Adebanji Samuel Ogbiye

Estimation of longitudinal dispersion co-efficient: A review

Abstract Accurate determination of longitudinal dispersion coefficient in rivers or streams is necessary for pollution control and management. This can be achieved through tracer studies and has proven to be a reliable method for measuring pollution spread. However, tracer studies practise which is expensive, time gulping and requiring large labour input have been substituted with empirical approaches thereby reducing the applicability of the dispersion coefficient models generated. This study reviews the various models derived as well as methods associated in the collection of tracer concentration data (measurement) existing in the literature. A sustainable approach to this study was identified and research needs were also listed.

Investigating Solanum Aethiopicum Leaf-Extract and Sodium-Dichromate Effects on Steel-Rebar Corrosion in Saline/Marine Simulating-Environment: Implications on Sustainable Alternative for Environmentally-Hazardous Inhibitor

This paper investigates Solanum aethiopicum leaf-extract and the well-known but environmentally-hazardous sodium-dichromate inhibitor effects on concrete steel-rebar corrosion in 3.5% NaCl medium (simulating saline/marine environment). Different equal-concentration models (wt% cement) of the natural-plant leaf-extract and of sodium-dichromate were admixed in steel-reinforced concrete slabs from which electrochemical test-measurements were obtained for comparing admixture performance. Test-results, analyzed as per ASTM G16-95 R04, showed that only the 0.083% sodium-dichromate admixture outperformed the 0.083% Solanum aethiopicum leaf-extract in corrosion-inhibition effectiveness. The other natural-plant leaf-extract exhibited better inhibition-efficiency performance than their equal-concentration models of sodium-dichromate. The 0.25% Solanum aethiopicum leaf-extract exhibited optimal performance, η = 98.28%, at inhibiting steel-rebar corrosion among the also effective different concentrations of the plant-extract and of sodium-dichromate admixtures employed. These and phytochemical test-results bare indications that Solanum aethiopicum leaf-extract is a suitable, sustainable and eco-friendly alternative for the environmentally-hazardous sodium-dichromate inhibitor of steel-rebar corrosion in concrete designed for saline/marine environments.

C3H7NO2S effect on concrete steel-rebar corrosion in 0.5 M H2SO4 simulating industrial/microbial environment

This paper investigates C3H7NO2S (Cysteine) effect on the inhibition of reinforcing steel corrosion in concrete immersed in 0.5 M H2SO4, for simulating industrial/microbial environment. Different C3H7NO2S concentrations were admixed, in duplicates, in steel-reinforced concrete samples that were partially immersed in the acidic sulphate environment. Electrochemical monitoring techniques of open circuit potential, as per ASTM C876-91 R99, and corrosion rate, by linear polarization resistance, were then employed for studying anticorrosion effect in steel-reinforced concrete samples by the organic hydrocarbon admixture. Analyses of electrochemical test-data followed ASTM G16-95 R04 prescriptions including probability distribution modeling with significant testing by Kolmogorov-Smirnov and students t-tests statistics. Results established that all datasets of corrosion potential distributed like the Normal, the Gumbel and the Weibull distributions but that only the Weibull model described all the corrosion rate datasets in the study, as per the Kolmogorov-Smirnov test-statistics. Results of the students t-test showed that differences of corrosion test-data between duplicated samples with the same C3H7NO2S concentrations were not statistically significant. These results indicated that 0.06878 M C3H7NO2S exhibited optimal inhibition efficiency η = 90.52±1.29% on reinforcing steel corrosion in the concrete samples immersed in 0.5 M H2SO4, simulating industrial/microbial service-environment.

Cassia fistula Leaf-Extract Effect on Corrosion-Inhibition of Stainless-Steel in 0.5 M HCl

This paper investigates Cassia fistula leaf-extract effects on the inhibition of stainless-steel corrosion in 0.5 M HCl. Measurements of corrosion rate were obtained through linear sweep voltammetry (LSV) technique, at the ambient temperature of 28 °C from stainless-steel specimens immersed in the acidic medium, containing different Cassia fistula leaf-extract concentrations. Results showed that inhibition effectiveness on stainless-steel corrosion increases with increasing concentration of the leaf-extract. The 10 g/L Cassia fistula leaf-extract, the highest concentration of the leaf-extract employed in the study, exhibited optimal inhibition efficiency η = 88.46% on the corrosion of the stainless-steel metal. Adsorption isotherm modelling shows that the experimental data followed the Flory-Huggins isotherm with excellent model efficiency, r 2 = 90.27%, and the Langmuir model with very good model efficiency, r 2 = 78.83%. Other isotherm parameters indicate favourable adsorption and suggest physisorption as the prevalent mechanism of corrosion protection by the leaf-extract on stainless-steel in the acidic chloride environment.

