Optimum configuration and design of a photovoltaic–diesel–battery hybrid energy system for a facility in University of Port Harcourt,Nigeria

Optimum configuration, using a hybrid optimisation model for electric renewable software, and design of a photovoltaic (PV)–diesel–battery hybrid energy system has been proposed to power a facility in the University of Port Harcourt, which is located in the suburb of Port Harcourt city, Nigeria. The configuration of the optimum hybrid system is selected based on top-ranked system configuration, according to the net present cost. An optimal system design delivers the best components alongside appropriate operating strategies to provide the most efficient, reliable cost-effective system possible. The system investigated reduces CO₂ emissions by 36.3%/year. This will reduce costs imposed on CO₂ emissions by future environmental legislation. The system has a better potential for providing the energy needs of the facility considered in this paper compared with a stand-alone PV–battery system as capital costs are reduced by 55%. Reliability was improved as the diesel generator can provide power as and when it is needed.     

Exergy and exergoeconomic analysis of a municipal waste-to-energy steam reheat power plant for Port Harcourt city

This paper presents the exergy and exergoeconomic analysis of a proposed steam reheat power plant powered by the municipal waste of Port Harcourt city in Nigeria, latitude 4°45′ N and longitude 7°00′ E. The projected municipal waste generation of the city for the year 2020 was employed for this work to ascertain the amount of power obtainable via a waste incineration plant, taking into consideration the cost effectiveness of the plant. The thermodynamic analysis of the plant showed that 117?MW could be generated from the projected waste, with plant's first and second law efficiencies of 36.91% and 31.36%, respectively. The plant equipment cost was calculated to be US$326,460,000 with a payback period of about six years. The exergy and exergoeconomic analysis was used to estimate the plant’s unit cost of electricity and evaluate the exergy destruction and cost rates, with respect to the prevalent ambient temperature.     

Utilization of marginal lands for construction in the Niger Delta

Increased population in the cities within the Niger Delta particularly Port Harcourt, and the consequent demand for increased residential space, have forced State and Federal Governments to reclaim coastal marginal lands which comprise mainly swampy soils. Reclamation is by hydraulic filling with fine to coarse sand. Two case histories of such reclamation are discussed in this paper. The minimum sandfill thickness required to eliminate 97% consolidation settlement of the underlying compressible soils are computed using graphs developed from Terzaghi's one—dimensional consolidation theory.     

Daily urinary excretion of uranium in members of the public of Southwest Nigeria

The main aim of this study was to determine and evaluate urinary excretion values of uranium in members of the public of Southwest Nigeria living in areas of low environmental uranium. As several uranium mines are running in Nigeria and the operations could be a risk of contamination for the workers as well as for the members of the public, biomonitoring of urine could provide information about the exposure to uranium for the subjects. Therefore, baseline values of uranium in urine are needed from subjects living in areas without mining activities. Volunteers of both genders (age range 3 to 78 years) were asked to collect 24 h-urine samples. The concentration measurements of uranium in urine were performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In addition, urinary creatinine values were determined for normalization of the renal uranium relative to the creatinine concentrations.The urinary uranium concentrations and their creatinine normalized values ranged from < 10.4 to 150 ng L^? 1 (median 13.8 ng L^? 1) and from 2.52 to 252.7 ng g^? 1 creatinine (median 33.4 ng g^? 1 creatinine), respectively, for adult subjects above 15 years of both genders. An increased uranium excretion value of 61.6 ng L^? 1 (median), and of 76.0 ng g^? 1 creatinine, respectively, were found in young subjects below 15 years. The median of daily excreted uranium was estimated to be 14.2 ng d^? 1 for adults and of 45.1 ng d^? 1 for children, respectively. The uranium excretion from males and females living in Nigeria in a non-mining area was comparable to reference values reported from other countries with low level of environmental uranium. The data can be considered as baseline values of urinary uranium in unexposed subjects in Nigeria.     

