Stephen Theophilus
Coventry University
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Publication
Featured researches published by Stephen Theophilus.
International Journal of Environmental Science and Technology | 2010
Augustine Ifelebuegu; Stephen Theophilus; M. J. Bateman
This study investigated the sorption behaviour of two endocrine disrupting chemicals; 17β-estradiol (E2) and 17β-ethinylestradiol and their thermodynamic properties in an activated sludge biomass. The partition coefficient values measured for E2 and EE2 at varying temperatures range from 245–604 L/kg ( log Kd 2.39–2.78) and 267–631 L/kg (Log Kd 2.43–2.80), respectively. The Kd values were inversely related to temperature. The average percentages of E2 and EE2 adsorbed to the solid phase at 4.3 % dry solid were 87.2 % and 92.5 %, respectively. Sorption of E2 and EE2 to the activated sludge biomass was found to be spontaneous and entropy retarded with ΔG values in the range of −13 to −16 KJ/mol and ΔS value of−105.2J/mol/K and 96.7 J/mol/k for E2 and EE2, respectively. The enthalpy changes for E2 and EE2 were −45.7KJ/mol and −43.4KJ/mol respectively, demonstrating that the sorption process is exothermic. The values of the enthalpy changes also show that the mechanism of sorption is physisorption with some element of chemisorption.
Reliability Engineering & System Safety | 2017
Stephen Theophilus; Victor Nsikan Esenowo; Andrew Arewa; Augustine Ifelebuegu; Ernest O. Nnadi; Fredrick U. Mbanaso
The oil and gas industry has been beset with several catastrophic accidents, most of which have been attributed to organisational and operational human factor errors. The current HFACS developed for the aviation industry, cannot be used to simultaneously analyse regulatory deficiencies and emerging violation issues, such as sabotage in the oil and gas industry. This paper presents an attempt to improve the existing HFACS investigation tool and proposes a novel HFACS named the Human Factors Analysis and Classification System for the Oil and Gas Industry (HFACS-OGI). Results found the HFACS-OGI system to be suitable for categorising accidents, following the analysis of 11 accident reports from the US Chemical Safety Board (US CSB). The HFACS-OGI system moreover revealed some significant relationships between the different categories. Furthermore, the results indicated that failures in national and international industry regulatory standards would automatically create the preconditions for accidents to occur.
Chemical Enhanced Oil Recovery (cEOR) - a Practical Overview | 2016
Lezorgia N. Nwidee; Stephen Theophilus; Ahmed Barifcani; Mohammad Sarmadivaleh; Stefan Iglauer
Enhanced oil recovery (EOR) processes are well known for their efficiency in incre‐ menting oil production; however, the selection of the most suitable method to adopt for specific field applications is challenging. Hence, this chapter presents an overview of different EOR techniques currently applied in oil fields, the opportunities associated with these techniques, key technological advancements to guide the decision‐making process for optimum applicability and productivity and a brief review of field applications.
Environmental Monitoring and Assessment | 2017
Augustine Ifelebuegu; Justina Ukpebor; Anita U. Ahukannah; Ernest O. Nnadi; Stephen Theophilus
Oil spill pollution has remained a source of several international litigations in the Niger Delta region of Nigeria. In this paper, we examined the impacts of small recurrent crude oil spills on the physicochemical, microbial and hydrobiological properties of the Nun River, a primary source of drinking water, food and recreational activities for communities in the region. Samples were collected from six sampling points along the stretch of the lower Nun River over a 3-week period. Temperature, pH salinity, turbidity, total suspended solids, total dissolved solids, dissolved oxygen, phosphate, nitrate, heavy metals, BTEX, PAHs and microbial and plankton contents were assessed to ascertain the quality and level of deterioration of the river. The results obtained were compared with the baseline data from studies, national and international standards. The results of the physicochemical parameters indicated a significant deterioration of the river quality due to oil production activities. Turbidity, TDS, TSS, DO, conductivity and heavy metals (Cd, Cr, Cu, Pb, Ni and Zn) were in breach of the national and international limits for drinking water aquatic health. They were also significantly higher than the initial baseline conditions of the river. Also, there were noticeable changes in the phytoplankton, zooplankton and microbial diversities due to oil pollution across the sampling zones.
