurement evolved as a non-invasive, reliable surrogate of intracranial pressure.
Objectives: This research aimed to assess the impact of neck collars and headblocks strapped on the backboard as methods of cervical immobilization on ONSD, a surrogate of intracranial pressure, in healthy individuals.
Materials and methods: The prospective comparative study involved 100 healthy volunteers of both sexes who were over eighteen years of age and divided into two groups. Cervical immobilization was done by neck collar in Group A and head blocks strapped on the backboard in Group B. ONSD was measured in both groups at baseline and subsequently at 20, 40, and 60-minute intervals and statistically analyzed.
Results: Baseline ONSD measurement of both eyes was insignificantly different; however, it became significantly higher after 20 min, 40 min, and 60 min compared to baseline in both groups (P<0.05). Notably, ONSD measurements were more elevated at 20, 40, and 60 min in group A compared to group B (P <0.05).
Conclusion: Headblocks strapped on the backboard were superior to the neck collar as evidenced by a lower elevation rate of ONSD, which may reflect a lower increase in ICP