Establishment of the moth: Niphograpta albiguttalis (Warner) (Lepidoptera: Pyralidae), a biological control agent of water hyacinth (Eichhornia crassipes) in waterways of Lagos and Ogun states,southwestern Nigeria

The moth Niphograpta albiguttalis was found infesting water hyacinth on waterways in Nigeria in 2009 in the areas of Badagry, Ejirin and Epe in Lagos State and Iwopin in Ogun State. This moth has not been released in Nigeria but it was released as a biological control agent for water hyacinth in Ghana in 1996 and in Benin in 1993. It is not reported to have established in those countries, but it would appear that as a result of those releases N. albiguttalis is now present in Nigeria. The larval instars found were damaging only water hyacinth with bulbous petioles. The larval developmental periods ranged between 10 and 15 days (n = 3).     

Oxygen utilization and biochemical stabilization rate constants for a brewery effluent

Composite samples of brewery effluents were obtained from a brewery in Benin City, Nigeria. They were analysed for their biochemical oxygen demand (BOD) values at 20°C for definite periods in days. From the values obtained, oxygen utilization and biochemical stabilization rate constants, k and K, respectively, were determined. The mean values obtained for them were 0.37 day^‐1 and 0.16 day^‐1 respectively. The ultimate BOD (L_o) value for the brewery effluent was 757.1 mg/l, and the ratio of the 5‐day BOD (BOD₅) to the Ultimate BOD (L_o) (i.e., BOD₅/L_o) was found to be 0.85.     

Urban Space Administration in Nigeria: Looking into Tomorrow from Yesterday

Urban space administration is a branch of public administration designated for ordering, re-ordering, regulating and controlling urban systems and urban land uses for the purpose of human comfort, convenience, urban aesthetic or city’s branding and economic and environmental sustainability. Urban space administration is not new in Nigeria; it dated back to precolonial periods when city management was vested in kings and a team of advisers including the local priests. The advent of colonial government introduced paper-assisted urban administration which continued after independence. The 1976 local government reforms and the subsequent fragmentations of states to many local government resulted in multiplicity of admirations and agencies governing urban areas in Nigeria. The results are manifested in blighted condition and pockets of slums in all Nigeria cities. The paper examined trends in urban administration in Nigeria and advanced two approaches to solving multifarious urban problems in Nigeria. The approaches include devolution of urban administration powers to local authorities and deployment of geospatial technology tools for urban system administrators ( Knaap et al 1998). The paper further suggested recommendations for bridging the digital shortfall in the applications of modern technologies to city administration in Nigeria.     

n‐Alkane distributions in soil and water samples collected near Agbabu bitumen field of southwestern Nigeria

Soil and water samples from the vicinity of Agbabu bitumen field of Southwestern Nigeria were analysed by GC‐FID for n‐alkanes, in order to characterize their distributions and to gather information on the degree of contamination by bitumen exploration and processing and other biogenic contributions. Total concentrations of n‐alkanes in water and soil samples analysed ranged from 61.5 to 472.7 µg L^?1 and 422.8 to 2289.4 ng g^?1 dw, respectively. On the basis of the total n‐alkane concentrations, carbon preference index (CPI) values and the odd‐even carbon predominance, it is suggested that both natural (e.g. aquatic input) and anthropogenic (e.g. bitumen and synthetics) sources contribute to the n‐alkanes load in soil and water samples of the area studied.     

Concentrations of selected metals in honey consumed in Nigeria

The concentration of metals, cadmium (Cd), lead (Pb), nickel (Ni), chromium (Cr), copper (Cu), cobalt (Co), iron (Fe), manganese (Mn), and zinc (Zn) was measured in selected samples of honey in Nigeria with a view to providing information on the regional concentration profile of metals in these honeys. The honey samples were digested with a mixture of acids and analysed for metal concentrations using atomic absorption spectrophotometry. The concentrations of metals (mg kg^?1) in these honeys ranged from < 0.3 for Cd,<0.50–39.75 for Pb,<0.25–6.98 for Ni,<0.25–55.25 for Cr,<0.25–71.25 for Cu,<0.25–3.50 for Co,<5.0–163.15 for Fe,<11.0–31.75 for Mn and 1.0–31.0 for Zn. The concentrations of metals were relatively high but lower than their respective permissible limits in food except for Pb and Cu in some samples. The regional distribution patterns of metals indicated that honey samples from the Niger Delta region of Nigeria had higher mean concentrations of Ni, Cr, Co, Fe and Zn than honey samples from other regions. The honey samples from the northern region had higher mean concentrations of Pb and Cu.     

