Abstract.Excess phosphorus in water body will lead to eutrophication. This study investigated the phosphate removal efficiencies of unaerated and aerated filter systems using high composition of Calcium (Ca) steel slag as the filter media at different pH values of the wastewater influents. Lab-scale filters were developed using 25 mg/L synthetic wastewater and weekly sampling was done to monitor the phosphate removal efficiencies together with the concentration of metals (Calcium (Ca) and Magnesium (Mg). The results show that both unaerated and aerated systems have excellent phosphate removal efficiency at all acidic, neutral and alkaline pH feed, though unaerated systems removed slightly better compared to aerated systems; 76-98% and 69-97% respectively. The dominant phosphate removal mechanism for aerated systems was adsorption, meanwhilefor unaerated systems; both adsorption and precipitation for acidic and neutral pH, whileprecipitation was more dominant at basic pH. The performance of unaerated systems are slightly better compared to aerated systems, however, aerated systems are recommended to be applied when simultaneous removal of nutrients (phosphorus and nitrogen) are concerned.
This study was conducted to isolate and identify bacteria associated with spent diesel oil contaminated site by collecting three replicates contaminated soil from the works department of Admiralty University of Nigeria, while the pristine soil was obtained from the biological garden. pH and temperature of all the samples were checked and the bacteria isolates were identified by morphological and biochemical techniques using the taxonomy scheme of Bergey's Manual of determinative bacteriology. The pH and temperature was highest (6.06 to 6.26) and (27 to 30 0 C) in the contaminated soil than the pristine soil (5.83) and (23 0 C). The mean microbial load count was highest (10.0x10 5 cfu/ml)in the diesel oil contaminated soils than the pristine uncontaminated soils (9.0x0x10 5 cfu/ml). However, there was no significant difference between the microbial loads in the soil samples. Eight bacteria species were obtained from the contaminated soil while six were obtained from the pristine soil. Klebsiella spp., Enterobacterae riginosa, Pseudomonas sp. and Escherichia coli showed highest growth in the contaminated soil and therefore may be considered as effective in the degradation of spent diesel oil hydrocarbons. It is likely that these bacteria when employed independently may be used to degrade hydrocarbons. Further research is necessary to assay for the degradative ability of the microorganisms.
Previous researches have shown the presence of heavy metals (HMs) such as lead (Pb) at different levels in Olusosun dumpsite, Lagos. This study aimed at finding out if the anatomical differences found in Luffa cyclindrical and Amaranthus viridis grown on the dumpsite is an indication of the HMs and also determine the distribution of HMs on the dumpsite. The results showed the HMs detected in the dumpsite soil at three spots were significantly higher than the control (p=0.5). The concentrations of HMs were in sequence for soils A: Pb>Zn=Cr>Fe>Cu>Ni. Spot B: Fe>Cr>Pb>Zn>Cu>Ni, spot C: Fe>Pb>Cr>Zn>Cu>Ni and Control: Pb>Fe>Zn>Cu>Ni. All the HMs detected at the three spots and control were below the World Health Organization (WHO) and Dutch pollutant standard level, except for (Zn) which was at the exact limit (50.000Mg/kg). The plants obtained from both the dumpsite and control sites didn't show marked visible morphological changes. However, anatomical changes in the leaves epidermis such as irregular shape of the epidermis, absence of trichomes and decrease in quality and stomata size were all witnessed in the dumpsite plant as against the control. Hence, it is likely that all detected differences in the epidermal structures of the test plant grown on dumpsite soil were caused by the high level of HMs present in the dumpsites and therefore suggested that, changes in epidermal structures of L. cyclindrical and A. viridis grown on Olusosun dumpsite soils is an indication of HMs such as Zn and Pb present.
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