Effect of seasonal drawdown variations on groundwater quality in Nigeria

Water samples from twenty (20) shallow wells in Akure were analyzed during the wet and dry seasons in 2009 to ascertain the effect of drawdown on their qualities. Twenty (20) parameters consisting of five physical, twelve chemical and three heavy metals were tested for in the samples. The parameters included dissolved and suspended solids, turbidity, the pH, alkalinity, calcium, sulphate, nitrate, magnesium, electrical conductivity, lead, iron and manganese, were determined using standard procedures. Preliminary findings showed that 40% of the wells had poor drainage system and water levels expectedly varied significantly with seasonal change. However, most of the analysis showed significantly negative and weak correlations for the observed parameters during the two seasons of study. The revealed water quality was independent on drawdown but dependent on other parameters such as hygiene, pollution due to usage, underlying rock formation materials and proximity to polluting sources peculiar to emerging African cities.Keywords: Shallow well, pollution, water level, seasonal change, parametersAfrican Journal of Biotechnology Vol. 12(30), pp. 4777-478

Phytoremediation of domestic wastewaters in free water surface constructed wetlands using Azolla pinnata

Two constructed wetlands, one with Azolla pinnata plant (CW1) and the other without (CW2) for treating domestic wastewaters were developed. Fifteen water parameters which include: Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), Total Phosphorus (TP), Total Nitrogen (TN), Ammoniacal Nitrogen (NH3N), Turbidity, pH, Electrical Conductivity (EC), Iron (Fe), Magnesium (Mg), Manganese (Mn), and heavy metals such as Lead (Pb) and Zinc (Zn) were analyzed using standard laboratory procedures. The experiments were conducted in two (dry and wet) seasons simultaneously. Results showed considerable reductions in all parameters and metals including Zn in CW1 compared with CW2 in the two seasons considered while Pb and Mn were not detected throughout the study. Zn concentration levels reduced significantly in both seasons just as removal efficiencies of 70.03% and 64.51% were recorded for CW1 while 35.17% and 33.45% were recorded for CW2 in both seasons. There were no significant differences in the removal efficiencies of Fe in both seasons as 99.55%, 59.09%, 88.89%, and 53.56% were recorded in CW1 and CW2 respectively. Azolla pinnata has proved effective in domestic wastewater phytoremediation studies

Comparison of heavy metal and nutrients removal in Canna indica and Oryza sativa L. based constructed wetlands for piggery effluent treatment in north-central Nigeria

Batch-fed horizontal sub-surface flow constructed wetlands (HssFCW) were developed to compare the potential of Canna indica and Oryza sativa L. in removing heavy metals and nutrients from piggery effluent. Piggery effluent samples were characterized for nutrients (N and P) and metals (Mg, Al, Ca and Fe) before and after introducing them to the HssFCW with hydraulic retention time (HRT) of 3 days and operational flowrate of 0.014 m3 /day. Three sets of constructed wetlands (CWs) were monitored during the dry season for 3 months. The bioconcentration factor (BCF) and translocation factor (TF) for the plants were evaluated. The results were all significantly different at p � 0.05. O. sativa L removes more nutrients and metals than C. indica. The BCF for O. sativa L. was higher than for C. indica, while the TF for C. indica was higher for O. sativa L., indicating a higher metal translocation potential. Use of C. indica, a non-food crop, poses no health risks in HssFCWs whereas the grains of O. sativa L. are consumed directly by humans, presenting potential risks when used in HssFCWs. Compared to an annual O. sativa L., the perennial C. indica can be grown continuously in CWs for the phytoremediation of piggery effluent