No abstract

The menace of wastewater pollution in the 21st century is becoming alarming. Application of the low-cost adsorbents for wastewater treatment has received more attention this moment in environmental history than never. Most industrial wastewater has not been receiving adequate treatment prior to disposal into the nearby stream, and this is a potential threat to plants and animals feeding therefrom. There is therefore the need to proffer an effective solution to this pollution problem. An approach of bioremediation with a cost-effective plant waste is considered apt, with the application of Azadirachta indica (Neem tree) bark as adsorbent in this study. Galvanizing/wire-gauze industrial wastewater effluents were collected and subjected to Atomic Absorption Spectrophotometry (AAS) analysis to determine the concentrations of heavy metals. Phytochemical and Proximate analyses of the adsorbent were performed while adsorption study with the effects of adsorbent dosage, contact time, stirring speed and pH on the adsorption process during the wastewater treatment was carried out. The adsorption isotherms and kinetic models that best described the adsorption of Pb 4+ and Cr 3+ were established.

No abstract

There has been an increasing groundwater usage through the abstraction of water from shallow wells without any form of treatment. The effect of using water from a shallow and untreated well is prone to water-borne diseases. This study investigated the groundwater quality of some selected wells in Ogbomoso North Local Government Area (LGA) of Oyo State, Nigeria. One hundred samples were collected for analyses in dry and rainy seasons using Global Positioning System (GPS 72) tools. The sampling points were located based on the existing delineation of ten (10) wards in the LGA, and their nearness to sources of possible pollution such as sewage, waste dump sites, mechanics workshop, cassava processing units, and drainages. These samples were subjected to physical (pH, turbidity), chemical (hardness, chloride, sulphate, zinc, chromium), and bacteriological (coliform and E-coli) examinations by using American Public Health Association (APHA) Standard procedures. The results of the analyses were compared to Nigerian Industrial Standards (NIS) and World Health Organization (WHO) Standards. Statistical analysis was carried out using descriptive (tables and percentages) analyses and inferential Analysis of variance (ANOVA) while a water quality map was developed by interpolating data obtained on a Geographical Information System (GIS) Arc map version 10.0 packages. The results of pH, turbidity, hardness, chloride, sulphate, zinc and chromium values of the samples ranged from 5.8-7.3 mg/l, 5.4-7.3 mg/l; 0-8 NTU, 0-1 NTU; 5.2-25.4 mg/l, 4.05-27.23 mg/l; 2.2-13.2 mg, 0.49-6.41mg/l; 103 15-604.29 mg/l, 44 9-191.42 mg/l; 0.00- 0.23 mg/l, 0.0 4- 0.19 mg/l; 0.00-0.27 mg/l, 0.01-0.19 mg/l for dry and rainy season, respectively. E-coli and T-coli values of the samples ranged from 16-64 mg/l; 20-52 mg/l and 20-64 mg/l; 12-68 mg/l for dry and rainy seasons, respectively. The mean effect of the tested parameters in the ten (10) wards is significantly (p<0.05) different for rainy and dry season. The developed water quality map indicated the strength of contaminants present in water in Ogbomoso North LGA. Hence treatment will be required for the wells investigated before domestic use.

This study presents the experimental investigation on the effect of dimpled arrangements on flow and heat transfer characteristics. Three plate surfaces were prepared (smooth, evenly distributed spherical dimples and unevenly distributed spherical dimples) and were placed successively in a channel. The unevenly distributed dimpled plate had the same dimple density with the evenly distributed dimpled plate but had varying transverse pitches to concentrate the dimples at mid-plate in flow direction. Data obtained from the experiment were analysed to determine the performance of each dimpled plate channel. It was observed that the average Nusselt number due to the heat interaction with the air-flow increases with the Reynolds number. The evenly and unevenly dimple plate channels had respectively, 75.7% and 91.8% increase in Nusselt number over the smooth channel. The flow friction factors of the evenly and unevenly dimple plate channels were merely more than that of smooth plate channel by 0.59% and 0.67%, respectively. Thus, the unevenly dimple plate channel had the highest overall thermal-hydraulic performance, followed by the evenly dimple plate channel.