WIT Transactions on Ecology and the Environment | 2014
Stephen Theophilus; J.H. Shaibu
The ever increasing need for energy resources creates complex health and safety challenges in petroleum and petrochemical companies and human participation is crucial to the management of health and safety particularly in K-Refinery and Petrochemical companies (K-RPC). The research set out to differentiate management safety performance behaviour into two different types, assess the impact of employee and management safety participation on overall safety performance and to evaluate the impact of employees’ safety knowledge/perception on compliant behaviour in K-RPC. Methods employed in the assessment are the Mann Whitney U Test, Correlation Analysis and descriptive statistics. The results suggested that there is no difference in mean ranking between management and employees regarding the level of management commitment, indicating a high level of participation. A significant negative correlation was found between employees’ safety knowledge and safety compliant behaviour, which implies a low practical application of safety knowledge gained through training. Therefore, though management participation in safety issues in K-RPC is perceived to be high, this commitment did not impact on the overall levels of safety performance in K-RPC. Hence, the manner in which participation in work-related safety is exhibited has an overwhelming impact on safety performance. When participation takes the form of directives rather than direct and true active involvement during work operations, the empowering safety leadership which is a fundamental drive to the attainment of an incident-free work will be missing.
Safety and health at work | 2018
Andrew Arewa; Stephen Theophilus; Augustine Ifelebuegu; Peter Farrell
Background The study analyzes penalties imposed on organizations for breaching safety and health regulations. The research questions are as follows: what are the commonly breached safety and health regulations? How proportional are penalties imposed on organizations for breaching health and safety regulations in the United Kingdom? Methods The study employed sequential explanatory mixed research strategies for better understanding of health and safety penalties imposed on organizations. Actual health and safety convictions and penalties data for 10 years (2006 to 2016) were obtained through the United Kingdom Health and Safety Executive (HSE) public register for convictions. Overall, 2,217 health and safety cases were analyzed amounting to total fines of £37,179,916, in addition to other wide-ranging penalties. For thorough understanding, eight interviews were conducted with industry practitioners, lawyers, and HSE officials as part of the study qualitative data. Results Findings show that the Health and Safety at Work (HSW) Act accounted for 46% of all HSE prosecution cases in the last decade. This is nearly half of the total safety and health at work prosecutions. Moreover, there is widespread desire for organizations to comply with the HSW Act, but route fines are seen as burdensome and inimical to business growth. Conclusion A key deduction from the study reveal significant disproportionality concerning penalties imposed on organizations for breaching safety and health regulations. On aggregate, small companies tend to pay more for health and safety offenses in a ratio of 1:2 compared to large companies. The study also reveals that the HSW Act accounted for nearly half of the total safety and health at work prosecutions in the last decade.
Process Safety Progress | 2018
Stephen Theophilus; Chizaram Nwankwo; Elijah Acquah-Andoh; Enobong Bassey; Udeme Umoren
Human factors and process safety management (PSM) have become key factors in preventing exposure to both hazardous materials and major accidents. Therefore, comprehensive process safety management is required to address all aspects of human factors. Currently, there are several‐process safety management models all of which have some weaknesses with respect to the control of human factors inherent in the process industry. Moreover, there is as yet no universally accepted process safety management model that treats process safety management as an integral part of the management system. Therefore, a need has arisen to integrate human factors and the existing frameworks and models into a single integrated management system to ensure a holistic approach of control and a continuous learning system. This article identifies the missing human factors in the current system and describes an integrated process safety management system (IPSMS) model drawn from screening all existing PSM frameworks, while integrating the Human Factors Analysis and Classification System (HFACS). The model, which adopts the PLAN, DO, CHECK, and ACT framework, also outlines an implementation strategy. We conclude that IPSMS provides both a theoretical and a practical framework with which to manage, measure and analyse process safety management systems.
Processes | 2018
Augustine Ifelebuegu; Egetadobobari E. Lale; Fredrick U. Mbanaso; Stephen Theophilus
Process Safety and Environmental Protection | 2018
Augustine Ifelebuegu; Esiwo O. Awotu-Ukiri; Stephen Theophilus; Andrew Arewa; Enobong Bassey
Environmental Science and Pollution Research | 2018
Stephen Theophilus; Fredrick U. Mbanaso; Ernest O. Nnadi; Kingsley T. Onyedeke