Book Reviews and Notes

City Development: Studies in Disintegration and Renewal, by Lewis Mumford. New York: Harcourt, Brace & Co., 1945. 248 pages, $2.00

A Million Homes a Year, by Dorothy Rosenman. New York: Harcourt, Brace & Co., 1945. 333 pages. $3.50.

State and Local Finance in the National Economy, by Alvin H. Hansen and Hrvey S. Perloff. New York: W. W. Norton & Company, 1944. 310 pages. $3.75.

Planning Neighborhood Shopping Centers; a Study of Neighborhood Retail Trades Requirements and the Use of Purchasing Power as a Yardstick in Planning to Meet Them, by Marcel Villanueva. New York: National Committee on Housing, Inc. c1945. 34 pages. $1.00.

Planning by Lease Control, by Henry W. Wells in the Journal of the Royal Institute of British Architects, Vol. 51, No. 12. London, October, 1944.

A Factual Basis for Reconstruction, by F. A. C. Maunder, in the Journal of the Town Planning Institute, Vol. XXXI, No. 2. London, January-February, 1945.

Better Training for the Planner, by G. Cozen, in the Journal of the Town Planning Institute, Vol. XXXI, No. 2. London, January-February, 1945.     

Basic geotechnical properties,chemistry and mineralogy of some laterite soils from S.W. Nigeria

Laterite soils derived from four basement complex rocks and a sedimentary formation from Southwestern Nigeria are analysed for their basic geotechnical properties, chemistry and mineralogy. Results obtained show that the granite gneiss derived and the sedimentary laterite soils are good engineering materials. The amphibolite derived laterite soil has a linear shrinkage of 10% and contains SO ₄ ^2? ions. The quartz schist derived and the micaschist derived laterite soils contain rather high amounts of muscovite ?30% and 25% respectively. The usability of the laterite soils and the implications of the presence of SO ₄ ^2? ions and mica and the high linear shrinkage are discussed.     

Geotechnical characteristics of soils susceptible to severe gullying in eastern Nigeria

The geotechnical characteristics of soils that are susceptible to severe gullying in the rain forest zone of Nigeria were studied. The soils are predominantly sands whose fines (silt/clay) contents are very negligible. The sands are loose (dry density 1.42–1.73 g/cm³) and highly permeable (permeability 9.43×10³?3.4×10²cm/s) with permeability increasing with depth. Porosities and void ratios are also high (41.6–50.3% and 0.71–1.01 respectively), while cohesion is small to zero (0–85 kN/m²). It is thought that although these conditions favour less runoff and high infiltration, they lead to high internal flow velocities and seepage pressures, and ultimately high internal erosion. It is concluded that once a gully is initiated, the soil properties become responsible for rapid propagation. Non response of the gullies studied to afforestation control measures is thought to result from these soil properties.     

Coagulation of turbid water and softening of hardwater with Moringa oleifera seeds

In this study, the effects of 5 process variables on softening hardwater and coagulation of surface water with a M. oleifera seed extract were investigated. Multiple regression analysis showed a strong correlation (R² (adj.) = 0.99 between M. oleifera seed dosage and the initial hardness of synthetic hardwater. Since M. oleifera is known to be a polyelectrolyte, the softening mechanism is likely to be adsorption. An adsorption isotherm developed was approximately linear and conformed to the Langmuir type. For the coagulation studies, the water samples were from three rivers in Kano, Nigeria over a three month period during the rainy season (June‐August 1994). The turbidity of the water sample varied from 105–350 NTU. When used as primary coagulant, M. oleifera was able to achieve up to 99% turbidity removal for two of the water samples at the optimum dosage of 250 mg/l. For the third water sample, the optimum dosage was 450 mg/l which is assumed to be due the high value of the colour of the water. Saving in alum usage of up to 40% was achievable when M. oleifera was used in conjunction with alum.     

