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Assessment of water quality of the Ogu Creek impacted by seaport activities in Onne, near Port Harcourt, Rivers State
Get PDFThis thesis is for the award of Master of Technology Degree (M.TECH) in Environmental TechnologyThe physicochemical parameters of the Ogu Creek serving the Onne Port of the Nigerian Ports Authority in Port Harcourt, which is impacted by Port transport activities were investigated in September 2011 at 6 sampling points. In situ measurements were made for water temperature, pH, salinity, dissolved oxygen (DO), turbidity, and conductivity using HORIBA U-10 Water Quality Checker and for total dissolved solids (TDS) with HACH conductivity/TDS meter. Other parameters were determined using standard methods of APHA. Water samples were collected in replicates with 2 litres plastic containers and transferred to the laboratory in iced-coolers for analysis. The test of homogeneity in mean variance was used to determine spatial variation in the physicochemical variables, and the Pearson correlation coefficient (r) used to explore the interrelationship existing between the parameters. Mean parameters were observed as follows: temperature 28.25 ± 0.12 °C, pH 6.02 ± 0.20, salinity 36.32 ± 0.12 ‰, DO 3.38 ± 0.14 mg/L, BOD 1.74 ± 0.21 mg/L, TSS 25.05 ± 2.45 mg/L, TDS 53.60 ± 5.75 mg/L, turbidity 81.23 ± 5.22 NTU, alkalinity 17.92 ± 1.61 mg/L, conductivity 1815.00 ± 238.24 µS/cm, total petroleum hydrocarbons 2.10 ± 0.15 mg/L, NO3-3.62 ± 0.36 mg/L, PO42-2.59 ± 0.38 mg/L, SO4 2-78.07 ±8.70 mg/L, Cl95.55 ± 16.66 mg/L, Al 0.95 ± 0.08 mg/L, Cd 0.022 ± 0.011 mg/L, Cr 0.05 ± 0.01mg/L, Cu 0.08 ± 0.01 mg/L, Fe 2.67 ± 0.38 mg/L and Pb 0.030 ± 0.009 mg/L. The lower ranges of pH, the upper ranges of Al and Fe, and Cd and Cu levels were outside permissible limits of the Federal Ministry of Environment for aquatic life. The control sampling location recorded highest concentrations in several of the variables, even as there was marked spatial heterogeneity [F(8.41)<Fcrit(3.88)] at P<0.05, with conductivity being most responsible for the observed difference. TDS correlated positively with NO3-(r=0.883) and PO4 2-(r=0.881), and conductivity with SO42-(r=0.825) at P<0.05, while TDS correlated with turbidity (r=0.923), and conductivity with NO3-ion (r=0.928) at P<0.01. However, pH correlated negatively with Cu ions (r=-0.946) at P<0.01. It is recommended that environmental regulatory agencies should enforce laws and standards in order to save the Port from further pollution
Comparative analysis of rice husk ash and saw dust ash on tensile strengths of concrete
Get PDFThis thesis is for the award of Master of Engineering (M.Eng) in Civil Engineering (Structure)This study focuses on the comparative analysis of rice husk ash (RHA) and saw dust ash (SDA) on tensile strengths of concrete. RHA and SDA were obtained from open burning. The physical properties and chemical composition of the ashes were investigated. Ordinary Portland cement (OPC) was replaced with RHA, SDA, and RHA-SDA at 5%, 10%, and 15%. Concrete mix design was done using SCALE149 (Structural Calculations Ensemble) Software. Nine concrete cylinders of dimension 150×300mm with 100% OPC or 0% replacement with pozzolan were produced. Eighty one concrete cylinders were also produced for each of the percentage replacement of OPC with RHA, SDA, RHA-SDA, making a total of 252 concrete cylinders. The concrete cylinders were cured by immersion and tested for split tensile strength at 28, 90, and 150 days. The results showed that RHA is a better pozzolana with combined (SiO2 + Al2O3 + Fe203) of 87.67% compared to SDA which was 50.03% . The Split tensile strength decreased with increasing RHA, SDA, and RHA-SDA OPC percentage replacement. Laboratory values of 0.86N/mm2 and 0.78N/mm2 were obtained at 5% and 10% RHA-OPC replacement, 0.77N/mm2 and 0.58N/mm2 were obtained at 5% and 10% SDA-OPC replacement. Similarly, 0.82N/mm2 and 0.64N/mm2 were obtained at 5% and 10% RHA-SDA-OPC replacement. Split tensile strength of concrete with RHA, SDA, and RHA-SDA were lower at early age of curing but improved at later ages of curing. For example, at 5% RHA-OPC replacement, 1.42N/mm2 and 1.85N/mm2 were obtained at 90 and 150 days of curing. At 5% SDA-OPC replacement, 1.28N/mm2 and 1.65N/mm2 were obtained at 90 and 150 days of curing. Similarly, at 5% RHA-SDA-OPC replacement, 1.35N/mm2 and 1.66N/mm2 were obtained at 90 and 150 days of curing, as against 1.34N/mm2 and1.61N/mm2 attained by the control at 90 and 150 days of curing. Models were developed to predict the tensile strengths of concrete containing RHA and SDA as binary and ternary blend with OPC at varying percentage replacements and curing ages. The models were tested and found to be adequate