Anticorrosion Performance of Solanum Aethiopicum on Steel-Reinforcement in Concrete Immersed in Industrial/Microbial Simulating-Environment

This paper investigates anticorrosion performance of Solanum aethiopicum leaf-extract on steel-reinforcement in concrete immersed in 0.5 M H2SO4, simulating industrial/microbial environment. For this, corrosion rate by linear polarisation resistance and corrosion potential as per ASTM C876-91 R99 were monitored from steel-reinforced concrete slabs admix ed with different Solanum aethiopicum leaf-extract concentrations and immersed in the acidic test-environment. Obtained test-data were subjected to statistical probability distributions for which compatibilities were tested using Kolmogorov-Smirnov goodness-of-fit statistics, as per ASTM G16-95 R04. These identified all datasets of corrosion test-data, from the steel-reinforced concrete samples, as coming from the Weibull probability distribution. Analysed results showed that Solanum aethiopicum leaf-extract reduced rebar corrosion condition from “high” to “low” corrosion risks of ASTM C876-91 R99. Also, the corrosion rate analyses identified 0.25% Solanum aethiopicum leaf-extract with optimal inhibition efficiency performance, η = 93.99%, while the other concentrations also exhibited good inhibition of steel-reinforcement corrosion in the test-environment.

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.

Stainless Steel Corrosion Resistance in 0.5 M H 2 SO 4 Using Cassia fistula Extract

A study of the corrosion behavior of stainless steel (SS) in 0.5 M sulphuric acid using Cassia fistula leaf extract (CFLE) at 30 °C was carried out. The study was conducted by taking the SS samples, in inhibited and uninhibited solutions through linear sweep voltammetry tests, and then subjecting the recorded data from the experiment to analysis, to yield the surface coverage, inhibitor efficiency, inhibition mechanism and adsorption model. The analysed data showed that inhibitor efficiency ranged from 98.59 to 95.25% at 2 and 8 g/L respectively. Surface coverage data for the experiment fitted well to the Langmuir model with a separation factor parameter showing favourable adsorption. Inhibitor adsorption was spontaneous showing overriding physical adsorption, while an anodic inhibition mechanism was displayed. CFLE promoted the overriding influence of the chromium oxide passive film on the SS metal surface to forestall the aggressive effect of sulphuric acid.

Hydro-geometrical data analyses of River Atuwara at Ado-Odo/Otta, Ogun State

The dataset analyzed in this article contains spatial and temporal values of the hydro-geometric parameters of River Atuwara. The hydro-geometrical data analyses of various sampling point on River Atuwara was examined and their geometric properties were taken with the use of a paddled boat, depth meter and global positioning system (GPS). The co-ordinates, width, depth, slopes, area, velocity, flow were gotten in-situ while the area and wetted perimeter were computed ex-situ. The statistical relationships between separate variables were considered using scatter plots and regression line equations. Inferences drawn from various variable comparisons can be used to validate predictive models for various time seasons.

Treatment of Brewery Wastewater using Electro-Fenton and Granulated Activated Carbon

Abstract Improvement of electro-Fenton (EF) process with granulated activated carbon (GAC) for the treatment of brewery effluent obtained from Ota, South-West Nigeria was investigated. The GAC was obtained by crushing, carbonising, sieving, and activating cow bones. Duplicate samples of the raw effluent and 10 treated brewery effluent samples were analysed for conductivity, turbidity, total dissolved solids (TDS), chemical oxygen demand (COD), copper, manganese, cadmium, lead, and zinc. The average readings were taken as final values. Results showed that the combined use of EF and GAC treatment of the effluent yielded better result than use of EF alone. The removal efficiency was 1181, 50, 565, 4375, 160, and 840% for turbidity, COD, copper, cadmium, lead, and zinc respectively. EF and GAC treatment were, however, found to be inefficient for the treatment of conductivity, TDS, and manganese. It was also found that pH had a direct impact on the treatment media. Turbidity and cadmium, which had the highest removal rates were achieved at pH 2, while COD, copper, and zinc had optimum treatment at pH 6. It was concluded that the combined advantage of electrolytic separation from EF and adsorption from GAC yielded better treatment result for the brewery effluent samples.