Examination of Relationship Between Mercury Rate with Zinc and Copper Changes in Muscle Tissue of <Emphasis Type="Italic">Otolithes Rubber</Emphasis> in Mahshahr Port—the Persian Gulf

The current study was conducted with the aim of examination of changes scope as well as correlation between mercury with zinc and copper in the muscle tissue of tigertooth croaker as one of the most consumed fish in the area (Mahshahr Port) and its comparison with available standards. The obtained results suggested that, total average concentration of Hg, Zn and Cu (mean ± SE) accumulated in the muscle tissue of tigertooth croaker (Otolithes rubber) are respectively equal to 1426 ± 113; 15999 ± 1045 and 2279 ± 94 (ngg^–1) in summer as well as 955 ± 91; 13172893 and 1678 ± 178 (ngg^–1) in winter. Comparison among accumulation rate of elements Hg, Cu and Zn in two seasons showed a significant correlation between two mentioned seasons for Zn and Hg. The correlation result indicates a positive significant relationship between zinc and copper and a descending significant relationship between Hg with Cu and Zn. Concentration of total mercury accumulated in the muscle tissue of tigertooth croaker (Otolithes rubber) within two seasons, summer and winter, are lower than standard limit (500 ngg^–1) defined by WHO while it is higher than standard limit (300 ngg^–1) estimated by USEPA. Due to high concentrations of Hg, the results can be a serious warning for consumption of this fish in Mahshahr region.     

Slope stability analysis of mine waste dumps at a mine site in Southeastern Nigeria

This paper presents results on the stability of slopes of the mine tailing dumps at Enyigba, Southeastern Nigeria. The geotechnical parameters of the slopes were investigated, and stability analysis was carried out with GeoStudio® 2012 developed by Geoslope International Limited. The slope materials were composed of gravel (1.42–30.13%), sand (15.94–33.34%), silt (9.75–26.87%) and clay (32.1–56.25%). The materials have LL, PL and PI ranging from 24 to 49%, 24 to 35% and 9 to 26% respectively, signifying low to medium plastic materials. These results agree with the soil low permeability (10⁻⁴ – 10⁻⁸ cm/s) recorded. The MDD and OMC of the material ranged from 1.86 to 2.22 g/cm³ and 13.45 to 17.05%, while cohesion and internal friction angle were recorded to be 13–34 kN/m² and 8–37° respectively; implying moderately durable materials capable of slip and shear failures. XRD confirmed the presence of swelling mineral (illite) in soil material, hinting at clay plasticity on absorption of moisture, which is one of the factors influencing all forms of mass wasting. The slopes’ computed factor of safety ranged from 0.8 to 1.33, suggesting critical to poor slope stability when exposed to landslide triggering agents. Hence, slope stabilization is required on the mine tailing dumps at Enyigba to prevent major landslide occurrence.

     

Manpower requirements in a selected number of housing projects in Nigeria

The paper summarises the results of a recently completed study on manpower requirements in a selected number of housing projects in Nigeria and compares the findings with known previous works from both Nigeria and other advanced countries. It shows that manpower requirements for housing in Nigeria vary from 4.05 to 6.87 man-days per square metre in two previous studies compared with 6.44 to 16.78 man-days per square metre and 55–133 man-days per

1000 obtained from the present study. Similar studies carried out elsewhere were shown to vary from an average of 2.33 man-days per square metre for U.K., 3.28 and 1.53 man-days per square metre for Ireland and U.S.A. respectively. It was evident therefore that the productivity of Nigerian workers was much lower than in these other countries. The paper attributes the lower manpower requirements obtained elsewhere to better organisation, higher degree of supervision and adoption of mechanical power as well as a fair amount of prefabrication outside the building sites. The paper showed that the very variability in performance of the Nigerian contractors was mainly due to the form of construction, the size of contractor and size of contract executed by them. It concludes by suggesting various ways in which the manpower requirements for capital projects can be minimised.     

