Ben U. Ngene

A laboratory assessment of the effect of varying roughness on dissolved oxygen using error correction method

Abstract Dissolved Oxygen (DO) is an important parameter to be monitored as far as water quality of rivers and streams are concerned. On the other hand, in rivers and streams, varying roughness occurs naturally but their contributions to DO availability is yet unknown. This paper examines the effects of varying roughness of different sizes and arrangement patterns on DO and also reveals how Error Correction Methodology as a modelling technique can be applied in river studies rather than using the traditional ordinary least square method with velocity (V), Froude number (Fr), roughness coefficient (K) and dispersion coefficient (d) captured as explanatory variables. The findings of this study revealed that roughness coefficient (K) had no effect on DO i.e. negative relationship with coefficient value of −0.796, with corresponding t-statistics (t = 0.615) suggesting its non-significance. In addition, Froude number (Fr) and dispersion coefficient (d) also showed negative relationships respectively (−77.71 and −2.039) with DO but with sharp significance as revealed by the corresponding t-ratio (t-ratio = −2.75 and −4.08). Thus, the study suggests that dispersion coefficient or its dimensionless number as a variable is important and should be included in the modelling, otherwise, the spread of pollutants (BOD) in the transverse and vertical directions rather than their single centre point values are essential to improve the outcome of DO and reaeration coefficient (k 2) modelling.

QUALITY ASSESSMENT OF A UNIVERSITY CAMPUS WASTEWATER RESOURCE

Vast volumes of freshwater can be conserved if the practice of re-using wastewater is encouraged. In this study, the quality of wastewater from the Covenant University campus was assessed to determine its suitability for landscape irrigation purposes. The university uses a constructed wetland (CW) method in treating both its black-water and grey-water (wastewater). An estimated 874,081 litres/day of wastewater was generated and treated as of 2013, with nearly all of this volume discharged without being re-used. To assess the suitability of the wastewater for reuse, duplicate grab samples of treated effluent from the CW and from the grey water outlet were assessed for physical parameters such as pH, Temperature, Total Dissolved Solid (TDS), Salinity, Conductivity were analysed using handheld Hanna multi-meter instrument (model HI2040). Also, chemical parameters such as Nitrate, Nitrite, Lead, Nickel, Cadmium, Zinc and Copper were tested using Palintest photometer (model 8000). Moreover, total coliform was checked, using standard laboratory methods. Results indicated that none of the tested parameters exceeded the specified limits by Food and Agriculture Organization (FAO) of United Nations and Environmental Protection Agency (EPA) standards for wastewater reuse. Thus, the treated wastewater in Covenant University was found to be a valuable resource for multiple purposes that can add value other than outright discharge. Thus, it was recommended that appropriate infrastructure be put in place to harness and reuse treated wastewater coming from Covenant University.

EXPERIMENTAL INVESTIGATION OF COPPER REMOVAL FROM AQUEOUS SOLUTION USING MUSA PARADISIACA AS A NOVEL ADSORBENT

The adoption of agricultural waste materials in the removal of heavy metals from contaminated waters has gained more recognition in recent times. This study capitalizes on the production of adsorbents from one of the predominant agricultural waste materials (Plantain Peel) in Ado-Odo Ota, to access its metal-removal efficiency. This work investigated Cu2+ adsorption using activated carbon processed from chemically modified unripe plantain (Musa paradisiaca) peel. Adsorption studies were performed using batch experiments wherewith the influence of pH of the solution, initial concentration, temperature and contact time have been cross-examined. The results displayed a 99.8% removal efficiency of Cu2+ at pH 7.5, 30°C and 150 mg/L concentration. The equilibrium adsorption capacity of unripe Musa paradisiaca peel has been obtained using linear models of Langmuir and Freundlich isotherms. The result is poised to elucidate the metal retention mechanism as a process involving ion exchange as the divalent metal ion binds to the activated unripe plantain peel.

Assessment of KOH-activated unripe Musa paradisiaca peel for adsorption of copper from aqueous solution

Abstract Adsorption of copper ions out of aqueous solution by preparing activated carbon from unripe Musa paradisiaca peel (UmpP) with KOH was investigated. Estimation of the adsorption constants was achieved by adopting the Langmuir and Freundlich models. Results revealed that the adsorption process was fast and equilibrium was reached at 55 mins. The adsorption efficiency was highly influenced by the pH of the solution, and the maximum adsorption was attained at pH 7.5. In addition, an increase in adsorption capacity was observed with increase in contact time and initial copper concentration. The adsorption process was explained by both Langmuir and Freundlich models having R2 value of 0.9977 and 0.9959 at 303 K respectively and R2 value of 0.9922 and 0.9904 at 308 K respectively. The maximum adsorption capacity of KOH-modified UmpP at the specified conditions was found to be 9.980 and 9.766 mg/g at 303 and 308 K respectively. Sequel to modelling the kinetic data, the Pseudo-second-order model gave the best fit with R2 = 0.9990 and 0.9977 at 303 and 308 K respectively, indicating that the adsorption process is restricted to chemisorption. KOH-modified UmpP can serve as an economically and environmentally viable sorbent for the removal of copper from contaminated waters.

ASSESSMENT OF STUDENTS’ CLASSROOM LEARNING OUTCOME: INFLUENCE OF ENVIRONMENTAL FACTORS

Classroom environment is not supposed to be attractive for teaching and learning alone but conducive for the test or assessment of the degree of learning taking place there. Classroom tests and examinations are means of establishing a students’ level of accomplishment in a given subject. The classroom is expected to protect the learner from the vagaries of weather, air pollution, noise and when tests are to be conducted, the time of the day, invigilation and seating arrangements has to be conducive and appropriate also. The aim of this work is to determine how these environmental factors influence the performance of students in test and examination. The research was conducted using the survey instrument of questionnaire to obtain the perception of the respondents to the effect of environmental factors on learning outcome assessment. The questionnaire was subjected to mean score analysis to obtain respondents satisfaction value of the ordinal data on Likert scale. It is reasonable to assert from the analysis of the data that a test/examination conducted in a poor physical environment, such as those with poor lighting, under poor weather, noisy environment and polluted air will not be conducive to both the student and teacher hence produce poor performance in results of test /examinations. The findings revealed that due to the poor infrastructural development of Nigeria educational system, it is obvious that there is agreement to the effect that the environment factors affect learning. It is therefore advocated that apart from good teachers being employed in our educational system, location of schools should be considered very critically using these environmental parameters before approval is given for its establishment in the country.

Strength and microstructure of eco-concrete produced using waste glass as partial and complete replacement for sand

Abstract The sustainable benefits of waste glass usage in concrete include the possibility of reducing solid waste and greenhouse gas emission and preservation of raw materials. This current study examines the effect of recycled waste glass as a partial and complete substitute for natural sand in producing eco-friendly concrete. The recycled waste glass was proportioned in levels of 25, 50, 75 and 100% by weight to substitute sand in the concrete using a mix ratio of 1:2:4 (cement:sand:gravel) at a W/C ratio of 0.5 targeting 20 MPa strength at 28 days. Tests, which include X-ray fluorescence (XRF), were conducted on the waste glass and cement materials; slump test was performed on the freshly prepare concrete at different percentage glass content. Compressive and tensile strength tests were performed on 60 specimens after 3, 7, 28 and 90 days of curing. The concrete microstructure was examined using the scanning electron microscope (SEM). Results showed that workability and the mechanical strength of the concrete produced decreased with increasing waste glass content. However, concrete containing 25% and 50% waste glass contents showed significant enhancement in strength, but it is recommended that the optimum glass content should be 25% for the production of sustainable eco-concrete.