The geotechnical properties of lateritic and non-lateritic soils of southeastern Nigeria and their evaluation for road construction

The soils within the entire length of the Port Harcourt—Enugu expressway consist of (1) concretionary laterite gravels (2) non-lateritic tropical sandy/clayey soils which are gravelly in some places and (3) silty to fat clays formed from shales. The particle size distribution and the plasticity of the majority of the soils indicate that by standard acceptance specifications they are unsuitable for base materials. Field compaction results revealed that the relative compaction of 95–100% can be easily achieved in the field using 10–12 ton vibratory rollers. Although the pavement materials used for the expressway are inferior under conventional standards, mostly isolated rather than widespread pavement failures have so far occurred. Such failures are presumed to be more related to poor field compaction rather than the inferior quality of the construction materials. Where the troublesome weathered shale forms the subgrade, severe pavement failure usually occurs.     

Housing Reform And Fishermens Bend 1900–1913

Abstract

This paper examines the development of the Port Melbourne Council's (PMC) housing campaign between 1910 and 1913. In addition, it explores the contest between the PMC, the harbour trust and the lands department over the use of Fishermens Bend, an area of vacant crown land adjacent to Port Melbourne and the proposed site of the PMC's workers' housing scheme.     

Engineering properties and slope stability of road cuttings along the enugu-onitsha express road,Southeastern Nigeria

The new express highway linking Enugu (in Enugu State) and Onitsha (in Anambra State) both in Southeastern Nigeria, is plagued with landslides, a few years after completion. The active landslides are concentrated on the road cuttings between Otuocha junction and Awka, specifically between km 29 and km 40 from the Onitsha end of the road. Three of these slides have been studied. The investigation involved detailed field and laboratory studies of the physical conditions and geotechnical properties of the sites and soils therein. The laboratory tests performed included grainsize distribution analysis, Atterberg limits, specific gravity, natural water content, bulk density, permeability and shear strength. Each site was analysed for stability using the strength parameters obtained from laboratory tests and Bishop's 1955 simplified method of analysis. There is evidence from the analyses results that although the cut slopes are vulnerable to toe undermining and over-steepening by runoff, the generally “loose” nature of the soils as evidenced by the low bulk density (1580–1960 kg/cm³), fairly high void ratio (0.53–0.66) but low permeability (2.15–3.25×10^?3 cm/s) and consequent high saturation and strength reduction during the rains, are the major contributors to instability of the cut slopes.     

Wind characteristics and energy potential assessment in Akure,South West Nigeria: econometrics and policy implications

This paper analysed 11 years of daily mean wind-speed data, measured at Akure, Ondo State, Nigeria, using Weibull and Rayleigh distribution functions. While both distributions showed good agreements in extreme-value estimation patterns, investigation of their wind-speed characteristics modelling criteria, using goodness-of-fit statistics, revealed that the wind data followed the Weibull more than Rayleigh. Monthly wind-speed of Akure city ranged from 1.41 to 4.24 m/s by the Weibull fittings and from 1.40 to 4.16 m/s by the Rayleigh fittings. Overall results, of 2.71 m/s (Weibull) or 2.70 m/s (Rayleigh) mean wind-speed and 18.51 W/m² (Weibull) or 22.26 W/m² (Rayleigh) mean power density, indicated Akure a low wind-speed site, requiring low wind-speed turbine for generating wind energy. Econometric analyses of power output simulations using such turbine system resulted in affordable wind energy cost. These bear policy implications for sustainable wind energy usage in this and similar regions of the world.